Background and study aims
Only 10% people survive after having a cardiac arrest in the community. Delivering an
electric shock to the heart using a defibrillator greatly improves someone's chance of
surviving.
Automated External Defibrillators (AEDs) are a type of defibrillator that may be found in
public places. You can attach an AED to someone who is having a cardiac arrest. The AED
may give them an electric shock and help their heart beat normally again. They are safe
for members of the public to use, even if they are not trained to use them.
However, if a person is helping someone who has had a cardiac arrest it may be very
difficult to find a nearby AED soon enough to make a real difference. There may be better
ways to deliver AEDs quickly to more people who need them. In Sweden, ambulance services
use flying drones to deliver AEDs to people after cardiac arrest. Nobody has yet
demonstrated how the investigators will do this in the UK.
This study aims to explore the optimisation and integration of a drone-delivered AED
system into the pre-hospital response to out-of-hospital cardiac arrest, as a necessary
pre-requisite to real-life flight operations.
What does the study involve?
The investigators will build a fully-functioning system to deliver an Automated External
Defibrillator using a flying drone to someone who has had a cardiac arrest.
The study has two main parts:
Part one - interview study
The investigators will ask people who have previously used an AED in real-life
cardiac arrests about their experiences. The investigators will ask them what they
think about how a drone bringing them an AED might have helped them at the time.
The investigators will analyse their responses using the Theoretical Domains
Framework, which links to the COM-B (Capability, Opportunity and Motivation -
Behaviour) framework and the BCW (Behaviour Change Wheel). This will allow the
investigators to identify the main barriers and facilitators to drone-delivery of
AEDs, and to determine interventions to overcome them and policies to help with the
implementation of these interventions.
This work will help determine how to optimise future real-world drone-delivered AED
systems
The investigators will recruit primarily through Welsh Ambulance Service NHS Trust's
existing contacts with cardiac arrest survivor and bystander groups, but will also
recruit via the social media platforms of Welsh Ambulance Service NHS Trust and Warwick
University. The investigators will approach national charities with whom we have existing
relationships (Resuscitation Council UK, British Heart Foundation and Sudden Cardiac
Arrest UK) to help with study advertisement if required.
This will be a semi-structured interview conducted remotely, either using Microsoft TEAMS
or, if the participant prefers, over the phone. The investigators will interview a mix of
people who did and did not use an AED during their cardiac arrest experience. Interviews
will last up to 45 minutes and will be audio-recorded before being sent to a
University-approved transcription company for transcription. The participant information
sheet provides information about support for participants should the interview process
and talking about this sensitive topic prove difficult for them. All audio files and
transcripts will be stored on a University of Warwick-managed computer, in an encrypted
folder.
A senior research fellow will conduct and analyse the interviews, with assistance from
the Chief Investigator. The investigators will perform a framework analysis using the
Theoretical Domains Framework (TDF) to identify barriers and facilitators to
drone-delivered AED use and to effective interaction with the 999 call-handler.
The investigators will group the 14 domains of the TDF so that we can characterise
barriers and facilitators to effective use of a drone-delivered AED according to a
bystander's 'Capability', 'Opportunity' and 'Motivation' - the so-called COM-B
(Capability, Opportunity, Motivation - Behaviour) framework (38). We will then map the
three core targets for behavioural change to identify potential interventions to enact
this change using the Behaviour Change Wheel.
The key outcomes are a list of barriers and facilitators to drone-delivered AED use, and
a list of potential interventions (for future testing or implementation) to optimise the
future use of drone-delivered AEDs in the real-world cardiac arrest response.
Part two - test flights and simulated cardiac arrests
The investigators will show that a drone can effectively and safely make a
long-distance ('beyond visual-line-of-sight', or BVLOS) flight carrying an AED.
The investigators will integrate drone systems with ambulance systems. The
investigators will show how the investigators can automatically and quickly activate
a drone after an emergency (999) call is made about a cardiac arrest.
The investigators will develop real-time communication systems between drone pilots
and the ambulance service during flight.
The investigators will perform test flights:
A participant in our research study will find a simulated cardiac arrest
patient (a resuscitation manikin) and make an emergency (999) call.
The ambulance service will activate the drone and the investigators will test
how effective the entire system works from the start of the emergency (999)
call to final delivery of the AED.
The investigators will record key timings including flight timings, and how
long it takes the participant to retrieve and then apply the AED
The investigators will review audio recordings of the mock emergency (999)
calls and video from the drone and from the simulation site to identify
additional information about how the participants interacted with the drone and
with the AED.
The simulations will be performed in an outdoor location, and at a site where
investigators can control access. The drone will fly 'beyond visual line of sight' up to
2km away from the cardiac arrest site. The 'patient' will be a manikin, but in all other
respects the simulation will run as the investigators envisage a real-world cardiac
arrest call would: the 999 call goes through to a trained operator (at a training
centre), following established cardiac arrest scripts and, once cardiac arrest is
diagnosed, the communication processes with the remote drone operator will occur in
real-time.
Members of the study team will be on hand to make timings and to administer a
post-simulation questionnaire (based on a 'System Usability Scale', to gauge how the
participant found the interaction with the drone) and to conduct a brief (<5 min)
interview to record their thoughts on the process, particularly the interaction with
drone and call-handler.
Audio and visual recordings will be securely transferred in electronic format to the
Chief Investigator, who will store them in a University of Warwick managed computer, in
an encrypted folder.
Key outcomes are:
Time from start of emergency (999) call and diagnosis of cardiac arrest to drone
having started flight
Total flight time
Time from drone arrival at scene and when it is safe for participant to retrieve
AED. (AED will be lowered by winch to the ground. The call-handler will have
real-time communications with the drone operator and will be informed when it is
safe to approach - they will then inform the participant)
Total time from emergency call to AED application and (simulated) shock
Hands off CPR time (time from stopping CPR to retrieve AED to time that CPR starts
again after AED has been applied and delivered a (simulated) shock
Time that participant spends away from the patient's side (retrieving the AED)
Where is the study run from?
The study is run by researchers at the University of Warwick, UK, in collaboration with
Welsh Ambulance Service National Health Service Trust and a commercial drone company
(SkyBound Rescuer, Southampton, UK). All three organisations are based in the United
Kingdom
When is the study starting and how long is it expected to run for?
Development work on the system began on 1st May 2023. The investigators will recruit to
the interview study in April and May 2024, and perform the cardiac arrest simulations in
August 2024. The study analyses will be completed by 31st October 2024.
Who is funding the study?
The National Institute for Health and Care Research (NIHR) Research for Patient Benefit
(RfPB) scheme. Health and Care Research Wales are supporting excess treatment costs. Both
are organisations in the UK.