Identifying the Operational Bottleneck to Shock Delivery After Automated External Defibrillator Activation

INTRODUCTION: Cardiac arrest registries record automated external defibrillator (AED) use and shock delivery but not post-activation operational timing. We aimed to identify the largest measurable bottleneck and an exploratory pad-application target for shock delivery within 60 seconds of AED power-on. METHODS: We retrospectively analyzed timestamps from remotely monitored Nihon Kohden AEDs between January 2018 and February 2026. After excluding inspection records, we grouped records into activation events and quantified intervals. Shock-timing and receiver operating characteristic (ROC) analyses were restricted to initially shock-advised events with recorded shock delivery. RESULTS: We analyzed 8,115 activation events. Median times were 42 seconds (interquartile range [IQR], 30-56) from power-on to completion of pad application, nine seconds (IQR, 9-11) from pad application to the first analysis, and 52 seconds (IQR, 40-66) from power-on to the first analysis endpoint. The power-on-to-pad-application interval accounted for a median of 81% (IQR, 75-85) of the total power-on-to-first-analysis interval, increasing to 87% (IQR, 85-90) when first analysis occurred more than 60 seconds after power-on. Among 900 initially shock-advised events with recorded shock delivery, the median pad-application-to-shock interval was 15 seconds (IQR 13-17). Exploratory ROC analysis yielded a power-on to pad-application threshold of ≥ 51 seconds in relation to first recorded shock delivery occurring more than 60 seconds after AED power-on. CONCLUSIONS: The interval from AED power-on to electronically detected completion of pad application, encompassing all intervening actions, was the largest measurable post-activation bottleneck. Completion within 50 seconds may serve as an exploratory process target for first recorded shock delivery within 60 seconds among initially shock-advised events.