Drones with defibrillators could respond to cardiac arrests

In the UK there are more than 40,000 out-of-hospital cardiac arrests (OHCA) annually, but fewer than 10% of people survive. In an effort to increase chances of survival, researchers at the University of Warwick have teamed up with the Welsh Ambulance Services University NHS Trust and autonomous drone specialist SkyBound to test the feasibility of drone-delivered automated external defibrillators (AEDs).

The researchers used drones to fly defibrillators in response to 999 calls as part of emergency simulations in a remote countryside location which ambulance crews would usually be delayed in reaching by road, having designed a system to deliver an AED attached by a winch to a DJI M300 drone (Skybound’s automated drone software activated and controlled the drone’s flight). The AED was lowered to a member of the public to help them carry out resuscitation on a CPR mannequin, all while receiving instructions from ambulance service call handlers.

“Ambulance services work as swiftly as possible to get to patients who have suffered cardiac arrests; however, it can sometimes be difficult to get there quickly,” explained chief investigator Dr Christopher Smith, from the University of Warwick. “AEDs can be used by members of the public before the ambulance gets there, but this rarely happens. We’ve built a drone system to deliver defibrillators to people having cardiac arrest, which could help save lives.”

The National Institute for Health and Care Research (NIHR) study, which recruited 11 participants and was published in the journal Resuscitation Plus, involved assessing real-time communications between the drone pilot, call handler and public bystander. Experts observed how those taking part behaved and interacted with each other. They also timed how quickly the mock cardiac arrest patient would be reached.

The researchers found that drone start-up procedures were quick: it took just 2.18 minutes from emergency call to drone take-off. The drone flew autonomously and safely, with good links to the ambulance service and effective real-time communication. Participants also reacted positively to drone delivery of the AED.

However, there were delays once the drone arrived on the scene. It took a further 4.35 minutes after the drone had arrived before a shock was given to the simulated patient using the AED. Hands-off CPR time was 2.32 minutes, but only 0.16 minutes of this was spent retrieving the AED.

The researchers concluded that bystanders interacted well with the drone but struggled using the AED, showing that bystanders and call handlers need more support to use drone-delivered AEDs for this to be effective. The next stage will involve funding larger studies to test the technology and evaluate whether it can be used in the NHS.

“We have successfully demonstrated that drones can safely fly long distances with a defibrillator attached and maintain real-time communications with emergency services during the 999 call,” Smith said. “We are in a position where we could operationalise this system and use it for real emergencies across the UK soon.”

Retired surgeon Steve Holt and his son Mark both see great potential for delivering defibrillators by drone, with Steve having collapsed in a remote country pub in the Lake District in 2019. Mark began CPR and used the defibrillator located outside the pub, but bad weather thwarted an air ambulance, so it took 25 minutes for paramedics to arrive by road.

“While I was resuscitating Dad it felt like an eternity waiting for help,” Mark said. “Ambulances can be delayed, especially when trying to get to remote areas like those we were in. But in the future a call handler may be able to explain that help is on the way with a drone, which can arrive much quicker.”

Carl Powell, Clinical Lead (Acute Care) at the Welsh Ambulance Service, concluded: “In a cardiac arrest, every second counts. We will always send an ambulance as quickly as possible, but starting chest compressions and delivering an electric shock with a defibrillator in the meantime could mean the difference between life and death.

“We’re grateful to NIHR and others for funding this research, which has demonstrated that the technology shows a great amount of promise.”

Image credit: University of Warwick.