Effectiveness of the oxygen reserve index in detecting and preventing hyperoxia in critically ill patients on mechanical ventilation: a randomized controlled trial.

Aim: To assess the effectiveness of fraction of inspired oxygen (FiO2) titration guided by oxygen reserve index (ORi) in preventing hyperoxia in intensive care unit (ICU) patients receiving mechanical ventilator support.

Methods: Patients aged 18 years and older who were admitted to a tertiary ICU and required mechanical ventilator support were randomly divided into two groups: the control group (n=30) and the oxygen saturation (SpO2) +ORi group (n=30). In the SpO2+ORi group, the goal was to maintain SpO2 between 95% and 98% and ORi at 0.00. In both groups, SpO2, ORi, partial pressure of oxygen (PaO2), partial pressure of carbon dioxide, positive end-expiratory pressure, FiO2, and hemodynamic parameters were recorded every six hours for two consecutive days.

Results: A very strong positive linear correlation was found between PaO2 and ORi (r=0.937; P<0.001). In the ORi+SpO2 group, PaO2 values were significantly lower and decreased with FiO2 titration over time. Severe hyperoxia was observed in 24.8% of the control group and in only 3.3% of the ORi+SpO2 group. When PaO2>120 mm Hg, FiO2>0.40 was found in 83.5% of the control group, and in 40% of the ORi+SpO2 group.

Conclusion: FiO2 titration guided by ORi+SpO2 effectively prevents hyperoxia and reduces the exposure time to hyperoxia in critically ill patients.