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

Abstract

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.

Keywords: abdominal surgery; hyperoxia; hypoxemia; oxygen therapy; postoperative complications; thoracic surgery.

Figure 1

Participant timeline of the FreeO₂ PostOp study. Inclusion is performed during the anaesthesia consultation, prior to a scheduled major surgery (≥2 hours’ duration; ARISCAT score ≥26). Eligibility criteria are verified and the patient needs to sign the informed consent. Randomisation is performed no later than 1 hour following extubation in the recovery room. Clinical data will be recorded each hour during the first 3 hours of care and twice daily for up to 3 days. Continuous SpO₂ recording will be performed in each randomisation groups for up to 3 days. Outcome parameters will be assessed at day 28. LOS, length of stay (days); SpO₂, pulse oximetry (%).

Figure 2

Consort diagram of the FreeO₂ PostOp study. Randomisation will be performed after verification of the eligibility criteria and it will be stratified according to the presence of a medical history of chronic obstructive pulmonary disease (COPD). For patients without COPD, the target will be a SpO₂ range=92%–96%; for patients with COPD, the target will be a SpO₂range=88%–92%. Patients will be assigned either to standard continuous O₂ administration (Standard: manual adjustment) or automated closed-loop O₂ administration (FreeO₂: automated adjustment, up to each second); in both groups, continuous SpO₂ recordings will be performed during up to 3 days according to the FreeO₂ system. SpO_2, pulse oximetry (%).