“The Resuscitation Outcomes Consortium (ROC), the largest clinical research network to study prehospital treatments for cardiac arrest in the U.S. and Canada, tested both resuscitation strategies as part of the Prehospital Resuscitation using an IMpedance valve and Early versus Delayed (ROC PRIMED) clinical trial. An impedance valve, also called an impedance threshold device (ITD), is a small, hard plastic device about the size of a fist that’s attached to the face mask or breathing tube during CPR administered by EMS providers. The device is designed to improve circulation by enhancing changes in pressures within the chest during CPR.
The study’s independent monitoring board and the National Heart, Lung, and Blood Institute (NHLBI), the lead sponsor of the study, stopped enrollment based on preliminary data suggesting that neither strategy significantly improved survival.” (1)
The recent announcement by the National Institutes of Health (NIH) that their multi-site, multi-million dollar, multi-factorial, randomized clinical trial, called the Resuscitation Outcomes consortium (ROC) PRIMED study, was terminated prematurely raises anew the question of what is the best way to evaluate the limited tools we have available today to restore life after out-of-hospital cardiac arrest. This clinical problem, often still considered futile by many, remains the leading cause of death among Americans—100-fold higher than, for example, H1N1 in 2009. Despite a half of century of effort and excellent research, we have yet another huge and inconclusive study, which many have erroneously interpreted as confirming the futility of cardiac arrest resuscitation.
What should we think about this scientific process of prospective, randomized clinical trials in resuscitation research? Aren’t they the gold standard in CPR research? In addition, how should we in the EMS community think about performing CPR before defibrillation and should we use the ResQPOD, also known as the impedance threshold device (ITD)? ROC PRIMED revealed neither positive nor negative findings in one study arm related to early analysis (perform 30 seconds of CPR before analyzing and shocking) versus analyze late (perform three minutes of CPR prior to analyzing and shocking), and concluded similarly neutral findings related to an active (functional) versus sham (placebo) ITD.
Perhaps it’s time to ask a more fundamental question: Why do we continue to look for a single silver bullet to treat cardiac arrest when we know that every complex disease in modern medicine was conquered with a multi-pronged approach? Take HIV infection, for example. This scourge is treatable only when three or more drugs are used simultaneously and continuously to prevent the deadly virus from mutating and replicating. Or, consider lymphoma, for which the combination of drugs and radiation therapy is now very often curative.
Isn’t it time to admit there’s no single device, drug or intervention that, used alone, will significantly improve survival from cardiac arrest but instead, only a combination of therapies implemented in a systems-based approach is the answer? Even the AED, now considered an essential element in the resuscitation arsenal, was found to actually increase mortality rates when deployed on all first-responder vehicles in Seattle from 1975–1993 until Cobb showed that CPR was needed before defibrillation to prevent the harmful and unintended effects of the AED, when used in the absence of good CPR. (2)
Now back to the PRIMED study, the ITD and randomized trials. If I were going to design an animal study of the ITD’s efficacy, would I select an animal model with an eight-fold variability in baseline response, or a more uniform animal model population to test my hypothesis? The neurologically intact survival rates at baseline in the ROC PRIMED study groups ranged from 1.1% in Alabama to 8.1% in Seattle. (3) Why did ROC use some cities where a poor outcome was nearly certain given the baseline survival rates (e.g., Birmingham, Ala.: 1.1%)? The ITD would have to possess magical powers in that clinical site in order to demonstrate a difference.
Further, why were there three different BLS CPR protocols in the ROC PRIMED study: 1) continuous CPR with a face mask, 2) 30:2 compression-to-ventilation ratio per American Heart Association (AHA) Guidelines and 3) one site that tested only the ITD (no analyze early versus late study arm), but instead used uninterrupted chest compressions during CPR with a facemask? What happened to some of the most basic scientific principles of evaluating one variable at a time to see if something new makes a difference? There were too many arms with uncontrolled variables; therefore, it’s no surprise that its results are neutral and unconvincing.
Another major flaw of this study relates to post-resuscitation care. With no standardization of post-resuscitation care, is it fair to expect any technology or intervention to make a difference when the primary outcome of neurological function at the time of hospital discharge is so impacted by the quality of post-resuscitation care? In the ROC PRIMED study, investigators didn’t track who was treated with therapeutic hypothermia and who was not. I’m surprised the study was even undertaken given how much we know about the chaotic field laboratory and the challenges of finding the truth with so many moving and uncontrolled parts.
In 2005 I wrote an article called “Keep on Pumpin’,” in which I discussed the ResQPOD. My EMS personnel have used it for the past four years with good success. I’ve read a series of clinical studies from across the country related to how the device works, how it works best when CPR is done correctly, especially when chest compressions are started right away and the ResQPOD is added first to a facemask with a tight seal and then to an advanced airway. The ResQPod makes a difference when it’s incorporated into a system of care per the 2005 AHA CPR Guidelines.
As the EMS medical director for the state of Minnesota, I’m actively involved in a statewide effort to deploy all of the highly recommended 2005 AHA CPR Guidelines for patients in cardiac arrest, including the ResQPOD (which has a Class IIa recommendation to increase circulation and the chances for a return of spontaneous circulation), in a program called Take Heart America (www.takeheartamerica.org). This systems-based approach has already been shown to almost double survival rates for patients with out-of-hospital cardiac arrest and the most effective way I know that we’ll ever be able to really change outcomes for patients in cardiac arrest. (4, 5) Our EMS colleagues in Wake County, N.C., saw the value of a systems-based approach years ago, and their data are demonstrative of the effect on cardiac arrest survival. They started with a baseline survival rate well below the national average of 5% and almost quadrupled their overall survival after adopting the 2005 CPR guidelines, the ResQPOD and therapeutic hypothermia.
So let’s forget the quick fix, the easy way out, the search for the silver bullet. Let’s instead get serious about reducing the death toll from this all too common tragic event. We can do so by refocusing our research efforts on building and evaluating best practice systems of care. We must cease performing large multi-site clinical trials with multiple uncontrolled variables that only add confusion, not clarity.
We need to wait to see the final results from the ROC PRIMED study; I suspect there will be some pearls of wisdom that come from it, but we need to remember that no single intervention listed in the 2005 AHA CPR Guidelines has ever been shown in a prospective, randomized clinical trial to improve neurologically intact survival rates. Let’s continue to teach and perform all of the AHA-recommended interventions. Additionally, let’s concentrate on post-resuscitation care, such as induced hypothermia and early coronary revascularization. (6) When used together in a systems-based approach, we can truly make progress against this deadly disease state.
More research is still needed in the field of cardiac arrest. However, the future lies not in searching for the silver bullet but instead in researching what a combination of therapies in a systems-based approach can do to significantly move the needle toward improved neurologically intact survival.