VENTILATORY MECHANICS AND GAS-EXCHANGE DURING EXERCISE BEFORE AND AFTER LUNG-VOLUME REDUCTION SURGERY

Many patients with emphysema are able to meet ventilatory demands duri ng resting conditions, but they show severe limitations during exercis e. To examine the effect of lung volume reduction (LVR) surgery on exe rcise performance and the mechanism of possible improvement, we measur ed ventilatory mechanics (pulmonary resistance [RL], work of breathing [WOB], dynamic intrinsic positive end-expiratory pressure [PEEPi,dyn] , peak expiratory flow rate [PEFR]), breathing pattern, oxygen uptake ((V) over dot o(2)), and carbon dioxide removal ((V) over dot co(2)) a t rest and during cycle ergometry in eight patients before and 3 mo af ter LVR surgery. Ventilatory mechanics were evaluated assessing esopha geal pressure and air flow. Three months after LVR surgery, the tolera ted workload was doubled when compared with the preoperative value (p < 0.0005), associated with a reduction of RL (p < 0.05), PEEPi,dyn (p < 0.005), and WOE (p < 0.005) at comparable workloads. Maximal ventila tory capacity and maximal tidal volume (VT) increased significantly (p < 0.01). Maximal (V) over dot o(2) increased from 474 +/- 23 to 601 /- 16 ml/min (p < 0.005) and maximal (V) over dot co(2) from 401 +/- 1 3 to 558 +/- 21 ml/min (p < 0.005), though no significant difference a t comparable workloads could be observed. In conclusion, emphysema sur gery leads to an improvement of ventilatory mechanics at rest and duri ng exercise. Higher maximal VT and minute ventilation were observed, r esulting in improvement of maximal (V) over dot o(2) and (V) over dot co(2) and exercise capacity.