Predicting intraoperative hypoxemia in lung resection surgery: assessing the utility of oxygen reserve index measurements during one-lung ventilation before pleural opening.

Abstract

One-lung ventilation (OLV) is crucial for collapsing the lung and improving access to the operative field during lung surgery. Intraoperative OLV may increase the intrapulmonary shunt, potentially leading to intraoperative hypoxemia. The Oxygen Reserve Index (ORI) is a continuous, noninvasive parameter that provides a broader range of oxygen reserve data than conventional oxygen saturation measurements. We aimed to determine whether ORI values measured during OLV before pleural opening are reliable predictors of intraoperative hypoxemia. We included 113 adult patients who underwent lung resection surgery at a tertiary medical center between January 2024 and April 2024. Patients were positioned laterally for surgery, and preemptive OLV was performed with a tidal volume of 5 mL/kg and a fraction of inspired oxygen (FiO₂) of 60% for at least 5 min before pleural opening, with concurrent ORI measurements. ORI values obtained during this period were analyzed using ROC curve analysis to predict intraoperative hypoxemia (SaO₂ ≤ 90%). AUC values were compared using DeLong's test. Among the 113 patients, 13 (11.5%) developed intraoperative hypoxemia. The predictive power of ORI measured 5 min after initiating OLV for intraoperative hypoxemia was reflected by an AUC of 0.955 (95% CI: 0.899-1.000). Additionally, the predictive power of the change in ORI over 5 min for intraoperative hypoxemia was demonstrated by an AUC of 0.966 (95% CI: 0.935-0.997). The optimal cut-off values for the ORI and its change measured 5 min after preemptive OLV to predict intraoperative hypoxemia were 0.040 and 0.110, respectively. In patients receiving OLV during lung surgery, ORI values and their changes measured during preemptive OLV before pleural opening can predict intraoperative hypoxemia. These findings support an individualized approach to intraoperative FiO₂ management, which may help prevent unnecessary oxygen overdose and enable early identification and intervention in patients at high risk of hypoxemia during OLV.