Comparison of respiratory mechanics in adult patients undergoing minimally invasive repair of the pectus excavatum and removal of a pectus bar

Objective: The objective of this study was to compare the respiratory mechanics and gas exchange in adult patients undergoing minimally invasive repair of the pectus excavatum (MIRPE group) and removal of a pectus bar (bar removal group). Design: A prospective observational study. Setting: A tertiary university hospital. Participants: Thirty-two patients scheduled for elective MIRPE or removal of a pectus bar. Interventions: None. Measurements and Main Results: Spirometry was used to measure the peak inspiratory airway pressure (PIP), static compliance, and respiratory resistance. The measurements were recorded at 1 minute after beginning mechanical ventilation (T0), 15 minutes after beginning sevoflurane inhalation (T1), and after the insertion (or removal) of a pectus bar through the chest wall (T2). Pulmonary gas exchange was assessed by calculating the alveolar arterial oxygen tension difference (AaDO₂) before surgical incision and after insertion (or removal) of the pectus bar. In the MIRPE group, static compliance was decreased significantly (p < 0.001), and PIP was increased significantly (p < 0.001) after insertion of the pectus bar (T2) compared with baseline. In contrast, the bar removal group showed the opposite results. There were significant differences in static compliance and PIP at T2 between the groups (p = 0.002 and 0.026, respectively). AaDO₂ was increased significantly in the MIRPE group compared with the bar removal group (p = 0.012). Conclusions: Insertion of the pectus bar through the chest wall results in significant changes in respiratory mechanics and gas exchange. Therefore, close attention to pulmonary function is required during and after these surgical procedures.