Dispatcher referral of bystanders to retrieve drone-delivered automated external defibrillators in cases of suspected out-of-hospital cardiac arrest

Drone dispatch in out-of-hospital cardiac arrest (OHCA) may shorten time to AED-attachment, however little is known about barriers for dispatchers to refer bystanders to retrieve and attach AEDs after delivery. This study aims to evaluate characteristics of drone delivered AEDs (D-AEDs) before and after implementing an educational bundle. This retrospective before–after observational study included all cases of D-AEDs arriving before EMS in suspected OHCA in Sweden (2020–2023). A supportive educational bundle was implemented at the dispatch centre in June 2022. Dispatcher–caller interactions were evaluated through audits of 112 voice logs using a modified CARES protocol. Out of 123 deliveries of D-AEDs to suspected OHCAs before EMS arrival, 62 cases (50%) received bystander CPR. Dispatcher referral of bystanders to retrieve the D-AED occurred in totally 30/62 (48%) cases with an increase from 7/22 (32%) before, to 23/40 (58%) after bundle implementation. D-AED attachment occurred in 26/62 (42%), increase from 6/22 (27%) to 20/40 (50%). Cases with referral to a D-AED more often involved multiple bystanders onsite, 77% vs 23% in single bystander cases (p=0.005). Median time difference between D-AED and EMS arrival was 03:14 (IQR 01:46-05:31) in the referral group and 01:49 (IQR 01:10-05:03) with non-referral (p=0.8). Drones can deliver AEDs at an early stage in selected suspected OHCA cases. Implementation of an educational bundle at the dispatch centre was associated with increased dispatcher referral and bystander attachment of D-AEDs. D-AED referral was influenced by the number of bystanders onsite. When dispatcher referral occurred, D-AEDs were used in a majority of cases.