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SGEM#64: Classic EM Papers (OPALS Study)

SGEM#64: Classic EM Papers (OPALS Study)

Podcast Link: SGEM64
Date:  February 28, 2014

Guest Skeptic: Dr. Anand Swaninathan is an assistant program director at NYU/Bellevue Hospital in the department of EM. His interests are in resident education, critical care and EBM. Swami loves debunking urban legends in EM and is a strong supporter of FOAMed.

Case Scenario: A 43-year-old man experiences a cardiac arrest on the street. You are the first provider on scene with EMS. A cardiac defibrillator is hooked up and the patient is in ventricular fibrillation. He is unsuccessfully shocked and chest compressions are started. The paramedics ask you if you want to intubate and administer medications or load for transport.

Questions: Do advanced life support techniques, specifically pharmacologic interventions, improve survival to discharge versus basic life support (rapid defibrillation and CPR) in patients with out-of-hospital cardiac arrest (OHCA)?

Background: Sudden cardiac arrest is common and, obviously, very bad. In the US, there are about 500,000 cardiac arrests each year. About half of these cardiac arrests are OHCA and the survival rate is pretty poor. The most recent survival estimates put it at 7 – 9.5% in most communities. About 10-12 years ago, the American Heart Association built the 4-step “chain-of-survival.”

  • Step One – Early access to emergency care
  • Step Two – Early CPR
  • Step Three – Early defibrillation

In fact, in communities with high layperson basic life support (BLS) training and automatic electronic defibrillators (AEDs) in the community, the rate of survival after OHCA is higher.

The 4th Step in the chain, however is slightly more controversial; early advanced care. This basically means rapid access to ACLS type resuscitation skills (intubation and intravenous drug therapy). The AHA now has Five Links in the chain of survival with Step Five being Integrated post-cardiac arrest care.


ACLS has little evidence to defend it. Of course, ACLS is not a single treatment. It’s a bundle of treatments much like early goal directed therapy. It involves airway management with intubation and drug administration based on set algorithms. In spite of the lack of evidence behind it, ACLS is standard of care. Patients who have OHCA get ACLS treatment in the field (which may delay their transport). Additionally, there are a ton of providers trained in ACLS. It costs about $174-250/2 years to get certification and a number of hospitals require ACLS certification in order to practice.

If ACLS isn’t proven to help, it brings up a number of issues. Is ACLS training a waste of time and money for providers? Do the therapies in ACLS detract from critical interventions like CPR and defibrillation? Do delays in transit matter now that hospitals are doing ED ECMO? Are we harming patients with ACLS by bringing back more people with severe neurologic disabilities?


Dr. Ian Stiell

The authors of the study we are going to discuss saw these issues more than a decade ago and attempted to tackle it head on. People should be familiar with the lead author on this paper, Dr. Ian Stiell. He is arguably the most famous/cited Canadian EM researcher. If you don’t know his name you certainly know his significant contribution to the area of clinical decision instruments. These are the Ottawa Ankle and Knee Rules, Canadian C-Spine and CT Head Rules and his latest, Ottawa SAH Rules. We have covered some of these topics on past episodes of the SGEM:

  • SGEM#3: To X-ray or not to X-ray (Ottawa Ankle Rules)
  • SGEM#5: Does Johnny “kneed” an X-ray? (Ottawa Knee Rules)
  • SGEM#48: Thunderstruck (Subarachnoid Hemorrhage)

Reference: Stiell IG et al. Advanced Cardiac Life Support in Out-of-Hospital Cardiac Arrest. NEJM 2004; 351: 647-56.

  • Population: All persons > 16 yo who had an OHCA and for whom resuscitation was attempted.
  • Intervention: Advanced-life-support program whereby paramedics were trained in inutbation, IV line placement and IV medication administration.
  • Control: Basic-life-support – defibrillation + CPR
  • Outcome:
    • Primary –Survival to hospital discharge (defined as patient leaving hospital alive).
    • Secondary  – ROSC, admission to hospital and cerebral performance category.
  • Excluded: < 16, persons who were dead, patients with trauma, disorders of clearly noncardiac cause.

Authors Conclusions: “The results of the OPALS study did not show any incremental benefit of introducing a full advanced-life-support program to an emergency-medical services system of optimized rapid defibrillation.”


  • 5638 patients over 48 months in 17 communities and 11 hospitals
  • 1391 Rapid-defibillation phase (no ACLS) over 12 months
  • 4247 Advanced-life-support phase over 36 months
  • Initial cardiac rhythm
    • VFib/VTach 34.5% vs. 31.5%
    • PEA 25.8% vs. 25.3%
    • Asystole 38.8% vs. 42.0%
  • Medications (ACLS phase)
    • Epinephrine 95.8%
    • Atropine 87.3%
    • Lidocaine 23.6%
  • ROSC 12.9% vs. 18.0% (absolute change 5.1% p < 0.001)
  • Admission to hospital 10.9% vs. 14.6% (absolute change 3.7% p < 0.001)
  • Survival to hospital discharge 5.0% vs. 5.1% (absolute change 0.1% p 0.83)
  • Survivors’ Cerebral-performance category level 1 – 78.3% vs. 66.8% (p 0.73)
  • Survivors’ median Health Utility Index at one year 0.84 vs. 0.79 (p 0.67)

Screen Shot 2014-02-28 at 11.40.35 AM

Screen Shot 2014-02-28 at 11.57.41 AM

Critical Appraisal Toolkit for Cohort Studies:

Dr. Anand Swaminathan

Dr. Anand Swaminathan

  1. Did the review ask a clear question? – Yes. The issue here was whether ACLS management increased patient survival to hospital discharge
  2. Appropriate method to answer their question? – Yes. Ideally, a randomized control trial would have been better but not possible. This was a “before-after” multicenter, cohort trial (before and after ACLS was instituted) with rapid defibrillation only for 12 months and advanced-life-support for 36 months. The methods were very good and specifically cite following Ustein-style guidelines for reporting the data about cardiac arrests. Doing a RCT would not be feasible.  You would have to provide ACLS to half of patients (which is believed to be the standard of care) and BLS to the other half. Ethically you cannot do trials that may involve harm. Evidence based medicine has a hierarchy of evidence. A before/after trial is less robust than a RCT. EBM also has limitations and this well-done cohort trial identifies some of these limitations. Sometimes a lower form of evidence will be the “best” evidence we can get.
  3. Cohort recruited in an acceptable way? – Yes, All OHCA in the Ottawa enchantment area were included for analysis.
  4. Was the exposure accurately measures to minimize bias?– Yes. Objective measures were used. The outcomes are ones that both doctors and patients would care about. In fact if there was any bias it was probably in favour the intervention (ACLS). Given the fact that there was no difference in the primary outcome strengthens the conclusion.
  5. Was the outcome accurately measured to minimize bias? – There could be no blinding for the patients or doctors in this type of study design. However, the abstractors who are collecting data can be blinded to outcomes. It’s not clear if that occurred. Lack of blinding for outcome should not have impacted on the mortality data. Either the patient was or was not alive at discharge. Secondary outcome of CPC also validated in past.
  6. All important confounding factors identified? – Hard to say. There is a problem of multiple interventions with the OPALS study. Incorporating ACLS into OHCA treatment involves multiple interventions including drugs (epi, lidoc, atropine), fluids and procedures (intubation). Any of these could individually improve outcomes or worsen outcomes but we have to regard them as a bundle (much like EGDT).
  7. Follow-up complete and long enough? – Yes (ROSC, admit to hospital, survive to discharge, cerebral-performance category at discharge and quality of life at one year
  8. What are the results? – No benefit for survival to discharge neurologically intact
  9. How precise are the results? – Yes. The confidence intervals were pretty small.
  10. Do you believe the results? – Yes
  11. Can you apply them to your local population? – Not sure. This study was not ED focus but rather on the pre-hospital setting. However, many systems have MDs working in the field with EMS. It would be important for those individuals to be aware of this study. Also we do not work in isolation but in a continuum of care from pre-hospital, emergency department and then in-patient units (ICU, CCU, trauma). These results apply to the pre-hospital setting in Ontario, Canada. We cannot necessarily extrapolate them to other EMS systems. With regards to the ED setting, there have not been any trials showing benefit of ACLS medications for in-hospital cardiac arrest. In addition, there have been some observational studies suggesting ACLS medications could cause harm. (Dr. David Newman The NNT)
  12. Do the results fit with other available evidence? – Yes, There was another study published five years later from Norway published (JAMA 2009). It was a RCT of 851 adults with out of hospital non-traumatic cardiac arrests. Patients were randomized to ACLS with or without intravenous drugs. Like OPALS, they showed improved ROSC and admit to hospital but not benefit for discharge from hospital neurologically intact or alive at one year.

Does this change what you do? No because it’s now 10 years later and ACLS is still the standard of care treatment. However, OPALS is one paper in a group that questions the quality of ACLS care and there should be readdressing of this algorithm. Also, we do not work in the pre-hospital setting. We should focus on good CPR and early defibrillation.

Bottom Line: Addition of an advanced life support algorithm to BLS management did not increase the survival to hospital discharge for patients with out of hospital cardiac arrest.

Case Resolution: You tell the paramedics to support the patient with bag mask ventilation and rapidly transport to the hospital.

27 Man with book sitting in chairThis concludes the first ever SGEM Classic Paper critical review. Let me know what you think. Should we do more podcasts on historic/practice changing papers? If so, what papers would you like the SGEM to put under the skeptical lens? Send me your suggestions to with “classic” in the subject heading.

Keener Kontest: Last weeks winner was Dr. Mark McAllister. He knew that PDS or polydioxanone sutures take greater than 90 days for complete absorption. Listen to this weeks episode of the SGEM for the Keener Kontest? If you know the answer send an email to with “keener” in the subject line. The first person will receive a skeptical prize.

BEEM Conferences: SweetBEEM March 17th and 18th. PrairieBEEM May 12th and 13th.

Remember to be skeptical of anything you learn,

even if you heard it on the Skeptics’ Guide to Emergency Medicine.

  • akroeze

    Thank you for this excellent review of the paper. I fully agree with the conclusions that addition of advanced life support to BLS management only improves surrogate end points (ROSC, hospital admission, etc) while having no benefit for the only end point that matters (neurologically intact discharge). We should only be performing interventions on these patients that have been proven to improve that outcome.

    I do want to point out that in your case resolution you then encourage the paramedics to do other procedures that have no evidence of benefit: BVM ventilation and rapid transport to hospital. Why are some unproven/possibly harmful procedures like ACLS unacceptable but others such as these are acceptable? The only two things that have been proven to help standard cardiac arrest patients are continuous chest compressions with minimal pauses as well as rapid and frequent defibrillation, anything else (including BVM and transport) is distracting from and/or reducing the quality of CPR and defib.

    Alex Kroeze
    Advanced Care Paramedic

    • Alex:
      Thanks for the feedback. I will send your comment to Swami about the case resolution to respond. Keep being skeptical.

    • Anand Swaminathan

      Alex – Great point. I wanted to stress BMV instead of intubation for supplying ventilation. I agree that compression only CPR is reasonable early but at some point, I think ventilation and oxygenation should be provided.
      As far as transport, Ken and I didn’t want to get into it but ECMO is becoming more and more present in the ED and may be the next big thing in cardiac arrest for selected patients. The evidence is anecdotal at this point so we clearly need more work to be done. If ROSC is achieved, TTM and cath (again for selected patients) are reasonable interventions that need a hospital to be done. Good critical care management is vital as well.

      We can debate stay and play versus scoop and run forever but I think if we’re not doing ACLS in the field, early transport makes sense.

      • Brooks Walsh

        Anand –
        Great choice for a review, and you highlight important points. However, I wonder if, in your conclusion, you aren’t going beyond the evidence you just discussed.

        Unless the “before” group had early transport to the ED, with on-going CPR, I would be hesitant to draw the conclusion that such a strategy is preferred. Just as the ACLS/EMS community has a greater understanding these days that “the basics” are far more important than the “drugs and devices,” there is also a growing understanding that the basics of good CPR have to emphasized. Since CPR in a moving ambulance is fraught with problems (e.g. decreased effectiveness of CPR, higher risk to crew, < 0.5% rate of ROSC if not achieved by EMS), there has been a greater push to "work 'em where they drop." The AHA notes, in part 3 of the 2010 ACLS guidelines, that "the quality of CPR is compromised during transport, and survival is linked to optimizing scene care rather
        than rushing to hospital."

        As for ECMO… For the love of pete, can we not push this resource-intense intervention until we have some outcomes data?! I've heard you speak eloquently about tPA for CVA, and this strikes me as pretty analogous to endovascular intervention for acute CVA – lots of promise, but no outcomes data. (At least tPA has NINDS!) Perhaps we can put a moratorium of discussing this intervention if it's not in an experimental context.


        • Anand Swaminathan

          Brooks – totally agree with everything you said. Let’s start with ECMO. Very promising but no outcome data that’s worth resting on. We clearly need more and this is extremely time and resource intensive. I’m supportive but would like to see more before I jump on board.

          The difficulty with continuing CPR while transporting is a real one. The LINC trial (and others like it) have tried to show improvements with mechanical devices and haven’t. Presumably, compressions were good with the device even while the patient was moving but it didn’t matter. I’ve commented on Emergency Medicine Literature of Note ( that when patients don’t get ROSC in the field, they are usually not going to get ROSC after transport so I think you have a valid point here. We could just as easily have recommended to continue CPR and defib when necessary in the field and then call it in the field if ROSC was not achieved.

          All of this is to say that I don’t have a good argument for why early transport would be necessary and our conclusion to the case could simply have been to just continue with good CPR and defibrillation if necessary in the field and hold off on medications.
          Appreciate your thoughts and for calling us on that one! Thanks, Brooks.

  • Great review! Loving the “classic” practice-changing article model (especially because I’m too young to have caught these the first go-around). Looking forward to future episodes!

    Also: check your cited reference. I believe the “goldfinger” citation found its way onto this page.

    Thanks again,


    • Derek:
      Thanks for your kind feedback and catching the editing glitch. It was picked up by another smart guy too Dr. Chris Bond in Calgary. Sorry for any confusion and it has be updated with correct reference.
      Keep listening and being skeptical,

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