MSM Post 003 Do CPR Devices work?

“We are powerless against the paralysis of circulation.”

-Unattributed Physician 1890

            In EMS and emergency medicine, we tend to search for products or devices that will act as a magic wand to cure all patients and improve all outcomes. Over time, this had led to numerous innovations in patient care that aim to improve outcomes and general health. A focus of these innovations recently has been automated CPR devices such as the Lucas2 from Physio Control and the Zoll AutoPulse. Here we will evaluate the efficacy of these products, and whether they are effective enough to change practice.

First, as always, we want to add context to the use of these devices. CPR research is an ever-evolving field and preferred methods change frequently. Over the course of medical treatment, basic cardiac arrest treatment has changed over a dozen times ranging from rectal infusion of tobacco smoke (not kidding)[1] to bloodletting to the more contemporary 5:1 CPR algorithm that we knew worked (it didn’t) to the more common 30:2 compression rate that we know works (it doesn’t) and now we’ve moved on the advent of mechanical CPR devices for the treatment of cardiac arrest (maybe these will work?).

The goal of all cardiac arrest treatment should be survival to discharge. After all, if we’re only performing CPR to allow the patient to survive to the hospital, have we truly done any good? The entrance to the E.D. is not a magic portal that absolves EMS providers of all responsibility for treatment of the patient. Given these parameters, there are simply no data to show that the use of automated CPR devices improve survival to discharge when compared with hands-on CPR. In 2014 JAMA published the results of the LINC trial, a randomized multi-center study that included more than 2500 patients[2] and analyzed primary and secondary outcomes of ROSC, 4-hour survival, survival to discharge, 1 month survival, and 6 month survival. The study found that while the devices improved organ perfusion pressure, ETCO2, and cerebral blood flow in the peri-arrest phase, there was no significant difference in outcomes when comparing the Lucas device and hands-on CPR. That is to say that while the CPR device may be a good step forward, hands-on CPR is not inferior to the automated device.

The LINC study was a follow-up on human patients after numerous studies were performed on animals showing similar results. In 2012 Heart published a systematic review of the Lucas device that found that there was “insufficient evidence to make any recommendations for clinical practice” and suggested large-scale, randomized trails to determine efficacy. This is further supported by a prospective randomized trial that was published in Resuscitation in 2011 that showed no difference in early survival using the Lucas device when compared to hands-on CPR.[3]

Of course, in EMS and in Emergency Medicine we are often in situations when crew resources are at a minimum, and using an automated device may be beneficial to reduce crew exhaustion and enhance available resources. 2 studies in 2013[4],[5] analyzed the efficacy of the Lucas or AutoPulse in the HEMS setting. Both studies found that as far as crew resources are concerned, it may be beneficial to apply an automated device if a cardiac arrest patient is to be transported via helicopter. Of course, this opens up a greater debate as to whether a patient in cardiac arrest should be flown, or transported at all. We’ll get to that in a later post.

There is some additional research that shows that the Lucas device and the Autopulse are fundamentally not designed to support survival based on the available research. Specifically, the AHA recommends, and data supports that a compression rate of 100-120 bpm support improved survival. The AutoPulse is designed to provide 80 compressions per minute. Zoll’s position regarding this discrepancy is that the “thoracic squeeze” that the AutoPulse delivers is sufficient to adjust for this discrepancy, but there is no data available to support that claim. Additionally, the ideal depth for chest compressions should be 5cm or more. The Lucas2 device is designed to provide compressions at exactly 5cm, which may be beneficial, but data suggests that slightly deeper compressions may be more beneficial for patients.[6]

Beyond all of this available data is the issue of cost. Each system prior to making such a commitment to purchasing a product must perform a cost-benefit analysis. The initial outlay of both devices exceeds $15,000 (Lucas: $17,150 Zoll: $16,380). The per-use cost of the Lucas is significantly less ($42.97) than Zoll ($130.75) and the annual cost of the Lucas device is 3 times less than the Zoll (Lucas-$4,297 Zoll-$13,075).[7]

It is possible that there is a place for automated CPR devices in the toolkit of EMS and emergency medicine providers. Specifically regarding crew resources, these devices seem to be beneficial. But there is simply no data that suggest that the use of these devices improves patient outcomes, or that they are generally worth the cost of purchase. At present, any system manager who is looking to purchase a mechanical CPR device should consider these results prior to purchase or use.

[1] http://www.bcmj.org/special-feature/special-feature-tobacco-smoke-enemas

[2] Rubertsson et. al Mechanical Chest Compressions and Simultaneous Defibrillation vs Conventional Cardiopulmonary Resuscitation in Out-of-Hospital Cardiac Arrest:
The LINC Randomized Trial JAMA January 1, 2014 311:1

[3] D. Smekal et al. / Resuscitation 82 (2011) 702–706

[4] K. Omori et al. / Resuscitation 84 (2013) 1045–1050

[5] Putzer, et al American Journal of Emergency Medicine (2013) 31, 384–389

[6] K. Trivedi et al. / American Journal of Emergency Medicine 31 (2013) 1154.e1–1154.e2

[7] Physio Control product comparison 2011