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 (%).