PFT Interpretive Strategies: American Thoracic Society/ European Respiratory Society 2005 Guideline Gaps

All pulmonologists, including those recently completing training, should be competent in critically evaluating and interpreting pulmonary function tests (PFTs). In addition, some authorities recommend that respiratory therapists learn to provide preliminary PFT interpretations for the medical directors of PFT labs. The 2005 American Thoracic Society/European Respiratory Society guidelines for interpreting PFTs lack recommendations for the best reference equations for lung volumes and diffusing capacity of the lung for carbon monoxide (D_LCO), and lack reference equations for non-whites. The pre-test probability of lung disease should be determined using a short questionnaire. The “nonspecific pattern” occurs in about 15% of patients referred to a PFT lab, but it has many clinical correlates and the course is usually benign. Less common PFT patterns and those resulting from comorbid conditions (such as obesity, respiratory muscle weakness, or heart failure) are not discussed by the guidelines. More than half of patients with interstitial lung disease have a normal ratio of D_LCO/V_A (alveolar volume), and many have a normal total lung capacity.