Does Apneic Oxygenation Help Prevent Desaturation during RSI? An RCT.
Caputo, Nicholas, et al. “Emergency Department use of Apneic Oxygenation versus usual care during rapid sequence intubation: A randomized controlled trial (The ENDAO Trial).” Academic Emergency Medicine 24.11 (2017): 1387-1394. https://doi.org/10.1111/acem.13274
Preventing desaturations during endotracheal intubation is of critical importance. Persistent hypoxia can, of course, cause significant complications, including arrhythmias, cardiac arrest, and ultimately death. In the past decade, the idea of apneic oxygenation – i.e., delivering oxygen via nasal cannula while attempting to intubate – has become exceedingly popular and widespread. Previous studies have been split on whether apneic oxygenation adds value to the standard approach of simple preoxygenation in urgent or emergency intubations. This study attempts to add evidence from a randomized controlled trial to adjudicate the argument by testing to see if there was a difference in lowest mean arterial oxygen saturation between a group who received apneic oxygenation and a group who did not. Additionally, they looked at several secondary end points: (1) first pass success; (2) rate of desaturation; (3) time to desaturation; and (4) mortality. The study differs from a prior RCT of apneic oxygenation (the FELLOW trial) in that both groups in this study underwent a period of preoxygenation (and denitrogenation) prior to intubation.
200 patients enrolled at a large level 1 trauma center/academic hospital in a 1:1 ratio. Inclusion criteria: > 18 yrs old; received preoxygenation for 3 minutes via bag-valve mask, non-rebreather, or BiPAP; no trauma or cardiac arrest. The design included two groups: one that received preoxygenation alone and one that received both preoxygenation and flush flow nasal cannula beginning at the initiation of preoxygenation and extending through successful endotracheal intubation. The authors used Cohen’s d test to power the study to detect a difference of 5% in lowest average desaturation. For the purposes of the study, the authors defined apneic time as the period from insertion of laryngoscope blade to the time of end-tidal CO2 confirmation of successful ET tube placement. Lowest average desaturation was defined as the lowest O2sat during the apneic period and the two minutes that followed.
The demographics of the two groups, both in terms of patient characteristics and intubator skill, were comparable. There was no difference in O2sat at 80 seconds, 100 seconds or 195 seconds. There was no difference in time to desaturation, rate of desaturation, first-pass success or mortality.
The takeaway is that for patients that can safely be preoxygenated, there appears to be little-to-no added benefit of providing apneic oxygenation. That said, there is also little-to-no potential for harm from providing supplemental oxygen during the apneic period. Moreover, the study did not include crashing patients – cardiac and trauma arrests were exclusion criteria – or others who could not be preoxygenated, and the intubations were relatively quick (90% with completed within 100 seconds). It would seem reasonable, therefore, that apneic oxygentaion would help most in those instances where the patient is critically ill or is likely to be a difficult airway (e.g., obese patients). And in stable patients where there is ample time to set up prior to intubating, there appears to be little downside to adding additional oxygen during the preox and apneic periods.