PLETHYSMOGRAPHIC PARAMETERS IN THE ASSESSMENT OF REVERSIBILITY OF AIRWAYS OBSTRUCTION IN PATIENTS WITH CLINICAL EMPHYSEMA

Slow inspiratory vital capacity (IVC) and forced expiratory volume in 1 s (FEV1) before and after an inhaled beta-agonist are widely used to detect reversible airflow limitation in patients with chronic obstruc tive lung disease. The measurement of airways resistance (Raw) during quiet breathing with the body plethysmograph is less frequently used. It may well be of importance in clinical emphysema where measurement o f FEV, is confounded by the collapse of the bronchi, which does not oc cur when measuring Raw during quiet breathing. We assessed whether Rrs , in addition to IVC and FEV1, can be used to gain a better insight in to the reversibility with 400 mug of fenoterol in patients with clinic al emphysema. We studied a group of 51 patients (9 women and 42 men; m ean [+/- SD] age, 64.7 [7.7] years) who had a clinical diagnosis of em physema. Significant reversibility was identified by spirometry (IVC, FEV1) and body plethysmography (Raw) in 20 patients (39 percent). Insp iratory vital capacity alone identified reversibility of airflow limit ation in 11 patients (22 percent). In 5 patients (10 percent), the pos tbronchodilator improvement was seen exclusively in the Raw measuremen t. In the remaining patients, absence of improvement in spirometric an d plethysmographic parameters was found. Subjective improvement occurr ed to the same extent in patients whose Raw and IVC improved. We concl uded that Raw gives important information about the reversibility of a irways obstruction in patients with clinical emphysema. Therefore, we suggest that tests during quiet breathing should be part of the routin e examination of airways obstruction in patients with ''irreversible'' obstruction by conventional spirometry.