Who would have figured that giving patients more oxygen during simulated emergency airway management results in better oxygenation?
Ok... I’m being overly cynical.
Some clinicians provide extra oxygen through nasal cannula in addition to either a nonrebreather (NRB) or bag-valve mask (BVM) prior to RSI. But does this really matter? Or is it just an extra step in an otherwise stressful situation that could be avoided?
This Australian study randomized 60 young healthy volunteers to either a NRB or BVM with or without a supplemental nasal cannula running at 10L/min. In addition, they also investigated whether the addition of a simulated mask leak changed the results.
The primary outcome was a comparison of end-tidal oxygen between the groups.
The addition of a nasal cannula to a NRB or BVM did not seem to do much unless there was a mask leak. The BVM achieved higher oxygenation than the NRB. (I don’t think the actual numbers are important, but if you are interested then click on the link to the abstract below.)
The major limitations of this study are obvious.
Unless you are sadistic, healthy volunteers are not the patients we typical intubate in the ED. The primary outcome was a surrogate marker and not necessarily a meaningful patient oriented one. Looking at real morbidity would have required a much larger study of actual patients.
What should we take from this?
The addition of a nasal cannula might be beneficial (or not) when performing RSI in the ED. This is not great evidence and it probably doesn’t matter in the vast majority of patients. Sure, give it a try when you really want to maximize pre-oxygenation. Also make sure you have a good mask seal.
Pedantic adherence to a supplemental nasal cannula adjunct during RSI is probably silly. But depending on the situation it might make sense and probably won’t hurt.
Hayes-Bradley C, Lewis A, Burns B, et al. Efficacy of Nasal Cannula Oxygen as a Preoxygenation Adjunct in Emergency Airway Management. Ann Emerg Med. 2015; Dec 31 [ePub]