I am researching the AP for my service. We had the ZOLL rep to demo it for us before we do a dept. wide presentation and decide whether the device will be of use to us or not.
The compressions actually looked more effective than violent. The advantage of the AP is that it is a true Load Distributing Band (LDB - as described by the AHA), thus minimizing the amount of force placed centrally on the patient reducing trauma. You can place your hand under the device and it only gets snug, not painful. The AP utilizes the entire thoracic cavity to manually compress the heart.
A service to the north of me purchased 7 and are happy with the results. A different service that I used to work with reported patients went from grey to pink, ETC02 to >35mmhg, systolic pressures > 100mmhg, and with high pressures, actually getting "flash" in the IV Cath.
I am very impressed by the device regardless of the Aspire trial. The ASPIRE trial's negative results were in ONE city (Seattle) and that dept. used different protocols than the other cities. The results from the other trial cities with the aspire study showed increased long term mortality. (not to mention the other trials).
One of the other trials, used on terminally ill patients after they were in arrest for 30minutes, displayed coronary perfusion pressures on the patients with the AP. The AP pressures were scaled beside manual CPR pressures and the AP CPP pressures were 2-3 times greater. ZOLL research states that min CPP for ROSC is 15mmhg, manual cpr with interuptions rarely gets above 15.
The above is only my words, look it up for yourself, and make your own decisions.