Cognitive limitations in depth estimation for dispatcher-assisted cardiopulmonary resuscitation: a prospective simulation study

Abstract

Background Dispatcher-assisted cardiopulmonary resuscitation (DACPR) protocols often instruct bystanders to perform chest compressions to a target depth of 50-60 mm. However, whether laypersons can accurately perceive and achieve these depth targets remains unclear. This study evaluated laypersons&apos; ability to estimate 50 mm in horizontal length, vertical depth, and chest compression depth. Methods We conducted a prospective simulation study enrolling adult laypersons without cardiopulmonary resuscitation (CPR) training within two years. Participants were asked to draw a 50 mm line, press a vertical measurement plate to an estimated depth of 50 mm, and perform chest compressions to 50 mm. Tasks were repeated after provision of a 50 mm visual reference. Accuracy was assessed by calculating the mean difference from 50 mm and the proportion of estimations within the acceptable range (45-55 mm). Results 100 participants were enrolled. Horizontal length was significantly underestimated (mean difference -3.5 +/- 16.6 mm, p = 0.036), with 25.0 % (95 % confidence interval [CI], 16.9 %-34.7 %) within the acceptable range. Vertical depth was significantly overestimated (mean difference +4.9 +/- 19.4 mm, p = 0.044), with 26.0 % (95 % CI, 17.7 %-35.7 %) within range. Chest compression depth was significantly underestimated both before (44.5 +/- 10.7 mm) and after (44.7 +/- 11.0 mm) provision of visual reference (both p < 0.001), with no significant improvement after reference exposure (p = 0.548). Conclusion Laypersons have significant difficulty estimating 50 mm in length, vertical depth, and applying target chest compression depth. Providing a visual reference did not significantly improve performance.