Respiratory system examination- Methods of investigation in pulmonology
75PULMONARY FUNCTION TESTS
Pulmonary function testing has progressed from simple spirometry to sophisti cated physiologic testing over the past decade. This chapter will attempt to survey the major clinically applicable tests available and then will attempt to identify their role in clinical management, including recommendations for ordering tests.
In the normal respiratory system, the volume and pattern of ventilation are initiated by neural output from the respiratory center in the medulla of the brain-stem. This output is influenced by afferent information from several sources, in cluding higher centers in the brain, carotid chemoreceptors (PaO2), central chemoreceptors (Paco2 [H+]), and neural impulses from moving tendons and joints. Nerve impulses travel via the spinal cord and peripheral nerves to the intercostal and diaphragmatic muscles where appropriate synchronous contrac tion generates negative intrapleural pressure. If the resulting inspiration is trans mitted through structurally sound, unobstructed airways to patent, adequately perfused alveoli, then O2 and CO2 are respectively added to and removed from mixed venous blood. This feedback mechanism of control of breathing is nor mally very sensitive, so that alveolar ventilation is kept proportional to the meta bolic rate and the arterial blood gas tensions are maintained within a very narrow range.
Malfunction of the respiratory system at any point in this pathway can result in deviation from this normal range, and consequent respiratory insufficiency. A disturbance at a given point can often be specifically measured if available tests and known patterns of pathophysiologic disturbances are understood. This chap ter discusses tests of pulmonary function.
Static Lung Volumes
The vital capacity (VC or "slow VC") is the maximum volume of air that can be expired slowly and completely after a full inspiratory effort. This simply per formed test is still one of the most valuable measurements of pulmonary function. It characteristically decreases progressively as restrictive lung disease increases in severity, and, along with the diffusing capacity, can be used to follow the course of a restrictive lung process and its response to therapy.
The forced vital capacity (FVC) is a similar maneuver utilizing a maximal forceful expiration. This is usually performed in concert with determination of expiratory flow-rates in simple spirometry (see Dynamic Lung Volumes and Flow Rates, below).
The (slow) VC can be considerably greater than the FVC in patients with air ways obstruction. During the forceful expiratory maneuver, terminal airways can close prematurely (i.e., before the true residual volume is reached), and the distal gas is "trapped" and not measured by the spirometer.
Functional residual capacity (FRC) is physiologically the most important lung volumebecauseit incorporates the normal tidal breathing range. It is defined as the volume of air in the lungs at the end of a normal expiration when all the respiratory muscles are relaxed. It is determined by the balance between the elas tic forces (stiffness) of the chest wall, which tend to increase lung volume, and the elastic forces of the lungs, which tend to reduce it. These forces are normally equal and opposite at about 40% of total lung capacity (TLC). Changes in the elastic properties of the lungs or of the chest wall result in changes in the FRC. The loss of elastic recoil of the lung seen in emphysema results in an increase in the FRC. Conversely, the increased lung stiffness of pulmonary edema, interstitial fibrosis, and other restrictive lung processes results in a decreased FRC. Kyphoscoliosis leads to a decrease in FRC and in the other lung volumes because the stiff, noncompliant chest wall restricts ventilation.
PULMONARY FUNCTION ABBREVIATIONS
CC- Closing capacity
Cdyn- Dynamic Lung compliance
CSTART- Static Lung COmpliance
Cv- Closing Volume (L)
DIco- Diffuse capacity for Carbon monoxide (ml/min/mmHg)
ERV- Expiratory reserve volume
FEV1- Forced expiratory volume in 1sec (L)
FEV3- Forced expiratory volume in 3s (L)
FVC- forced vital capacity
FRC- Functional residual capacity
[H+]- Concentration of hydrogen ions (monomoles/L)
IRV- Inspiratory reserve volume
MEF50% vc- Mid-expiratory flow at 50% vital capacity (L/sec)
MEF50% vc- Mid-inspiratory flow at 50% vital capacity (L/sec)
MMEF- Mean maximal expiratory flow (L/sec)
MVV- maximal voluntary ventilation
PaCO2- Arterail partial pressure of CO2 (mmHg)
PaO2- Arterial partial pressure of O2 (mmHg)
PEF- peak expiratory flow (L/sec)
PTP- Transpulmonary pressure (mmHg)
Q- Perfusion (L/min)
RAW- Airway resistance
RV- Residual volume
TLC- Total Lung capacity
V- Lung Volume (L)
VC- Vital capacity
V- Ventilation
VA- ALveolar ventilation (L/min)
Vco2- CO2 production (L/min)
VO2- O2 consumption (L/min)
The FRC has 2 components, the residual volume (RV), the volume of air remain ing in the lungs at the end of a maximal expiration, and the expiratory reserve volume (FRC = RV + ERV).
The RV normally accounts for about 25% of the TLC. It changes with the FRC with 2 exceptions. In restrictive lung diseases, RV tends to remain nearer to nor mal than other lung volumes (shown in FIG. Ib). In small airways diseases, presumably because premature closure of the airways leads to air trapping, the RV may be elevated while the FRC and FEV1 remain normal.
TLC equals the VC + the RV. In obstructive airways disease, RV increases more than does TLC, resulting in some decrease in VC, particularly in severe disease.
In obesity the ERV is characteristically diminished because of a markedly de creased FRC and a relatively well-preserved RV.
DYNAMIC LUNG VOLUMES AND FLOW RATES
Dynamic lung volumes reflect the nonelastic properties of the lungs, primarily the status of the airways. The spirogram (see Fig. la) records lung volume against time on a water or electronic spirometer during an FVC maneuver. The FEV1 is the volume of air forcefully expired during the first second after a full breath and normally comprises > 75% of the VC. The mean maximal expiratory flow over the middle half of the FVC (MMEF25-75%) is the slope of the line that intersects the spirographic tracing at 25% and 75% of the VC. The MMEF is less effort-dependent than is the FEV1and is a more sensitive indicator of early air ways obstruction.
Airway caliber (and therefore flow) is directly related to lung volume, being greatest at TLC, and decreasing progressively to RV. During a forced expiratory maneuver, the airways become further narrowed because of positive intrathoracic pressure. This "dynamic compression of the airways" limits maximum expiratory flow rates. The opposite effect is seen during an inspiratory maneuver, when nega tive intrathoracic pressure tends to maintain the caliber of the airways. The differ ences in airway diameter during inspiration and expiration thus result in greater flow rates during inspiration than expiration during much of the breathing cycle . In chronic obstructive pulmonary disease(COPD) and asthma, prolongation of expiratory flow rates is further exaggerated because of airway narrowing (asthma), loss of structural integrity of the airways (bronchitis), and loss of lung elastic recoil (emphysema). In fixed obstruction of the trachea or larynx, flow is limited by the diameter of the stenotic segment rather than by dynamic compression, resulting in equal reduction of inspiratory and expiratory flows.
In restrictive lung disorders, the increased tissue elasticity tends to maintain airway diameter during expiration so that, at comparable lung volumes, flow rates are often greater than normal. (Tests of small airways function, however, may be abnormal—see below.)
Retesting of pulmonary function after inhalation of a bronchodilator aerosol (e.g., isoproterenol) provides information about the reversibility of an obstructive process (i.e., asthmatic component). Improvement in VC and/or FEV1(L) of > 10% is usually considered a significant response to a bronchodilator.
The maximal voluntary ventilation (MW) is determined by encouraging the pa tient to breathe at maximal tidal volume and respiratory rate for 12 seconds; the amount of air expired is expressed in L/min. The MW generally parallels the FEV1 and can be used as a test of internal consistency and as an estimate of patient cooperation (MW = FEV1[L] X 40). The MW decreases with respira tory muscle weakness and may be the only demonstrable pulmonary function abnormality in moderately severe neuromuscular disease. The MW is considered an important preoperative test as it reflects the severity of airways obstruction as well as being an index of the patient's respiratory reserves, muscle strength, and motivation.
Flow-Volume Loop. The disadvantage of the simple measurements discussed above is that they fragment the complex dynamic interrelationships of flow, volume, and pressure into simple dimensions for arbitrary measurement. The continuous analysis of these parameters during forced respiratory maneuvers is more physiologic and can be more revealing. An analogy in cardiology is the additional information obtained by vectorcardiography above that provided by the conventional ECG. For the flow-volume loop the patient breathes into an electronic spirometer and performs a forced inspiratory and expiratory VC maneuver while flow and volume are displayed continuously on an oscilloscope. The shape of the loop reflects the status of the lung volumes and of the airways throughout the respiratory cycle and can be diagnostic. Characteristic changes are seen in restrictive and in obstructive disorders. The loop is especially helpful in the assessment of laryngeal and tracheal lesions. It can distinguish between fixed (e.g., tracheal stenosis) and variable (e.g., tracheomalada, vocal cord paralysis) obstruction. Fio. 30-2 illustrates some characteristic flow-volume loop abnormalities.
Lung Mechanics
Airway resistance (RAW) can, with the help of a body plethysmograph, be directly measured in the laboratory by determining the pressure required to produce a given flow. More commonly, however, it is inferred from dynamic lung volumes and expiratory flow rates more easily obtainable in the clinical laboratory.
Static lung compliance (CSTAT) is defined as volume-change/unit of pressure-change and reflects lung elasticity or stiffness. This requires the use of an esophageal balloon and is seldom utilized in the clinical laboratory. Lung compliance is inferred by the resultant changes in static lung volumes (see Fig. 3).
Maximal inspiratory and expiratory pressures reflect the strength of the respira tory muscles. These are measured by having the patient forcibly inspire and ex pire through a closed mouthpiece attached to a pressure gauge. Maximal pressures are reduced in neuromuscular disorders (e.g., myasthenia gravis, muscu lar dystrophy, Guillain-Barre syndrome).
Diffusing Capacity (DLco) DLco is defined as the number of ml of CO absorbed/min/mm Hg. It is deter mined by having the patient inspire maximally a gas containing a known small concentration of CO, hold his breath for 10 seconds, then slowly expire to RV. An aliquot of alveolar (i.e., end-expired) gas is analyzed for CO and the amount absorbed during that breath is then calculated. It is generally agreed that an abnormally low DLco is not due to physical thickening of the alveolar-capillary membrane alone, but probably reflects abnor mal ventilation/perfusion (V/Q) in diseased lungs. DLco is low in processes that destroy alveolar-capillary membranes; these include emphysema and interstitial inflammatory fibrotic processes. The DLco also tends to be diminished in severe anemia (less Hb available to bind the inhaled CO) and will be artifactually low ered if the patient's Hb already is occupied by CO (e.g., smoking within several hours prior to the test). The DLco increases with increases in pulmonary blood flow as occurs during exercise and also in mild (interstitial) congestive heart fail ure (increase in blood flow to the usually poorly perfused lung apices).
Distribution of Ventilation
The distribution of ventilation is studied by continuously recording the concen tration of expired N2 at the mouth following a single maximal inspiration of 100% 02. If the distribution of ventilation is normal (i.e., the majority of alveoli fill and empty synchronously), there should be a < 2% increase in N concentration be tween 750 and 1250 ml of expired breath (see FIG. 4). A > 2% change implies asynchronous emptying of alveoli, which most commonly is due to airways obstruction. A more direct though more complex study involves lung scanning after the inhalation of radioactive xenon gas.
Peripheral "Small" Airways Studies
RAW and FEV measurements reflect primarily the condition of the large air ways. In the normal lung, bronchi < 2 mm in diameter contribute < 10% of the total airways resistance, yet their aggregate surface area is large. Disease affecting primarily the smaller airways can be very extensive and yet not affect the RAW or any tests dependent on this such as the FEV1. This is true of early obstructive lung disease and probably also of interstitial granulomatous, fibrotic, or inflammatory disorders. The status of the small airways is reflected by the MMEF and by expiratory flows in the last 25 to 50% of the FVC, best determined from the flow-volume loop (see FIG. 2a). More complex and sophisticated tests of small airways function have been devised. These include frequency-dependent changes in lung compliance (dynamic compliance), closing volume, and closing capacity. The latter can be determined by a modification of the N washout technic (see Distribution of Ventilation, above, and FIG. 3), but in general, measurement of these more complex tests adds little to those more readily available (see above) and has little place in the clinical laboratory.
Control of Breathing
Recent emphasis on the clinical importance of obstructive sleep apnea and central hypoventilation (pickwickian syndrome) has brought the study of the con trol of breathing to the clinical physiology laboratory.
Hypoxic drive (function of the carotid chemoreceptors) can be studied by plot ting the ventilatory response to progressive decrements in inspired O2.
CO2 sensitivity (function of the central, medullary chemoreceptors) is reflected by the ventilatory response to progressive increments in inspired CO2.
Central and obstructive sleep apnea can be distinguished by monitoring respi ration during sleep. An ear oximeter monitors Ch saturation. ACO2 electrode placed in a nostril monitors Pco2 and also serves as an indicator of air flow. Chest wall motion is monitored by a strain gauge or by impedance electrodes. In ob structive sleep apnea, air flow at the nose ceases despite continued excursion of the chest wall, 02 saturation drops, and Pco2 increases. In central apnea, chest wall motion and air flow cease simultaneously.
How to Order and Interpret Pulmonary Function Tests
A "complete" set of pulmonary function tests in a good clinical laboratory includes determination of all lung volumes (VC, FRC, RV, TLC), spirometry (FVC, FEV1, MMEF), diffusing capacity, flow-volume loop, MW, and of maxi mum inspiratory and expiratory pressures. This extensive testing is tiring, time-consuming, expensive, and often not necessary for adequate clinical assessment.
Any physician who evaluates patients with pulmonary disorders should have access to simple spirometry in the office. Simple spirometry is the backbone of pulmonary function evaluation and usually provides sufficient information. A number of inexpensive electronic spirometers are now available capable of mea suring VC, FEV1, and PEF. The procedure is readily taught to both patient and operator and yields permanent, reproducible, and accurate data. While spirom etry alone may not permit specific diagnosis, it can differentiate between obstruc tive and restrictive disorders and permits estimation of the severity of the process.
With a few simple guidelines, a great deal of useful information can be gathered from the simple spirogram. A low VC in association with normal flow rates ordi narily suggests restrictive disease (see Fig. Ib). COPD and asthma have the characteristic exponentially decreasing flows seen in FIG. 30-Ic. In the patient with predominant emphysema, the airways can be intrinsically normal, and ex piratory flow is limited by dynamic compression of the airways because of the loss of elastic supporting tissues. A finite amount of time is necessary for the airways (wide open at TLC) to snap shut after the onset of the FVC maneuver. Thus a transient of rapid flow is often reflected by a notch at the beginning of the tracing. The spirogram in Fig.Ic shows such an "emphysematous notch", and suggests that there has been substantial loss of lung elastic recoil; i.e., there is a significant component of emphysema present. In very severe COPD, expiratory flow can be so prolonged as to appear almost linear on visual analysis of the spirographic tracing. Since lung volume is a major determinant of airway caliber, the slope of the spirogram should continuously decrease from TLC to RV. A truly linear decrease in flow from TLC to RV is pathognomonic of fixed obstruction of the larynx or trachea (e.g., tracheal stenosis or tumor). The limitation to maximal flow here is no longer dynamic compression of airways but a fixed area of narrow ing in the large airway.
The spirogram can occasionally be misleading in asthma because it may mimic restrictive disease if there is severe obstruction predominating in the smaller air ways. Total occlusion of the airways precludes any air flow and much gas is trapped distally, thus underestimating the VC. The larger airways are patent, so the overall RAW is not much increased and the FEV1 is normal.
CHARACTERISTIC CHANGES IN PULMONARY FUNCTION IN RESTRICTIVE AND OBSTRUCTIVE DISEASE OF VARYING SEVERITY
Restrictive diseases
VC (% predicted): None (>80), mild (60-80), moderate (50-60), severe (35-50), very severe (<35)
FEV, (%VC): None (>75), mild (>75), moderate (>75), severe (>75), very severe (>75)
MW (% predicted): None (>80), mild (>80), moderate (>80), severe (60-80), very severe (<60)
RV (% predicted): None (80-120), mild (80-120), moderate (70-80), severe (60-70), very severe (<60)
Dlco: None (Normal), mild (reduced at exercise), moderate (reduced at rest), severe (reduced ¯), very severe (badly reduced ¯¯)
Dyspnea (severity): None (0), mild (+), moderate (++), severe (+++), very severe (++++)
Obstructive Diseases
VC (% predicted): None (>80), Mild (>80), Moderate (>80), severe (Low), very severe (Low)
FEV1 (%VC): None (>75), Mild (60-75), Moderate (40-60), Severe (<40), very severe (<40)
MW (% predicted): None (>80), Mild (65-80), Moderate (45-65), severe (30-45), very severe (<30)
RV (% predicted): None (80-120), Mild (120-150), Moderate (150-175), severe (>200), very severe (>200)
Dlco: None (Normal), Mild (Normal), Moderate (Normal), severe (Low -), very severe (Low --)
Dyspnea (severity): None (0), Mild (+), Moderate (++), severe (+++), very severe (++++)
The severity of COPD and the potential for response to bronchodilator can be adequately assessed by simple spirometry (± flow-volume loop) before and after inhalation of bronchodilator. Simple spirometry with determination of the FVC, FEV1, and MW usually suffices as a general preoperative screen and should be performed in all smokers > 40 and in all patients with respiratory symptoms prior to chest or abdominal surgery. The response to treatment during an exacerbation of asthma can and should be monitored by portable (bedside) spirometry or by serial measurement of peak expiratory flow rates.
Patients with suspected laryngeal or tracheal pathology are adequately and specifically studied by a flow-volume loop
If weakness of the respiratory muscles is suspected, the MW, maximal inspiratory and expiratory pressures, and VC are the appropriate tests.
Full tests should be requested when the clinical picture (history, physical ex amination, chest x-ray) does not coincide with the data obtained by simple spirometry, or when more complete characterization of an abnormal pulmonary process is desired. They are indicated prior to thoracotomy or extensive abdomi nal surgery (particularly in the patient with known or suspected pulmonary impairment) and to document the severity of interstitial pulmonary disorders. PeriodicVCs and Dlco2usually suffice to follow the course of a restrictive pro cess.
The following tables are intended as general guides to the interpretation of pulmonary function tests. TABLE 2 illustrates several simple patterns of pul monary function abnormality. These are not necessarily mutually exclusive; a patient may have a combination of disorders (e.g., restrictive and obstructive disease), which complicates the interpretation. TABLE 3 details the expected changes in pulmonary function in restrictive and obstructive disorders of varying severity.
Peakfluorymetry– method of estimation of peak expiratory flow (PEF, L/sec) by portable device usually used by patients to estimate the changes of bronchial obstruction.
CHEST RADIOGRAPHY
Chest radiography is often the initial diagnostic study performed to evaluate patients with respiratory symptoms but it can also provide the initial evidence of disease in patients who are free of symptoms Perhaps the most common example of the latter situation is the finding of one or more nodules or masses when the radiograph is performed for a reason other than evaluation of respiratory symptoms
A number of diagnostic possibilities are often suggested by the radiographic pattern. A localized region of opacification involving the pulmonary parenchyma can be described as a nodule (usually <6 cm in diameter) a mass (usually >= 6 cm in diameter) or an infiltrate Diffuse disease with increased opacihcation is usually characterized as having an alveolar an interstitial or a nodular pattern In contrast increased radiolucency can be localized as seen with a cyst or build or generalized as occurs with emphysema The chest radiograph is also particularly useful for the detection of pleural disease especially if manifested by the presence of air or liquid in the pleural space An abnormal appearance of the hilus and/or the mediastinum can suggest a mass or enlargement of lymph nodes
A summary of representative diagnoses suggested by these common radiographic patterns is presented in Table
Additional Diagnostic Evaluation Further information for clarification of radiographic abnormalities is frequently obtained with computed tomographic scanning of the chest. This technique is more sensitive than plain radiography in detecting subtle abnormalities and can suggest specific diagnoses based on the pattern of abnormality Alteration in the function of the lungs as a result of respiratory system disease is assessed objectively by pulmonary function tests and effects on gas exchange are evaluated by measurement of arterial blood gases or by oximetry. As part of pulmonary function testing quantitation of forced expiratory flow assesses the presence of obstructive physiology which is consistent with diseases affecting the structure or function of the airways such as asthma and chronic obstructive lung disease Measurement of lung volumes assesses the presence of restrictive disorders seen with diseases of the pulmonary parenchyma or respiratory pump and with space occupying processes within the pleura.
Major Respiratory Diagnoses with Common Chist Radiography Patterns
Solitary circumscribed density nodule (<6 cm) or mass (>= 6 cm)
Primary or metastatic neoplasm
Localized infection (bacterial abscess mycobacterial or fungal infection)
Wegener’ s granulomatosis (one or several nodules)
Rheumatoid nodule (one or several nodules)
Vascular malformation
Bronchogenic cyst
Localized opacification (infiltrate)
Pneumonia (bacterial, atypical, mycobacterial or fungal infection)
Neoplasm
Radiation pneumonitis
Bronchiolitis obliterans with organizing pneumonia
Bronchocentric granulomatosis
Pulmonary infarction
Diffuse interstitial disease
Idiopathic pulmonary fibrosis
Pulmonary fibrosis with systemic rheumatic disease
Sarcoidosis
Drug induced lung disease
Pneumoconiosis
Hypersensitivity pneumonitis Infection (Pneumocystis, viral pneumonia)
Eosinophilic granuloma
Diffuse alveolar disease
Cardiogenic pulmonary edema
Acute respiratory distress syndrome
Diffuse alveolar hemorrhage
Infection (Pneumocyitis viral or bacterial pneumonia)
Sarcoidosis
Diffuse nodular disease.
Metastatic neoplasm
Hematogenous spread of infection (bacterial mycobacterial fungal)
Pneumoconiosis
Eosinophilic granuloma
Sputum Examination
Examination of the sputum remains the mainstay of the evaluation of a patient with lung inflammation. Unfortunately expectorated material is frequently contaminated by potentially pathogenic bacteria that colonize the upper respiratory tract (and sometimes the lower respiratory tract) without actually causing disease This contamination reduces the diagnostic specificity of any lower respiratory tract specimen In addition it has been estimated that the usual laboratory processing methods detect the pulmonary pathogen in fewer than 50% of expectorated sputum samples from patients with bacteremic Spneumomae pneumonia This low sensitivity may be due to misidentification of the a hemolytic colonies of S pneumonie as nonpathogenic a hemolytic streptococci ( normal flora ) overgrowth of the cultures by hardier colonizing organisms or loss of more fastidious organisms due to slow transport or improper process ing In addition certain common pulmonary pathogens such as an aerobes mycoplasmas chlamydiae Pneumocystis mycobacteria fungi and legionellae cannot be cultured by routine methods.
Since expectorated material is routinely contaminated by oral an aerobes the diagnosis of anaerobic pulmonary infection is frequently inferred Confirmation of such a diagnosis requires the culture of an aerobes from pulmonary secretions that are uncontammated by oropharyngeal secretions which in turn requires the collection of pulmonary secretions by special techniques such as transtracheal aspiration (TTA) transthoracic lung puncture and protected brush via bronchoscopy These procedures are invasive and are usually not used unless the patient fails to respond to empirical therapy
Gram s staining of sputum specimens screened initially under low power magnification (10X objective and 10X eyepiece) to deter mine the degree of contamination with squamous epithelial cells is of utmost diagnostic importance In patients with the typical pneumonia syndrome who produce purulent sputum the sensitivity and specificity of Gram s staining of sputum minimally contaminated by upper respiratory tract secretions (>25 polymorphonuclear leukocytes and < 10 epithelial cells per low power field) m identifying the pathogen as S pneumomae are 62 and 85% respectively Gram s staining in this case is more specific and probably more sensitive than the accompanying sputum culture The finding of mixed flora on Gram s staining of an uncontammated sputum specimen suggests an anaerobic infection Acid fast staining of sputum should be undertaken when mycobacterial infection is suspected Examination by an experienced pathologist of Glemsa stained expectorated respiratory secretions from patients with AIDS has given satisfactory results in the diagnosis of PCP The sensitivity of sputum examination is enhanced by the use of monoclonal antibodies to Pneumocystis and is diminished by prior prophylactic use of inhaled pentamidine. Blastomycosis can be diagnosed by the examination of wet preparations of sputum. Sputum stained directly with fluorescent antibody can be examined forLegionella but this test yields false negative results relatively often Thus sputum should also be cultured for Legionella on special media
Expectorated sputum usually is easily collected from patients with a vigorous cough but may be scant in patients with an atypical syndrome in the elderly and in persons with altered mental status If the patient is not producing sputum and can cooperate respiratory secretions should be induced with ultrasonic nebulization of 3% saline. An attempt to obtain lower respiratory secretions by passage of a catheter through the nose or mouth rarely achieves the desired results m an alert patient and is discouraged usually the catheter can be found coiled in the oropharynx.
In some cases that do not require the patient s hospitalization an accurate microbial diagnosis may not be crucial and empirical therapy can be started on the basis of clinical and epidemiologic evidence alone This approach may also be appropriate for hospitalized patients who are not severely ill and who are unable to produce an induced sputum specimen Use of invasive procedures to establish a microbial diagnosis carries risks that must be weighed against potential benefits However the decision to initiate empirical therapy without an evaluation of induced sputum should be undertaken with caution and in the case of hospitalized patients should always be accompanied by the culture of several blood samples The ability to understand the cause of a poor response to empirical antimicrobial therapy may be compromised by the lack of initial sputum and blood cultures Establishing a specific microbial etiology in the individual patient is important for it allows institution of specific pathogen directed antimicrobial therapy and reduces the use of broad spectrum combination regimens to cover multiple possible pathogens Use of a single narrow spectrum antimicrobial agent exposes the patient to fewer potential adverse drug reactions and reduces the pressure for selection of antimicrobial resistance Emergence of antimicrobial resistance is a type of adverse drug re action unlike others because it is contagious. In addition establishing a microbial diagnosis can help define local community outbreaks and antimicrobial resistance patterns.
In case of allergic process many eossinophils are found microscopically, frequently arranged in sheets. Eosinophilic granules from disrupted cells may be seen throughout the sputum smear. Elongated dipyramidal crystals (Charcot-Leyden) originaiting from from eosinophils are commonly found.
In case of lung cancer is possible to evaluate the atypical cells.
PLEURAL PUNCTION
Pleural punction normally is done under the local anesthesia. For this purposes 0,5 – 1,0 % solution of Novocain infiltration of chest tissues is used. First of all anesthesia of skin is done (so called “lemon cover”). After that, changing the needle on “muscular” one is done the anesthesia of muscles. Pleural punction is performed by third needle connected with syringe by rubber or silicone tube. After the punction of pleural cavity the content of it is aspirated. When the syringe is full for prevention of ear income to pleura the transmitter (rubber or silicone tube) is closed by assistant. The syringe is disconnected. It content transmitted to sterile tube for histological and bacteriological analysis.
After the effusion aspiration from pleural cavity it is necessary to infuse the antimicrobal remedies for prevention of infection complications. After the finish of manipulation the needle is removed and the skin is sterilized by alcohol. After the estimating of effusion amount it transmitted to laboratory study.
CLOSED TUBE THORACOTOMY
(Tube Drainage)
Indications: Pneumothorax, spontaneous and traumatic, is the condition most commonly treated with tube drainage. Massive and recurrent pleural effusions unmanageable by needle aspiration also require this treatment; the etiology may be infection, malignancy, chylothorax, etc. Other indications are empyema, hemo thorax, and hemopneumothorax.
Contraindications: Adhesions which may prevent introduction of the tube, clot ted hemothorax, and/or empyema with pachypleuritis preclude successful tube drainage and require a thoracotomy.
Procedure: The location is chosen for introduction of the tube. For pneumothorax, the anterior chest wall, 2nd or 3rd intercostal space, midclavicular line is used. For pleural effusion, hemothorax, empyema, etc., the axillary line is pre ferred in the 5th mid or posterior intercostal space. The skin and the intercostal space are infiltrated with 2% procaine or similar agent, a small incision is made, the intercostal muscles are separated, and the tube is introduced through a trocar or directly with the aid of a clamp. The tube is sutured to the skin and connected to an underwater drainage system. Sometimes drainage is promoted by the use of a pump that can generate up to 20 cm H2O negative pressure.
Complications: Bleeding from an intercostal vessel injured by the trocar, subcu taneous emphysema if the side holes of the drainage tube are not properly placed inside the pleural space, infection of the local skin site, and pain are common.
THORACOSCOPY
Indication: To obtain a biopsy from a peripheral lesion of the lung or pleura under direct vision through a mediastinoscope or similar instrument.
Contraindications: Adhesions, central location of the lesions to be biopsied, bleeding tendency, or air leak.
Procedure: Under general anesthesia, the location is chosen in the anterior or lateral chest wall according to the location of the lesion. A small incision is made in the skin and the intercostal muscles. A mediastinoscope or a bronchoscope is introduced to explore the pleura and the lung. A biopsy is taken through the instrument with a forceps. The lung is then reinflated. Usually, a tube for drainage is left after the procedure.
Complications: Most are due to bleeding or air leak from the location of the biopsy. Infection of the pleural space in the course of the procedure is uncommon except when infected lesions are biopsied.
good views of bronchoscopy
FIBERBRONCHOSCOPY
Direct visual examination of the tracheobronchial tree using a flexible tube (flexi ble bronchoscope; fiberbronchoscope) containing light-transmitting glass fibers that return a magnified image (picture). Fiberbronchoscopes range in external diameter from 3 to 6 mm; the proper diameter depends on the size of the patient. The small caliber of the instrument makes it possible to enter segmental bronchi and to visualize subsegmental bronchi. The central channel of the scope is 2 to 2.5 mm in diameter and is used to aspirate secretions, to give anesthetic agents, to obtain brush or forceps biopsies, and to introduce bronchographic contrast material. It is also possible to obtain uncontaminated cultures through the channel. Lavage fluid, such as saline, acetylcysteine, and heparin can be introduced through the channel. Cuffing of the scope makes it possible to lavage a lobe via its lobar bronchus.
Diagnostic indications: It is used to explore the cause of an unexplained persis tent cough, wheeze, or hemoptysis, or unresolved pneumonia or atelectasis, espe cially in a male smoker above age 30. The flexible bronchoscope is used for small hemoptysis, i.e., blood-tinged sputum or small quantities of blood; for large he moptysis, rigid bronchoscopy is used. Fiberoptic bronchoscopy is also used to perform transbronchial lung biopsy and/or bronchial lavage in diffuse lung dis ease of obscure etiology, to investigate paralysis of the recurrent laryngeal or phrenic nerves, to search for the origin of positive cytology obtained from sputum or endobronchial aspiration or of any other suggestion of lung tumor, to deter mine the state of the tracheobronchial tree after acute inhalation injury, to deter mine the anatomy of the endobronchial tree, to visualize a bronchiectatic area, and postoperatively to evaluate the stump of a resected bronchus.
Therapeutic indications: Attempt to open atelectasis; attempt to drain lung ab scess; assist a weakened patient to raise secretions; performing extensive suction through an endotracheal or tracheostomy tube; removal of certain foreign bodies;
perform lung lavage after aspiration of add or alkaline material especially; and identification of acute laryngeal obstruction to direct treatment. For removal of large amounts of secretions or foreign bodies, a rigid bronchoscope is generally preferred.
Contraindications depend, in part, on the clinical state. A few, such as an intrac table bleeding disorder or severe cardiopulmonary failure, are usually absolute contraindications. But even in bleeding disorders, temporary correction of the defect by transfusion may sometimes allow enough time for visualization of the airways, although biopsy is avoided. An uncooperative patient can be made tractable by preoperative medication or general anesthesia. Cardiac arrhythmias, especially bradyarrhythmias, are contraindications unless they can be brought under control by premedication.
Procedure
The patient to be bronchoscoped fasts for at least 8 h before the procedure is done. P-A and lateral chest x-rays should be done within 24 h of the procedure Clotting function should be known to be normal within 24 h of the procedure. Patients with a history of cardiac disease or arrhythmias or > 50 yr of age should be monitored using the ECG.
Premedication consists of atropine average dose 1 mg s.c. and morphine or valium in appropriate dose. Topical anesthesia is accomplished with 2 or 4% lidocaine by first spraying the mouth, throat, and tongue and then through the nose. The patient inhales with each spray and, after one nostril is well sprayed, the other is anesthetized. A nasal Catheter is then placed through the least open nostril to the level of the uvula and O2 4 to 6 L/min is given throughout the procedure.
Before inserting the fiberbronchoscope, lidocaine jelly is used as a lubricant to protect both the patient's mucosa and the fiberbronchoscope from abrasion. The scope may be inserted through the nose providing there is no block, and through the mouth providing a simple curved endotracheal tube is used both as guide and protection for the instrument. The fiberbronchoscope is advanced to the epiglottis and anesthesia of the glottis is completed through the bronchoscope. Additional anesthetic is administered through the fiberbronchoscope as sensitive areas are reached by injecting 1 to 2 ml of the agent through the open channel. It is impor tant to avoid excessive anesthetic agent because of the increasing prospect of untoward reactions as dosage increases.
Insertion of the fiberbronchoscope through endotracheal tubes or tracheostomy tubes that are already in place is quite easy; the main concern is to ensure adequate ventilation of the patient while the procedure is going on. Attachments are available to enable ventilation to proceed during the examination.
The entire procedure can be done under general anesthesia if necessary. Even then topical anesthesia of the glottic structures is advised to minimize the possi bility of laryngospasm during or after the procedure is completed.
Complications: The main complications include laryngospasm, cardiac arrhyth mias (cardiac arrest is a particular threat in asthmatic patients), hemorrhage due either to biopsy or to injury of the bronchial mucosa by the bronchoscope, pneumothorax secondary to bronchial biopsy, arterial hypoxemia due either to ob struction of a major bronchus by the bronchoscope or to spillover in the course of bronchial lavage, allergic reactions either to premedication or to anesthetic agent, urinary retention or respiratory depression due to premedication, bronchospasm due to irritation of the mucosa by the bronchoscope, and infections of the tra-cheobronchial tree and lung introduced during the procedure.
One complication is potentially useful for cytologic or microbiologic studies— the almost invariable mild bronchitis that follows the procedure increases sputum production for a few days.
Since the patient's swallowing and cough reflexes are depressed for an hour or so, care must be taken to prevent aspiration by abstaining from eating or drinking for a few hours after the procedure.
Mediastinoscopy with biopsy
MEDIASTINOSCOPY
Indications: The prime indication is the need to biopsy a tumor of the upper mediastinum or to determine whether lymph node metastases have occurred. In systemic diseases (e.g., Hodgkin's disease or lymphoma) both primary diagnosis and staging of the process may be achieved by mediastinoscopy and biopsy.
Contraindications: Superior vena cava syndrome, aneurysm of the aortic arch, and primary tuberculosis of the lung with lymph node involvement are the major conditions that militate against performing this operation. If the indication is urgent enough for the procedure to be performed, even these conditions are not absolute contraindications.
Procedure
Under general anesthesia in supine position with the neck extended, a trans verse incision is made in the suprastemal notch. ^Because of anatomic limitations imposed by the aortic arch and the fascial compartments, the operator has easiest access to structures on the right side, particularly those in the same plane as the trachea and anterior to it. The mediastinoscope is introduced, the dissection is performed in the pretracheal fascia and extended under direct vision to the re gional lymph nodes, where biopsy is performed. At the close of the procedure, the fascia and skin are sutured without drainage.
Complications are rare. Pneumothorax may occur if the pleura is opened. Local bleeding may be a problem, especially if superior vena caval obstruction exists. Infection is unusual. Arrhythmias may occur if the pericardium and the heart are touched.
MEDIASTINOTOMY
Indications: The same indications apply as for mediastinoscopy. This procedure is used to biopsy areas that cannot be reached by mediastinoscopy, especially the left side of the mediastinum, the subaortic glands, and structures at or below the level of the hili.
Contraindications are the same as for mediastinoscopy (see above).
Procedure
Under general anesthesia, the patient is placed in the supine position. A para-sternal incision is made above the 3rd rib. The cartilage is excised. The approach is extrapleural. If a deeper approach is needed, a mediastinoscope is used. If the pleura is inadvertently entered during the procedure, drainage is established by leaving a catheter in the pleural space at the end of the procedure.
A lung biopsy may be performed through this approach. If indicated, the inci sion can be extended into a full thoracotomy for better exploration or excision.
Complications: Pneumothorax, bleeding from vessels such as the internal mam mary arteries, intercostal arteries, etc., and infection occur infrequently.
Acknoledgement and contributors
sources
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Pulmonary function tests
Pulmonary function tests are a group of tests that measure how well the lungs take in and release air and how well they move gases such as oxygen from the atmosphere into the body's circulation.
How the Test is Performed
In a spirometry test, you breathe into a mouthpiece that is connected to an instrument called a spirometer. The spirometer records the amount and the rate of air that you breathe in and out over a period of time.
For some of the test measurements, you can breathe normally and quietly. Other tests require forced inhalation or exhalation after a deep breath.
Lung volume measurement can be done in two ways:
The most accurate way is to sit in a sealed, clear box that looks like a telephone booth (body plethysmograph) while breathing in and out into a mouthpiece. Changes in pressure inside the box help determine the lung volume.
Lung volume can also be measured when you breathe nitrogen or helium gas through a tube for a certain period of time. The concentration of the gas in a chamber attached to the tube is measured to estimate the lung volume.
To measure diffusion capacity, you breathe a harmless gas for a very short time, often one breath. The concentration of the gas in the air you breathe out is measured. The difference in the amount of gas inhaled and exhaled measures how effectively gas travels from the lungs into the blood.
How to Prepare for the Test
Do not eat a heavy meal before the test. Do not smoke for 4 - 6 hours before the test. You'll get specific instructions if you need to stop using bronchodilators or inhaler medications. You may have to breathe in medication before the test.
How the Test Will Feel
Since the test involves some forced breathing and rapid breathing, you may have some temporary shortness of breath or lightheadedness. You breathe through a tight-fitting mouthpiece, and you'll have nose clips.
Why the Test is Performed
Pulmonary function tests are done to:
Diagnose certain types of lung disease (especially asthma, bronchitis, and emphysema)
Find the cause of shortness of breath
Measure whether exposure to contaminants at work affects lung function
It also can be done to:
Assess the effect of medication
Measure progress in disease treatment
Spirometry measures airflow. By measuring how much air you exhale, and how quickly, spirometry can evaluate a broad range of lung diseases.
Lung volume measures the amount of air in the lungs without forcibly blowing out. Some lung diseases (such as emphysema and chronic bronchitis) can make the lungs contain too much air. Other lung diseases (such as fibrosis of the lungs and asbestosis) make the lungs scarred and smaller so that they contain too little air.
Testing the diffusion capacity (also called the DLCO) allows the doctor to estimate how well the lungs move oxygen from the air into the bloodstream.
Normal Results
Normal values are based upon your age, height, ethnicity, and sex. Normal results are expressed as a percentage. A value is usually considered abnormal if it is less than 80% of your predicted value.
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean
Abnormal results usually mean that you may have some chest or lung disease.
Risks
The risk is minimal for most people. There is a small risk of collapsed lung in people with a certain type of lung disease. The test should not be given to a person who has experienced a recent heart attack, or who has certain other types of heart disease.
Considerations
Your cooperation while performing the test is crucial in order to get accurate results. A poor seal around the mouthpiece of the spirometer can give poor results that can't be interpreted. Do not smoke before the test.
Alternative Names
PFTs; Spirometry; Spirogram; Lung function tests
References
Mason RJ, Broaddus VC, Murray JF, Nadel JA. Murray and Nadel's Textbook of Respiratory Medicine. 4th ed. Philadelphia, Pa: Saunders; 2005.
Pulmonary function testing has come into widespread use since the 1970s. This has been facilitated by several developments.1,2 Because of miniaturization and advances in computer technology, microprocessor devices have become portable and automated with fewer moving parts. Testing equipment, patient maneuvers, and testing techniques have become widely standardized throughout the world through the efforts of professional societies. Widely accepted normative parameters have been established.
Definition
Pulmonary function testing is a valuable tool for evaluating the respiratory system, representing an important adjunct to the patient history, various lung imaging studies, and invasive testing such as bronchoscopy and open-lung biopsy. Insight into underlying pathophysiology can often be gained by comparing the measured values for pulmonary function tests obtained on a patient at any particular point with normative values derived from population studies. The percentage of predicted normal is used to grade the severity of the abnormality. Practicing clinicians must become familiar with pulmonary function testing because it is often used in clinical medicine for evaluating respiratory symptoms such as dyspnea and cough, for stratifying preoperative risk, and for diagnosing common diseases such as asthma and chronic obstructive pulmonary disease.
Pulmonary function tests (PFTs) is a generic term used to indicate a battery of studies or maneuvers that may be performed using standardized equipment to measure lung function. PFTs can include simple screening spirometry, formal lung volume measurement, diffusing capacity for carbon monoxide, and arterial blood gases. These studies may collectively be referred to as a complete pulmonary function survey.
Before a spirogram can be meaningfully interpreted, one needs to inspect the graphic data (the volume-time curve and the flow-volume loop) to ascertain whether the study meets certain well-defined acceptability and reproducibility standards. Tests that fail to meet these standards can provide useful information about minimum levels of lung function, but, in general, they should be interpreted cautiously. The interpretive strategy usually involves establishing a pattern of abnormality (obstructive, restrictive, or mixed), grading the severity of the abnormality, and assessing trends over time. Various algorithms are available. Automated spirometry systems usually have built-in software that can generate a preliminary interpretation, especially for spirometry; however, algorithms for other pulmonary function studies are not as well established and necessitate appropriate clinical correlation and physician oversight.
Back to Top
Physiology
Basic concepts of normal pulmonary physiology that are involved in pulmonary function testing include mechanics (airflows and lung volumes), the ventilation-perfusion interrelationship, diffusion and gas exchange, and respiratory muscle or bellows strength. Ventilation is the process of generating the forces necessary to move the appropriate volumes of air from the atmosphere to the alveoli to meet the metabolic needs of the body under a variety of conditions. Simply, the contraction of the diaphragm and other inspiratory muscles expands the thorax, generating negative pressure in the pleural space. One component of pleural pressure, known as transpulmonary pressure, causes a flow of air into the airways and lungs (inspiration). When the transpulmonary and alveolar pressures equilibrate, airflow stops, the inspiratory muscles relax, and the lungs and chest wall elastic recoil raise pleural pressure, forcing air out of the lungs (expiration).
With a forced exhalation, the early portion of the spirometry maneuver is characterized by high flows, mostly from large airways, and the latter portion is characterized by low flows with a larger contribution from the smaller airways.3 Forced inspiration is generally not flow limited and is a function of overall muscular effort. In contrast, a variety of factors affect expiratory flow, including the overall driving pressure, airway diameter, overall distensibility of the lungs and chest wall, dynamic airway collapse (from a flow-limiting segment), and muscular effort. The overall driving pressure is the pressure head at the alveolus, or PALV, which is the difference between pleural pressure (PPL) and negative transpulmonary pressure (PTP). So:
PALV = PPL + PTP
The mechanism for the maximal expiratory airflow limitation seen in normal airways results from the gradual drop in pressure inside the conducting airways from the alveoli to the mouth, creating a transmural pressure gradient with the pleural pressure. This can cause dynamic airway compression and narrowing or closure of airways that have lost elastic recoil support from the lung parenchyma.
Back to Top
Battery of maneuvers
Pulmonary function studies use a variety of maneuvers to measure and record the properties of four lung components. These include the airways (large and small), lung parenchyma (alveoli, interstitium), pulmonary vasculature, and the bellows-pump mechanism. Various diseases can affect each of these components.
Spirometry
Spirometry is the most commonly used lung function screening study. It generally should be the clinician's first option, with other studies being reserved for specific indications. Most patients can easily perform spirometry when coached by an appropriately trained technician or other health care provider. The test can be administered in the ambulatory setting, physician's office, emergency department, or inpatient setting. The indications for spirometry are diverse (Box 1). It can be used for diagnosing and monitoring respiratory symptoms and disease, for preoperative risk stratification, and as a tool in epidemiologic and other research studies.
Box 1: Indications for Spirometry
Diagnostic
To evaluate symptoms
Chest pain
Cough
Dyspnea
Orthopnea
Phlegm production
Wheezing
To evaluate signs
Chest deformity
Cyanosis
Diminished breath sounds
Expiratory slowing
Overinflation
Unexplained crackles
To evaluate abnormal laboratory tests
Abnormal chest radiographs
Hypercapnia
Hypoxemia
Polycythemia
To measure the effect of disease on pulmonary function
To screen persons at risk for pulmonary diseases
Smokers
Persons in occupations with exposures to injurious substances
Some routine physical examinations
To assess preoperative risk
To assess prognosis (lung transplant, etc.)
To assess health status before enrollment in strenuous physical activity programs
Monitoring
To assess therapeutic interventions
Bronchodilator therapy
Steroid treatment for asthma, interstitial lung disease, etc.
Management of congestive heart failure
Other (antibiotics in cystic fibrosis, etc.)
To describe the course of diseases affecting lung function
Pulmonary diseases
Obstructive small airway diseases
Interstitial lung diseases
Cardiac diseases
Congestive heart failure
Neuromuscular diseases
Guillain-Barré syndrome
Pulmonary function testing has come into widespread use since the 1970s. This has been facilitated by several developments.1,2 Because of miniaturization and advances in computer technology, microprocessor devices have become portable and automated with fewer moving parts. Testing equipment, patient maneuvers, and testing techniques have become widely standardized throughout the world through the efforts of professional societies. Widely accepted normative parameters have been established.
Definition
Pulmonary function testing is a valuable tool for evaluating the respiratory system, representing an important adjunct to the patient history, various lung imaging studies, and invasive testing such as bronchoscopy and open-lung biopsy. Insight into underlying pathophysiology can often be gained by comparing the measured values for pulmonary function tests obtained on a patient at any particular point with normative values derived from population studies. The percentage of predicted normal is used to grade the severity of the abnormality. Practicing clinicians must become familiar with pulmonary function testing because it is often used in clinical medicine for evaluating respiratory symptoms such as dyspnea and cough, for stratifying preoperative risk, and for diagnosing common diseases such as asthma and chronic obstructive pulmonary disease.
Pulmonary function tests (PFTs) is a generic term used to indicate a battery of studies or maneuvers that may be performed using standardized equipment to measure lung function. PFTs can include simple screening spirometry, formal lung volume measurement, diffusing capacity for carbon monoxide, and arterial blood gases. These studies may collectively be referred to as a complete pulmonary function survey.
Before a spirogram can be meaningfully interpreted, one needs to inspect the graphic data (the volume-time curve and the flow-volume loop) to ascertain whether the study meets certain well-defined acceptability and reproducibility standards. Tests that fail to meet these standards can provide useful information about minimum levels of lung function, but, in general, they should be interpreted cautiously. The interpretive strategy usually involves establishing a pattern of abnormality (obstructive, restrictive, or mixed), grading the severity of the abnormality, and assessing trends over time. Various algorithms are available. Automated spirometry systems usually have built-in software that can generate a preliminary interpretation, especially for spirometry; however, algorithms for other pulmonary function studies are not as well established and necessitate appropriate clinical correlation and physician oversight.
Back to Top
Physiology
Basic concepts of normal pulmonary physiology that are involved in pulmonary function testing include mechanics (airflows and lung volumes), the ventilation-perfusion interrelationship, diffusion and gas exchange, and respiratory muscle or bellows strength. Ventilation is the process of generating the forces necessary to move the appropriate volumes of air from the atmosphere to the alveoli to meet the metabolic needs of the body under a variety of conditions. Simply, the contraction of the diaphragm and other inspiratory muscles expands the thorax, generating negative pressure in the pleural space. One component of pleural pressure, known as transpulmonary pressure, causes a flow of air into the airways and lungs (inspiration). When the transpulmonary and alveolar pressures equilibrate, airflow stops, the inspiratory muscles relax, and the lungs and chest wall elastic recoil raise pleural pressure, forcing air out of the lungs (expiration).
With a forced exhalation, the early portion of the spirometry maneuver is characterized by high flows, mostly from large airways, and the latter portion is characterized by low flows with a larger contribution from the smaller airways.3 Forced inspiration is generally not flow limited and is a function of overall muscular effort. In contrast, a variety of factors affect expiratory flow, including the overall driving pressure, airway diameter, overall distensibility of the lungs and chest wall, dynamic airway collapse (from a flow-limiting segment), and muscular effort. The overall driving pressure is the pressure head at the alveolus, or PALV, which is the difference between pleural pressure (PPL) and negative transpulmonary pressure (PTP). So:
PALV = PPL + PTP
The mechanism for the maximal expiratory airflow limitation seen in normal airways results from the gradual drop in pressure inside the conducting airways from the alveoli to the mouth, creating a transmural pressure gradient with the pleural pressure. This can cause dynamic airway compression and narrowing or closure of airways that have lost elastic recoil support from the lung parenchyma.
Back to Top
Battery of maneuvers
Pulmonary function studies use a variety of maneuvers to measure and record the properties of four lung components. These include the airways (large and small), lung parenchyma (alveoli, interstitium), pulmonary vasculature, and the bellows-pump mechanism. Various diseases can affect each of these components.
Spirometry
Spirometry is the most commonly used lung function screening study. It generally should be the clinician's first option, with other studies being reserved for specific indications. Most patients can easily perform spirometry when coached by an appropriately trained technician or other health care provider. The test can be administered in the ambulatory setting, physician's office, emergency department, or inpatient setting. The indications for spirometry are diverse (Box 1). It can be used for diagnosing and monitoring respiratory symptoms and disease, for preoperative risk stratification, and as a tool in epidemiologic and other research studies.
Box 1: Indications for Spirometry
Diagnostic
To evaluate symptoms
Chest pain
Cough
Dyspnea
Orthopnea
Phlegm production
Wheezing
To evaluate signs
Chest deformity
Cyanosis
Diminished breath sounds
Expiratory slowing
Overinflation
Unexplained crackles
To evaluate abnormal laboratory tests
Abnormal chest radiographs
Hypercapnia
Hypoxemia
Polycythemia
To measure the effect of disease on pulmonary function
To screen persons at risk for pulmonary diseases
Smokers
Persons in occupations with exposures to injurious substances
Some routine physical examinations
To assess preoperative risk
To assess prognosis (lung transplant, etc.)
To assess health status before enrollment in strenuous physical activity programs
Monitoring
To assess therapeutic interventions
Bronchodilator therapy
Steroid treatment for asthma, interstitial lung disease, etc.
Management of congestive heart failure
Other (antibiotics in cystic fibrosis, etc.)
To describe the course of diseases affecting lung function
Pulmonary diseases
Obstructive small airway diseases
Interstitial lung diseases
Cardiac diseases
Congestive heart failure
Neuromuscular diseases
Guillain-Barré syndrome
Dynamic lung volumes (forced vital capacity, forced expiratory volume in 0·5 second and in 1·0 second), static lung volumes (total lung capacity, functional residual capacity, residual volume), and ventilation-perfusion relationships (alveolar-arterial oxygen tension difference, alveolar dead space ventilation to tidal volume ratio, arterial oxygen and carbon dioxide tension, and the fractional ventilation and perfusion relationship by the three-compartment lung model) were measured in adult asthmatics during the acute, recovery, and stable or asymptomatic phases of an asthmatic attack. Eighteen patients were studied during 20 separate asthmatic attacks.
The patients behaved in one of three ways with regard to total lung capacity (TLC): group I had an elevated TLC during the acute asthmatic attack which returned to normal, group II had a normal TLC throughout the attack, and group III had an elevated TLC that did not return to normal on recovery from the asthmatic attack. With the patients separated into the three groups, the other pulmonary function measurements, especially the measurements of ventilation-perfusion abnormality, were compared. There were no statistically significant differences of ventilation-perfusion abnormality between groups I, II, or III. There was a tendency for perfusion abnormality to be less during the acute phase of the asthmatic attack in patients with an elevated TLC (group I). The three-compartment lung model revealed the major abnormality in all groups to be an increased fraction of unventilated but perfused lung.
The measurement of static lung volumes is important for the accurate diagnosis of lung disorders, and when making volume-dependent measurements, such as airways resistance. There are a variety of methods available. The most accurate method is that of constant volume body plethysmography, which provides an estimate of total lung capacity regardless of the presence of airflow obstruction. Whilst this method may overestimate lung volumes in asthmatics, and is technically more demanding than gas dilution methods, this should be regarded as the principal method for estimating lung volumes. Gas dilution estimates of multi-breath helium or nitrogen dilution or single-breath estimates using the same gases all underestimate total lung capacity in the presence of airflow obstruction. Single-breath methods will underestimate volumes to a greater extent than multi-breath methods. Multi-breath helium dilution is currently regarded as the acceptable alternative to body plethysmography. Estimates of lung volumes from chest radiographs provide an estimate of lung volumes independent of airflow obstruction. They are probably prone to greater variability than body plethysmographic estimates, and it is regarded as unacceptable to expose patients to excess radiation. Other methods being developed include estimates from nuclear magnetic imaging and computed tomography.
The measurement of static lung volumes is important for the accurate diagnosis of lung disorders, and when making volume-dependent measurements, such as airways resistance. There are a variety of methods available. The most accurate method is that of constant volume body plethysmography, which provides an estimate of total lung capacity regardless of the presence of airflow obstruction. Whilst this method may overestimate lung volumes in asthmatics, and is technically more demanding than gas dilution methods, this should be regarded as the principal method for estimating lung volumes. Gas dilution estimates of multi-breath helium or nitrogen dilution or single-breath estimates using the same gases all underestimate total lung capacity in the presence of airflow obstruction. Single-breath methods will underestimate volumes to a greater extent than multi-breath methods. Multi-breath helium dilution is currently regarded as the acceptable alternative to body plethysmography. Estimates of lung volumes from chest radiographs provide an estimate of lung volumes independent of airflow obstruction. They are probably prone to greater variability than body plethysmographic estimates, and it is regarded as unacceptable to expose patients to excess radiation. Other methods being developed include estimates from nuclear magnetic imaging and computed tomography.
capacity /ca·pac·i·ty/ (kah-pas´?-te) the power to hold, retain, or contain, or the ability to absorb; usually expressed numerically as the measure of such ability.
forced vital capacity (FVC) vital capacity measured when the patient is exhaling with maximal speed and effort.
functional residual capacity the amount of air remaining at the end of normal quiet respiration.
heat capacity the amount of heat required to raise the temperature of a specific quantity of a substance by one degree Celsius. Symbol C.
inspiratory capacity the volume of gas that can be taken into the lungs in a full inhalation, starting from the resting inspiratory position; equal to the tidal volume plus the inspiratory reserve volume.
maximal breathing capacity maximum voluntary ventilation.
thermal capacity heat c.
total lung capacity the amount of gas contained in the lung at the end of a maximal inhalation.
Subdivisions of total lung capacity: TLC, total lung capacity; VT, tidal volume; IC, inspiratory capacity; FRC, functional residual capacity; ERV, expiratory reserve volume; VC, vital capacity; RV, residual volume.
virus neutralizing capacity the ability of a serum to inhibit the infectivity of a virus.
vital capacity VC; the volume of gas that can be expelled from the lungs from a position of full inspiration, with no limit to duration of inspiration; equal to inspiratory capacity plus expiratory reserve volume.
Flow volume loops are perhaps the most recognizable of all pulmonary function tests. The shape of the curves are extremely diagnostic but the very nature of the effort required to reproduce the shape (loop) means that often data is of a poor quality. In ComPAS Freedom™ we have gone to extraordinary lengths to help the technician acquire high quality clinical data. Each of the test efforts is automatically reviewed against ATS standards and furthermore a "confidence" rating is applied by an even stricter performance scan utilizing Morgan Scientific experience.
In most pulmonary function labs, flow volume loops are usually the first tests gathered from the spirometry testing. By examining the information and shape of the loop, it helps clinicians further understand the way air is moving into and out of the lungs and help identify specific diseases that can otherwise be very hard to diagnose.
From the information gathered with this test certain deductions about what is happening throughout the lung can be made. In particular we comment on obstructive lung disorders and degree of the disease. Obstructive lung disease is simply put, a problem with the airways that do not allow airflow to move smoothly from the alveoli (air sacs of the lungs) and smallest airways out through the trachea (main windpipe) and ultimately out through the mouth when exhaling or inhaling. There are a number of common processes that can lead to this kind of a problem including emphysema, asthma and chronic bronchitis.
The results of dynamic PFT tests place patients in 1 of 3 categories:
normal lung function
obstructive disease
or restrictive disease
In obstructive lung disease, patients have decreased airflow (decreased FEV1/FVC ratio) and usually have normal or above-normal lung volumes.
In restrictive lung disease, patients have decreased lung volumes or TLC with normal airflow (normal FEV1/FVC ratio but with reduced values for both FVC and FEV1 individually).
For many years, the forced expiratory effort was only represented as a plot of volume against time.
Vital capacity is the maximum amount of air a person can expel from the lungs after a maximum inspiration. It is equal to the inspiratory reserve volume plus the tidal volume plus the expiratory reserve volume.
A person's vital capacity can be measured by a spirometer which can be a wet or regular spirometer. In combination with other physiological measurements, the vital capacity can help make a diagnosis of underlying lung disease. The unit that is used to determine this vital capacity is millilitres (ml).
A normal adult has a vital capacity between 3 and 5 litres. After the age of 20 the vitalcapacity decreases approximatley 250 cc per ten years.
Functional Residual Capacity (FRC) is the volume of air present in the lungs at the end of passive expiration. At FRC, the elastic recoil forces of the lungs and chest wall are equal but opposite and there is no exertion by the diaphragm or other respiratory muscles.
FRC is the sum of Expiratory Reserve Volume (ERV) and Residual Volume (RV) and measures approximately 2400 ml in a 70 kg, average-sized male. It can not be estimated through spirometry, since it includes the residual volume. In order to measure RV precisely, one would need to perform a test such as nitrogen washout, helium dilution or body plethysmography.
A lowered or elevated FRC is often an indication of some form of respiratory disease. For instance, in emphysema, the lungs are more compliant and therefore are more susceptible to the outward recoil forces of the chest wall. Emphysema patients often have noticeably broader chests because they are breathing at larger volumes.
The helium dilution technique is a common way of measuring the functional residual capacity of the lungs.
FRC - functional residual capacity
The FRC, the volume of gas contained in the lung after a normal expiration, is mainly determined by the interaction between elastic recoil of the chest and lungs (animation on the left).
In the newborn both the thorax and lung are very compliant, so that the FRC is very small. Particularly in the supine posture, when the diaphragm is pushed up by the abdominal contents, gas transport is hampered by the occurrence of airway closure. Newborns elevate their FRC by glottis closure and by postinspiratory stimulation of inspiratory muscles during expiration.
Increased FRC in airway obstruction
In severe airway obstruction many lung compartments may be incapable of emptying due to airway closure. In addition expiratory flow may be so limited that insufficient time is available to reach the lung volume that would be obtained in the case of elastic equilibrium between lung and chest. This gives rise to a higher endexpiratory volume and a concomitant increase in elastic recoil pressure (pleural pressure falls), slight widening of the airway due to the larger distending pressure and hence some benefit to expiratory flow. The endexpiratory volume increases to the point where a new dynamic equilibrium is reached between inspiratory and expiratory tidal volume. It follows that severe airway obstruction is associated with an increase in FRC (hyperinflation). If FRC is normal in a patient with airway obstruction when at rest, it may increase during exercise; due to flow limitation the time available for lung emptying may not suffice at the increased tidal volume.
Diminished FRC
A low FRC occurs in restrictive ventilatory defects. The FRC also diminishes in the supine posture because the abdominal contents the push the diaphragm upwards; this phenomenon is most pronounced with space occupying intra-abdominal processes (e.g. pregnancy, hepatosplenomegaly, ascites). Unilateral paralysis of the diaphragm is usually not associated with a change in the FRC; bilateral paralysis of the diaphragm is associated with a smaller FRC in both the sitting and supine posture.
Helium Dilution - Functional Residual Capacity (FRC)
This test measures the Functional Residual Capacity (FRC). In people with normal lungs the FRC is equal to the Thoracic Gas Volume (TGV) measured in the body plethysmograph. The helium dilution method only measures the air in the lung that under goes gas exchange. The plethysmograph method measures all air in the lung, including any trapped air. Inspiratory and expiratory volumes must also be measured with the FRC. A technologist will instruct you on how to perform the test and coach and encourage you to do your best.
Performing the test
You will be asked to come on the mouthpiece with noseclips on and to breathe normally
You will be asked to slowly blow out all of your air until you are empty
You will then return to normal breathing for a few minutes
Then you will be asked to slowly blow out until empty and then to take a slow deep breath in until your lungs are completely filled
You will then be asked to blow out slowly until you are completely empty
You will then return to normal breathing for a few breaths before coming off the mouthpiece
You will rest 5 to 10 minutes before repeating the test
Measurements
This test will measure static lung volumes:
Functional Residual Capacity (FRC)
Inspiratory Capacity (IC)
Expiratory Residual Volume (ERV)
Slow Vital Capacity (SVC)
Total Lung Capacity (TLC)
After a short rest period, the test is repeated until there are two reproducible tests. This test may be done with or without a bronchodilator.
Functional Residual Capacity (FRC) is the volume of air present in the lungs at the end of passive expiration. At FRC, the elastic recoil forces of the lungs and chest wall are equal but opposite and there is no exertion by the diaphragm or other respiratory muscles.
FRC is the sum of Expiratory Reserve Volume (ERV) and Residual Volume (RV) and measures approximately 2400 ml in a 70 kg, average-sized male. It can not be estimated through spirometry, since it includes the residual volume. In order to measure RV precisely, one would need to perform a test such as nitrogen washout, helium dilution or body plethysmography.
A lowered or elevated FRC is often an indication of some form of respiratory disease. For instance, in emphysema, the lungs are more compliant and therefore are more susceptible to the outward recoil forces of the chest wall. Emphysema patients often have noticeably broader chests because they are breathing at larger volumes.
The helium dilution technique is a common way of measuring the functional residual capacity of the lungs.
Lung volume and lung capacities refer to the volume of air associated with different phases of the respiratory cycle. Lung volumes are directly measured. Lung capacities are inferred from lung volumes.
The average total lung capacity of an adult human male is about 6 litres of air, but only a small amount of this capacity is used during normal breathing.
The breathing mechanism in mammals is called "tidal breathing". Tidal breathing represents the volume of air that is inhaled and exhaled in normal, resting breathing.
An average human breathes some 12-20 times per minute.
RV - residual volume
The volume of the lung after maximal exhalation started from the functional residual capacity.
In children and adolescents residual volume grows slightly faster than the total lung capacity, mostly on account of changes in chest geometry (references below).
In healthy adults RV increases with age since a maximal expiration is increasingly impeded by airway closure, preventing dependent alveoli from emptying. In contrast, the total lung capacity does not change with age in adults. As a result the VC decreases with age in healthy subjects.
Small airway pathology (inflammation, accumulation of secretions, hypertrophy and hyperplasia of glands and smooth muscles) and loss of lung elastic recoil (and therefore diminished elastic stretch of small airways) lead to premature airway closure during a maximal expiration; this causes the RV to increase, and the VC to decrease. Any factors that influence the TLC also affect the VC.
In patients with airway obstruction an FVC maneuver usually ends at a higher lung volume than a maximal expiration started from FRC level; only in the latter instance should end-expiratory volume be called RV.
RV grows faster than TLC in adolescents
1 Merkus PJFM, Borsboom GJJM, van Pelt W, Schrader PC, van Houwelingen JC, Kerrebijn KF, Quanjer PhH. Growth of airways and airspaces in teenagers is related to sex but not to symptoms. J Appl Physiol 1993; 75: 2045-2053.
2 DeGroodt EG, van Pelt W, Borsboom GJJM, Quanjer PhH, van Zomeren BC. Growth of lung and thorax dimensions during the pubertal growth spurt. Eur Respir J 1988, 1, 102-108.
Lung volume and lung capacities refer to the volume of air associated with different phases of the respiratory cycle. Lung volumes are directly measured. Lung capacities are inferred from lung volumes.
The average total lung capacity of an adult human male is about 6 litres of air, but only a small amount of this capacity is used during normal breathing.
The breathing mechanism in mammals is called "tidal breathing". Tidal breathing represents the volume of air that is inhaled and exhaled in normal, resting breathing.
An average human breathes some 12-20 times per minute.
Factors affecting volumes
Several factors affect lung volumes; some can be controlled and some cannot. Lung volumes can be measured using the following terms:
Larger volumes
taller people, non smokers, people living in high altitude.
Smaller volumes
shorter people, smokers, people living in low altitude.
A person who is born and lives at sea level will develop a slightly smaller lung capacity than a person who spends their life at a high altitude. This is because the partial pressure of oxygen is lower at higher altitude which, as a result means that oxygen less readily diffuses into the bloodstream. In response to higher altitude, the body's diffusing capacity increases in order to process more air.
When someone living at or near sea level travels to locations at high altitudes (eg. the Andes, Denver, Colorado, Tibet, the Himalayas, etc.) that person can develop a condition called altitude sickness because their lungs remove adequate amounts of carbon dioxide but they do not take in enough oxygen. (In normal individuals, carbon dioxide is the primary determinant of respiratory drive.)
[edit]Values
These values vary with the age and height of the person. For males, the values that follow are the average ones for a healthy 70 kg (154 lb), average-sized adult male [1]; for females, the editors of this article have not yet produced data from primary sources; until they do, the data listed are estimates obtained by reducing the values for males by 22.5%
The tidal volume, vital capacity, inspiratory capacity and expiratory reserve volume can be measured directly with a spirometer. These are the basic elements of a ventilatory pulmonary function test. Determination of the residual volume can be done by radiographic planemetry, body plethysmography, closed circuit dilution and nitrogen washout.
In absence of such , estimates of residual volume have been prepared as a proportion of body mass for infants (18.1ml/kg), [8] or as a proportion of vital capacity (0.24 for men and 0.28 for women)[9] or in relation to height and age ((0.0275*AgeInYears+0.0189*HeightInCentimetres-2.6139) litres for normal-weight individuals and (0.0277*AgeInYears+0.0138*HeightInCentimeters-2.3967) litres for overweight individuals).[10] Standard errors in prediction equations for residual volume have been measured at 579ml for men and 355ml for women, while the use of 0.24*FVC gave a standard error of 318ml
Previous research in this laboratory demonstrated a reduction in expiratory reserve volume of the lungs (ERV) with increasing body fatness (%F, by densitometry). The present study was done to determine if smaller ERV values could be demonstrated in lean female athletes with greater than normal upper-body muscle development. Expiratory reserve volume, vital capacity (VC), and segmental body volumes by densitometry were measured in members of two collegiate women's teams--gymnastics (G) (N = 10) and track (R) (N = 10). The runners provided a control group by being similar to gymnasts in age, weight, and body fatness, but they did not engage in upper-body weight training or gymnastic exercises. The two groups were not significantly different in body weight (means G +/- SD = 53.0 +/- 6.1 kg; means R = 50.8 +/- 4.6 kg) or %F (means G = 16.8 +/- 3.2%; means R = 14.8 +/- 3.8%), but R subjects were taller (means = 165.4 +/- 5.5 cm vs 158.7 +/- 4.8 cm, P less than 0.01). Expiratory reserve volume, expressed as a percent of VC, (ERV X VC-1) 100, was significantly (P less than 0.001) less in the gymnasts (means +/- SD = 29.7 +/- 7.1) as compared to the runners (43.1 +/- 6.4). All other lung capacities as volumes were comparable in both groups. Arm and thorax volumes indicated greater upper-body size in the G subjects (arm volume, means +/- SD of G = 4.8 +/- 0.6 liters, of R = 4.0 +/- 0.6 liters, P less than 0.01; thorax volume, means +/- SD of G = 7.8 +/- 1.4 liters, or R = 5.6 +/- 1.0 liters, P less than 0.001).(ABSTRACT TRUNCATED AT
Endobronchial valve placement improves pulmonary function in some patients with chronic obstructive pulmonary disease, but its effects on exercise physiology have not been investigated. In 19 patients with a mean (SD) FEV1 of 28.4 (11.9)% predicted, studied before and 4 weeks after unilateral valve insertion, functional residual capacity decreased from 7.1 (1.5) to 6.6 (1.7) L (p = 0.03) and diffusing capacity rose from 3.3 (1.1) to 3.7 (1.2) mmol · minute–1 · kPa–1 (p = 0.03). Cycle endurance time at 80% of peak workload increased from 227 (129) to 315 (195) seconds (p = 0.03). This was associated with a reduction in end-expiratory lung volume at peak exercise from 7.6 (1.6) to 7.2 (1.7) L (p = 0.03). Using stepwise logistic regression analysis, a model containing changes in transfer factor and resting inspiratory capacity explained 81% of the variation in change in exercise time (p < 0.0001). The same variables were retained if the five patients with radiologic atelectasis were excluded from analysis. In a subgroup of patients in whom invasive measurements were performed, improvement in exercise capacity was associated with a reduction in lung compliance (r2 = 0.43; p = 0.03) and isotime esophageal pressure–time product (r2 = 0.47; p = 0.03). Endobronchial valve placement can improve lung volumes and gas transfer in patients with chronic obstructive pulmonary disease and prolong exercise time by reducing dynamic hyperinflation.
Key Words: bronchoscopic lung volume reduction • chronic obstructive pulmonary disease • diaphragm • dynamic hyperinflation
Patients with advanced chronic obstructive pulmonary disease (COPD) frequently experience exertional breathlessness despite optimal medical therapy. In selected patients lung volume reduction surgery (LVRS) has been shown to improve mortality, exercise capacity, and quality of life (1–3). However, it is associated with significant morbidity and an early mortality rate of about 5% (1, 2). For these reasons and because the procedure poses an unacceptable risk in patients with the most severe disease (1, 4), alternatives have been sought including bronchoscopic lung volume reduction (BLVR). This involves obstructing the airways that supply the most hyperinflated, emphysematous parts of the lung. The rationale for this approach is that endobronchial obstruction should cause these areas to collapse as a result of absorption atelectasis. By reducing lung volumes, symptoms could be improved without recourse to surgery. The technique was first performed with airway blockers (5) and subsequently our group (6) and others (7, 8) have described early experience with the use of endobronchially placed valves. However, our experience suggests that lobar collapse is not necessary for clinically apparent benefit to occur and we reasoned therefore that other physiologic mechanisms must operate.
A key element in ventilatory limitation of exercise in COPD is the development of dynamic hyperinflation, in which expiratory flow limitation leads to a progressive increase in end-expiratory lung volume during exercise and consequently restricts the tidal volume that can be achieved (9). Reductions in dynamic hyperinflation have been demonstrated after treatment with bronchodilators (10–12) and after lung volume reduction surgery or bullectomy (13). BLVR could be expected to reduce dynamic hyperinflation either by causing the worst affected areas of lung to collapse or by excluding them from ventilation. In the presence of significant atelectasis BLVR should lead to a better matching of lung and chest wall dimensions, thus increasing available vital capacity as occurs after LVRS (14). By collapsing the most compliant areas of lung this should lead to an increase in lung elastic recoil at any given lung volume, reducing airflow obstruction.
In the absence of atelectasis BLVR might still have benefits, first by reducing physiological dead space, which would improve the efficiency of ventilation, and second by reducing the dynamic hyperinflation that occurs at higher levels of ventilation by diverting airflow to less obstructed areas of lung.
Therefore the aim of the present study was to investigate the effect of endobronchial valve placement on exercise capacity in patients with emphysema and to relate this to changes in dynamic hyperinflation assessed through changes in end-expiratory lung volumes. Some of the results of these studies have been reported previously in abstract form (15).
METHODS
TOP
ABSTRACT
METHODS
RESULTS
DISCUSSION
REFERENCES
Patients with COPD consistent with the GOLD guidelines (16) entered the study if they had significant dyspnea despite optimal medical therapy including pulmonary rehabilitation; presented a heterogeneous pattern of disease with a target area identified by computed tomography (CT) scanning and ventilation perfusion scintigraphy (6); and were either considered too great a risk for LVRS (1, 4), or declined the surgery. The Royal Brompton Hospital (London, UK) Research Ethics Committee approved the study and patients gave their informed consent. Some data from the first eight patients in our series have been published previously (6).
Endobronchial occlusion was performed with one-way valves (Emphasys Medical, Redwood City, CA) made of nitinol and silicone (see Figures E1 and E2 in the online supplement), placed to occlude segmental bronchi leading to the most affected area of lung. All procedures were unilateral. Initially, valves were inserted on a single occasion under general anesthesia (6, 17). Subsequently some procedures were performed with sedation only and some of these were staged, with valves being inserted on two separate occasions 1 to 2 weeks apart. Measurements were made in the week preceding and 4 weeks after valve insertion had been completed. A radiologist blinded to clinical outcome assessed CT evidence of atelectasis, defined as changes in the position of interlobar fissures adjacent to the targeted area.
Quality of life was assessed on the basis of St George's Respiratory Questionnaire and the Short Form-36.
Pulmonary and Respiratory Muscle Function
Spirometry, gas transfer, and lung volumes assessed by body plethysmography were measured with a CompactLab system (Jaeger, Hoechberg, Germany). PaO2 and PaCO2 were measured in arterialized earlobe capillary samples. Static lung compliance was measured by an interrupter technique during a relaxed expiration from total lung capacity (TLC).
In all subjects we measured maximal static inspiratory (PImax) and expiratory (PEmax) mouth pressures (18) as well as maximal sniff nasal pressure (Pn,sn) (19). When patients consented to and were able to tolerate the placement of catheter-mounted balloons, esophageal and gastric pressures were determined and transdiaphragmatic pressure was calculated (19). In these patients sniff transdiaphragmatic pressure (Pdi,sn) and the response to bilateral anterolateral magnetic phrenic nerve stimulation (Pdi,tw) were also determined (20).
Exercise Testing
Patients performed endurance cycle ergometry at 80% of the maximal workload achieved on a previous incremental test before and after BLVR, with inspiratory capacity (IC) maneuvers performed every minute to assess changes in end-expiratory lung volume. Both peak and isotime values were compared. Isotime was defined as the final 30-second period achieved on the shorter of the two tests. Leg and breathing discomfort were assessed on the basis of the Borg scale.
In some patients we recorded esophageal and gastric pressures during exercise, calculating esophageal and diaphragmatic pressure–time product (PTP) (21, 22). Further methodologic details are given in the online supplement.
Statistical Analysis
The primary end point in this study was change in cycle endurance time (Tlim) 4 weeks after the procedure as a continuous variable. In addition, patients with an increase of both 60 seconds and 30% were defined a priori as "improvers." Changes from baseline were assessed using appropriate test for paired comparisons. Baseline predictors and correlates of improvement in Tlim were sought, using linear regression and then stepwis
Maximal Voluntary Ventilation: Measure of the maximum amount of air that can be breathed in and blown out over a sustained interval such as 15 or 20 seconds. Common abbreviations are MVV and MBC.
Read more at http://www.wrongdiagnosis.com/medical/maximal_volu
Spirometry (meaning the measuring of breath) is the most common of the Pulmonary Function Tests (PFTs), measuring lung function, specifically the measurement of the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled. Spirometry is an important tool used for generating pneumotachographs which are helpful in assessing conditions such as asthma, pulmonary fibrosis, cystic fibrosis, and COPD.
Le test de spirométrie est réalisée en utilisant un dispositif
appelé spiromètre, qui vient dans plusieurs
différentes variétés. La plupart des spiromètres afficher le
graphiques suivants, spirogrammes appelé:
une courbe volume-temps, le volume montrant (litres) ainsi que
l'axe Y et le temps (en secondes) le long de l'axe X
une boucle débit-volume, ce qui représente graphiquement la
débit d'air sur l'axe Y et le volume total
inspiré ou expiré sur l'axe X
[Modifier] Procédure
La capacité de volume de base vitale forcée (CVF)
varie légèrement selon le matériel utilisé.
Généralement, le patient est invité à prendre les
respiration très profonde, ils peuvent, puis expirez dans la
capteur aussi fort que possible, aussi longtemps que
possible, de préférence au moins 6 secondes. Il est
parfois directement suivie par une inhalation rapide
(Inspiration), en particulier lors de l'évaluation
possible obstruction des voies aériennes supérieures. Parfois, le
test sera précédée par une période de calme
inspirer et d'expirer par le capteur (marée
volume), ou le souffle rapide (forcé
partie inspiratoire) sera soumis à la force
exhalation.
Pendant l'essai, pince-nez souple peut être utilisé pour
éviter que l'air s'échappe par le nez. Filtrer
porte-parole peuvent être utilisés pour prévenir la propagation de
micro-organismes, en particulier pour inspiratoire
manœuvres.
Limitations of test
The maneuver is highly dependent on patient cooperation and effort, and is normally repeated at least three times to ensure reproducibility. Since results are dependent on patient cooperation, FEV1* and FVC can only be underestimated, never overestimated.(*FEV1 can be overestimated in people with some diseases - a softer blow can reduce the spasm or collapse of lung tissue to elevate the measure
Due to the patient cooperation required, spirometry can only be used on children old enough to comprehend and follow the instructions given (typically about 4–5 years old), and only on patients who are able to understand and follow instructions - thus, this test is not suitable for patients who are unconscious, heavily sedated, or have limitations that would interfere with vigorous respiratory efforts. Other types of lung function tests are available for infants and unconscious persons.
Another major limitation is the fact that many intermittent or mild asthmatics have normal spirometry between acute exacerbation, limiting spirometry's usefulness as a diagnostic. It is more useful as a monitoring tool: a sudden decrease in FEV1 or other spirometric measure in the same patient can signal worsening control, even if the raw value is still normal. Patients are encouraged to record their personal best measures.
The most common parameters measured in spirometry are Vital capacity (VC), Forced vital capacity (FVC), Forced expiratory volume (FEV) at timed intervals of 0.5, 1.0 (FEV1), 2.0, and 3.0 seconds, Forced expiratory flow 25–75% (FEF 25–75) and Maximal voluntary ventilation (MVV).[1] Other tests may be performed in certain situations.
Results are usually given in both raw data (litres, litres per second) and percent predicted - the test result as a percent of the "predicted values" for the patients of similar characteristics (height, age, sex, and sometimes race and weight). The interpretation of the results can vary depending on the physician and the source of the predicted values. Generally speaking, results nearest to 100% predicted are the most normal, and results over 80% are often considered normal. However, review by a doctor is necessary for accurate diagnosis of any individual situation.
A bronchodilator is also given in certain circumstances and a pre/post graph comparison is done to access the effectiveness of the bronchodilator. See the example printout.
Functional residual capacity (FRC) cannot be measured via spirometry, but it can be measured with a plethysmograph or dilution tests (for example, helium dilution test).
Forced Vital Capacity (FVC)
Forced Vital Capacity (FVC) is the volume of air that can forcibly be blown out after full inspiration, measured in liters. FVC is the most basic maneuver in spirometry tests.
[edit]Forced Expiratory Volume in 1 second (FEV1)
Average values for FEV1 in healthy people depend mainly on sex and age, according to diagram at left. Values of between 80% and 120% of the average value is considered normal.[3]
[edit]FEV1/FVC ratio (FEV1%)
FEV1/FVC (FEV1%) is the ratio of FEV1 to FVC. In healthy adults this should be approximately 75–80%. In obstructive diseases (asthma, COPD, chronic bronchitis, emphysema) FEV1 is diminished because of increased airway resistance to expiratory flow and the FVC may be decreased (for instance by premature closure of airway in expiration). This generates a reduced value (
Forced Inspiratory Flow 25–75% or 25–50%
Forced Inspiratory Flow 25–75% or 25–50% (FIF 25–75% or 25–50%) is similar to FEF 25–75% or 25–50% except the measurement is taken during inspiration.
[edit]Peak Expiratory Flow (PEF)
Normal values for Peak Expiratory Flow (PEF), shown on EU scale.[5]
Peak Expiratory Flow (PEF) is the maximal flow (or speed) achieved during the maximally forced expiration initiated at full inspiration, measured in liters per minute.
[edit]Tidal volume (TV)
Tidal volume (TV) is the specific volume of air drawn into, and then expired out of, the lungs during normal tidal breathing.
[edit]Total Lung Capacity (TLC)
Total Lung Capacity (TLC) is the maximum volume of air present in the lungs.
[edit]Diffusion capacity (DLCO)
Diffusing Capacity (DLCO) is the carbon monoxide uptake from a single inspiration in a standard time (usually 10 sec). This will pick up diffusion impairments, for instance in pulmonary fibrosis. This must be corrected for anemia (because rapid CO diffusion is dependent on hemoglobin in RBC's a low hemoglobin concentration, anemia, will reduce DLCO) and pulmonary hemorrhage (excess RBC's in the interstitium or alveoli can absorb CO and artificially increase the DLCO capacity).[dubious – discuss]
[edit]Maximum Voluntary Ventilation (MVV)
Maximum Voluntary Ventilation (MVV) is a measure of the maximum amount of air that can be inhaled and exhaled with in one minute. For the comfort of the patient this is done over a 15 second time period before being extrapolated to a value for one minute expressed as liters/minute. Average values for males and females are 140-180 and 80-120 liters per minute respectively.
Static lung compliance (Cst)
When estimating static lung compliance, volume measurements by the spirometer needs to be complemented by pressure transducers in order to simultaneously measure the transpulmonary pressure. When having drawn a curve with the relations between changes in volume to changes in transpulmmonary pressure, Cst is the slope of the curve during any given volume, or, mathematically, ?V/?P. Static lung compliance is perhaps the most sensitive parameter for the detection of abnormal pulmonary mechanics. It is considered normal if it is 60% to 140% of the average value in the population for any person of similar age, sex and body composition.
Forced Expiratory Time (FET)
Forced Expiratory Time (FET) measures the length of the expiration in seconds.
Slow Vital capacity (SVC)
Slow Vital capacity (SVC) is the maximum volume of air that can be exhaled slowly after slow maximum inhalation.
Maximal pressure (Pmax and Pi)
Pmax is the asymptotically maximal pressure that can be developed by the respiratory muscles at any lung volume and Pi is the maximum inspiratory pressure that can be developed at specific lung volumes.[8] This measurement also requires pressure transducers in addition. It is considered normal if it is 60% to 140% of the average value in the population for any person of similar age, sex and body composition.[3] A derived parameter is the coefficient of retraction (CR) which is Pmax/TLC .
Mean transit time (MTT)
Mean transit time is the area under the flow-volume curve divided by the forced vital capacity.[9]
[edit]Technologies used in spirometers
Volumetric Spirometers
Water bell
Bellows wedge
Flow measuring Spirometers
Fleisch-pneumotach
Lilly (screen) pneumotach
Turbine (actually a rotating vane which spins because of the air flow generated by the subject. The revolutions of the vane are counted as they break a light beam)
Pitot tube
Hot-wire anemometer
Ultrasound
Mediastinoscopy is introduction of an endoscope into the mediastinum. Mediastinotomy is surgical opening of the mediastinum. The two are complementary. Mediastinotomy gives direct access to aortopulmonary window lymph nodes, which are inaccessible by mediastinoscopy. Both procedures are done to evaluate or excise mediastinal lymphadenopathy or masses and to stage cancers (eg, lung cancer, esophageal cancer), although PET scanning is decreasing the need for these procedures for cancer staging.
Contraindications: Contraindications include the following:
Superior vena cava syndrome
Previous mediastinal irradiation
Mediastinoscopy
Median sternotomy
Tracheostomy
Aneurysm of the aortic arch
Mediastinoscopy and mediastinotomy are done by surgeons in an operating room using general anesthesia. For mediastinoscopy, the soft tissue of the neck is bluntly dissected down to the trachea and distally to the carina through an incision in the suprasternal notch. A mediastinoscope is inserted into the space allowing access to the paratracheal, tracheobronchial, azygous, and subcarinal nodes and to the superior posterior mediastinum. Anterior mediastinotomy (the Chamberlain procedure) is surgical entry to the mediastinum through an incision in the parasternal 2nd left intercostal space, allowing access to anterior mediastinal and aortopulmonary window lymph nodes, common sites of metastases for left upper lobe lung cancers.
Complications: Complications occur in < 1% of patients and include bleeding, infection, vocal cord paralysis from recurrent laryngeal nerve damage, chylothorax from duct injury, and pneumothorax.
Mediastinoscopy is a surgical procedure that enables visualization of the contents of the mediastinum, usually for the purpose of obtaining a biopsy. Mediastinoscopy is often used for staging of lymph nodes of lung cancer or for diagnosing other conditions affecting structures in the mediastinum such as sarcoidosis or lymphoma.
Mediastinoscopy involves making an incision approximately 1 cm above the suprasternal notch of the sternum, or breast bone. Dissection is carried out down to the pretracheal space and down to the carina. A scope (mediastinoscope) is then advanced into the created tunnel which provides a view of the mediastinum. The scope may provide direct visualization or may be attached to a video monitor.
Mediastinoscopy provides access to mediastinal lymph node levels 2, 4, and 7.
[edit]Extended mediastinoscopy
Extended mediastinoscopy is a technique which allows access to the pre-aortic (station 6) and aortopulmonary window (station 5) lymph nodes.
[edit]Parasternal mediastinotomy
Parasternal mediastinotomy, aka, a Chamberlain procedure, is the standard approach to access lymph nodes at
Computer-Tomographically Guided Fiberbronchoscopic Transbronchial Biopsy of Small Pulmonary Lesions: A Feasibility Study
Small pulmonary lesions localized in peripheral airways or lung parenchyma are mostly not visible by means of flexible or rigid bronchoscopy for they are distal to the inspectable airway caliber. Therefore fluoroscopy is necessary to direct the flexible biopsy forceps or biopsy needle to the lesion. Even a two-dimensional fluoroscopic guidance does not guarantee an access to the focus. Therefore we investigated a method to overcome these problems. In 9 patients with peripheral lung lesions where the conventional method had failed to provide sufficient biopsies CT-guided bronchoscopy was done. Central airways were carefully inspected, and the flexible forceps was introduced into the bronchial branch leading to the focus under fluoroscopic control. Then the forceps was localized in the axial plane by CT and guided directly to the lesion. Subsequently the forceps was opened and contact to the lesion was confirmed by CT scan before the biopsies were taken. Thus the three-dimensional control of the position of the forceps made it possible to get biopsies directly from the region of interest. The method provides the possibility of reaching even small peripheral lesions that have been missed by the conventional techniques, thereby, although technically more difficult for the examiner, providing a smaller risk of complications and no additional discomfort for the patient.
taken from
Thoracoscopy is a medical procedure involving internal examination, biopsy, and/or resection of disease or masses within the pleural cavity and thoracic cavity.[1] Thoracoscopy may be performed either under general anaesthesia or under sedation with local anaesthetic.
from
Thoracoscopy was developed by Hans Christian Jacobaeus, a Swedish internist in 1910 for the treatment of tuberculous intra-thoracic adhesions. He used a cystoscope to examine the thoracic cavity, developing his technique over the next twenty years. Today, thoracoscopy is performed using specialized thoracoscopes. These instruments include a light source and a lens for viewing and may have ports through which other instruments may be inserted for the purpose of tissue removal and manipulation.
Video-assisted thoracoscopic surgery (VATS) is a surgical operation involving thoracoscopy, usually performed by a thoracic surgeon using general or local/regional anaesthesia with additional sedation as necessary. It has historically also been referred to as pleuroscopy. A wide variety of diagnostic and therapeutic procedures may be performed with this technique which has become very popular and increasingly so since the early 1990s. Prior to this, limited diagnostic procedures were done using variations on the cystoscope since 1910. Advances in direct optical visualization were quickly surpassed when video cameras were attached to the endoscopes. The advent of endoscopic stapling was also a major advance so that complicated procedures such as pulmonary lobectomy could be performed safely.
Trauma is the leading cause of death for individuals younger than 40 years of age, with approximately 140,000 deaths annually in the United States alone.1 Of these deaths, thoracic injuries are primarily responsible for 25% of cases2 and are a major contributing factor in up to 75% of cases.1 However, most injuries may be effectively treated with thoracostomy and simple fluid resuscitation.3,4
Tube thoracostomy is the insertion of a tube (chest tube) into the pleural cavity to drain air, blood, bile, pus, or other fluids.5 Whether the accumulation is the result of rapid traumatic filling or insidious malignant seepage, placement of a chest tube allows for continuous, large volume drainage until the underlying pathology can be more formally addressed. The list of specific treatable etiologies is extensive (see Indications), but without intervention, patients are at great risk for major morbidity or mortality.
Indications
Pneumothorax6
Open or closed
Simple or tension7
Hemothorax6
Hemopneumothorax
Hydrothorax
Chylothorax8
Empyema
Pleural effusion9
Patients with penetrating chest wall injury who are intubated or about to be intubated
Considered for those about to undergo air transport who are at risk for pneumothorax
Contraindications
The need for emergent thoracotomy is an absolute contraindication to tube thoracostomy.
Relative contraindications include the following:
Coagulopathy
Pulmonary bullae
Pulmonary, pleural, or thoracic adhesions
Loculated pleural effusion or empyema
Skin infection over the chest tube insertion site
Tube thoracostomy is insertion of a tube into the pleural space. It is used to drain air or fluid from the chest (eg, for large or recurrent effusion refractory to thoracentesis, pneumothorax, complicated parapneumonic effusions, empyema, hemothorax) and to do pleurodesis or fibrinolytic adhesiolysis.
Procedure: Chest tube insertion is best done by a physician trained in the procedure. Other physicians can handle emergency situations (eg, tension pneumothorax) using a needle and syringe. Tube insertion requires 1 or 2 hemostats or Kelly clamps, a silk suture, gauze dressing, and a chest tube. Recommended tube sizes are 16 to 24 French (F) for pneumothorax; 20 to 24 F for malignant pleural effusion; 28 to 36 F for bronchopleural fistula, complicated parapneumonic effusions, and empyema; and 32 to 40 F for hemothorax.
The insertion site and patient position depend on whether air or fluid is being drained. For pneumothorax, the tube is usually inserted in the 4th intercostal space and for other indications in the 5th or 6th intercostal space, in the midaxillary line with the ipsilateral arm abducted above the head.
No specific patient preparation is necessary except, in some cases, conscious sedation. Under sterile conditions, the skin, subcutaneous tissue, rib periosteum, and parietal pleura are locally anesthetized, more generously than for thoracentesis (see Diagnostic and Therapeutic Pulmonary Procedures: Thoracentesis). Proper location is confirmed by return of air or fluid in the anesthetic syringe. A purse-string suture can be placed but not yet tied around the site while the anesthetic takes effect. A 2-cm skin incision is made, and the intercostal soft tissue down to the pleura is then bluntly dissected by advancing a clamped hemostat or Kelly clamp and opening it; the pleura is then perforated with the clamped instrument and opened in the same way. A finger can be used to widen the tract and confirm entry into the pleural space. The chest tube, with a clamp grasping the tip, is inserted through the tract and directed inferoposteriorly for effusions, or apically for pneumothorax, until all of the tube's holes are inside the chest wall. The purse-string suture is closed, the tube is sutured to the chest wall, and a sterile dressing with petroleum gauze to help seal the wound is placed over the site.
The tube is connected to water seal to prevent air from entering the chest through the tube and to allow drainage without suction (for effusions or empyema) or with suction (for pneumothorax). Posteroanterior and lateral chest x-rays are obtained after insertion to check the tube's position.
The tube is removed when the condition for which it was placed resolves. In the case of pneumothorax, suction is stopped and the tube is placed on water seal for several hours to ensure that the air leak has stopped and that the lung remains expanded. At the moment of removal, the patient is asked to take a deep breath and then to forcibly exhale; the tube is removed during exhalation and the site is covered with petroleum gauze, a sequence that reduces the chance of pneumothorax during removal. For effusions or hemothorax, the tube is typically removed when the drainage is < 100 mL/day.
Complications: Complications include the following:
Malpositioning of the tube in the lung parenchyma, in the lobar fissure, under the diaphragm, or subcutaneously
Clotting, kinking, or dislodgement of the tube, requiring replacement
Re-expansion pulmonary edema
Subcutaneous emphysema
Infection of residual pleural fluid or recurrent effusion
Pulmonary or diaphragmatic laceration
Rarely, perforation of other structures
Pleural Puncture and Drainage
Accumulations of air and / or fluid within the pleura-, pericardial or abdominal space can cause life-threatening disorders of the respiration as well as the cardiac function. Therefore, the objective of every emergency therapy is to totally remove the air or fluid. This used to be done either by needle puncture or by placing a sterile, surgical suction drainage. Large bore catheters (so-called Bülau Drainages) are to be avoided whenever possible, from the costs´ point of view and the advantages of a minimal invasive surgery for the patient. B. Braun developed a special, small bore PUR catheter which also allowed safe drainage, and if necessary irrigation, of visceral cavities being under negative pressure (Pneumothorax Drainage), without any additional surgical devices by means of a 3-way stopcock and an adjacent back check valve. Pleuracan® has become widely accepted for thorax drainage from the beginning, also in pediatrics. For short term decompression and drainage of the pleural cavity B. Braun offers the Pleurofix®-Sets.
Is the volume of a pleural effusion predictable using the thickness of the pleural lamella measured by sonography as a reference?
M Cardon, N Müller, M Van de Velde, J Ghekiere,
The aim of this study was to quantify the volume of pleural effusions (PEs) in the critically ill using ultrasound. PE was suggested on the daily postero-anterior chest radiography [1] in the semirecumbent position. All patients with suspected PE were investigated with ultrasound. We hypothesize that there is a strong correlation between the maximal width of the fluid lamella along the lateral chest wall (seen on sonography) and the volume of pleural fluid punctured.
Materials and methods
The study was approved by the hospital Ethics Committee. Eighty-seven consecutive critically ill patients underwent a pleural puncture when ultrasound analysis revealed a lamella of more than 2 cm [2]. A total of 138 pleural punctures was performed in 87 individuals. Ultrasound was performed using the ACUSON, sequoia 512, with the patient in the semirecumbent position. The deepest possible puncture side in this position was marked for pleural puncture. The PE was gradually drained, 200 ml at a time, until the fluid was completely evacuated. The width of the pre-puncture effusion lamella as measured with ultrasound was compared case by case with the actual punctured volume. Statistical analysis was performed using linear regression analysis and Spearman (rank) correlation coefficient.
Results
Due to technical difficulties or missing data, 7 punctures had to be excluded. 131 punctures (67 on the left hemithorax and 64 on the right) remained for analysis. No complications were encountered as a consequence of the pleural puncture.
The sonographic measurements correlated very well with actual effusion volume on the left (rs = 0.83) and the right side (rs = 0.77). For both sides the level of statistical significance was taken as P < 0.001.
The thickness of the fluid lamella was taken as the independent variable, while the actual effusion volume was taken as the dependent variable. The linear sonographic method was represented by the equation y = 208.77×-317.12 (left), and y = 178.38×-159.7 (right). Y is the predicted effusion volume in milliliters and × is the sonographically measured thickness of the effusion lamella in centimeters. The mean predicted error was 199.7 ml for the left side and 285.3 ml for the right side.
Discussion
There is a strong correlation between the sonographic measurements and the actual effusion volume which was punctured. Unlike the findings of other authors, we were not able to predict the punctured volume, based on the width of the lamella measured by sonography probably due to the wide spread of obtained data (scatter plot).
Sputum Examination in the Screening and Diagnosis of Pulmonary Tuberculosis in the Elderly
Pulmonary tuberculosis is not uncommon in the elderly, particularly those in institutions, and is notoriously difficult to diagnose. Few bacilli are excreted by individuals with non-cavitating disease and positive cultures are usually required to confirm the diagnosis. Radiography is a poor screening method, and the role of the Mantoux test in this population controversial. The value of sputum culture as a screening procedure in elderly people with a productive cough was therefore investigated. In a prospective surveillance study over 26 months, all permanent residents in homes for the elderly were entered on the basis of a productive cough for 3 weeks or more irrespective of any known or presumed cause. Both smears and cultures were performed on sputum specimens, and Mantoux tests and chest radiographs were performed on those who were sputum positive.
The 205 subjects investigated yielded 446 smears, seven of which were positive for acid-fast bacilli, and 433 cultures, 32 of which were positive for M. tuberculosis. From this 19 patients with pulmonary tuberculosis were identified, 18 of whom had non-cavitating disease on chest radiography. The numbers of bacilli in these patients were shown to be low and the excretion pattern haphazard. Smears were not sufficiently sensitive to diagnose non-cavitating tuberculosis in this population, and the sputum must be cultured in order to exclude the diagnosis. Four negative cultures are required in order to exclude the presence of pulmonary tuberculosis.
sorry, our translation may be too bad, but we have a little to contribute to your wonderful and super-great work!
It is well known that repeat sputum
examination increases the yield of positive cases
of pulmonary tuberculosis (Barton, 1958;
Chandrasekhar et al, 1970; Nair et al, under
print). For the purpose, overnight collected
sputum specimens are considered superior to
spot specimens (Andrews & Radhakrishna,
1959) though not always (Rao et al, 1966).
Practical considerations, however, tend to
restrict
the number and type of specimens that may be
obtained from each individual.
In surveys, where ‘culture only positive’
cases preponderate, though examination of two
specimens from each eligible individual
discovers a majority of the cases, yet each
succeeding specimen may add about 10% to the
initial yield, till six to eight more specimens
have
been examined (Nair et al, ibid). Among
symptomatics attending TB Centres, however,
examination of two specimens discovered over
85 % of all smear positives ho could be found on
examination of as many as eight specimens from
each individual (Nagpaul et al, 1974). This is
because relatively advanced cases attend TB
centres, which may also explain why the yield
from two smear examinations nearly
equalled that from one culture.
The preliminary screening to decide
eligibility for sputum examination, in the clinic
as well as survey situations, is by X-ray
examination except in peripheral health
institutions under the National Tuberculosis
Programme (NTP). It would be worthwhile to
investigate the relation-ship between the X-ray
screening and bacteriological results, in terms of
the initial yield as well as further additions by
repeated sputum examination. Since culture
facility is not always available, the relationship
in respect of the smear alone results may also be
of interest to NTP workers.
Method and Material
In the reported study by Nagpaul et al (ibid),
1701 symptomatic patients over 5 years of age
had attended an urban tuberculosis centre for
diagnosis over a period of five weeks. They were
examined by X-ray followed by sputum. To cast
the net for sputum examination wider, all the
Xrays
were adjudged as per the NTP code (DTP
manuals, 1974), independently by two X-ray
readers. The X-ray abnormals of either reader
were listed in. three sub-groups. A stratified
systematic sample comprising 236 patients was
then drawn from the sub-groups. Each sample
patient was subjected to eight successive sputum
examinations, by smear as well as culture.
All sputum specimens — four spot and four
overnight from each — were obtained by a
research team in the patients’ homes. The first
sputum container having been issued at the
centre, a minimum of four home visits was
essential for collection of all the eight
specimens.
Since many of the patients were put on
treatment, a fortnight was the maximum period
allowed to complete the collection. Each
specimen was examined without reference to the
results of the other specimens collected from the
same patient.
Of the 236 study patients, 42 (17.8%) had to
be excluded: 20 either did not co-operate or had
no sputum at times, 11 gave wrong or
insufficient address, 10 migrated and one died,
leaving 194 patients for analysis.
Results
a. X-ray Screening
Correlation between the results of the two Xray
readers is given in Table 1.
Of the 194 double readings, complete
agreement between the readers was in respect of
the 90 (46.4 %) shown on the diagonal. The
maximum agreement was for the TBP reading
only i.e., 64 out of 110 (58.2 % ) Frequencies
above the diagonal line being fewer, a
comparatively
more discriminative or “conservative”
reading by the second reader was obvious. Such
a wide disagreement in X-ray reading in clinical
material between experienced readers was not
expected. Instead of an umpire reading for
resolving
the disagreements, the difficulty about
studying the relationship
Sputum examination in the diagnosis of Pneumocystis carinii pneumonia.
Toma E, Pirzadeh B, Ravaoarinoro M, Cyr L; International Conference on AIDS.
Int Conf AIDS. 1994 Aug 7-12; 10: 179 (abstract no. PB0729).
Hotel-Dieu de Montreal, Canada.
OBJECTIVE: To assess whether the examination of spontaneously expectorated sputum has any value in comparison with the bronchoalveolar lavage (BAL) for the diagnosis of Pneumocystis carinii pneumonia (PCP) in HIV-infected persons. METHODS: A monoclonal antibody fluorescent stain was used in the last 3 years for the diagnosis of PCP for both sputum and BAL specimens. The BAL examination was considered the standard method. The sensitivity, specificity, negative and positive predictive values for sputum were calculated in patients for whom both sputum and BAL specimens were available. RESULTS: A total of 484 sputum and 347 BAL samples were examined for the presence of P. carinii from Jan. 1991 to Jan. 1994. Eighty one (16.7%) sputum and 154 (44.4%) BAL specimens were positive. For 103 patients with both sputum and BAL examined within 6 days, P. carinii was found in 30 sputum and 55 BAL samples. Forty-eight specimens were negative with both methods. All patients with a BAL positive P. carinii had a clinically proven PCP. The sensitivity, specificity, negative and positive predictive values for sputum examination in BAL positive patients were 54.5%, 100%, 65.7% and 100% respectively. DISCUSSION AND CONCLUSIONS: Sputum examination by a specific and sensitive method could detect half of the patients with PCP diagnosed by performing a BAL, though reducing the need for bronchoscopy. This simple, low cost examination might be useful in setting were neither the induced sputum nor the BAL could be performed.
Publication Types:
Meeting Abstracts
Keywords:
Acquired Immunodeficiency Syndrome
Bronchoscopy
Costs and Cost Analysis
Evaluation Studies
HIV Infections
HIV Seropositivity
Humans
Laboratory Techniques and Procedures
Pneumonia, Pneumocystis
Sensitivity and Specificity
Sputum
Staining and Labeling
diagnosis
economics
methods
organization & administration
Other ID:
94371342
UI: 102210175
From Meeting Abstracts
What is a Chest X-ray (Chest Radiography)?
The chest x-ray is the most commonly performed diagnostic x-ray examination. A chest x-ray makes images of the heart, lungs, airways, blood vessels and the bones of the spine and chest.
An x-ray (radiograph) is a noninvasive medical test that helps physicians diagnose and treat medical conditions. Imaging with x-rays involves exposing a part of the body to a small dose of ionizing radiation to produce pictures of the inside of the body. X-rays are the oldest and most frequently used form of medical imaging.
What are some common uses of the procedure?
The chest x-ray is performed to evaluate the lungs, heart and chest wall.
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A chest x-ray is typically the first imaging test used to help diagnose symptoms such as:
shortness of breath.
a bad or persistent cough.
chest pain or injury.
fever.
Physicians use the examination to help diagnose or monitor treatment for conditions such as:
pneumonia.
heart failure and other heart problems.
emphysema.
lung cancer.
line and tube placement.
other medical conditions.
How should I prepare?
A chest x-ray requires no special preparation.
You may be asked to remove some or all of your clothes and to wear a gown during the exam. You may also be asked to remove jewelry, dentures, eye glasses and any metal objects or clothing that might interfere with the x-ray images.
Women should always inform their physician and x-ray technologist if there is any possibility that they are pregnant. Many imaging tests are not performed during pregnancy so as not to expose the fetus to radiation. If an x-ray is necessary, precautions will be taken to minimize radiation exposure to the baby. See the Safety page (www.RadiologyInfo.org/en/safety/) for more information about pregnancy and x-rays.
What does the equipment look like?
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The equipment typically used for chest x-rays consists of a wall-mounted, box-like apparatus containing the x-ray film or a special plate that records the image digitally and an x-ray producing tube, that is usually positioned about six feet away.
The equipment may also be arranged with the x-ray tube suspended over a table on which the patient lies. A drawer under the table holds the x-ray film or digital recording plate.
A portable x-ray machine is a compact apparatus that can be taken to the patient in a hospital bed or the emergency room. The x-ray tube is connected to a flexible arm that is extended over the patient while an x-ray film holder or image recording plate is placed beneath the patient.
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How does the procedure work?
X-rays are a form of radiation like light or radio waves. X-rays pass through most objects, including the body. Once it is carefully aimed at the part of the body being examined, an x-ray machine produces a small burst of radiation that passes through the body, recording an image on photographic film or a special digital image recording plate.
Different parts of the body absorb the x-rays in varying degrees. Dense bone absorbs much of the radiation while soft tissue, such as muscle, fat and organs, allow more of the x-rays to pass through them. As a result, bones appear white on the x-ray, soft tissue shows up in shades of gray and air appears black.
On a chest x-ray, the ribs and spine will absorb much of the radiation and appear white or light gray on the image. Lung tissue absorbs little radiation and will appear dark on the image.
Until recently, x-ray images were maintained as hard film copy (much like a photographic negative). Today, most images are digital files that are stored electronically. These stored images are easily accessible and are frequently compared to current x-ray images for diagnosis and disease management.
wooow! As usual... your people are here again to give us what they've got... Lucky you, you are really expanding. I can even read some french from some french hospital and I also reaize some German and Japanese Hospitals are also giving their contribution. I wonder how your real hospital would be if your internet one is making so much internation wave like this. Keep it up ma! Here is my own little contribution.... not from my head though, so I am gonna like paste the site I got the info from. Keep the good work my dear Doc.... U now have 10 detailed and well researched hubs.... This is great
How is the procedure performed?
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Typically, two views of the chest are taken, one from the back and the other from the side of the body as the patient stands against the image recording plate. The technologist, an individual specially trained to perform radiology examinations, will position the patient with hands on hips and chest pressed against the image plate. For the second view, the patient's side is against the image plate with arms elevated.
Patients who cannot stand may be positioned lying down on a table for chest x-rays.
You must hold very still and may be asked to keep from breathing for a few seconds while the x-ray picture is taken to reduce the possibility of a blurred image. The technologist will walk behind a wall or into the next room to activate the x-ray machine.
When the examination is complete, you will be asked to wait until the radiologist determines that all the necessary images have been obtained.
The chest x-ray examination is usually completed within 15 minutes.
Additional views may be required within hours, days or months to evaluate any changes in the chest.
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What will I experience during and after the procedure?
A chest x-ray examination itself is a painless procedure.
You may experience discomfort from the cool temperature in the examination room and the coldness of the recording plate. Individuals with arthritis or injuries to the chest wall, shoulders or arms may have discomfort trying to stay still during the examination. The technologist will assist you in finding the most comfortable position possible that still ensures diagnostic image quality.
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Who interprets the results and how do I get them?
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A radiologist, a physician specifically trained to supervise and interpret radiology examinations, will analyze the images and send a signed report to your primary care or referring physician, who will discuss the results with you.
The results of a chest x-ray can be available almost immediately for review by your physician.
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What are the benefits vs. risks?
Benefits
No radiation remains in a patient's body after an x-ray examination.
X-rays usually have no side effects in the diagnostic range.
X-ray equipment is relatively inexpensive and widely available in emergency rooms, physician offices, ambulatory care centers, nursing homes and other locations, making it convenient for both patients and physicians.
Because x-ray imaging is fast and easy, it is particularly useful in emergency diagnosis and treatment.
Risks
There is always a slight chance of cancer from excessive exposure to radiation. However, the benefit of an accurate diagnosis far outweighs the risk.
The chest x-ray is one of the lowest radiation exposure medical examinations performed today. The effective radiation dose from this procedure is about 0.1 mSv, which is about the same as the average person receives from background radiation in 10 days. See the Safety page (www.RadiologyInfo.org/en/safety/) for more information about radiation dose.
Women should always inform their physician or x-ray technologist if there is any possibility that they are pregnant. See the Safety page (www.RadiologyInfo.org/en/safety/) for more information about pregnancy and x-rays.
I can't say more than what Dchosen_01 has just said. You are indeed going viral. My dad used to say that the best medical practitioner is the most dedicated apprentice. I hope you would not just read, do research and write, but as well practice it well to be very good. U have already proven to the world what you are made of, what is left is to go out there and manifest it. I wish you all the best in your quest man! I read Dchosen_01's comment and I decided to do the same. I realized he didn't paste all the info, so I finished up the job.... Our little contribution as we join hands with you in this prestigious community service of yours...
A Word About Minimizing Radiation Exposure
Special care is taken during x-ray examinations to use the lowest radiation dose possible while producing the best images for evaluation. National and international radiology protection councils continually review and update the technique standards used by radiology professionals.
State-of-the-art x-ray systems have tightly controlled x-ray beams with significant filtration and dose control methods to minimize stray or scatter radiation. This ensures that those parts of a patient's body not being imaged receive minimal radiation exposure.
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What are the limitations of Chest Radiography?
The chest x-ray is a very useful examination, but it has limitations. Because some conditions of the chest cannot be detected on a conventional chest x-ray image, this examination cannot necessarily rule out all problems in the chest. For example, small cancers may not show up on a chest x-ray. A blood clot in the lungs, a condition called a pulmonary embolism, cannot be seen on chest x-rays.
Further imaging studies may be necessary to clarify the results of a chest x-ray or to look for abnormalities not visible on the chest x-ray.
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Additional Information and Resources
RadiologyInfo
Radiation Therapy for Lung Cancer:
www.RadiologyInfo.org/en/info.cfm?pg=lungcancer
RTAnswers.org
Radiation Therapy for Lung Cancer:
www.rtanswers.org/treatmentinformation/cancertypes/lung/index.aspx
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Locate an ACR-accredited provider: To locate a medical imaging or radiation oncology provider in your community, you can search the ACR-accredited facilities database.
Exam costs: The costs for specific medical imaging tests and treatments vary widely across geographic regions. Many—but not all—imaging procedures are covered by insurance. Discuss the fees associated with your medical imaging procedure with your doctor and/or the medical facility staff to get a better understanding of the portions covered by insurance and the possible charges that you will incur.
woooow! This is amazing. I missed all those long comments and contributions from such organization. Yeah! Japanese, French and German hospitals are now getting involved with this little project of mine. This is fantastic and lovely. I never knew this project will go this far, but I Glory be to God for this achievement. Maybe I should begin a German, japanese and French segment of this project (lol!). Yeah, as for your suggestion (al_masculine), I will do well to practice well and have lots of experience and skills in the field I have chosen. This is just the top-most tip of the iceberg, more is to come and by God's grace, I will make good use of my holidays (especially the summer ones very well). The aspect of this project I am expecting now is for this little Hospital clinic to gain some popularity and then individuals, coming here to ask questions and seek help. I wish to reach that height but before then I think I should concentrate and move on.
Thank you everyone and keep on reading and contributing, so that we can make the world a better place- 'health-wise'..
My dear doctor. Here is a very complicated case, I want you to solve.....
A man (82 years old) was complaining of wet cough with white sputum which is accompanied with pain in the chest region. 16 years ago, he started feeling such pains after an operation on his heart. He feels such pains twice a day. But also, he remembers inhaling smoke from burning dry marple tree leaves which triggered the symptoms. He has a history of surgery and hernia after surgery on the abdominal region (didn't say which kind of surgery). Also had cholecystitis, Adenoma of prostrate and has smoked for 35 years, but stopped 15 years back. No allergies, no family history of disease. Presently, there is cyanosis on his lips, redness of face (especially, the nose), barrel-like chest (anterior-posterior chest); buffalo hump and no signs of edema. He experiences dypsnea at rest and most often for the past 18 years, he has been experiencing palpitations and general weakness which were treated at home.
What can you say about this illness?
wow! This is a nice case. Quite complicated as you have said, but the diagnosis is also very easy. He has been a chronic smoker for 35 years, and now he is 82 yrs. Even though he might have stopped for his last 15 years, it still very important in diagnosing this ailment. His buffalo hump indicates the side effect of taking corticorsteriods/glucocorticoids. So, initial diagnosis would be Chronic Obstructive Pulmonary disease ( further test and instrumental examination will either confirm this as my clinical diagnosis or say otherwise. Not just confirming this, but we need to know its severity. If you had told me about his physical state, and some laboratory results, I may have an idea of his diagnosis. But nevertheless, I think and am 85-99% sure its COPD.
At his age, I think Teopek (theophyllin of pro-longed action- aerosol should be given to him as well as Ventolin (Salbutamol) also an aerosol of short action ( a bronchio-dilator). As for the cholecystitis, adenoma of prostrate and abdominal hernia, they can be taken are of appropraitely, but I do not think they contribute to the diagnosis of this disease.
I am happy to get such questions, please ask more if you have them....
D.Virtual.Doctor...
wow! So fast, thank you very much...
Good Hub, you sure have done your research. It's good to have this info.
Thank you so much SUSIE405. I need people like you to put in your contributions here so that I can work header and serve the community better.
Very indepth, great research, keep up the very good work you have produced on this hub. SB
Thank you BlackSea for your own contribution.... Its encouraging to me.
Very informative and useful hub, I voted you up here! Check out my anti-smoking hub about lung disease and cancer, people forced to sleep sitting up or elevated to breath through the night. I have quite a few family members suffering with this today, and I assist. in there care now. Help me in my fight against smoking, the leading cause of these terrible ailments. Thank you so very much for sharing all your good wisdom here with us on hubpages, keep writing and I'll keep reading.
D.Virtual.Doctor Hub Author 19 months ago
hi guys.... This hub in particular may be too professional, nevertheless, most of us still need it. If a patient will undergo any of the processes above, its not wrong for him or her to know what its all about. Hence its worth knowing, isn't it? Your contributions and questions are welcome and as usual, I would be expecting a flood of comments from my usual medical groups (Universities, clinics and websites).Thanks and cheers!
D.Virtual.Doctor