aa Lung volume reduction surgery (LVRS) has become a novel palliative therapeutic option for a subgroup of patients who are impaired in their daily activity by dyspnoea due to pulmonary emphysema with severe hyperinflation. The surgical principle is based on the concept of BRANTIGAN et al. [1] which was revived by COOPER et al. [2] . From the published experience of several groups it has become obvious that bilateral resection results in greater improvement of pulmonary function [2-8] than

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... teral resection [9] [10] [11] , and that stapled resection causes larger changes than laser resection [9] . Patients with moderate to severe chronic obstructive pulmonary disease are primarily limited in their exercise performance by a decrease in ventilatory capacity due to abnormal pulmonary mechanics [12] . Studies in a relatively small number of patients after bilateral LVRS by median sternotomy [13] and after unilateral video-assisted thoracoscopic LVRS [14] have suggested that a decrease in bronchial obstruction and reduction in pulmonary hyperinflation enable the patient to achieve a higher maximal minute ventilation after LVRS and therefore contribute to reduce the patients' exercise limitation. The goal of this study was to investigate exercise performance and gas exchange in patients with severe pulmonary emphysema before and after bilateral video-assisted thoracoscopic LVRS in relation to changes in pulmonary function. Patients and methods Patients We studied 40 consecutive patients with severe pulmonary emphysema, selected for bilateral LVRS by videoassisted thoracoscopy according to previously established criteria [15] . These included the following (incomplete list): advanced emphysema with dyspnoea at rest or on minimal exertion, a forced expiratory volume in one second (FEV1) <35% predicted, a total lung capacity (TLC) of >130% predicted and no significant coronary artery disease [16] . The mean (±SEM) age of the 27 males and 13 females was 63.2±1.4 yrs (range 42-78 yrs). Their mean body mass index (BMI) was 21.8±0.5 kg·m -2 (range: 15.2-30.9). All Exercise performance and gas exchange after bilateral video-assisted thoracoscopic lung volume reduction for severe emphysema. ABSTRACT: Lung volume reduction surgery (LVRS) improves dyspnoea and pulmonary function in selected patients with severe emphysema. The purpose of this study was to assess the effects of LVRS on exercise performance and gas exchange in relation to changes in pulmonary function. In 40 patients (63.2±1.4 yrs, mean±SE) with severe emphysema (forced expiratory volume in one second (FEV1) 29±1% predicted, residual volume/total lung capacity (RV/TLC) ratio: 0.63±0.01) we assessed dyspnoea, pulmonary function and exercise performance before and 3 months after bilateral video-assisted thoracoscopic LVRS. The Medical Research Council dyspnoea score fell from 3.5±0.1 to 1.4±0.1 (p<0.0005); FEV1 increased by 55±9% to 44±2% pred (p<0.0005), RV/TLC decreased from 0.63± 0.01 to 0.51±0.02 (p<0.0005). The diffusing capacity remained unchanged. Maximal work load during bicycle ergometry increased from 34.3±2.0 to 48.9±2.4 W (p< 0.0005), maximal oxygen uptake (V 'O 2 ,max) from 10.0±0.4 to 12.8±0.3 mL·kg -1 ·min -1 (p<0.0005). The increase in maximal ventilation during exercise (V 'E,max) from 29.5± 1.5 to 38.6±1.8 L·min -1 (p<0.0005) was associated with increases in tidal volumes at isowatt and maximal exercise while corresponding breathing frequencies remained unaltered. The increases in V 'O 2 ,max and V 'E,max correlated with the increases in FEV1 and the decreases in RV/TLC. We conclude that the improvement in pulmonary hyperinflation and airflow obstruction after bilateral thoracoscopic lung volume reduction surgery may reduce ventilatory limitation, thereby increasing exercise capacity. Eur Respir J 1998; 12: 785-792.