Drone-delivered Automated External Defibrillators for out-of-hospital cardiac arrest. A simulation study.

Background: Cardiopulmonary resuscitation (CPR) and defibrillation at least doubles survival to hospital discharge following out-of-hospital cardiac arrest. Members of the public can perform both before the ambulance service arrives. However, bystanders use a public-access Automated External Defibrillator (AED) in around 5% of cases. Using Unmanned Aerial Vehicles (drones) to deliver AEDs may overcome many of the barriers preventing public-access AED use. We investigated how quickly and easily bystanders performing CPR could use drone-delivered AEDs. Methods: We developed an AED-capable drone between May and November 2020. In July and September 2021, we conducted eighteen out-of-hospital cardiac arrest simulations. A single participant found a simulated patient inside a building and made a 999-call to a Welsh Ambulance Services NHS Trust call-handler. Once cardiac arrest was confirmed during the 999-call a nearby drone launched, reached hovering altitude and delivered the AED immediately outside the building. The participant retrieved the AED when instructed to do so, attached it to the patient and delivered a single shock. The primary outcome was hands-off CPR time. We investigated ease of AED retrieval via a questionnaire adapted from the System Usability Scale and explored participant behaviours via brief post-simulation interviews and reviews of audio (999-call) and video recordings of the simulation. Results: Hands-off CPR time was (median) 109s (interquartile range 87-130s). Participants spent 19s (16-22s) away from the patients side when retrieving the AED. They found it easy to use the AED but often sought reassurance from the call-handler that it was appropriate for them to retrieve it. Conclusion: Participants found it easy to retrieve and use an AED delivered by drone in simulated out-of-hospital cardiac arrests. Hands-off CPR time was potentially clinically relevant in this lone bystander simulation, but there was only a small increase in hands-off time caused by retrieval of the drone-delivered AED.