Monitoring Oxygen Metabolism Using the Oxygen Reserve Index in Patients Undergoing Robotic Prostatectomy: A Prospective Observational Study

Background:The oxygen reserve index (ORi), as an adjunct to standard intraoperative pulse oximetry (SpO 2 ), enables prediction of hypoxia and detection of hyperoxia.The aim of this study was to analyze intraoperative variations in oxygen metabolism using ORi and partial pressure of oxygen in arterial blood (PaO 2 ) under conditions of ventilation compromised by the Trendelenburg tilt and pneumoperitoneum during a robot-assisted prostatectomy. Material/Methods:One hundred adult patients scheduled for an elective robotic prostatectomy participated in this study from January 2023 to March 2024.They were all anesthetized in the same way.ORi was monitored at 10 time points.Arterial blood gas analyses were performed to determine PaO 2 : before the induction of anesthesia (G1), after the patient was placed in the Trendelenburg position (G2), and after returning the patient to initial position (G3).The obtained data were then analyzed. Results:In multivariable analysis, statistically significant positive correlations were observed between ORi and PaO 2 at the following time points: (BEG) before the induction of anesthesia (Rho=0.410)and (PP+T) after the patient was placed in the Trendelenburg position (Rho=0.521).However, no relationship was observed between ORi and PaO 2 and the duration of the Trendelenburg position and pneumoperitoneum. Conclusions:ORi strongly correlates with PaO 2 values and is sensitive in detecting hyperoxia.Therefore, it appears that ORi can serve as a non-invasive monitoring tool for better oxygen management during anesthesia.Further research is needed on its use in detecting impending hypoxia in conditions of steep Trendelenburg position and pneumoperitoneum.