Comparative usability of manual defibrillators - A human factors study.

Background: A manual defibrillator represents key equipment for resuscitation of cardiac arrest scenario. Improper or slow operation of a defibrillator may adversely affect acute care. A self-explanatory interface facilitates handling and decreases the risk of operating errors. Therefore, we evaluated the usability of four commercially available defibrillators.

Methods: 31 medical students executed 15 consecutive tasks on each defibrillator (Physio-Control Lifepak 20e, Schiller Defigard Touch 7, Corpuls 3 and Zoll X-Series). The operators' gaze was measured via eye-tracking and frequencies of required assistances and task completion times were recorded. Additionally, subjective perception of usability was assessed by a standardized questionnaire.

Results: Least assistances (16) were required when operating the Lifepak 20e and most (63) when operating the X-Series. Cumulative task completion times were shortest in the Lifepak 20e (124 ± 31 s), followed by the Corpuls 3 (220 ± 69 s), the Defigard Touch 7 (225 ± 81 s) and the X-Series (289 ± 85 s;  < 0.001). Completion times of specific tasks differed considerably between the devices. Eye-tracking revealed associated interface issues that impeded the operators' performance. Overall standardized usability was rated best for the Lifepak 20e (81 ± 15) and worst for the X-Series (44 ± 20).

Conclusions: The usability of defibrillators differs considerably and task specifically between devices. Interface issues of tasks impaired the operators' efficiency specifically. The perceived usability and the perceived stress-level after operating the devices corresponded with objective measures of usability. Eliminating specific usability issues may improve the operator's performance and, as a consequence patient outcome.