Choice of Respiratory Support During Cardiac Bypass in Cardiac Surgical Patients (Pilot Study)

Abstract

Currently, there is no uniform respiratory support strategy during cardiopulmonary bypass (CPB) in cardiac anesthesiology.The aim of the study was to examine possible variants of respiratory support during CPB and determine the most effective technique capable to reduce the incidence of postoperative pulmonary complications.Material and methods. Ninety cardiac surgery patients were enrolled in the pilot study and divided into groups (CPAP, VC, and apnea). In the CPAP group, positive airway pressure of + 5 cm H2O was maintained during CPB. The VC group patients underwent mechanical ventilation during CPB with a reduced tidal volume of 3 mL/kg, respiratory rate of 6/min, and REER of + 5 cm H2O. In the apnea group, patients received no respiratory support (non-rebreathing system).Results. In both the apnea and CPAP (constant positive airway pressure) group, there was a decrease in oxygenation index (OI) at the end of the CPB compared with baseline values. In the apnea group, the OI dropped from 316.31±81.76 to 230.10±102.48, while in the CPAP group it decreased from 319.37±80.01 to 223.17±152.36 (P<0.001). No significant changes in this parameter were observed in the VC group. The frequency of recruitment maneuvers after CPB to correct the impaired respiratory oxygenation was maximal in patients from apnea group (22 cases (73%) versus 13 cases (43%) in the CPAP group and 5 cases (16%) in the VC group) (P<0.001). Frequency of pulmonary atelectasis on chest radiology in postoperative period was 47, 37, 10% in apnea, CPAP, and VC groups, respectively, and the difference was also significant (P=0.006).Conclusion. Low-volume ventilation is the preferable method of respiratory support in cardiac surgery patients during CPB.