The diagnosis of chronic obstructive pulmonary disease

Abstract

Background: Estimates of the prevalence of chronic obstructive pulmonary disease (COPD) in Germany range from 1.9% to 13.2%, depending on the population studied and the investigative methods used. About 30% of all patients already have severe airway obstruction by the time the condition is diagnosed.

Methods: Review of pertinent literature retrieved by a selective search, including current guidelines and textbooks.

Results: Smoking is the main risk factor for COPD. The diagnosis is based on characteristic symptoms that patients at risk should be actively asked about-cough, dyspnea, diminished physical reserve, and frequent airway infections-together with abnormal pulmonary function tests. Spirometry usually suffices to document impaired air flow. The clinical evaluation and the treatment strategy are based on the severity of airway obstruction and dyspnea, and the frequency of exacerbations. According to a European study, dyspnea is present in 73% of persons with severe COPD, expectoration in 64%, cough in 59%, and wheezing in 42%. Asthma, congestive heart failure, and interstitial lung disease are the main differential diagnoses.

Conclusion: COPD may begin with symptoms that are only mild at first even in a longstanding smoker. The available diagnostic techniques need better prospective validation with respect to relevant endpoints, including mortality, symptom progression, quality of life, and frequency of exacerbations.

Figure 1

Diagram of the pathogenesis and pathophysiology of COPD, created by the authors on the basis of the articles by Hogg et al. (20) and Tuder and Petrache (e26). COPD, chronic obstructive pulmonary disease

Figure 2

Diagnostic algorithm for COPD, after Vogelmeier et al (12). COPD, chronic obstructive pulmonary disease; FVC, forced vital capacity; FEV1, forced expiratory volume in one second

Figure 3

Ideal flow-volume curves for breathing at rest (smaller loop) and a forced maneuver (larger loop), with inspiration below and expiration above, the total lung capacity (TLC) indicated at left, and the residual volume (RV) at right on the volume axis. a) Normal; b) mild obstruction; c) moderate obstruction with reduced FVC (forced vital capacity) and shift of respiration at rest toward inspiration; d) severe obstruction with limitation of expiratory flow at rest. In b)–d), the normal curve is shown in gray in the background. The expiratory portion of the curve becomes more concave with increasing obstruction. Diagram: H.-J. Smith

Figure 4

Static lung volumes. The portions above the horizontal line can also be measured by spirometry. IRV, inspiratory reserve volume TV, tidal volume ERV, expiratory reserve volume RV, residual volume. Inspiratory capacity (IC) = IRV + TV Vital capacity (VC) = IRV + TV + ERV Functional residual capacity (FRC) = ERV + RV Total capacity (TLC) = VC + RV, corresponding to the total height of the column. Note the similarity of the spirometrically measured volumes in restrictive disease and emphysema

Figure 5

Abnormal flow-volume curves superimposed on a normal curve (gray, background): a) reduced IVC (inspiratory vital capacity) and FVC (forced expiratory vital capacity) with normal flow values, indicating a restrictive ventilatory impairment; b) reduced inspiratory and/or expiratory flow values, indicating stenosis of major airways. Diagram: H.-J. Smith