Written by Clay Smith
Spoon Feed
High-flow nasal oxygen (HFNO) compared to conventional oxygenation in the OR reduced desaturation, improved lowest oxygen saturation, and prolonged safe apnea time.
Why does this matter?
The literature has been back and forth on HFNO for preoxygenation (PROTRACH) and apneic oxygenation (i.e. FELLOW trial). This study largely focused on HFNO for preoxygenation, but the lines blur as flow is continued after induction.
O’s for the nose
This was a systematic review and meta-analysis of four small RCTs using HFNO for induction for endotracheal intubation and four during procedural sedation. I am going to focus on the trials for intubation. Oxygen desaturation was much lower in the HFNO group, OR 0.06 (95%CI 0.01-0.59); this means a 94% reduction in the odds of desaturation. That is really good. Here is the catch – only 2 RCTs looked at this outcome for induction; one had 80 patients, and one had 10. Desaturation was variably defined as <90-93%; flow rates were 40-70 L/min. That said, the effect size was large, and the upper 95% CI of 0.59 is still clinically significant (i.e. 41% lower odds of desaturation). Minimum oxygen saturation was 5% higher (3 RCTs) and safe apnea time 33 seconds longer with HFNO compared to conventional oxygenation (3 RCTs, 1 excluded for significant heterogeneity). EtCO2 was not significantly different with HFNO. All studies were done in an OR setting and not in the ED, which limits generalizability. In practice, I use HFNO and a NRB to preoxygenate and keep the NC flowing once apneic. I see no downside, and this combined evidence suggests it helps.
Source
The Effectiveness of High-Flow Nasal Oxygen During the Intraoperative Period: A Systematic Review and Meta-analysis. Anesth Analg. 2020 Oct;131(4):1102-1110. doi: 10.1213/ANE.0000000000005073.
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