Mechanism of pulmonary function changes after surgical correction for funnel chest.

In 24 subjects with pectus excavatum we evaluated whether the previously detected unfavourable effects of corrective surgery on the ventilatory capacity were attributable to pulmonary or to chest wall factors. We found that 12.2 +/- 3.7 yrs postoperatively (i.e. at the age of 23.3 +/- 5.4 yrs) the vital capacity was decreased from 89 +/- 10% predicted (pred) preoperatively to 64 +/- 6% pred (p less than 0.001) and forced expiratory volume in one second from 88 +/- 17 to 66 +/- 11% pred (p less than 0.001). At total lung capacity (TLC; 69 +/- 5% pred) we found an obvious reduction in transpulmonary pressure (59 +/- 23% pred) and in transdiaphragmatic pressure (30 +/- 17 cmH2O) postoperatively. This indicated an extrapulmonary cause of the restrictive defect, attributable to abnormal chest wall mechanics secondary to the extensive surgery on the sternum and parasternal zones.