High-flow humidified nasal preoxygenation in pregnant women: a prospective observational study

Abstract

Background: Obstetric airway guidelines recommend preoxygenation in preparation for general anaesthesia to achieve end-tidal oxygen concentrations (etO2) of ≥90%, and mention the potential use of high-flow humidified nasal oxygen (HFNO). We investigated the new HFNO technique (Optiflow™) in term pregnant women. Methods: Seventy-three term participants underwent a 3 min HFNO protocol (30 L min−1 for 30 s, and then 50 L min−1 for 150 s). The etO2 was assessed for the first four breaths after simulated preoxygenation. The primary outcome was the proportion who achieved etO2 ≥90% for the first expired breath. The secondary outcomes were the proportion who achieved etO2 ≥80%; fetal heart rate bef..