Association of Dispatcher-Assisted Compression-Only Resuscitation with Survival Rate in Unwitnessed Out-of-Hospital Cardiac Arrest: A Temporal Trend and Analyses of 8-Years Trend

Background: Recent guidelines recommend that dispatchers instruct untrained bystanders to perform compression-only cardiopulmonary resuscitation. However, how bystander cardiopulmonary resuscitation (BCPR) composition and survival change in unwitnessed out-of-hospital cardiac arrest (OHCA) cases remains unclear. The aim of this study was to investigate (1) the changes in BCPR based on combined rescue breathing and dispatcher-assisted resuscitation; and (2) the association between changes in BCPR content and annual outcome improvement in unwitnessed OHCA cases compared to bystander-witnessed OHCA cases. Method: This study involved the retrospective analysis of data for OHCA cases that were prospectively collected nationwide and population-based. OHCA cases from 2009 to 2016 were evaluated to provide a complete dataset for the analysis. The primary outcome was neurologically favorable 1-month survival. Results: The rate of dispatcher-assisted compression-only resuscitation increased annually. Further, there was a shift from standard resuscitation to compression-only bystander resuscitation and an increased rate of dispatcher attempts of instructions in both unwitnessed and bystander-witnessed arrest cases. In a multivariable logistic regression model for cases with dispatcher attempts, the neurologically favorable 1-month survival rate of patients who experienced unwitnessed arrest in the dispatcher-assisted standard BCPR group was higher than that in the dispatcher-assisted compression-only BCPR group (adjusted odds ratio 1.23 [95% confidence interval: 95%CI 1.03–1.46]). Further, the outcome improvement for 8 years in the standard BCPR group was more prominent than that in the compression-only BCPR group (p < 0.01, interaction test). The neurologically favorable 1-month survival rate of patients with unwitnessed arrest in the voluntarily-initiated standard BCPR group without the dispatcher’s attempt of instructions was higher than that in the voluntarily-initiated compression-only BCPR group (adjusted odds ratio 1.21 [95%CI 1.01–1.52]). However, the outcomes improved similarly in both groups. The differences between standard and compression-only resuscitation were less prominent in patients with bystander-witnessed OHCA, particularly in cases without dispatcher instructions. Conclusions: Compression-only resuscitation may not be the ideal management strategy for unwitnessed OHCA when dispatchers attempt resuscitation instructions.