Figures
- Fig. 1—
a, b) Examples of obstructive pulmonary defects with a low (a; forced expiratory volume in one second (FEV1) 38%; FEV1/vital capacity (VC) 46%; peak expiratory flow (PEF) 48%; total lung capacity (TLC) 101%) or normal (b; FEV1 57%; FEV1/VC 73%; PEF 43%; TLC 96%) ratio of FEV1/VC. In both cases, TLC is normal, and flows are less than expected over the entire volume range. c) Example of a typical restrictive defect (FEV1 66%; FEV1/VC 80%; PEF 79%; TLC 62%). The TLC is low and flow is higher than expected at a given lung volume. d) Example of a typical mixed defect characterised by a low TLC and a low FEV1/VC ratio (FEV1 64%; FEV1/VC 64%; PEF 82%; TLC 72%). – – – –: predicted flow–volume curves; ––––: observed inspiratory and expiratory flow–volume curves (as indicated in a).
- Fig. 2—
A simplified algorithm that may be used to assess lung function in clinical practice. It presents classic patterns for various pulmonary disorders. As in any such diagram, patients may or may not present with the classic patterns, depending on their illnesses, severity and lung function prior to the disease onset (e.g. did they start with a vital capacity (VC) close to the upper or lower limits of normal (LLN)). The decisions about how far to follow this diagram are clinical, and will vary depending on the questions being asked and the clinical information available at the time of testing. The forced expiratory volume in one second (FEV1)/VC ratio and VC should be considered first. Total lung capacity (TLC) is necessary to confirm or exclude the presence of a restrictive defect when VC is below the LLN. The algorithm also includes diffusing capacity for carbon monoxide (DL,CO) measurement with the predicted value adjusted for haemoglobin. In the mixed defect group, the DL,CO patterns are the same as those for restriction and obstruction. This flow chart is not suitable for assessing the severity of upper airway obstruction. PV: pulmonary vascular; CW: chest wall; NM: neuromuscular; ILD: interstitial lung diseases; CB: chronic bronchitis.
- Fig. 3—
Idealised examples of a) fixed, b) variable extrathoracic, and c) variable intrathoracic airway obstruction.
- Fig. 4—
Example of unilateral main bronchus obstruction due to a valve-like mechanism occluding the main left stem bronchus during inspiration as a result of a surgical scar. There is a delay in gas filling towards the end of the forced inspiration as evidence of the variable unilateral main bronchus obstruction (forced expiratory volume in one second (FEV1): 76%; FEV1/vital capacity: 70%; peak expiratory flow: 93%; total lung capacity: 80%). -----: predicted expiratory flow–volume loop; ––––: recorded maximum inspiratory and expiratory flow–volume loops.
Tables
- Table. 1—
Outcomes of a MEDLINE search using the keywords“reference equations” and “spirometry”
First author Year Country/area/nature of study Journal Kotaniemi 2004 Finland; adults Int J Circumpolar Health 2004; 63: 129–139 Subbarao 2004 Canada; comparison of references Pediatr Pulmonol 2004; 37: 515–522 Falaschetti 2004 England; prediction equations from the Health Survey Eur Respir J 2004; 23: 456–463 Botsis 2003 Greece; neural networks for the prediction of spirometric reference values in the elderly Med Inform Internet Med 2003; 28: 299–309 Ben Saad 2003 Tunisia; vital capacity and peak expiratory flow rates in the elderly Rev Mal Respir 2003; 20: 521–530 (French) Mustajbegovic 2003 Croatia; comparison with European reference values Croat Med J 2003; 44: 614–617 Perez-Padilla 2003 Mexico; comparison with Mexican American children Pediatr Pulmonol 2003; 35: 177–183 Torres 2003 Brazil; height and arm span in children Pediatr Pulmonol 2003; 36: 202–208 Golshan 2003 Iran Eur Respir J 2003; 22: 529–534 Mohamed 2002 Italy Lung 2002; 180: 149–159 Boskabady 2002 Iran Respiration 2002; 69: 320–326 Havryk 2002 Himalayan Sherpas Respir Physiol Neurobiol 2002; 132: 223 Dejsomritrutai 2002 Thailand Respirology 2002; 7: 123–127 Langhammer 2001 Norway Eur Respir J 2001; 18: 770–779 Milivojevic-Poleksic 2001 Pacific Island Respirology 2001; 6: 247–253 Marion 2001 USA; American Indian Chest 2001; 120: 489–495 Kivastik 2001 Estonia; school children Clin Physiol 2001; 21: 490–497 Manzke 2001 Germany; children aged 6–16 yrs from “hospital normals” Eur J Pediatr 2001; 160: 300–306 Perez-Padilla 2001 Mexico; Mexican workers Salud Publica Mex 2001; 43: 113–121 (Spanish) Pistelli 2000 Italy Am J Respir Crit Care Med 2000; 161: 899–905 Vijayan 2000 India; South Indian children Indian J Chest Dis Allied Sci 2000; 42: 147–156 Baltopoulos 2000 Greece; Greek elderly Lung 2000; 178: 201–212 Ip 2000 Chinese children and adolescents in Hong Kong Am J Respir Crit Care Med 2000; 162: 424–429 Dejsomritrutai 2000 Thailand J Med Assoc Thai 2000; 83: 457–466 Quadrelli 1999 Italy Respir Med 1999; 93: 523–535 Morato Rodriguez 1999 Spain; children of Basque Autonomic Community An Esp Pediatr 1999; 51: 17–21 (Spanish) Crapo 1999 Comparison of Mongolians/Caucasians Eur Respir J 1999; 13: 606–609 Hankinson 1999 USA population sample, aged 8–80 yrs (NHANES III) Am J Respir Crit Care Med 1999; 159: 179–187 Baur 1999 Germany; comparison of lung function reference values Int Arch Occup Environ Health 1999; 72: 69–83 McDonnell 1998 USA; older adults Respir Med 1998; 92: 914–921 Martin 1998 Canada; Quebec Rev Mal Respir 1998; 15: 781–788 (French) Castellsague 1998 ECRHS; European populations Respir Med 1998; 92: 401–407 Roca 1998 ECRHS; validation Eur Respir J 1998; 11: 1354–1362 Pan 1997 China; Taiwan Chin J Physiol 1997; 40: 165–174 Rajkappor 1997 India; school children Indian J Chest Dis Allied Sci 1997; 39: 97–105 Luttmann 1997 Germany; 7–18-yr-old probands Pneumologie 1997; 51: 47–54 (German) Chin 1997 Singapore; nonsmoking adults Respirology 1997; 2: 143–149 Oyarzun 1996 Chile Rev Med Chil 1996; 124: 1365–1367 (Spanish) Gutierrez 1996 Chilean population >5 yrs old Rev Med Chil 1996; 124: 1295–1306 (Spanish) Enright 1996 USA; elderly Blacks Chest 1996; 110: 1416–1424 Diez-Herranz 1996 Comparison reference values recommended by the pneumology Spanish and European societies Arch Bronconeumol 1996; 32: 459–462 (Spanish) Louw 1996 South African males (normative values) S Afr Med J 1996; 86: 814–819 Parma 1996 Male Italians aged 7–18 yrs Eur J Epidemiol 1996; 12: 263–277 Giri 1996 Bhutan J Assoc Physicians India 1996; 44: 320–322 Brandli 1996 Adult Swiss population Thorax 1996; 51: 277–283 Sharp 1996 Japanese-American males aged 71–90 yrs Am J Respir Crit Care Med 1996; 153: 805–811 Quintero 1996 Healthy Nicaraguan male workers Am J Ind Med 1996; 29: 41–48 Enright 1995 USA; healthy Minnesota 65–85-yr-old males and females Chest 1995; 108: 663–669 Sirotkovic 1995 Croatia; school children from Dalmatia Monaldi Arch Chest Dis 1995; 50: 258–263 Gore 1995 Healthy adult lifetime nonsmokers in Australia Eur Respir J 1995; 8: 773–782 Quanjer 1995 White European children and adolescents Pediatr Pulmonol 1995; 19: 135–142 Dufetel 1995 Togo; Senegalese Black children and adolescents Rev Mal Respir 1995; 12: 135–143 (French) Fulton 1995 USA; MVV in African American adolescent females Pediatr Pulmonol 1995; 20: 225–233 NHANES: National Health and Nutrition Examination Survey; ECRHS: European Community Respiratory Health Survey; MVV: maximum voluntary ventilation.
- Table. 2—
Outcomes of a MEDLINE search under the keywords“reference equations” and “lung volumes”
First author Year Country/area/nature of study Journal Torres 2003 Brazil; height and arm span in children Pediatr Pulmonol 2003; 36: 202–208 Verma 2003 India; dimensional statistics for estimation of lung volumes in children and adolescents Anthropol Anz 2003; 61: 79–84 Neve 2002 France; puberty and thoracic volume index Eur Respir J 2002; 20: 1292–1298 Zheng 2002 China; survey on clinical application Zhonghua Jie He He Hu Xi Za Zhi 2002; 25: 69–73 (Chinese) Manzke 2001 Germany; children aged 6–16 yrs from “hospital normals” Eur J Pediatr 2001; 160: 300–306 Cotes 2001 UK workers; body mass index Thorax 2001; 56: 839–844 Ip 2000 Chinese children and adolescents in Hong Kong Am J Respir Crit Care Med 2000; 162: 424–429 Neder 1999 Brazil Braz J Med Biol Res 1999; 32: 729–737 Baur 1999 Germany; comparison of lung function reference values Int Arch Occup Environ Health 1999; 72: 69–83 Cordero 1999 Latin population of Spanish descent Respiration 1999; 66: 242–250 Roca 1998 Spain Respir Med 1998; 92: 454–460 Corzo-Alvarez 1998 Nonsmoking healthy males in Maracaibo, Venezuela Invest Clin 1998; 39: 3–17 (Spanish) Mahajan 1997 Healthy females of Haryana Indian J Chest Dis Allied Sci 1997; 39: 163–171 Chin 1997 Singapore; nonsmoking adults Respirology 1997; 2: 143–149 McCoy 1995 USA; normal infants Pediatr Pulmonol 1995; 19: 282–290 Rosenthal 1993 UK; body plethysmographic gas volumes in prepubertal and pubertal school children in London Thorax 1993; 48: 803–808 - Table. 3—
Outcome of a MEDLINE search under the keywords“reference equations” and “diffusing capacity” or “diffusion”
First author Year Country/area/nature of study Journal Neve 2002 France; puberty and thoracic volume index Eur Respir J 2002; 20: 1292–1298 Zheng 2002 China; survey on clinical application Zhonghua Jie He He Hu Xi Za Zhi 2002; 25: 69–73 (Chinese) Zanen 2001 The Netherlands; alveolar membrane diffusion capacity and pulmonary capillary blood volume Eur Respir J 2001; 18: 764–769 Cotes 2001 UK workers; body mass index Thorax 2001; 56: 839–844 Hughes 2001 UK; in defence of KCO (TL/VA) Eur Respir J 2001; 17: 168–174 Johnson 2000 USA; correction for VA for both DL,CO and KCO Respir Med 2000; 94: 28–37 Neder 1999 Brazil Braz J Med Biol Res 1999; 32: 729–737 Baur 1999 Germany; comparison of lung function reference values Int Arch Occup Environ Health 1999; 72: 69–83 Martin 1998 Canada/Québec Rev Mal Respir 1998; 15: 781–788 (French) Mahajan 1997 India; healthy females of Haryana Indian J Chest Dis Allied Sci 1997; 39: 163–171 Chin 1997 Singapore; nonsmoking adults Respirology 1997; 2: 143–149 Guenard 1996 France; elderly subjects Eur Respir J 1996; 9: 2573–2577 Collard 1996 Belgium; obstructive sleep apnoea and obesity Chest 1996; 110: 1189–1193 Chinn 1996 UK workers; standardised for alveolar volume Eur Respir J 1996; 9: 1269–1277 Stam 1996 The Netherlands; at reduced alveolar volumes in children Pediatr Pulmonol 1996; 21: 84–89 KCO: transfer coefficient of the lung for carbon monoxide; TL: transfer factor of the lung; VA: alveolar volume; DL,CO: carbon monoxide diffusing capacity.
- Table. 4—
Summary of the usage of reference values
Item Reference values General Predicted values should be obtained from studies of “normal” or “healthy” subjects with the same anthropometric (e.g. sex, age and height) and ethnic characteristics of the patient being tested Height and weight should be measured for each patient at the time of testing If possible, all parameters should be taken from the same reference source When comparing selected reference equations with measurements performed on a sample of healthy subjects in a laboratory, it is suggested to choose the reference equation that provides the sum of residuals (observed – predicted computed for each adult subject, or log observed – log predicted for each subject in the paediatric age range) closest to zero When using a set of reference equations, extrapolation beyond the size and age of the investigated subjects should be avoided For each lung function index, values below the 5th percentile of the frequency distribution of values measured in the reference population are considered to be below the expected “normal range” Spirometry In the USA, ethnically appropriate NHANES III reference equations published in 1999 for those aged 8–80 yrs, and the equations of Wang et al. 29 for children aged <8 yrs are recommended In Europe, the ECCS combined reference equations published in 1993 8 are often used for 18–70-yr-old people, and those from Quanjer et al. 30 for paediatric ages Currently, a specific set of equations is not recommendable for use in Europe. A new Europe-wide study to derive updated reference equations for lung function is needed Table 1 includes reference equations published from 1995 to August 2004 Lung volumes No specific set of equations can be recommended In practice, many USA and European laboratories use the reference equations for TLC, FRC and RV recommended by the 1995 ATS/ERS workshop 7 or by the ECCS in 1993 8 Table 2 reports studies on reference equations published from 1993 to August 2004 Diffusing capacity No specific set of equations is generally recommended Commonly used equations appear to be those by the ECCS in 1993 38 and those of Crapo and Morris 40. In Europe, equations from Cotes et al. 41, Paoletti et al. 42 and Roca et al. 43 are also used Table 3 shows studies on reference equations published from 1995 to August 2004 NHANES: National Health and Nutrition Examination Survey; ECCS: European Community for Coal and Steal; TLC: total lung capacity; FRC: functional residual capacity; RV: residual volume; ATS: American Thoracic Society; ERS: European Respiratory Society.
- Table. 5—
Types of ventilatory defects and their diagnoses
Abnormality Diagnosis Obstruction FEV1/VC <5th percentile of predicted A decrease in flow at low lung volume is not specific for small airway disease in individual patients A concomitant decrease in FEV1 and VC is most commonly caused by poor effort, but may rarely reflect airflow obstruction. Confirmation of airway obstruction requires measurement of lung volumes Measurement of absolute lung volumes may assist in the diagnosis of emphysema, bronchial asthma and chronic bronchitis. It may also be useful in assessing lung hyperinflation Measurements of airflow resistance may be helpful in patients who are unable to perform spirometric manoeuvres Restriction TLC <5th percentile of predicted A reduced VC does not prove a restrictive pulmonary defect. It may be suggestive of lung restriction when FEV1/VC is normal or increased A low TLC from a single-breath test should not be seen as evidence of restriction Mixed defect FEV1/VC and TLC <5th percentile of predicted FEV1: forced expiratory volume in one second; VC: vital capacity; TLC: total lung capacity.
- Table. 6—
Severity of any spirometric abnormality based on the forced expiratory volume in one second(FEV1)
Degree of severity FEV1 % pred Mild >70 Moderate 60–69 Moderately severe 50–59 Severe 35–49 Very severe <35 % pred: % predicted.
- Table. 7—
Summary of the considerations for severity classification
The severity of pulmonary function abnormalities is based on FEV1 % pred. This does not apply to upper airway obstruction. In addition, it might not be suitable for comparing different pulmonary diseases or conditions FEV1 may sometimes fail to properly identify the severity of a defect, especially at the very severe stages of the diseases FEV1 % pred correlates poorly with symptoms and may not, by itself, accurately predict clinical severity or prognosis for individual patients Lung hyperinflation and the presence of expiratory flow limitation during tidal breathing may be useful in categorising the severity of lung function impairment<1?twb?> FEV1: forced expiratory volume in one second; % pred: % predicted.
- Table. 8—
Selected studies of bronchodilator response
Population Agent/mode of delivery FVC FEV1 MEF25–75% or MEF50% Comments Selected population studies 1063 subjects 8–75 yrs of age; general population 108 IP 2 puffs via MDI 10.7% (0.40 L) 7.7% (0.31 L) 20% 95th percentile for per cent change from baseline 2609 subjects; random sample of 3 areas in Alberta, Canada 109 TB 500 µg via spacer Males 9% (0.34 L); females 9% (0.22 L) 95th percentile for per cent change from baseline in asymptomatic never-smokers with FEV1 >80% pred 75 selected normal subjects 110 Two puffs via MDI 5.1% (0.23 L) 10.1% (0.36 L) 48.3% Upper 95% CL (two-tailed) for per cent change from baseline Selected patient studies 40 patients referred to PFT laboratory 112 Placebo 14.9% (0.34 L) 12.3% (0.18 L) 45.1% Upper 95% CI change after placebo 985 COPD patients in the IPPB trial 111 IP 250 µg via air nebuliser 15% Per cent change from baseline 150 patients with airway obstruction 113 SB 200 µg or TB 500 µg via MDI 15% (0.33 L) 10% (0.16 L) 95% CI for absolute change 78 patients with COPD/asthma 101 SB 200 µg via MDI 14% (0.51 L) 15% (0.25 L) 95% CL per cent change of baseline FVC: forced vital capacity; FEV1: forced expiratory volume in one second; MEF25–75%: mean flow between 25% and 75% of FVC; MEF50%: flow at 50% of FVC; IP: isoproterenol; MDI: metered dose inhaler; TB: terbutaline; % pred: % predicted; SB: salbutamol; CL: confidence limits; PFT:pulmonary function tests; CI: confidence interval; COPD: chronic obstructive pulmonary disease; IPPB: intermittent positive pressure breathing; Other variables as in table 6⇑.
- Table. 9—
Summary of the procedures relating to bronchodilator response
Procedures suggested to minimise differences within and between laboratories Assess lung function at baseline Administer salbutamol in four separate doses of 100 µg through a spacer Re-assess lung function after 15 min. If you want to assess the potential benefits of a different bronchodilator, use the same dose and the same route as used in clinical practice. The wait time may be increased for some bronchodilators An increase in FEV1 and/or FVC ≥12% of control and ≥200 mL constitutes a positive bronchodilator response In the absence of a significant increase in FEV1 and/or FVC, an improvement in lung function parameters within the tidal breathing range, such as increased partial flows and decrease of lung hyperinflation, may explain a decrease in dyspnoea The lack of a bronchodilator response in the laboratory does not preclude a clinical response to bronchodilator therapy FEV1: forced expiratory volume in one second; FVC: forced vital capacity.
- Table. 10—
Lung function parameters capable of differentiating extrathoracic from intrathoracic obstruction
Extrathoracic obstruction Intrathoracic obstruction Fixed Variable PEF Decreased Normal or decreased Decreased MIF50 Decreased Decreased Normal or decreased MIF50/MEF50 ∼1 <1 >1 PEF: peak expiratory flow; MIF50: maximum inspiratory flow at 50% of forced vital capacity (FVC); MEF50: maximum expiratory flow at 50% of FVC.
- Table. 11—
Summary of the issues concerning central or upper airway obstruction
Special attention should be paid by the technicians to obtain maximal and repeatable PEFs and forced inspiratory manoeuvres if there is a clinical or spirometric reason to suspect upper airway obstruction Be aware of how to distinguish intrathoracic from extrathoracic airway obstruction (table 10) Confirm the presence of central and upper airway obstruction with imaging and/or endoscopic techniques PEF: peak expiratory flow.
- Table. 12—
Reported significant changes in forced vital capacity(FVC), forced expiratory volume in one second (FEV1), mid-expiratory flow (MEF25–75%) and carbon monoxide diffusing capacity (DL,CO) over time
FVC FEV1 MEF25–75% DL,CO Within a day Normal subjects ≥5 ≥5 ≥13 >7% COPD patients ≥11 ≥13 ≥23 Week to week Normal subjects ≥11 ≥12 ≥21 >6 units COPD patients ≥20 ≥20 ≥30 >4 units Year to year ≥15 ≥15 >10% The variables are the same as in tables 6⇑ and 8⇑. Results for spirometry are rounded to the nearest integer 25, 128. The within-day DL,CO variability is from a study of diurnal variation in healthy nonsmokers 133. The week-to-week coefficient of repeatability (CR) is given for DL,CO in units of mL·min−1·mmHg−1, as calculated from CRs originally stated in units of mmol·min−1·kPa−1 138. The year-to-year variability of healthy adults is given using a 95% confidence interval 139. CRs from repeatability testing performed in your own laboratory should be substituted for the values in this table. COPD: chronic obstructive pulmonary disease.
- Table. 13—
Summary of the considerations for the interpretation of change in lung function
Be aware of possible significant changes in lung function parameters over time (table 12) Multiple measurements over time are more likely to signal a real change in lung function than two measurements When too many indices of lung function are tracked simultaneously, the risk of false-positive indications of change increases Clinical interpretation of serial tests should not be based solely on the coefficient of repeatability, but also on the clinical findings - Table. 14—
Degree of severity of decrease in diffusing capacity for carbon monoxide(DL,CO)
Degree of severity DL,CO % pred Mild >60% and <LLN Moderate 40–60% Severe <40 % pred: % predicted; LLN: lower limits of normal.
- Table. 15—
Summary of the considerations for diffusing capacity for carbon monoxide(DL,CO) interpretation
Refer to a scheme to grade the severity of reductions in DL,CO (table 14) Interpreting DL,CO in conjunction with spirometry and lung volumes may assist in diagnosing the underlying disease (fig. 2) Adjustments of DL,CO for changes in haemoglobin and carboxyhaemoglobin are important The relationship between DL,CO and lung volume is not linear, so DL,CO/VA or DL,CO/TLC do not provide an appropriate way to normalise DL,CO for lung volume Nonlinear adjustments may be considered, but their clinical utility must be established before they can be recommended VA: alveolar volume; TLC: total lung capacity.
- Table. 16—
List of abbreviations and meanings
ATPD Ambient temperature, ambient pressure, and dry ATPS Ambient temperature and pressure saturated with water vapour BTPS Body temperature (i.e. 37°C), ambient pressure, saturated with water vapour C Centigrade CFC Chlorofluorocarbons cm Centimetres COHb Carboxyhaemoglobin DL,CO Diffusing capacity for the lungs measured using carbon monoxide, also known as transfer factor DL,CO/VA Diffusing capacity for carbon monoxide per unit of alveolar volume, also known as KCO DM Membrane-diffusing capacity DT Dwell time of flow >90% of PEF EFL Expiratory flow limitation ERV Expiratory reserve volume EV Back extrapolated volume EVC Expiratory vital capacity FA,X Fraction of gas X in the alveolar gas FA,X,t Alveolar fraction of gas X at time t FEF25–75% Mean forced expiratory flow between 25% and 75% of FVC FEFX% Instantaneous forced expiratory flow when X% of the FVC has been expired FEV1 Forced expiratory volume in one second FEVt Forced expiratory volume in t seconds FE,X Fraction of expired gas X FIFX% Instantaneous forced inspiratory flow at the point where X% of the FVC has been inspired FI,X Fraction of inspired gas X FIVC Forced inspiratory vital capacity FRC Functional residual capacity FVC Forced vital capacity H2O Water Hb Haemoglobin Hg Mercury Hz Hertz; cycles per second IC Inspiratory capacity IRV Inspiratory reserve volume IVC Inspiratory vital capacity KCO Transfer coefficient of the lung (i.e. DL,CO/VA) kg Kilograms kPa Kilopascals L Litres L·min−1 Litres per minute L·s−1 Litres per second lb Pounds MEFX% Maximal instantaneous forced expiratory flow where X% of the FVC remains to be expired MFVL Maximum flow–volume loop mg Milligrams MIF Maximal inspiratory flow mL Millilitres mm Millimetres MMEF Maximum mid-expiratory flow ms Milliseconds MVV Maximum voluntary ventilation PA,O2 Alveolar oxygen partial pressure PB Barometric pressure PEF Peak expiratory flow PH2O Water vapour partial pressure PI,O2 Inspired oxygen partial pressure θ (theta) Specific uptake of CO by the blood RT Rise time from 10% to 90% of PEF RV Residual volume s Seconds STPD Standard temperature (273 K, 0°C), pressure (101.3 kPa, 760 mmHg) and dry TB Tuberculosis TGV (or VTG) Thoracic gas volume tI Time taken for inspiration TLC Total lung capacity Tr Tracer gas ttot Total time of respiratory cycle TV (or VT) Tidal volume VA Alveolar volume VA,eff Effective alveolar volume VC Vital capacity Vc Pulmonary capillary blood volume VD Dead space volume VI Inspired volume VS Volume of the expired sample gas µg Micrograms
Jump To
- Article
- BACKGROUND
- REFERENCE EQUATIONS
- TYPES OF VENTILATORY DEFECTS
- COMMENTS ON INTERPRETATION AND PATTERNS OF DYSFUNCTION
- SEVERITY CLASSIFICATION
- BRONCHODILATOR RESPONSE
- CENTRAL AND UPPER AIRWAY OBSTRUCTION
- INTERPRETATION OF CHANGE IN LUNG FUNCTION
- DL,CO INTERPRETATION
- ABBREVIATIONS
- Acknowledgments
- Footnotes
- References
- Figures & Data
- Info & Metrics