CPR Feedback Devices: The Challenges of Measuring Compression Depth

Cardiopulmonary resuscitation (CPR) feedback devices are designed to give CPR providers real-time feedback and coaching to help them perform CPR according to the guidelines issued by the American Heart Association (AHA) and the European Resuscitation Council (ERC). While such devices are intended to provide accurate feedback on all CPR parameters, including compression rate and chest wall recoil, accurately determining compression depth can be more difficult—either with a CPR feedback device or with other laboratory equipment.

Consequently, one of the key requirements of our CPR feedback device Evaluations (​Philips Q-CPR, Physio-Control TrueCPR, Zoll Real CPR Help) was that devices should provide feedback that accurately quantifies the anterior-posterior compression of the chest. This article describes the thinking that went into our testing of that performance, along with the challenges that may explain why our compression-depth results differed from those of the device manufacturers.

To test each device's accuracy, we asked testers to use each device while performing chest compressions on a foam manikin, which we had instrumented to measure compression depth (i.e., the change in distance between the front and back of the manikin). We compared our depth measurement for each compression to the depth measured by each...