Pectus excavatum repair improves exercice tolerance and respiratory pump efficacy in adult patients

Objective. The effect of surgical repair of pectus excavatum (PEx) on cardiopulmonary function remains controversial. Our study objective was twofold: to assess changes of pulmonary function at rest and exercise tolerance after PEx repair; and to study the mechanism by which exercise tolerance would increase after the procedure.Methods. In a first series of patients, we compared cardiopulmonary function at rest and at maximal exercise, before and at 1-year follow-up after PEx repair in 70 adults. A second study was then conducted in a group of 20 patients, in which assessment of inspiratory muscle strength by means of maximal static inspiratory pressure (PImax) and sniff nasal inspiratory pressure (SNIP) were performed to get insight into the mechanisms involved in PEx repair-induced cardiopulmonary function changes.Results. Cardiopulmonary tests at rest were within the normal range, whereas maximal oxygen uptake (VO2max) was reduced (34±7 mL/kg/min; 77% of the predicted value). At 1-year follow-up, PEx repair was associated with minor cardiopulmonary function changes at rest and significant increase of VO2max (38±6 mL/kg/min; 87% of the predicted value, p<0.0001). Postoperative O2 pulse increased at maximal exercise (13.3±2.5 vs 15.7±2.6 ml/beat, p<0.003) suggesting that aerobic capacity improvement was mainly the result of better cardiovascular adaptation at maximal workload. Consistently, in the second set of 20 patients, significant improvements of both VO2max and O2 pulse 1 year after surgery were also observed. In addition, this group of patients displayed significant decreases of PImax and SNIP (p <0.01), which were significantly improved after surgery. Postoperative increases of PImax and SNIP were correlated with O2 pulse increase (r2=0.23; p=0.04 et r2 = 0.38; p <0.01, respectively). Conclusion. These results demonstrate sustained improvement in exercise cardiopulmonary function at 1-year follow-up of PEx repair, due to improved capacity of inspiratory muscle system to generate intrathoracic negative pressure, facilitating venous return (the so-called respiratory pump) and consecutive improvement of aerobic capability.