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

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%); p<0.0001) 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%); p<0.0001). 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%); p<0.0001), 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%); p<0.0001). 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 (p<0.0001). 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.

Automated summary

Automated closed-loop oxygen administration after high-risk abdominal or thoracic surgeries significantly increases the time within the oxygenation target range and reduces the occurrence of hypoxaemia and hyperoxaemia.