Effectiveness of Apnoeic Oxygenation Questioned

Everyone knows I’m a huge fan of apnoeic oxygenation. I use it for sedation, for intubation, heck I sprinkle some on my cereal in the morning. But here is a study published this week, whose conclusions do not support the use apnoeic oxygenation during endotracheal intubation of critically ill adults.
Semler et al of the Fellow investigators published the paper on October 1st 2015 titled, Randomized Trial of Apneic Oxygenation during Endotracheal Intubation of the Critically Ill in the Am J Respir Crit Care Med. 

This was a randomised trial of 150 patients during endotracheal intubation and compared

(a) Apnoeic oxygenation to
(b) “Usual Care”
Pre-oxygenation was allowed.


The primary outcome measured, was the lowest arterial oxygen saturation, by pulse oximetry between induction and two minutes after successful endotracheal tube placement.
Results show that there was no statistically significant difference between the two groups leading to the conclusion that it adds no benefit.


Some important points:
This is a good study and an interesting one, as it is the only one that has found no benefit. When that happens it’s important to ask some questions. When reading the paper, what wasn’t clear was what was done in terms of pre-oxygenation procedure in the two arm.  Scott Weingart, of EMcrit, (the author of the original apnoeic oxygenation paper), interviewed the lead author of this paper and discussed some of these procedural issues. The two most important are:

1. There was not true apnoea in both groups.  A significant number of the patients in the control arm had either bag valve mask or BiPAP performed up until intubation. I certainly don’t BiPAP patients until I’m about to tube. So it would make sense that there might be no benefit if we compare BiPAP with nasal cannula.
2. It is unclear if there was a patent airway ie open glottis, which is necessary.

This study gives me no reason to stop using apnoea oxygenation. What it does raise in my mind, is the question of the effect of some gentle bagging during the apnoeic period. Now let’s see if some studies have been done on that.

Watch this space. No doubt more will come.
 
​Peter Kas