Drone-delivered Automated External Defibrillators for out-of-hospital cardiac arrest. A simulation study
Authors: Smith Christopher M , Phillips Joe , Rees Nigel , Powell Carl , Sheehan Anthony , Sullivan Mary O’ 
Published: December 2024

Abstract

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 patient’s 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.

What is already known on this topic – summarise the state of scientific knowledge on this subject before you did your study and why this study needed to be done
Drones have been used to deliver AEDs in simulation studies across the world and in a real-life pilot in Sweden. Real-world success is so far limited, and no functioning system for this to happen in real-world out-of-hospital cardiac arrests in the UK.

What this study adds – summarise what we now know as a result of this study that we did not know before
We have demonstrated a feasible drone-delivered AED system. Lone bystanders spent a median of 19 seconds away from the patient to retrieve the drone-delivered AED. Interaction with the drone and AED was not difficult, and the 999 call-handler has a vital role in facilitating safe and timely retrieval of the drone-delivered AED.

How this study might affect research, practice or policy – summarise the implications of this study
Lone bystanders are currently not instructed by ambulance services to leave a patient to retrieve a nearby public-access AED, but collecting an AED delivered directly to them may be appropriate.
The next step in developing a drone-delivered AED system for real-world use in the UK is to integrate a drone-delivered AED system into an ambulance service’s Emergency Operations Centre system and to test the out-of-hospital cardiac arrests response in prolonged ‘beyond visual-line-of-sight’ drone flights.