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 oxygen administration versus conventional oxygen therapy after major abdominal or thoracic surgery: study protocol for an international multicentre randomised controlled study.

INTRODUCTION: Hypoxemia and hyperoxia may occur after surgery with potential related complications. The FreeO2 PostOp trial is a prospective, multicentre, randomised controlled trial that evaluates the clinical impact of automated O2 administration versus conventional O2 therapy after major abdominal or thoracic surgeries. The study is powered to demonstrate benefits of automated oxygen titration and weaning in term of oxygenation, which is an important surrogate for complications after such interventions. METHODS AND ANALYSIS: After extubation, patients are randomly assigned to the Standard (manual O2 administration) or FreeO2 group (automated closed-loop O2 administration). Stratification is performed for the study centre and a medical history of chronic obstructive pulmonary disease (COPD). Primary outcome is the percentage of time spent in the target zone of oxygen saturation, during a 3-day time frame. In both groups, patients will benefit from continuous oximetry recordings. The target zone of oxygen saturation is SpO2=88%-92% for patients with COPD and 92%-96% for patients without COPD. Secondary outcomes are the nursing workload assessed by the number of manual O2 flow adjustments, the time spent with severe desaturation (SpO2 <85%) and hyperoxia area (SpO2 >98%), the time spent in a hyperoxia area (SpO2 >98%), the VO2, the duration of oxygen administration during hospitalisation, the frequency of use of mechanical ventilation (invasive or non-invasive), the duration of the postrecovery room stay, the hospitalisation length of stay and the survival rate. ETHICS AND DISSEMINATION: The FreeO2 PostOp study is conducted in accordance with the declaration of Helsinki and was registered on 11 September 2015 (http://www.clinicaltrials.gov). First patient inclusion was performed on 14 January 2016. The results of the study will be presented at academic conferences and submitted to peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT02546830.