EFFECT OF SURGICAL LUNG-VOLUME REDUCTION ON BREATHING PATTERNS IN SEVERE PULMONARY-EMPHYSEMA

Surgical lung volume reduction may improve pulmonary function and dysp nea in advanced pulmonary emphysema. To investigate mechanisms of thes e beneficial effects we studied breathing patterns before and after su rgery. Nineteen patients with diffuse pulmonary emphysema (FEV1 < 35% of predicted, total lung capacity > 130% predicted) were studied withi n 1 mo before, and 1.5 to 7 mo after thoracoscopic volume reduction. C hanges of rib cage and abdominal volumes were monitored with calibrate d respiratory inductive plethysmography for 20 to 60 min during natura l breathing at rest. Pulmonary function and dyspnea were also assessed . Postoperative tidal volumes, respiratory cycle times, and minute ven tilation were not significantly different from preoperative values. Th e contribution of abdominal volume changes to tidal volumes increased from a mean +/- SD of 43 +/- 17% preoperatively to 58 +/- 14% postoper atively (p = 0.03). The fraction of inspiratory time with abdominal pa radoxical motion decreased from 12.3 +/- 8.3% preoperatively to 5.1 +/ - 5.1% postoperatively (p = 0.02). The phase shift between rib cage an d abdominal motion was reduced postoperatively. Hyperinflation, airway obstruction, and subjective ratings of dyspnea were significantly imp roved. The better synchronization of rib cage-abdominal motion and the greater contribution of abdominal volume changes to tidal volumes are consistent with a reduction of inspiratory loading and a greater forc e-generating capacity of the diaphragm after surgery.