Impact of Ventilation Discontinuation During Cardiopulmonary Bypass: A Prospective Observational Study

Background: The practice of discontinuing mechanical ventilation during cardiopulmonary bypass (CPB) has been widely adopted in various cardiac surgery centers. Nonetheless, concerns have emerged regarding its possible adverse effects on postoperative pulmonary function. This study aimed to evaluate the effects of discontinued mechanical ventilation during CPB on postoperative gas exchange, X-ray results, ICU stay, mortality, reintubation, re-exploration, and bleeding. Methods: A prospective observational study was performed involving adult patients scheduled for elective cardiac surgery requiring CPB. Participants were divided into two groups according to their intraoperative ventilation strategy: one group had ventilation halted for a period required to perform surgical intervention (non-ventilated group), while the other maintained it (ventilated group) throughout CPB. Postoperative arterial carbon dioxide levels (PaCO2), arterial partial pressure of oxygen (PaO2), PaO2/FiO2 ratio (P/F ratio), arterial oxygen saturation (SaO2), and the ratio of PaCO2 to minute ventilation (PaCO2/MV) were measured at induction, postoperatively (in the ICU), and in a 24 h postoperative period. Chest X-ray data, mechanical ventilation time, LOS in ICU, re-exploration, reintubation, and bleeding parameters were documented. Analyses were also conducted across seven distinct age categories: <30, 30–40, 40–50, 50–60, 60–70, 70–80, and >80 years. Results: Individuals in the non-ventilated group exhibited elevated postoperative PaCO2 and PaCO2/MV ratios and lower postoperative P/F ratios. The difference in gas exchange leveled off within 24 h. There was no difference in the incidence of atelectasis (postoperatively in a 24 h period), in mechanical ventilation time, LOS in ICU, or mortality. Interestingly, postoperative PaCO2/MV peaked in the 40–50-year age group. Conclusions: Continued mechanical ventilation during CPB correlates with better postoperative gas exchange and better CO2 clearance. These results imply that maintaining low tidal volume ventilation during CPB may provide benefits, especially for patients aged 40–60 years.