Effect of Instituting Upper Limits for Chest Compression Depth for Laypersons at Six-months After Chest Compression-Only Training: A Randomized Controlled Simulation Study

Context/ research question: Chest compression quality plays a major role in patient outcomes after cardiac arrest. The Japanese cardiopulmonary resuscitation (JRC) guidelines 2015 indicates that chest compression depth should be approximately 5 cm but not more than 6 cm. However, the upper limit of chest compression depth might be a barrier to the delivery of adequate chest compressions by laypersons. We hypothesized that laypersons may be able to perform chest compressions (approximately 5 cm) as per the JRC guidelines, without setting an upper limit for chest compression depth. Methods: Participants were randomly assigned to either the “unlimited group” (no recommendation regarding the upper limit of compression depth) or the “limited group” (“push to approximately 5 cm, don’t push over 6 cm”) and stratified according to sex using permuted blocks. All participants completed a 15-min chest compression training session, and their compression skills were individually evaluated immediately and at 6 months after the training using the Laerdal® PC SkillReporting System at Kyoto University. The primary outcome was the median compression depth during the 2-min test period 6 months after the training. Results: Seventy-two participants were enrolled; 33 participants in each group completed the study. The unlimited group performed significantly deeper chest compressions (>60 mm) immediately after the training than the limited group; however, there was no significant difference 6 months after training. Although not significant, the number of compressions with the recommended depth (49–59 mm) was higher in the limited group. Importance: These results suggest that simplified instructions that do not mention the upper limit of compression depth may help people perform deeper chest compressions; however, there are concerns about the risks associated with too deep compressions. Considering the situation of out-of-hospital cardiac arrest in Japan, studies focusing on compression depths in another aged people should be considered.