SGEM#189: Bring Me To Life in OHCA

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Date: September 19th, 2017

Reference: Cournoyer et al. Prehospital advanced cardiac life support for out-of-hospital cardiac arrest: a cohort study. Academic Emergency Medicine. September 2017.

Guest Skeptic: Dr. Corey Heitz is an emergency physician in Roanoke, Virginia. He is also the CME editor for Academic Emergency Medicine and the associate editor for emergency medicine simulation at the AAEM MedEdPORTAL.

Case: You are the medical director of an EMS system in a large city deciding on whether to respond to all out of hospital cardiac arrests (OHCA) with ACLS capabilities, or if resources should be directed to those candidates for extracorporeal CPR.

Background: There are about ½ million sudden cardiac arrests in the USA each year. About half of these cardiac arrests are OHCA and the survival rate is pretty poor. We have covered the topic of OHCA on the SGEM a number of times:

SGEM#143: Call Me Maybe for Bystander CPR
SGEM#152: Movin’ on Up – Higher Floors, Lower Survival for OHCA
SGEM#162: Not Stayin’ Alive More Often with Amiodarone or Lidocaine in OHCA

The American Heart Association came out with updated CPR & ECC Guidelines in 2015 that included its “Chain-of-Survival”. There are five steps in the Chain-of-Survival for OHCA:

Most of us can agree with the first three steps. You need to recognize an arrest and activate your EMS system. Bystander high-quality CPR can buy you some time until defibrillation. We know that rapid application of electricity to defibrillate shockable arrhythmias save lives.

It is the fourth step in the chain that is slightly more controversial; early advanced care. This basically means rapid access to ACLS type resuscitation skills (intubation and intravenous drug therapy). The classic paper on ACLS drugs is called OPALS (Ontario Pre-hospital Advanced Life Support) study and was done by Dr. Ian Stiell and team. Ian is a #LegendofEM and we covered his classic paper on SGEM#64.

OPALS was a before and after observational study, which showed the addition of ACLS was associated with more return of spontaneous circulation (12.9% vs. 18.0%, p<0.001) and improved survival to hospital admission (10.9% vs. 14.6%, p<0.001). However, adding ACLS to the pre-hospital system did not demonstrate an improvement in survival to hospital discharge (5.0% vs. 5.1%, p=0.83). It also did not show an increase in good neurologic outcome in the survivors (78.3% vs. 66.8%, p=0.73).

There have been a number of papers published since OPALS that support the findings of not using ACLS drugs like epinephrine for OHCA:

Olavseengen et al. Intravenous drug administration during out-of-hospital cardiac arrest: A randomized trial. JAMA 2009
Jacobs et al. Effects of adrenaline on survival in out-of-hospital cardiact arrest: A randomized double-blind placebo-controlled trial. Resuscitation 2011
Hagihara et al. Prehospital epinephrine use and survival among patients with out-of-hospital cardiac arrest. JAMA 2012

In recent years there has been an interest in the use of extracorporeal cardiopulmonary resuscitation (E-CPR) in selected patients suffering from refractory OHCA.

Sakamoto et al. Extracorporeal cardiopulmonary resuscitation versus conventional cardiopulmonary resuscitation in adults with out-of-hospital cardiac arrest: A prospective observational study. Resuscitation 2014
Johnson et al. Extracorporeal life support as rescue strategy for out-of-hospital and emergency department cardiac arrest. Resuscitation 2014
Pozzi et al. Extracorporeal life support for refractory out-of-hospital cardiac arrest: should we still fight for? A single-centre, 5-year experience. Internat J Cardiol 2016

Clinical Question: In patients with OHCA that are candidates for E-CPR, does ACLS in the pre-hospital setting improve rates of ROSC, survival to hospital discharge and survival with good neurological outcome?

Reference: Cournoyer et al. Prehospital advanced cardiac life support for out-of-hospital cardiac arrest: a cohort study. Academic Emergency Medicine. September 2017.

Population: Patients 18 years of age or older with prehospital cardiac arrest
- Exclusion: Traumatic arrests, deaths from obvious causes (decapitation, advanced putrefaction) or advanced do not resuscitate directive
Intervention: ACLS provider on scene during resuscitation
Comparison: No ACLS provider on scene during resuscitation
Outcome:
- Primary: Survival to hospital discharge
- Secondary: Prehospital ROSC and delay from call to hospital arrival
- Subgroup Analysis: Same metrics but for patients who were candidates for E-CPR

Dr. Alexis Cournoyer

Lead Author: Dr. Alexis Cournoyer is an emergency physician at the Hôpital du Sacré-Coeur de Montréal and a resident in the clinician-scientist program at the Université de Montréal. He is also currently doing a PhD at the Université de Montréal in pre-hospitals resuscitation.

Authors’ Conclusions: “In a tiered-response urban emergency medical service setting, prehospital ACLS is not associated with an improvement in survival to hospital discharge in patients suffering from OHCA and in potential E-CPR candidates, but with an improvement in prehospital ROSC and with longer delay to hospital arrival.“

Quality Checklist for Observational Study:

Did the study address a clearly focused issue? Yes
Did the authors use an appropriate method to answer their question? Yes
Was the cohort recruited in an acceptable way? Yes
Was the exposure accurately measured to minimize bias? Yes
Was the outcome accurately measured to minimize bias? Yes
Have the authors identified all-important confounding factors? Unsure
Was the follow up of subjects complete enough? Yes
How precise are the results? Very precise
Do you believe the results? Yes
Can the results be applied to the local population? Unsure
Do the results of this study fit with other available evidence? Yes

Key Results: A total of 7,134 patients were included in the study with 71.5% getting BLS and 28.5% receiving ACLS. The mean age was in the mid 60’s and 2/3 were male. Only 3.4% (246) were considered potential E-CPR candidates.

Primary Outcome: No difference in survival to hospital discharge

Primary Outcome: Survival to hospital discharge (ACLS 10.9% vs BLS 10.6%, p=0.67)
Secondary Outcomes:
- Prehospital ROSC (ACLS 37.5% vs. BLS 18.5%)
- Delay from call to hospital arrival was 16 minutes longer in the ACLS group than in the BCLS group (95% CI = 15–16 minutes, p < 0.001).
- E-CPR candidates: 51.2% got ROSC and 36.6% survived to discharge. No significant difference associated with ACLS.

We asked Alexis five questions about his research. The issue of it being an observations study was not one of the questions. This is because SGEMers are sophisticated enough to know with an observational design we can only conclude associations. Listen to the SGEM Podcast on iTunes to hear Alexis’ answers to our nerdy questions.

Selection Bias: How were ACLS units assigned during the period included and can you discuss the medical priority dispatch system card? It says the ACLS crews were not always available. Could they have self-selected not to go to calls they thought would probably be futile? Just because ACLS crews were there does not tell us what interventions were performed – can you comment on that?
Primary Outcome: The primary outcome was survival to hospital discharge. A more patient oriented outcome would have been survival with good neurologic function. Did you measure this important outcome and if not, why not?
Rural vs Urban: This study was done in a large, urban centre. How do you think these results should be applied, if at all, to a rural setting?
External Validity: The SGEM has an international audience. Your EMS model has BLS and ACLS paramedics but not physicians in the ambulance. Other EMS systems do have a physician on board. Do you think this would have changed your outcome?
Subgroup Analysis: Results from subgroup analyses should be viewed as hypothesis generating. ACLS was not associated with an increase or decrease in survival in the subgroup population of E-CPR candidates. Can you comment on your next steps based on this data?

Comment on Authors’ Conclusion Compared to SGEM Conclusion: We agree with the authors’ conclusion.

SGEM Bottom Line: Even in E-CPR candidate patients, there is no evidence that ACLS provides a patient oriented benefit.

Case Resolution: You decide to conserve resources and not to dispatch ACLS units to all cardiac arrests. You will however keep an eye on the literature to see if future results will change this decision.

Dr. Corey Heitz

Clinical Application: Patients undergoing OHCA arrest do not benefit from ACLS during transport. Efforts should be focused on increasing bystander CPR, decreasing EMS response times and decreasing time to defibrillation.

What do I tell my patient? Not applicable.

Keener Kontest: Last weeks’ winner was Blake Porter an EM pharmacy specialist form the University of Vermont Medical Centre. Blake knew the two giants of medicine who are credited with describing angioedema and determining the presence of a hereditary form were Heinrich Quincke and William Osler.

Listen to the SGEM podcast on iTunes to hear this weeks’ question. If you know the answer send an email to TheSGEM@gmail.com with “keener” in the subject line. The first correct answer will receive a cool skeptical prize.

Other FOAMed: The Brown University Emergency Medicine Blog as part of AEM Early Access initiative also covered this publication. Consider it spaced repetition. Dr. Gita Pensa and I will try to coordinate better next time in selecting our articles.

Dr. Justin Morgenstern

SGEMHOP: Now it is your turn SGEMers. What do you think of this episode? Tweet your comments using #SGEMHOP. What questions do you have for Dr. Cournoyer and his team? Ask them on the SGEM blog. The best social media feedback will be published in AEM.

Also, don’t forget those of you who are subscribers to Academic Emergency Medicine can head over to the AEM home page to get CME credit for this podcast and article. We will put the process on the SGEM blog: