Automated closed-loop versus standard manual oxygen administration after major abdominal or thoracic surgery: An international multicentre randomised controlled study

Abstract

Introduction: Hypoxaemia and hyperoxaemia may occur after surgery, with related complications. This multicentre randomised trial evaluated the impact of automated closed-loop oxygen administration after high-risk abdominal or thoracic surgeries in terms of optimising the oxygen saturation measured by pulse oximetry time within target range. Methods: After extubation, patients with an intermediate to high risk of post-operative pulmonary complications were randomised to "standard" or "automated" closed-loop oxygen administration. The primary outcome was the percentage of time within the oxygenation range, during a 3-day frame. The secondary outcomes were the time with hypoxaemia and hyperoxaemia under oxygen. Results: Among the 200 patients, time within range was higher in the automated group, both initially (3 h; 91.4±13.7% versus 40.2±35.1% of time, difference +51.0% (95% CI-42.8-59.2%); p0.0001) and during the 3-day period (94.0±11.3% versus 62.1±23.3% of time, difference +31.9% (95% CI 26.3-37.4%); p0.0001). Periods of hypoxaemia were reduced in the automated group (3 days; 32.6±57.8 min (1.2±1.9%) versus 370.5±594.3 min (5.0±11.2%), difference-10.2% (95% CI-13.9-6.6%); p0.0001), as well as hyperoxaemia under oxygen (3 days; 5.1±10.9 min (4.8±11.2%) versus 177.9±277.2 min (27.0±23.8%), difference-22.0% (95% CI-27.6-16.4%); p0.0001). Kaplan-Meier analysis depicted a significant difference in terms of hypoxaemia (p=0.01) and severe hypoxaemia (p=0.0003) occurrence between groups in favour of the automated group. 25 patients experienced hypoxaemia for 10% of the entire monitoring time during the 3 days within the standard group, as compared to the automated group (p0.0001). Conclusion: Automated closed-loop oxygen administration promotes greater time within the oxygenation target, as compared to standard manual administration, thus reducing the occurrence of hypoxaemia and hyperoxaemia.