Despite several campaigns to increase numbers of defibrillators in public places - and the English government's acknowledgement of their life-saving role - public access to them is low, as is understanding of their use, says a new UK study. The findings imply it would be a different story if defibrillators were as accessible and as well understood as fire extinguishers.
Estimates from the British Heart Foundation (BHF) suggest around 60,000 out of hospital cardiac arrests or heart attacks occur in the UK every year.
A defibrillator - also called an automated external defibrillator or AED - is a device that delivers an electric shock to the heart of someone who is having a cardiac arrest or heart attack. Prompt use of an AED can shock the heart back into rhythm.
Acting quickly when someone is in cardiac arrest before the ambulance arrives can save their life. Every minute without CPR and defibrillation reduces their chance of survival by 10%.
The aim of the new UK study was to find out how available AEDs were, given the effort that has been put in over the last 10 years to promote and deploy them in public places, such as shopping centers and train stations.
The study was conducted by researchers from the University of Southamptom, working with the South Central Ambulance Service, and it is published in the journal Heart.
Survival rates of people who have heart attacks outside hospital 'disappointingly poor'
One of the study leaders, Charles Deakin, a professor with the University of Southampton, medical director of South Central Ambulance Service and a consultant at Southampton General Hospital, explains:
"Survival from the 30,000 annual cardiac arrests where resuscitation is attempted remains disappointingly poor, with survival rates of only 7%. Bystander CPR and early defibrillation with public access defibrillators (PADs) have the potential to increase survival three-fold and we were therefore interested to see how often this intervention was available to patients prior to ambulance arrival."
He says despite efforts by health authorities and charities like the British Heart Foundation to promote, distribute and make public access defibrillators more available to community groups, they found many key places had none.
Places like GP surgeries, railway stations and gyms were devoid of public access defibrillators, he says, with the result that a "PAD was available in only 4% of confirmed cardiac arrests," and adds, "even then, only half of these patients had a PAD successfully attached."
Public access to and understanding how to use AEDs strengthens 'chain of survival'
He and his colleagues conclude that more needs to be done to increase public access to, plus confidence and understanding of how to use defibrillators.
The successful resuscitation of patients who have heart attacks outside of the hospital is an important early link in their "chain of survival" and this needs to be strengthened, they urge.
For the study, the researchers focused on the county of Hampshire in England because it has a typical mix of rural and urban communities. The county covers 1,400 square miles and has a population of about 1.76 million, including 12% over the age of 70.
The team looked at all the calls that were made to the South Central Ambulance Service over a period of 12 months following a heart attack.
When the ambulance service receives such a call, if it is not from a person's home, they always ask if the caller has access to a defibrillator. If they do, then they are given instructions on how to use it.
Over the study period, 1,035 calls were made following later-confirmed heart attacks that occurred out of the hospital.
In 44 of cases (4.25%) in 34 different public places, the caller was able to access an AED. But in only 18 incidents (41%, less than half of cases) was the caller able to attach the device to the victim before the ambulance arrived.
The authors calculated that this meant the overall deployment rate of AEDs for heart attacks in public places was only 1.74%, which they describe as "disappointingly low."
Across Hampshire, as of October 2012, there were 673 external defibrillators located in 278 places, including all large shopping centers. But on average, there was only just over 1 defibrillator for every 10 nursing homes, about 1 per 20 train stations, and similar numbers in other places like community centers and village halls.
While the findings apply to only one county, Prof. Deakin believes they are probably typical of the rest of the country.
In a paper published in Circulation in April 2013, researchers in Canada calculated that over a 5-year period in Toronto, only 23% of cardiac arrests occurred within 100 meters of an AED.
In a 1.5 minute walk to fetch an AED and use it to help a heart attack victim, 100 meters is about the distance a bystander covers. This time span is the maximum recommended by the American Heart Association.
Written by Catharine Paddock PhD