LUNG-VOLUMES BEFORE AND AFTER LUNG-VOLUME REDUCTION SURGERY - QUANTITATIVE CT ANALYSIS

The volume and severity of pulmonary emphysema in individual lungs wer e measured by means of quantitative computed tomography (CT) studies i n 28 patients (14 women, 14 men, median age 65 yr) who underwent eithe r bilateral (n = 15) or unilateral (n = 13) lung volume reduction surg ery (LVRS). Spirometric, total body plethysmographic, and CT data (at TLC and RV) were correlated before and after LVRS. Lung volumes determ ined by CT correlated well with volumes obtained by total body plethys mography (P < 0.0001). For individual lungs after LVRS, CT-derived mea n lung capacity decreased 13% and residual volume 20% (p < 0.00001 for each), while mean total functional lung volume (TFLV, defined as the volume of lung with CT attenuation greater than -910 Hounsfield units) increased 9% (p < 0.01), and the mean ratio of the air space to tissu e space volume (V-AS/V-TS) decreased more at RV (23%) than at TLC (14% ) (P < 0.0005 for each). In contrast, unilateral LVRS did not affect e xhalation from the unoperated lung (2% reduction in RV, p = NS). The m agnitude of the postoperative response (CT-derived TLC, RV, TFLV, V-AS /V-TS) Of each operated lung was comparable for unilateral and bilater al LVRS. Thus, a lung's response to LVRS was independent from that of the contralateral lung. Moreover, postoperative alterations in TFLV an d FEV1 correlated significantly (r = 0.80, p < 0.0001), which suggests that the expansion of functioning tissue may contribute to the mechan ism by which LVRS palliates airway obstruction.