Assessment of Intraoperative Fluctuations in Partial Pressure of Oxygen on Extubation Time in Adult Patients Undergoing Cardiac Surgery

Abstract

Background: Cardiopulmonary bypass (CPB) has a significant impact on physiological oxygen regulation in cardiac surgery. Despite high values of arterial partial pressure of oxygen (PaO₂) being a long-standing protective factor, there are emerging indications that high or unstable oxygen levels could also lead to oxidative stress, inflammatory activation, and postoperative pulmonary dysfunction. The correlation between the variability of intraoperative (PaO₂) and postoperative extubation time is not studied properly. Objective: To determine the effect of intraoperative changes in arterial partial pressure of oxygen (PaO₂) on postoperative extubation period in adult patients undergoing elective cardiac surgery with cardiopulmonary bypass. Methods: The study was a prospective, observational one, conducted in the Cardiac Perfusion Unit of Omer Hospital and Cardiac Perfusion Unit of Gulab Devi Chest Hospital to assess intra and post operative parameters in adult patients who underwent elective cardiac surgery with cardiopulmonary bypass. Arterial blood gas analyses were performed at predefined intraoperative stages (CPB initiation, cooling, rewarming, and weaning). According to predefined criteria of fluctuation, patients were divided into Stable and Variable groups, according to the level of fluctuation of the patients in terms of the (PaO₂). The time of extubation was the period between ICU admission and the success of removal of endotracheal tube. To ascertain the relationship between the variability of the (PaO₂) and the duration during which the extubation process was conducted, statistical analysis was conducted after accounting for the confounding factors. Results: Patients who had more intraoperative PaO₂ variation demonstrated longer extubation times. Increased variability in (PaO₂) was linked to higher chances of delayed extubation (>8 hours), indicating that the postoperative respiratory recovery is compromised. Intraoperative oxygen variability was concluded as being a clinically significant predictor of ventilatory recovery, not the absolute values of oxygen. Conclusion: On univariate analysis, intraoperative PaO₂ variability was associated with delayed extubation, but this association was not significant following adjustment for confounding variables. Aortic cross-clamp time continued to be an independent predictor of delayed extubation.. Physiologically stable oxygenation instead of liberal hyperoxia could be a possible solution to better postoperative respiratory outcomes. The results facilitate the creation of universal oxygenation management guidelines during CPB to improve recovery and maximize patient safety.

Keywords: Cardiopulmonary bypass, (PaO₂) variation, Hyperoxia, Oxidative stress, Extubation time, Cardiac surgery.