A usability study of a critical man–machine interface: Can layperson responders perform optimal compression rates when using a public access defibrillator with automated real-time feedback during cardiopulmonary resuscitation?

Objective: Many public access defibrillators (PADs) incorporate computer programs to provide audiovisual feedback to assist the user to deliver cardiopulmonary resuscitation (CPR) according to current international guidelines. This usability study assessed if a PAD integrated with a real-time audiovisual CPR feedback system can guide lay-users to optimum chest compression rates, and if it is detrimental to chest compression depth. Methods: Randomly selected volunteers (15+ years) were recruited for two experiments. Experiment 1 (n = 156) assessed the time taken to achieve the “good speed” audio prompt (i.e., perform compressions at a rate of 100-120 compressions/min) and chest compression fraction (CCF). Experiment 2 (n = 140) assessed the effect of rate-only CPR feedback on chest compression depth. Two devices of the same model were used: one with CPR rate feedback and the other with CPR feedback disabled. The difference in compression depths and CCF was assessed. Results: Experiment 1: A total of 136 (87.2%) participants achieved “good speed” within 45s with a mean CCF of 90.3% recorded. Experiment 2: The device with feedback lead to a mean (standard error-SE) depth of 24.61mm (0.99) compared with 20.08mm (0.96) for the feedback disabled device. Analysis of covariance provided a mean significant difference (SE) of 4.52mm (1.38mm; p-value = 0.001) favoring the device with CPR rate feedback. Conclusions: CPR rate-only feedback was not detrimental to chest compression depth and suggests rate-only feedback may improve compression depth. Significance: The incorporation of clear, intuitive, audiovisual CPR feedback systems can assist lay-users to optimize compression rates and maintain a high CCF.