Effect of Surgical Lung Volume Reduction on Breathing Patterns in Severe Pulmonary Emphysema

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Abstract
Surgical lung volume reduction may improve pulmonary function and dyspnea in advanced pulmo- nary emphysema. To investigate mechanisms of these beneficial effects we studied breathing pat- terns before and after surgery. Nineteen patients with diffuse pulmonary emphysema (FEV 1 , 35% of predicted, total lung capacity . 130% predicted) were studied within 1 mo before, and 1.5 to 7 mo after thoracoscopic volume reduction. Changes of rib cage and abdominal volumes were moni- tored with calibrated respiratory inductive plethysmography for 20 to 60 min during natural breath- ing at rest. Pulmonary function and dyspnea were also assessed. Postoperative tidal volumes, respira- tory cycle times, and minute ventilation were not significantly different from preoperative values. The contribution of abdominal volume changes to tidal volumes increased from a mean 6 SD of 43 6 17% preoperatively to 58 6 14% postoperatively (p 5 0.03). The fraction of inspiratory time with abdomi- nal paradoxical motion decreased from 12.3 6 8.3% preoperatively to 5.1 6 5.1% postoperatively (p 5 0.02). The phase shift between rib cage and abdominal motion was reduced postoperatively. Hyperinflation, airway obstruction, and subjective ratings of dyspnea were significantly improved. 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 force-generating capacity of the diaphragm after surgery. Bloch KE, Li Y, Zhang J, Bingisser R, Ka- plan V, Weder W, Russi EW. Effect of surgical lung volume reduction on breathing patterns in severe pulmonary emphysema. AM J RESPIR CRIT CARE MED 1997;156:553-560.