The return of consciousness without the return of a pulse is still rare, but may be more common with our increased focus on high quality chest compressions. There is still no evidence that interrupting chest compressions, for anything other than defibrillation, improves outcomes.
Is this due to the consistency of the machine? Maybe. Maybe not. We do not have enough evidence to draw that conclusion.
Is this growing population really growing? Maybe. Maybe not. We do not have enough evidence to draw that conclusion, either.
It could be that with the ability to use a cell phone camera to record these instances, there is more credibility to the reports. There is a suggestion that this could be common.
Parnia et al. conducted a multi-year, multi-center, prospective study of the frequency of awareness during resuscitation by interviewing cardiac arrest survivors after discharge. They found 55/140 (39%) had perceptions of awareness of being alive and even memories that originated during that time.2 
Should we be giving ketamine to these patients?
We should find out how common it is for people to regain consciousness without regaining a pulse. This is clearly an experimental protocol that is not supported by evidence of improved outcomes that matter – just like all of the rest of cardiac arrest treatment that is not compressions or defibrillation.
RESULTS: The search yielded 1997 unique records, of which 50 abstracts were reviewed. Nine reports, describing 10 patients, were relevant. Six of the patients had CPR performed by mechanical devices, three of these patients were sedated. Four patients arrested in the out-of-hospital setting and six arrested in hospital. There were four survivors. Varying levels of consciousness were described in all reports, including purposeful arm movements, verbal communication, and resuscitation interference. Management strategies directed at consciousness were offered to six patients and included both physical and chemical restraints.
6/1,997 is 0.3% – not anywhere near the 39.3% of 55/140, but it is still a large enough group that we should not ignore them.
Depression and anxiety following resuscitation are significant problems, so this might even be a way to help decrease those resuscitation side effects.
One fourth of OHCA-survivors reported symptoms of anxiety and/or depression at 6 months which was similar to STEMI-controls and previous normative data. Subjective cognitive problems were associated with an increased risk for psychological distress. Since psychological distress affects long-term prognosis of cardiac patients in general it should be addressed during follow-up of survivors with OHCA due to a cardiac cause.
The similarity to the outcome of STEMI (ST segment Elevation Myocardial Infarction) patients do not inspire confidence in this approach, but that does not mean that it should not be examined.
It is most important that we not make the mistake that has been made with ventilations, endotracheal tubes, extraglottic airways, antiarrhythmic drugs, pressor drugs, anti-acidosis drugs, antidote drugs, anti-hypoglycemic drugs, et cetera. We should insist that there be valid evidence of some sort of benefit before the ACLS (Advanced Cardiac Life Support) Committee of Failed Treatments adds this to the ACLS algorithms because of an abundance of wishful thinking.
This time will be different.
This use of ketamine is interesting. Ketamine is a sedative that should not depress vital signs, so it may do what we expect. There may be more benefit than harm, but there may be more harm than benefit, or there may be all harm and no benefit. We will not know until we have valid research.
We have added the other treatments without finding out if they improve outcomes. We continue to remove these treatments as we obtain evidence, because they have one thing in common – they don’t improve outcomes.
These treatments have increased the ignorance of those who work in EMS (Emergency Medical Services) and EM (Emergency Medicine). We keep convincing ourselves that we know what we are doing, but evidence keeps showing that we are lying to ourselves.
Maybe ketamine sedation during compressions will be beneficial. It is such a small patient population, that it will be difficult to study. Introducing a treatment without studying it will always be a mistake. Is Nebraska studying this? Probably, but it is not stated in the paper. Has this been approved by an IRB (Institutional Review Board)? I do not know.
 CPR induced consciousness: It’s time for sedation protocols for this growing population
Rice, D., Nudell, N., Habrat, D., Smith, J., & Ernest, E. (2016). Resuscitation DOI: 10.1016/j.resuscitation.2016.02.013
Free Full Text from Resuscitation.
 Return of consciousness during ongoing cardiopulmonary resuscitation: A systematic review.
Olaussen A, Shepherd M, Nehme Z, Smith K, Bernard S, Mitra B.
Resuscitation. 2015 Jan;86:44-8. doi: 10.1016/j.resuscitation.2014.10.017. Epub 2014 Nov 4. Review.
 Anxiety and depression among out-of-hospital cardiac arrest survivors.
Lilja G, Nilsson G, Nielsen N, Friberg H, Hassager C, Koopmans M, Kuiper M, Martini A, Mellinghoff J, Pelosi P, Wanscher M, Wise MP, Östman I, Cronberg T.
Resuscitation. 2015 Dec;97:68-75. doi: 10.1016/j.resuscitation.2015.09.389. Epub 2015 Oct 9.
Rice, D., Nudell, N., Habrat, D., Smith, J., & Ernest, E. (2016). CPR induced consciousness: It’s time for sedation protocols for this growing population Resuscitation DOI: 10.1016/j.resuscitation.2016.02.013
Olaussen A, Shepherd M, Nehme Z, Smith K, Bernard S, & Mitra B (2015). Return of consciousness during ongoing cardiopulmonary resuscitation: A systematic review. Resuscitation, 86, 44-8 PMID: 25447435
Lilja G, Nilsson G, Nielsen N, Friberg H, Hassager C, Koopmans M, Kuiper M, Martini A, Mellinghoff J, Pelosi P, Wanscher M, Wise MP, Östman I, & Cronberg T (2015). Anxiety and depression among out-of-hospital cardiac arrest survivors. Resuscitation, 97, 68-75 PMID: 26433116