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Obese Patient Preoxygenation — FRCA Final MCQ

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ModerateAirway ManagementObese Patient PreoxygenationFRCA Final

A 55-year-old man (ASA III, 100 kg) with known OSA is being induced for emergency laparotomy. Preoxygenation is critical. Which preoxygenation technique provides the longest safe apnoea time in an obese patient?

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Correct answer: A — Head-up position with 3 minutes of 100% O2 AND apnoeic oxygenation via nasal cannulae at 15 L/min during laryngoscopy

In obese patients, the combination of optimal positioning (head-up/ramped position to increase FRC), 3 minutes of tidal volume preoxygenation with 100% O2 (to maximise oxygen stores), AND apnoeic oxygenation via high-flow nasal cannulae during laryngoscopy provides the longest safe apnoea time. The NODESAT/THRIVE techniques demonstrate that nasal oxygen delivery during apnoea extends safe apnoea time by maintaining alveolar oxygen delivery. The head-up position alone extends safe apnoea time by approximately 50 seconds compared to supine in obese patients.

Reference: DAS – 2025 – Difficult intubation guidelines; AAGBI – 2015 – Obesity guidelines; Patel A – 2015 – THRIVE