Out of hospital cardiac arrest (OHCA) is associated with high rates of mortality and morbidity, even under clinically optimized conditions. The management techniques and treatment modalities for these pernicious events are constantly evolving based upon continuous research from centers all over the world. One of the only things that has remained constant is the value of high-quality CPR. In fact, early initiation of CPR is the primary predictive indicator for neurologically intact survival of OHCA. In an effort to improve the delivery of CPR mechanical devices to replace the human compressor have been developed and deployed since the 1960’s. Today, the use of MCPR devices such as the Physio-Control Lucas® device and the Zoll Autopulse® (Shown below) are becoming ubiquitous at EMS agencies across the country.
Does MCPR increase survival for OHCA?
Five multicenter randomized control trials (RCTs) have been completed in the United States and Europe that compared the survival of non-traumatic OHCA using MCPR devices and standard CPR. Two of the studies used the Zoll Autopulse® which employs a load distributing band to provide compressions and three used the Physio-control Lucas® device in which a piston and plunger system provide the compressions. The results of all five trials were similar. In all of the studies, the survival with MCPR was statistically equivalent or worse than with standard CPR.
MCPR devices are exceedingly expensive and can cost as much as $20,000 per device. There are additional costs associated with accessories, maintenance, and staff training. For many EMS agencies these costs are significant and possibly even prohibitive. It would be easy to infer from the available evidence that this equipment is not worth the investment. However, it may not be that simple.
The prehospital care environment is dynamic and unpredictable, subsequently, the research on the efficacy of MCPR is fraught with confounding variables. Consider the fact that in the field the number of clinicians available to be a part of the resuscitation team as well as their level of training is highly variable. In some cases, a crew of one paramedic and one EMT-basic may be tasked with performing a resuscitation without any additional resources. In others, a team including four paramedics, four BLS level firefighters, and a physician may be readily available. Some organizations prioritize high-performance resuscitation training as part of continuing education and others do not. We know that fatigue is significantly impactful on the quality of compressions so in situations where there are limited resources, personnel, and resuscitation training the value of MCPR will increase substantially. There is also evidence that suggests that the compressions performed during CPR in the back of a moving ambulance are ineffective. The constant starting, stopping, slowing down, speeding up, and back and forth swaying that inevitably occurs in the back of a moving vehicle appears to make it impossible to perform adequate chest compressions. It stands to reason that the efficacy of MCPR devices would remain constant in this environment.
In many systems, the incidence of transporting patients who remain in cardiac arrest after extended on-scene resuscitation is decreasing because it is understood to be futile. However, there is increasingly robust evidence that a cohort of patients will experience significantly increased neurologically intact survival when transported to the hospital and placed on ECMO while still in cardiac arrest. While this is a small subset of all OHCA patients, the increase in survival has been shown to be dramatic. Transport using MCPR is a requirement in most cases due to the poor outcomes associated with the performance of manual CPR in the back of a moving ambulance.
-The use of MCPR devices in prehospital resuscitation of OHCA is increasing.
-The currently available evidence suggests that the outcomes associated with MCPR compared to standard CPR for OHCA are the same or worse.
-If a robust team of highly trained prehospital resuscitationists is available, then standard CPR is more efficacious for on-scene management of OHCA than MCPR.
-In situations where there are limited personnel and resources, or the patient must be transported while still in cardiac arrest, MCPR may be more effective than standard CPR but more research is needed.
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