Should we be passive about oxygenation?

Over the last few years there has been considerable interest in the concept of passive oxygenation as an alternative to standard ventilation during CPR, particularly when used as part of a Cardiocerebral Resuscitation (CCR) protocol. This interest appeared to peak in the run up to the issue of the new American Heart Association (AHA) and European Resuscitation Council (ERC) guidelines in 2010, following on from the International Liaison Committee on Resuscitation (ILCOR) Consensus conference earlier the same year.
There had been some speculation as to how the ERC and AHA would respond to the published evidence related to passive oxygenation. In the end, their conclusions were not dissimilar. The ERC concluded:

There is insufficient evidence to support or refute the use of passive oxygen delivery during CPR to improve outcome when compared with oxygen delivery by positive pressure ventilation. Until further data are available, passive oxygen delivery without ventilation is not recommended for routine use during CPR.

The AHA concluded:

This time there is insufficient evidence to support the removal of ventilations from CPR performed by ACLS providers.

Given the encouraging published evidence, why the caution? Well, in general, passive oxygenation was one of a number of changes implemented to try and improve ROSC and/or survival, so it was usually not clear precisely which change, or combination of changes, was responsible for any outcome improvements shown in the studies published. On this basis, changes to the recommendations was always going to be unlikely.

Whilst there is an understandable desire for changes to guidelines to be implemented on the basis of robust evidence, particularly from randomised controlled trials, in reality, the variability in patients, type and quality of resuscitation undertaken and the need for informed consent, all make such studies a challenge to implement in practice. So, will we ever get robust evidence regarding passive oxygenation in CPR, positive or negative, and where does this leave us now and for the next few years?

The number of studies reporting data regarding passive oxygenation in CPR appears to have slowed down since the 2010 guidelines were published. However, the current (June) issue of ‘Current Opinion in Critical Care’, has a couple of interesting articles looking at advancing resuscitation science and reviewing traditional and alternative methods of ventilation during CPR, so perhaps its profile will rise again.

The countdown to the new ILCOR Consensus Conference in 2015, when the next round of guidelines will be issued, started with a meeting in November last year in Orlando. For many, 2015 is too long to wait for change, whilst for others, without the robust evidence, changes to protocols regarding ventilation techniques cannot be justified now, in 2015 or beyond. Whatever your own view, few people seem to be passive about the subject itself.