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Updated: Aug 8, 2026

A Model to Simulate Clinically Relevant Hypoxia in Humans
Published on: December 22, 2016
A prospective, randomised controlled trial comparing the efficacy of pre-oxygenation in the 20 degrees head-up vs
S Lane1, D Saunders, A Schofield
1Intensive Care, St George's Hospital, Sydney, Australia.
Abstract:
We investigated whether positioning patients undergoing general anaesthesia for cholecystectomy in a 20 degrees head-up position, as opposed to supine, improved the efficacy of 3 min of standard pre-oxygenation via a circle breathing system. Following pre-oxygenation, patients received a standard induction of anaesthesia and the apnoea time (from administration of rocuronium to the arterial oxygen saturation to fall to 95%) was recorded. Mean (95% CI) apnoea time was 386 (343-429) s in the 20 degrees head-up position (n = 17) vs 283 (243-322) s in the supine position (n = 18; p = 0.002). Pre-oxygenation is significantly more efficacious and by inference more efficient in the 20 degrees head-up position than in the supine position.
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