Category: Cardiac Arrest

Meta-analysis of published trials, 9 for trauma and 9 for non-trauma met their inclusion criteria after review, examining OR for survival when comparing ALS to BLS.

Trauma, unsurprisingly, derives no benefit from ALS in cardiac arrest.  They even found a pooled OR of 0.89 for survival with ALS, but the CI just barely crosses 1.

But, contrary to the two most recently published prospective trials, their meta-analysis of non-trauma arrest still shows a survival benefit for ALS.  They do include a few trials from before AEDs were available in BLS in 1995, but it still doesn’t explain the entire benefit.  They also cite a few studies in which a physician is part of the paramedic team, which may mean there’s more to ALS than AHA ACLS, so that might be a bit of a confounder.  Hard to know what to make of this data, considering the lack of demonstrable benefit from ACLS medications and the decreased survival of patients intubated in the field in out-of-hospital arrest.

My take is still that cardiac arrest, for the moment, is still a place where significant out-of-hospital resource investment is low yield, and CPR and AED is all they need en route to the ED.

I’m sure you’ve seen summary articles from various sources regarding updates to the ACLS algorithm for 2010.  The change in the BLS component from an A-B-C to a C-A-B with a focus on providing high-quality compression-only CPR is well-publicized.

On EM:RAP – an educational resource I simply cannot recommend highly enough as a way to mix entertainment with CME – Mel Herbert issued the challenge to submit proof of the “epinephrine-free code”.  They made this hypothetical challenge based on a close reading of the new ACLS guidelines for PEA/asystole – which, if you look closely, reflect a tacit acknowledgement of the futility of ACLS medications.  Between atropine, bicarbonate, epinephrine, and calcium – various pieces of the kitchen sink available in the code cart – only epinephrine still has a role in the guidelines, but the level of evidence has decayed to IIb, which is at the “expert opinion or consensus” level.

There are a couple large studies with limitations from Scandinavia that show associations of epinephrine with poorer outcomes, or no improvement in survival with ACLS medication administration pre-hospital.  And, if you consider the vasoactive properties of epinephrine – sure it increases CPP, but its effects on the oxygen-debt of the peripheral vascular bed, the effect on subendocardial perfusion and infarct size – imagine giving epinephrine to a STEMI patient.  We’re injuring the most important organ system of interest in cardiac arrest.  I am more than willing to take up the challenge of epinephrine-free resuscitation – I just need to find some evidence to support something else to give in the meantime so I’m not reported to the Chief of Staff so it looks like I’m trying.  Anyone have anything in mind?

http://circ.ahajournals.org/content/vol122/18_suppl_3/
http://www.ncbi.nlm.nih.gov/pubmed/12104107
http://www.ncbi.nlm.nih.gov/pubmed/19934423

This is, actually, an important avenue of contemporary research, highly funded by DARPA at Texas A&M – although this research is from Germany – and this article is about one of the methods tested that got into the lay press a year two back.

The driving principle is that, the best way to keep someone newly dead from starting to go down all those cellular pathways that make cells go “pop”, is to shut down cellular metabolism and starve those pathways of cellular energy.  This seems like a sound idea – although, a lot of other cellular pathways that maintain cellular integrity and electrochemical gradient stability are also funded by those same pathways.  But, the theory is that if you have a tissue hypoxic event, slow everything down to buy you more time, fix the overriding problem, and then resuscitate the patient.

Didn’t work for these folks.  61 Wistar rats given hydrogen sulfide as their agent to paralyze cellular metabolism.  Significantly better pH and less base excess initially during acute resuscitation from cellular hypoxia, so it is doing something to prevent tissue oxygen debt – but their primary outcome of neurologic preservation, they showed temporary neurologic preservation at an interim test, but no differences at the 7 day point, and no histochemical differences after sacrifice.

This sort of research is still clearly poking about in the dark right now, but it is absolutely the future of resuscitation – to give us a reason for hope in the trauma bay that return of circulation is neurologically intact and not simply just for organ donation.

http://dx.doi.org/10.1016/j.resuscitation.2011.03.038

Most recently, the new “hands-only” CPR guidelines have received a lot of press and attention, and there’s a lot of excellent research showing that any intervention that stops CPR decreases survival.  Well, the last time they revised the CPR guidelines, they were also intended to decrease CPR pauses, including changing the manner in which defibrillation was performed, making longer CPR intervals, and eliminating pulse checks after shocks.

The “Resuscitations Outcomes Consortium” did a crossover study looking at survival to hospital discharge before and after the implementation of the new guidelines…and they found no statistically significant differences.  They did find a clinically significant improvement in VT/VF survival that went from 14% to 18%, but the p-value was 0.06 – and it’s hard to attribute that solely to the guidelines because there are other significant baseline differences, particularly a 28% to 34% increase in bystander CPR.

Should be interesting to see if widespread implementation of the new CPR guidelines increase overall or subgroup survival.

The paper also mentions their current studies, looking at whether automated devices improve outcomes and when AED analysis should be performed in sequence.

http://www.ncbi.nlm.nih.gov/pubmed/21497983

There are nice studies in the U.S. defining and validating a rule that determines which patients are unlikely to have ROSC or survival to hospital discharge, e.g. BLS-TOR.  This is a study from France that looks at people who do have ROSC to see, not just if they’ll survive, but survival where the patient is not severely disabled or vegetative.  One of the nice things about Europe is that their cultural perception of “life” really has to do more with living, and not just simply “being alive”.  So, whether we can actually implement something like this in the U.S. may be difficult.

It’s a chart review, which limits its quality to some extent.  The other real issue I have with this OHCA score is its complexity – it incorporates initial rhythm, no-flow and low-flow intervals, and admission levels of creatinine and lactate.  The U.S. validation cohort had 34% therapeutic hypothermia, which is pretty good – the derivation cohort was only at 11%.  Predictors of good neurologic outcome, consistent with other articles: ventricular fibrillation, bystander CPR, lower creatinine and lactate.

Unfortunately, for this rule to get up to 100% specificity, the sensitivity drops to 19%.  Alternatively, you could say that’s 20% of out-of-hospital arrest ROSC that shouldn’t have further intervention, which would be an important cost and medical resource utilization savings.

So, this is something that your colleagues in critical care are going to use to discuss prognosis, although I’d like to see something along these lines that helps attenuate the number of people we resuscitate until our post-resuscitation care demonstrates much, much improved outcomes.

http://www.ncbi.nlm.nih.gov/pubmed/21494106

This is an idea that sounds great in theory – if you have a roving team of skilled resuscitation professionals in your hospital assisting nurses who are concerned about their patients, you can intervene on these patients before they deteriorate, keep people from escalating into the ICU, and improve outcomes.  It’s such a great idea that the entire country of Australia has been spurred into implementing these.  My hospital has them, and, no doubt, many other hospitals do as well.

The problem is, they’re having a hard time demonstrating their efficacy.

A study out of Stanford last year reported that, at their VA hospital, implementation of emergency response teams (ERTs) reduced mortality.  Unfortunately, on closer reading, ERTs reduced mortality on the floor, and their primary intervention was to move people to the ICU – where their mortality was no longer counted in the study.  While it is rather graceless to have people coding and dying on the floor, unfortunately they did not show the outcomes they claimed.

http://www.ncbi.nlm.nih.gov/pubmed/20624835

This more recent report, from Australia, as mentioned above, is a before and after analysis of hospital-wide mortality, CPR rates, etc. with their ERTs.  They likewise show benefits, with ICU admissions, CPR rates, and mortality all declining after implementation.  However – and they very astutely point this out themselves – one of the most significant functions of the ERTs was to clarify code status and affirm a greater number of people as DNR or futile resuscitation.  While this function, if it reduces ICU admissions, is absolutely a cost and resource savings, I don’t think it’s precisely how they wanted to justify implementation of ERTs.

There are many reasons to have ERTs, but a mortality and cost-benefit justification has not yet been well-demonstrated.

http://www.ncbi.nlm.nih.gov/pubmed/21411218