Continuous Titration of Inspired Oxygen Using Oxygen Reserve Index to Decrease Oxygen Exposure During One-Lung Ventilation: A Randomized Controlled Trial

Abstract

BACKGROUND: 

A high fraction of inspired oxygen (Fio₂) is administered during one-lung ventilation (OLV). However, a high Fio₂ is not physiologic and may lead to various complications. We hypothesized that continuous titration of Fio₂ using the oxygen reserve index (ORI) reduces oxygen exposure compared to conventional management during OLV.

METHODS: 

In this randomized, double-blinded trial, patients undergoing thoracic surgery were assigned to an ORI (n = 64) or a control group (n = 60). In the ORI group, ORI was continuously displayed using multiwavelength pulse co-oximetry (Masimo) between 0 and 1 (0, no reserve; 1, maximum reserve), and Fio₂ was titrated for a target ORI of 0.21 at 5-minute intervals during OLV. In the control group, Fio₂ was adjusted using arterial blood gas analysis measured at 15 minutes after OLV initiation. The primary end point was the time-weighted average Fio₂ during OLV.

RESULTS: 

Overall, time-weighted average Fio₂ did not differ between the groups (control versus ORI: median [interquartile range], 0.87 [0.73–1.00] vs 0.82 [0.68–0.93]; P = .09). However, in a subgroup analysis, the ORI group reduced time-weighted average Fio₂ after pulmonary vascular ligation compared to the control group (control versus ORI: median [interquartile range], 0.75 [0.70–1.00] vs 0.72 [0.59–0.89]; P = .0261). The incidence of intraoperative hypoxia (arterial oxygen saturation [Spo₂] <94%; control versus ORI: 32% [19/60; 95% confidence interval (CI), 20–45] vs 19% [12/64; 95% CI, 10–31]; P = .09), and postoperative complications within the first 7 days did not differ between the groups.

CONCLUSIONS: 

ORI-guided continuous Fio₂ titration does not reduce overall oxygen exposure during OLV.