Effects of Intraoperative Ventilation Strategies on Ventilation Inhomogeneity and Inflammatory Response in Pediatric...

Respiratory arrest during cardiopulmonary bypass (CPB) in pediatric cardiac surgery risks lung dysfunction including derecruitment, atelectasis, and inflammation. Continuous positive airway pressure (CPAP) and lung-protective ventilation (LPV) during aortic cross-clamping show inconsistent results in mitigating these risks.

To investigate whether LPV during aortic cross-clamping under CPB affects postoperative respiratory mechanics and ventilation inhomogeneity compared to apnea or CPAP.

This prospective, randomized pilot study compared three ventilation strategies during aortic cross-clamping under CPB: apnea, CPAP (5 mbar), and LPV. LPV was standardized using pressure-controlled ventilation at a positive end-expiratory pressure of 5 mbar, individualized driving pressure (20% of the pre-cross clamp inspiratory pressure), and age-adjusted respiratory rate. Recruitment maneuvers were applied at the end of CPB. Respiratory mechanics were assessed. Ventilation distribution was measured preoperatively and postoperatively under spontaneous breathing and mechanical ventilation using Electrical Impedance Tomography. Blood was analyzed pre- and postoperatively for pulmonary and systemic inflammatory markers. Feasibility of LPV was assessed. Statistical analysis used linear mixed-effects models.

Driving pressure increased (11.8 (2.6) to 12.9 (2.6) mbar) and dynamic compliance decreased (9.9 (7.3) to 8.5 (7.4) Pa L^-1) statistically significantly preoperatively to postoperatively. The number of ventilated pixels increased statistically significantly from spontaneous breathing (408.2 (77.2)) to mechanical ventilation (495.1 (44.9)) and returned toward baseline postoperatively (433.9 (72.6)). The Center of Ventilation shifted statistically significantly ventrally during mechanical ventilation (0.491 (0.039) to 0.442 (0.027)) and normalized afterward (0.485 (0.037)). These changes were unaffected by the ventilation strategy. Biomarker analysis showed no statistically significant changes between groups. LPV during aortic cross-clamping was feasible.

In this pilot study, ventilation strategies did not differ in their effect on ventilation distribution, respiratory mechanics, or inflammatory markers when recruitment maneuvers were uniformly applied after CPB. LPV was feasible.

German Clinical Trials Register: DRKS00030219; https://drks.de/search/de/trial/DRKS00030219.