Public Access Defibrillation and Sudden Cardiac Arrest
Public Access Defibrillation and Sudden Cardiac Arrest
With early defibrillation forming a key link in the chain of survival, and mortality increasing 7–10% for every minute's delay in defibrillation, the ability of bystanders to undertake basic life support and deploy a PAD prior to ambulance arrival significantly increases the chances of successful defibrillation and subsequent survival. The safety and benefits of PAD programmes for the estimated 6000–12 000 UK patients who suffer SCA in public places are now well established and, where implemented, can double survival from OOH cardiac arrest.
These benefits have been recognised by the Department of Health, British Heart Foundation and Resuscitation Council (UK), for the past decade, all of whom have supported the introduction of PAD schemes across the UK. The recent Department of Health's 'Cardiovascular Disease Outcomes Strategy' (a document endorsed by Government, NHS England and Public Health England) has also recognised the need to "…consider ways of increasing the numbers trained in cardiopulmonary resuscitation (CPR) and using AEDs". We are unaware of any UK study examining the public use of AEDs nor any recent study examining the availability of AEDs in the community, which is important to ascertain if this important strategy is to be developed.
Overall, less than 2% of all OOH cardiac arrest victims had potential access to a PAD (although it is likely that at some cardiac arrests PADs were available but their presence unknown by the rescuer), and of those who did, only approximately 1% benefitted from its actual deployment. This disappointingly low figure is of the same magnitude as that recently reported by London Ambulance Service, where only 31/9657 (0.32%) cardiac arrests benefitted from PAD and similar to the 2.1% reported from the USA overall, where similar PAD programmes have been introduced. Although distribution of AEDs is increasing, the usage rate is poor, even when trained bystanders are on scene. We found that when a PAD was known to be available, it was only used in 40.7% of cases. The reasons for this are unclear but appear related to a lack of bystander willingness to use an AED in an emergency situation, poor 'visibility' or accessibility of the AED, mistaken concerns over legal liabilities and poor levels of community knowledge about PAD, even following campaigns to improve public awareness. It would appear that there remains a significant barrier with public perception and education regarding the use of PADs.
Although the frequency of use of deployed PADs is relatively low, there is an inverse relationship between the geographic density of PADs and the time to first shock, with a positive relationship to survival. Where PADs are available, they are generally placed on the patient within 3–5 min. At the time of the study, the location of the nearest AED for each cardiac arrest was unknown. Matching the cardiac arrest location to PAD coverage would be a useful undertaking in future studies in order to ascertain whether geographic distribution of PADs could be optimised.
With SCAS median ambulance response times to cardiac arrest calls of 6 min, the majority of patients with OOH cardiac arrest should receive defibrillation prior to ambulance arrival in locations where a PAD is available and used. Ambulance call takers now routinely question the caller about the availability of a PAD in order to prompt PAD use if available. In addition to wider availability of AEDs, a more comprehensive national system for recording the presence and site of an AED, accessible to all ambulance services and to bystanders who witness an arrest, could greatly improve survival rates from OOH cardiac arrest.
The commonest location for an OOH cardiac arrest outside the private home is a care home, which accounts for approximately 10% of cardiac arrests. We identified a total of 18 PADs located at 658 registered care homes in Hampshire, representing only 2.7% of all care homes. Cardiac arrests occurring on public transport systems are also relatively common, particularly at railway stations. This contrasts with the very few PADs available on the Hampshire railway network, particularly considering the large number of passengers passing through rail stations or travelling on trains. During 2011–2012, people entered or left Hampshire's busiest station (Southampton Central Station) on 5,951,224 occasions, a location without a PAD. Almost as common a location for an OOH cardiac arrest is a leisure or sports facility, but only 9 of the estimated 68 facilities (13.2%) had a known PAD available. Although schools contain a mostly fit and healthy population, SCA, particularly during exercise, is known to occur as a result of inherited cardiac conditions. With approximately 400,000 primary and secondary school children in Hampshire, we were disappointed that so few schools had a PAD available. This is a missed opportunity to educate school children about the benefits of bystander resuscitation and use of PADs, particularly as a greater awareness of PAD benefits would be likely to translate into greater placement of devices in the future.
In estimating the number of PADs in Hampshire, our telephone survey relied on contacted individuals passing accurate information. A number of the institutions contacted appeared unsure as to whether a PAD was available, reinforcing suggestions that education of potential users is a priority. We may therefore have underestimated the availability of a PAD at some locations, although PAD equipment is unlikely to be used if staff are unaware of its existence. This study has not examined the benefits of rapid defibrillation by CFR who are dispatched by the ambulance service ahead of the ambulance arrival. Although CFR delivery of an AED generally takes longer than that achieved through PAD, it does offer some prospect of resuscitation for many patients who would otherwise receive no treatment.
This study demonstrates that PAD is not available or is not used for the vast majority (over 98%) of people suffering an OOH SCA in Hampshire. While we have not surveyed other parts of the UK, we believe our findings would probably be similar elsewhere. There are relatively few PAD devices available, and when they are, there is a lack of confidence by the lay public in using them. As a consequence, a real opportunity to save lives is missed. Greater numbers of PADs are required to improve rapid deployment at OOH SCA, and more people should be trained in their use and in basic life support techniques. It is impractical to deploy PADs to cover the entire population, but any location that has 1000 adults over the age of 35 years present during normal business hours can expect one incident of SCA every 5 years —a threshold that has been suggested as a level at which a PAD should be available.
From February 2007, responsibility for continuing the legacy of the National Defibrillator Programme was devolved to ambulance trusts. Although most ambulance trusts across the UK have community resuscitation departments or similar, these generally raise funds for AEDs and community responders schemes rather than AEDs placed in fixed locations in public areas. Fund raising campaigns to increase PAD availability should be commended, and the government has been petitioned to introduce defibrillators to all public buildings by 2017, together with providing staff with the appropriate training (http://epetitions.direct.gov.uk/petitions/29399). The need for a centrally coordinated database to maximise PAD availability is clear, preferably accessible to the ambulance service, so that whenever an OOH cardiac arrest is identified, the operator can immediately advise of an AED location. Improving confidence by members of the public in using the PAD would also appear to be a priority for successful deployment. Further, PAD publicity should focus on the safety, effectiveness and ease of use of AEDs and counter perceived fears over litigation if used by the public 'inappropriately', which are unfounded and hinder wider use.
This study highlights the need for both improved PAD availability and the need to improve bystander confidence in the use of these devices. With survival from OOH cardiac arrest doubling in cases where PAD is used, there is a need to improve PAD availability, publicise locations and support bystanders in deploying the device. OOH cardiac arrest and PAD is an area appropriately prioritised by the Cardiovascular Disease Outcomes Strategy.
Discussion
With early defibrillation forming a key link in the chain of survival, and mortality increasing 7–10% for every minute's delay in defibrillation, the ability of bystanders to undertake basic life support and deploy a PAD prior to ambulance arrival significantly increases the chances of successful defibrillation and subsequent survival. The safety and benefits of PAD programmes for the estimated 6000–12 000 UK patients who suffer SCA in public places are now well established and, where implemented, can double survival from OOH cardiac arrest.
These benefits have been recognised by the Department of Health, British Heart Foundation and Resuscitation Council (UK), for the past decade, all of whom have supported the introduction of PAD schemes across the UK. The recent Department of Health's 'Cardiovascular Disease Outcomes Strategy' (a document endorsed by Government, NHS England and Public Health England) has also recognised the need to "…consider ways of increasing the numbers trained in cardiopulmonary resuscitation (CPR) and using AEDs". We are unaware of any UK study examining the public use of AEDs nor any recent study examining the availability of AEDs in the community, which is important to ascertain if this important strategy is to be developed.
Overall, less than 2% of all OOH cardiac arrest victims had potential access to a PAD (although it is likely that at some cardiac arrests PADs were available but their presence unknown by the rescuer), and of those who did, only approximately 1% benefitted from its actual deployment. This disappointingly low figure is of the same magnitude as that recently reported by London Ambulance Service, where only 31/9657 (0.32%) cardiac arrests benefitted from PAD and similar to the 2.1% reported from the USA overall, where similar PAD programmes have been introduced. Although distribution of AEDs is increasing, the usage rate is poor, even when trained bystanders are on scene. We found that when a PAD was known to be available, it was only used in 40.7% of cases. The reasons for this are unclear but appear related to a lack of bystander willingness to use an AED in an emergency situation, poor 'visibility' or accessibility of the AED, mistaken concerns over legal liabilities and poor levels of community knowledge about PAD, even following campaigns to improve public awareness. It would appear that there remains a significant barrier with public perception and education regarding the use of PADs.
Although the frequency of use of deployed PADs is relatively low, there is an inverse relationship between the geographic density of PADs and the time to first shock, with a positive relationship to survival. Where PADs are available, they are generally placed on the patient within 3–5 min. At the time of the study, the location of the nearest AED for each cardiac arrest was unknown. Matching the cardiac arrest location to PAD coverage would be a useful undertaking in future studies in order to ascertain whether geographic distribution of PADs could be optimised.
With SCAS median ambulance response times to cardiac arrest calls of 6 min, the majority of patients with OOH cardiac arrest should receive defibrillation prior to ambulance arrival in locations where a PAD is available and used. Ambulance call takers now routinely question the caller about the availability of a PAD in order to prompt PAD use if available. In addition to wider availability of AEDs, a more comprehensive national system for recording the presence and site of an AED, accessible to all ambulance services and to bystanders who witness an arrest, could greatly improve survival rates from OOH cardiac arrest.
The commonest location for an OOH cardiac arrest outside the private home is a care home, which accounts for approximately 10% of cardiac arrests. We identified a total of 18 PADs located at 658 registered care homes in Hampshire, representing only 2.7% of all care homes. Cardiac arrests occurring on public transport systems are also relatively common, particularly at railway stations. This contrasts with the very few PADs available on the Hampshire railway network, particularly considering the large number of passengers passing through rail stations or travelling on trains. During 2011–2012, people entered or left Hampshire's busiest station (Southampton Central Station) on 5,951,224 occasions, a location without a PAD. Almost as common a location for an OOH cardiac arrest is a leisure or sports facility, but only 9 of the estimated 68 facilities (13.2%) had a known PAD available. Although schools contain a mostly fit and healthy population, SCA, particularly during exercise, is known to occur as a result of inherited cardiac conditions. With approximately 400,000 primary and secondary school children in Hampshire, we were disappointed that so few schools had a PAD available. This is a missed opportunity to educate school children about the benefits of bystander resuscitation and use of PADs, particularly as a greater awareness of PAD benefits would be likely to translate into greater placement of devices in the future.
In estimating the number of PADs in Hampshire, our telephone survey relied on contacted individuals passing accurate information. A number of the institutions contacted appeared unsure as to whether a PAD was available, reinforcing suggestions that education of potential users is a priority. We may therefore have underestimated the availability of a PAD at some locations, although PAD equipment is unlikely to be used if staff are unaware of its existence. This study has not examined the benefits of rapid defibrillation by CFR who are dispatched by the ambulance service ahead of the ambulance arrival. Although CFR delivery of an AED generally takes longer than that achieved through PAD, it does offer some prospect of resuscitation for many patients who would otherwise receive no treatment.
This study demonstrates that PAD is not available or is not used for the vast majority (over 98%) of people suffering an OOH SCA in Hampshire. While we have not surveyed other parts of the UK, we believe our findings would probably be similar elsewhere. There are relatively few PAD devices available, and when they are, there is a lack of confidence by the lay public in using them. As a consequence, a real opportunity to save lives is missed. Greater numbers of PADs are required to improve rapid deployment at OOH SCA, and more people should be trained in their use and in basic life support techniques. It is impractical to deploy PADs to cover the entire population, but any location that has 1000 adults over the age of 35 years present during normal business hours can expect one incident of SCA every 5 years —a threshold that has been suggested as a level at which a PAD should be available.
From February 2007, responsibility for continuing the legacy of the National Defibrillator Programme was devolved to ambulance trusts. Although most ambulance trusts across the UK have community resuscitation departments or similar, these generally raise funds for AEDs and community responders schemes rather than AEDs placed in fixed locations in public areas. Fund raising campaigns to increase PAD availability should be commended, and the government has been petitioned to introduce defibrillators to all public buildings by 2017, together with providing staff with the appropriate training (http://epetitions.direct.gov.uk/petitions/29399). The need for a centrally coordinated database to maximise PAD availability is clear, preferably accessible to the ambulance service, so that whenever an OOH cardiac arrest is identified, the operator can immediately advise of an AED location. Improving confidence by members of the public in using the PAD would also appear to be a priority for successful deployment. Further, PAD publicity should focus on the safety, effectiveness and ease of use of AEDs and counter perceived fears over litigation if used by the public 'inappropriately', which are unfounded and hinder wider use.
This study highlights the need for both improved PAD availability and the need to improve bystander confidence in the use of these devices. With survival from OOH cardiac arrest doubling in cases where PAD is used, there is a need to improve PAD availability, publicise locations and support bystanders in deploying the device. OOH cardiac arrest and PAD is an area appropriately prioritised by the Cardiovascular Disease Outcomes Strategy.