Once the EMS community has taken ownership of resuscitation and developed a plan for where resuscitations are going to be worked to completion, the greatest task is determining a method by which the quality of compressions can be assured. These range from personnel-intense to technologically-intense methods; the risks and benefits of each are discussed below. Unfortunately, the research is not yet complete regarding which of these methods is the most effective, and what is available is somewhat conflicting.
Frequent Rotation of Personnel with Scripted Response
This method involves an incident commander (aka "code commander") who visually monitors the compressions provided by responders and calls for correction of inappropriate compressions and/or rotation when there is evidence of fatigue. Code commanders can be specifically trained to monitor for common errors and inexpensive devices such as a metronome can be utilized to maximize the probability of good chest compressions. Many systems utilize this method, perhaps none with as much success as Dr. Michael Kellum in Wisconsin.(1) The simple, scripted technique is wonderfully described in a recent manuscript and, although the concepts are yet to be supported by a randomized clinical trial, the proposed method is compelling and reproducible in many systems.(2)
The benefits of this method include its relatively low cost, particularly in the area of capital expenditures, and the ease with which it can be implemented. Scripts and checklists can be shared with all EMS personnel and, as Dr. Kellum and others have noted, the continuing medical educations sessions related to cardiac arrest become easier for the students and take less time than they did prior to the scripting. On the other hand, this method will require multiple responders on a scene, particularly if there is a prolonged resuscitation. This is to mitigate rescuer fatigue, an important element that cannot be overlooked. Also, in systems that have determined transportation of working arrest will routinely be a part of resuscitation care, the difficulties and dangers associated with patient transport while humans provide compressions make this a less attractive option.
This method is best suited for EMS systems that can amass sufficient on-scene resources to assure minimal rescuer fatigue and have resuscitation plans that allow resuscitations to be worked to completion in the field.
Utilization of Compression-Feedback Devices
The majority (if not all) fully-functional EMS cardiac monitor/defibrillators currently offer some form of cardiopulmonary resuscitation feedback in real-time. To varying degrees, each device will provide feedback on the rate of compressions, depth of compressions and rate of ventilations. These data streams can then be utilized by all responders to correct common errors in resuscitation in a just-in-time manner, and thus theoretically improve techniques and improve outcomes. Dr. Lance Becker is currently conducting a before-and-after trial to evaluate the efficacy of this method; two other studies have been completed and appear to support the utilization of this type of feedback. It's worth noting, however, that one of the studies has only been presented in abstract form and the other utilized post-arrest debriefings in addition to the real-time feedback, so more research is needed before the benefit of this type of feedback can quantified.(3,4)
This method is similar to the code commander method described above, just with additional data input. Both common sense and the preliminary data suggest receiving this feedback will improve CPR techniques and, based on what we know today, there is no reason not to recommend utilization of these systems. Obviously, an EMS system still needs sufficient on-scene personnel to address such issues identified by the technology as rescuer fatigue. Perhaps most importantly, the monitor/defibrillator is often the most expensive piece of biomedical equipment on an ambulance, and thus replacing the entire stock of monitor/defibrillators in order to provide the CPR feedback data is simply out of the (financial) question for most EMS systems.
Utilization of Mechanical Compression Devices
The reliable provision of quality compressions from a mechanical CPR device is compelling for many reasons, among them the elimination of rescuer fatigue, reduction in unplanned pauses in compressions, and the ability to more safely transport patients who are undergoing continuing resuscitation while en route to hospital. The initial release of these devices was met with general acceptance and enthusiasm, with non-randomized trials indicating improved outcomes for patients being treated with these devices.(5–9) The first large, randomized trial to evaluate these devices, however, was halted by the data safety monitoring board due to the finding of worse outcomes in the group of patients receiving mechanical compressions.(10) The reasons for these disparate findings are unclear at best and have led to the call for more research in the area.(11)
Importantly, it appears the relative impact of manual vs. device-assisted compressions may depend upon the stage of arrest, such as electrical, mechanical or metabolic, with patients in earlier stages perhaps benefiting more from manual compressions and those in later stages benefiting from mechanical compressions. This evidence is far from conclusive, but if it were to prove correct, the deployment and utilization of these devices could certainly be affected. At any rate, it appears a group of patients may benefit from these devices but that more evidence is needed to clearly define this group.
While we await more evidence, deployment of these devices may be appropriate for certain communities. This is particularly true for EMS systems with a high transport rate for patients in cardiac arrest and/or those with limited personnel resources that can reliably respond to cardiac arrests. The cost of the devices and lack of conclusive evidence demonstrating benefit, however, must be weighed against these potential benefits.
A Unique Situation
Perhaps the most promising type of patient for mechanical compression devices is the patient in refractory arrest who may benefit from percutaneous cardiac intervention (PCI). With the focus on compressions comes the possibility of prolonged ventricular fibrillation, with many providers now searching for additional treatment modalities for these patients. In a small case series, the utilization of mechanical compressions during PCI has proved not only to be possible but also to be beneficial for patients.(12,13) Certainly more evidence is required before this becomes standard of care, but such aggressive intervention is technically possible only with mechanical compression devices so utilization for this group of patients may increase in the future.
It appears the ideal resuscitation will involve some combination of adequate on-scene personnel, simple feedback techniques and checklists, technological feedback from the cardiac monitor/defibrillator and/or use of mechanical compression devices. Currently available evidence is insufficient to recommend one technique over another. Preliminary evidence suggests a plan may be required for the "routine" resuscitation with perhaps a different approach for patients with persistent ventricular fibrillation who may benefit from intra-arrest PCI. Each community should employee a resuscitation plan based on the cost:benefit analysis in the context of their overall emergency medical system funding, goals, and objectives.
Disclosure: The author has reported no conflicts of interest with the sponsor of this supplement.