Title: Increasing the Use of Public Access Defibrillation in the Response to Out-of-Hospital Cardiac Arrest
Funder: Department of Health and Social Care

Abstract: Approximately 28,000 people suffer an out-of-hospital cardiac arrest each year in England. Fewer than 8% survive to hospital discharge, but the Department of Health aspires to save 1000 extra lives every year by improving survival by 50%. Early defibrillation is key, with 70% survival possible if defibrillation occurs within 2 minutes of collapse. However, an ambulance will reach a victim within 8 minutes in only two-thirds of cases.Public Access Defibrillation is the term given to the use of Automated External Defibrillators (AED) by members of the public before the arrival of the ambulance service. Public Access Defibrillation was used in just 2.4% of out-of-hospital cardiac arrests in England in 2014, greatly limiting its benefit at a population level. The important role of the ambulance service in the dispatch of AED is recognised in international resuscitation guidelines. Ambulance services have databases of public-access AED that are integrated with Computer Aided Dispatch systems, but evidence suggests that bystanders making 999 calls are often not directed to nearby AED.GoodSam is a mobile-phone, app-based alerting system allowing notification of trained volunteers to nearby cardiac arrests. The location of the cardiac arrest, as well as nearby AED, are displayed graphically. The volunteer can then attend, with or without an AED, and provide assistance. GoodSam is linked directly to London Ambulance Service dispatch systems and is activated automatically when a cardiac arrest is suspected by the 999 call-handler. This linkage between public and ambulance service is one potential way of improving AED use in cardiac arrest. In this project the aims are to:1. Identify the current and potential use of AED by GoodSam volunteers.The following will be investigated: proportion of out-of-hospital cardiac arrests when a GoodSam volunteer was activated, proportion (overall and in just GoodSam volunteer-activated cases) of cardiac arrest victims who had an AED applied, and survival to hospital discharge (overall and in GoodSam cases)The potential for AED use in the GoodSam system will be determined by mapping cardiac arrest and AED locations, and calculating what proportion of cardiac arrests occur within a range of specified distances of an AED (from 100m to 500m). 2. Identify the barriers to AED use by GoodSam volunteers, and develop an intervention to increase AED use.Epidemiological factors, including characteristics of the cardiac arrest victim, volunteer- and AED availability, will be entered into a multiple logistic regression model to identify their contribution to AED use.Organisational, technical and behavioural factors affecting AED use will be identified by brief interviews with GoodSam volunteers that receive a cardiac arrest notification and with people instrumental in setting up the technical interface between GoodSam and London Ambulance Service. Interviews will be coded and analysed using the Theoretical Domains Framework. Barriers to AED use will be categorised and potential interventions to overcome these barriers will be identified. 3. Identify if providing specific instructions to GoodSam volunteers to retrieve an AED affects the rate of AED use.The decisions that GoodSam volunteers make play an important part in determining whether an available AED is retrieved and taken to the patient. A feasibility randomised controlled trial will investigate whether providing specific instructions to volunteers to retrieve an available AED affects how often they are used. This small-scale trial will focus on process outcomes, but will guide a future multi-centre randomised controlled trial to determine whether AED use and survival to hospital discharge can be improved. This project will provide critical insights into the potential for AED use and represents a huge opportunity to improve cardiac arrest survival within the next five years.

Lay abstract: Cardiac arrest (when the heart stops beating effectively and a person collapses) is the most time-critical medical emergency. Around 28,000 people have a cardiac arrest outside a hospital each year in England. Fewer than one in ten survive to go home. The ambulance service in England reaches about two-thirds of cardiac arrest victims within eight minutes of a 999 call. Unfortunately, this means that the chance of survival may have passed when the ambulance arrives. What happens in those vital first minutes after a cardiac arrest makes the difference between life and death. The only things proven to improve survival are high-quality chest compressions during cardiopulmonary resuscitation and early defibrillation - the delivery of an electric shock to the heart.Public Access Defibrillation is the term given to delivery of an electric shock by a member of the public before an ambulance arrives, using an Automated External Defibrillator. These are safe, automated devices found in public places, and they can be used with little or no previous training.There is lots of evidence that shows better survival in cardiac arrest victims receiving Public Access Defibrillation compared to those who do not. However, it is only used in a small number of cardiac arrests (about 1 in 50 in England) and this greatly limits the benefit that it can have.The ambulance service has a vital role in helping to get public-access Automated External Defibrillators to a cardiac arrest victim. However, even if there is an Automated External Defibrillator nearby, and even if the ambulance service are aware of it, this information is not always communicated to the person making the 999 call.GoodSam is a mobile-phone app-based alert system linked directly to London Ambulance Service. When London Ambulance Service receive a 999 call and suspect a cardiac arrest, an alert is sent via the GoodSam mobile app to a nearby member of the public registered with the service. This person can see a map indicating the location of both the cardiac arrest and any nearby Automated External Defibrillators. This is one potential way of getting help and an Automated External Defibrillator to a person in need before an ambulance arrives.In this project the aims are to:1) Identify the current and potential use of Automated External Defibrillators by GoodSam volunteers responding to a cardiac arrest victim.In partnership with London Ambulance Service, GoodSam and the Out-of-Hospital Cardiac Arrest Outcomes registry at the University of Warwick I will identify:i) the proportion of cardiac arrests when a GoodSam volunteer was asked to attend ii) the proportion of those victims (overall and just when a GoodSam volunteer was activated) for whom an Automated External Defibrillator was used iii) survival rates (overall and just when a GoodSam volunteer was activated) and how it was affected by Automated External Defibrillator use iv) the potential for Automated External Defibrillator use, by mapping cardiac arrest locations and calculating what proportion occur close enough to an Automated External Defibrillator for one to be of potential use.2) Investigate the barriers to Automated External Defibrillator use by GoodSam volunteers, and to develop a list of interventions for future testing that might improve use.This will done by brief interviews with GoodSam volunteers after they have received a cardiac arrest notification, and with people who were instrumental in setting up the interface between GoodSam and London Ambulance Service. The focus in interviews with GoodSam volunteers will be on decisions to retrieve an Automated External Defibrillator. Once barriers are identified, possible methods to overcome these barriers will be developed by the project team.3) To test a specific intervention to improve Automated External Defibrillator use by GoodSam volunteers.Decisions made by volunteers choosing to respond to a GoodSam notification are important to the success of the system. I will investigate the effect that providing specific retrieval instructions has on the rate of Automated External Defibrillator use by GoodSam volunteers. Volunteers will randomly either receive these specific instructions (intervention group) or will be notified in the usual way (control group) to investigate whether providing instructions is effective. This will be a small-scale trial to find out if the intervention is feasible. If successful, it will be followed by a much larger trial in the future. This project will give us crucial insights into how many lives could be saved if public-access Automated External Defibrillators were used more often. The findings will be shared with NHS England to help improve survival from cardiac arrest within the next 5 years.

Research activity codes: 6.3 MEDICAL DEVICES
Health categories: CARDIOVASCULAR