Mechanical CPR Takes a Thumping

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CPR RMIf you listen to proponents of auto-resuscitation devices, you’d think they’re clearly superior to manual CPR. A review of the literature suggests otherwise.

If you listen to proponents of auto-resuscitation devices, you’d think they’re clearly superior to manual CPR. A review of the literature suggests otherwise.

CPR W
The LINC trial published earlier this year reported that band-style devices had greater odds of achieving one minute of ROSC than manual compression. The question remains: Is one minute of ROSC a meaningful outcome?

Mechanical CPR devices are nothing new. Emergency responders were using a device called “The Thumper” in Victoria as long ago as the 1970s. However, there seems to be a surge in interest in these auto-resuscitation devices as new products hit the market and old standbys roll out fancy upgrades. What is surprising is how positive the buzz seems to be surrounding these devices, given the relative weakness of the evidence for their effectiveness. Here is an excerpt from an email that landed in my inbox from a well known EMS journal a few weeks back:

EMS systems that are using mechanical compression devices have seen dramatic results in the number of patients not just resuscitated, but also leaving the hospital neurologically intact.

Attend this important Webcast Thursday to hear *** ******, MD, discuss how convinced he and many other medical and administrative leaders are that mechanical CPR offers significant benefits over manual CPR…

This is both surprising and concerning, given the relative weakness of the research. Let’s break down the evidence. The LINC trial was published earlier this year, comparing normal resuscitation with that using the LUCAS mechanical CPR device. No difference in survival to hospital, or discharge from hospital was found. This backs up the data from the earlier CIRC trial which found the same results with a different device, the Ong et al study (JAMA 2006) that showed no benefit (despite what the conclusion says), and the Hallstrom et al study (JAMA 2006) that showed harm (worse neurological outcomes) using mechanical devices. A recent study published in the Netherlands Heart Journal (Boyle et al) showed that survival from cardiac arrest in the population studied was a very impressive 43%, but it was attributed to widespread bystander CPR and AED use.

Finally, the PaRAMeDIC trial, just published in the Lancet, is the large, pragmatic trial of mechanical CPR devices that we have been waiting for. The result? I’ll quote from the article itself: “We noted no evidence of improvement in 30 day survival with LUCAS-2 compared with manual compressions. On the basis of ours and other recent randomised trials, widespread adoption of mechanical CPR devices for routine use does not improve survival.”

Also published in September of 2014 in Resuscitation was a small observational paper which noted a significantly increased number of injuries in patients who received mechanical CPR as compared to manual CPR. These injuries were more common in non-survivors, and it is not suggested that any of the injuries contributed to the death. CPR is a brutal intervention and none of us are phased when we feel a few ribs go; it just appears that mechanical CPR is more brutal than traditional CPR. It is not reported what, if any, effect injuries had on the recovery of survivors.

So, what did the EMS journal that emailed me know that these studies had missed? If there are systems that have found such positive results, why have they not been published? If the comments in the email are true, this represents a major improvement in cardiac arrest care and should be shared broadly.

Why do we tend to be uncritical of these devices? I’m sure it is partly because we love our toys, and these are pretty nifty toys. What’s more, the devices are certainly no worse than people-powered CPR, so it would seem that there is potential benefit to rescuers in terms of health and safety. After all, not doing CPR is far easier and less likely to cause injury than doing CPR. We must be clear, though, when we discuss these devices, who the benefit (real or perceived) is to. As things stand, when using these devices as part of a standard resuscitation, there appears to be no benefit to the patient, but there may be benefit to the provider. That’s OK, but we need to be clear and honest about it.

There are two areas where the perceived benefit is the greatest: in the rural setting (or other settings where humans are in limited supply), and in transporting the cardiac arrest patient to hospital with CPR ongoing.

I agree that there is potential for patient benefit in the resource-poor area as having CPR done for you frees up a great many hands to do other things. However, I’m still a bit skeptical as my experience with these devices is that they are not easy to set up, and actually require a fair number of hands to the pumps to ensure that it is done with minimal interruption to CPR. Nonetheless, I see the utility in this environment.

Transporting cardiac arrest patients to hospital is not something that is done in the services I have worked for, outside of exceptional circumstances. I appreciate that this may be different elsewhere. If we are going to transport, I believe that we need to have a clear goal in mind and take the patient to a center that can actually provide further, useful intervention. Throwing the body in the back and driving like the clappers in the hope that an ED might be able to do “something” is just crazy. CPR whilst moving with a mechanical device may be safer for the paramedics, but it is not any less futile.

In Australia I have been involved in the CHEER trial, a small non-blinded study that I hope will shed a ray of positive light on this topic. This pilot trial – we’re hoping to turn it into a larger blinded trial – involved patients who “should” survive (young, healthy person with a presumed reversible cause of arrest, who has refractory VF/VT, good CPR, short down-time, etc…). We take them and do our normal routine – good CPR, drugs, intubation and so forth. We then load them into a CPR device, cool them and head to the Alfred Hospital, where they are put on ECMO in the ED and taken for PCI.

The CHEER study had remarkable success with 54% survival to discharge, neurologically intact. Of course, this is a small, non-randomized trial, so we can’t hang our hat on this result yet. All it does is give us a good basis for further research, and some hope that maybe mechanical CPR devices might be good for something other than blowing budgets.

So why is study a departure from previous research, giving us new hope in mechanical resuscitation? Because it represents an intensive, multidisciplinary effort in a system that is well resourced and already has a high level of cardiac arrest care with good outcomes. Arrests are attended by two ALS and two Intensive Care Paramedics, as well as Firefighters as first responders/CPR devices. So the scene is set with ample manpower and ample brainpower to be able to make decisions and carry out tasks efficiently. This is then followed up by aggressive care delivered by highly experienced doctors in a large, regional hospital. There is a clear reason to attempt transport in a small subset of patients with a specific outcome in mind from a hospital that is able to provide such care as required.

Perhaps more importantly, though, are the patients for whom we apply these interventions. These interventions were limited to a select group of patients as noted above. This was not for the high care nursing home patient who has finally succumbed to one of 37 different chronic diseases. The patients in the CHEER trial are the people we were always meant to be resuscitating before things got out of hand. Consider this from one of the earliest publications on ‘modern’ resuscitation: “Not all dying patients should have cardiopulmonary resuscitation attempted. Some evaluation should be made before proceeding. The cardiac arrest should be sudden and unexpected. The patient should not be in the terminal stages of a malignant or other chronic disease, and there should be some possibility of a return to a functional existence” (Jude et al. JAMA 1961).

Does this sound like most of your arrests? Didn’t think so. But we need to consider who we can successfully resuscitate as opposed to who we can just attempt resuscitation on. To overuse these devices in the latter fashion represents an enormous outlay and mobilization of resources. Attempting such efforts in all comers would be a poor use of the limited healthcare dollar that we all must be stewards of and (it would appear) not improve patient outcomes.
With all of this in mind I think that the use of mechanical CPR devices has a genuine future for some patients. But it will require emergency care workers to take a hard look at who receives the intervention – as well as a more honest view of the current research.


Robert Simpson BHSc, Grad Dip ICP
 is an intensive care paramedic in Australia and the author of AmboFOAM, a medical education blog for paramedics.

Editor’s Note
Last year a meta-analysis was published which included 12 trials comparing mechanical CPR to manual chest compressions. The 8 trials of band-style mechanical CPR devices and 4 trials of piston-style devices were separately pooled and the end-point of at least 1 minute of ROSC (return of spontaneous circulation) was chosen. Two of the authors, it should be noted, had ties to device manufacturers.
The band-style devices had greater odds of achieving ROSC than manual compression (piston-style devices were not significantly better than manual compression).
What is 1 minute of ROSC, though? A patient-centered outcome like “survival to hospital discharge” or “meaningful neurologic recovery” would’ve been more relevant to clinicians, and administrators looking to equip EMS with these devices. It’s not clear that more ROSC events early in resuscitation translates to better outcomes days or weeks later.
But the authors were right when they called for large, randomized trials of patient-centered outcomes to settle the question.
And those trials came, in 2014 – the CIRC trial (conducted by Zoll) and the LINC trial (from LUCAS). CIRC compared manual to mechanical and showed equivalent survival rates to hospital discharge. LINC showed no significant difference in 4-hr survival and the vast majority in both mechanical and manual had good outcomes at 6 months.
There are still arguments to be made for mechanical CPR devices – when longer transport times are anticipated, or when there are barriers to applying consistent, high-quality manual compression. But it’s flat-out wrong to assert superior outcomes with mechanical devices; the best evidence yet suggests only equivalency.

Nicholas Genes, MD, PhD is a senior editor at EPM and a clinical informaticist at Mount Sinai Medical Center

6 Comments

  1. Scott Gallagher on

    There appears to be at least equivalency between mechanical and manual CPR, and mechanical CPR is clearly less physically taxing on medical personnel.

    In resource-limited scenarios with long transport times, this seems like a valuable advantage in favor of mechanical CPR: free hands and minds to deal with tasks other than monotonous, continuous, uninterrupted compressions.

    Even in the emergency department where resources are generally more robust, provider fatigue as well as the drama and distraction associated with manual compressions may be significant detractors from providing CPR much beyond the long-adopted standard of roughly 15-30 minutes time for cessation of resuscitation if there is no ROSC.

    There are defined patient populations where prolonged CPR does seem to improve survival, such as in-hospital cardiac and hypothermia. There may be other patient populations, such as identified in the CHEER trial (young, healthy person with a presumed reversible cause of arrest, who has refractory VF/VT, good CPR, short down-time, etc…), who may also benefit.

    What role does provider fatigue, limited personnel, drama and distraction associated with manual compression contribute to our perception that prolonged CPR is futile across the board?

    Scott Gallagher, MD FACEP

    Matos et al, “Duration of CPR and Illness Category Impact Survival and Neurologic Outcomes for In-Hospital Pediatric Cardiac Arrests,” Circulation, published Jan. 21, 2013.

    Goldberger et al, “Duration of resuscitation efforts and survival after in-hospital cardiac arrest: an observational study,” The Lancet, published Oct. 27, 2012, vol. 380, pp. 1473-1481

  2. Marvin A Wayne, MD on

    I too was an extreme skeptic of mechanical CPR until we ventured into the ResQ Trail. We had many of those ideal patients achieve ROSC and sometimes loose it. Doing CPR in an urban rural system with limited manpower, at times, presents the challenges you list. Having a level 1 cardiac center with all of the resources you listed opened up new opportunities for those patients. We acquired the LUCAS 2 systems and have now taken at least 5 pts to Cath lab and or ECMO/IMPELLA with 2 going home neurologically intact. We expect more in the future as we combine the ResQ Pod with this improved CPR. Until you try to save that young individual you allude to, in the back of a moving ambulance, without mechanical CPR you cannot appreciate the danger to the rescuer. Our experience if not a robust as I would like, but we started at 32% go home survival for all VT/VF with good neurologic function and 18.9% for all rhythms. We have added about 1% with mechanical but these are young or physiologically young. I agree with you on those at end of life. We have dropped injury at scene or during transport to near 0.

  3. Two issues:
    1. “Everybody gets CPR” – insane, but consistent with doing cardiac bypass on a 93 year old demented lady who hasn’t recognized her family in 10 years. NEED to determine who’s eligible for advanced interventions, push advanced directives, educate… oh what’s the use (dead horse, dead horse)
    2. Rural – I like the concept of the auto compressors because two basic emt’s are not going to deliver good CPR in the back of an ambulance for the 20 or 30 minutes of transport, not countining the lost time of loading a patient on a gurney while CPR is “in progress” (LOL – laughter mine) And when they land in the ED (exhausted after pumping), it’s me and a nurse… finding extra hands in a small rural hospital is not easy… it’s a function best automated and allow staff to do other dangerous things like administer tons of epi… another rapidly dying mainstay of ACLS

  4. Dr. Common Sense on

    When it comes to these devices. The reality is that the overwhelming majority of CPR that doesn’t involve the successful application of electricity is an exercise in futility for the patient and profit for the American Heart Association…

    …but so long as we are going to participate in this charade we might as well employ a device that cuts down on the number of sweaty anxious people in a come room.

  5. We have been investigating the failure of several large trials to show the superiority of mechanical vs manual chest compression.
    First, we measured the manual CPR capability of nearly 400 EMS workers. Well over half leaned excessively (an average of 17 pounds.)
    Second, we examined the time it took to get the victim onto the mechanical device. (The humans had plenty of time to mess the victim up to the point where nobody / no machine was going to bring the victim back.
    Third, Mechanical devices don’t compress to the wrong depth and at the wrong rate. And they don’t lean.
    We’re looking to analyze the survival records for SCA victims in major hospital ED’s where the switch to mechanical CPR occurred about three years ago. We will compare the manual survival with the mechanical survival. This setting should reduce – even thought it won’t be eliminated – the influence of improper CPR from humans and also ought to reflect a significant reduction in the interval from arrest to application of the device.

    • LUCAS does lean with a 150ms duration. Its compression duration is also 150ms. Decompression duration is 130m, time before compression is 150ms for LUCAS. How can you say 150ms wait in a full compression is not a leaning. Or you simply do not know about its timing. Do LEARN.

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