Which building types give optimal public access defibrillator coverage for out-of-hospital cardiac arrest?

INTRODUCTION: Public access defibrillation is a key component of the early links in the chain of survival. Despite growing numbers of PADs in the community, actual use remains poor, partly because of the difficulties in locating the nearest PAD. We aimed to establish the cover that would be provided if PADs were located in any given building type, which would enable the public to know where the nearest PAD was located. METHODS: Mapping software was used to classify each and every building type in the South Central Ambulance Service region. The 52 commonest building types were then mapped to all cardiac arrest calls in the same geographical area from Jan 2014 - July 2018. The walking distance from each cardiac arrest to each nearest building type was calculated. RESULTS: A total of 22,382 cardiac arrests were mapped to a total of 24,155 buildings considered suitable for potential PAD location. Post boxes ranked first in both urban and rural areas, covering 11.7% of cardiac arrests at 100 m and 85.6% of cardiac arrests at 500 m. In urban areas, bus shelters and telephone boxes also provided good coverage (9.7%, 9.5% @ 100 m; 69.2%, 71.9% @ 500 m respectively). In rural areas, good coverage was provided by nursing/care homes and pubs/bars (4.9%, 4.6% @ 100 m; 15.2%, 31.8% @ 500 m respectively). CONCLUSION: Locating PADs at all post boxes would provide the most effective geographical coverage in both urban and rural areas according to building type. This may be an effective strategy to improve rapid PAD locating.

Underutilisation of public access defibrillation is related to retrieval distance and time-dependent availability.

INTRODUCTION: Public access defibrillation doubles the chances of neurologically intact survival following out-of-hospital cardiac arrest (OHCA). Although there are increasing numbers of defibrillators (automated external defibrillator (AEDs)) available in the community, they are used infrequently, despite often being available. We aimed to match OHCAs with known AED locations in order to understand AED availability, the effects of reduced AED availability at night and the operational radius at which they can be effectively retrieved. METHODS: All emergency calls to South Central Ambulance Service from April 2014 to April 2016 were screened to identify cardiac arrests. Each was mapped to the nearest AED, according to the time of day. Mapping software was used to calculate the actual walking distance for a bystander between each OHCA and respective AED, when travelling at a brisk walking speed (4 mph). RESULTS: 4012 cardiac arrests were identified and mapped to one of 2076 AEDs. All AEDs were available during daytime hours, but only 713 at night (34.3%). 5.91% of cardiac arrests were within a retrieval (walking) radius of 100 m during the day, falling to 1.59% out-of-hours. Distances to rural AEDs were greater than in urban areas (P<0.0001). An AED could potentially have been retrieved prior to actual ambulance arrival in 25.3% cases. CONCLUSION: Existing AEDs are underused; 36.4% of OHCAs are located within 500 m of an AED. Although more AEDs will improve availability, greater use can be made of existing AEDs, particularly by ensuring they are all available on a 24/7 basis.

Saving lives with public access defibrillation: A deadly game of hide and seek.

BACKGROUND: Early defibrillation is a critical link in the chain of survival. Public access defibrillation (PAD) programmes utilising automated external defibrillators (AEDs) aim to decrease the time-to-first-shock, and improve survival from out-of-hospital cardiac arrest. Effective use of PADs requires rapid location of the device, facilitated by adequate signage. We aimed to therefore assess the quality of signage for PADs in the community. METHOD: From April 2017 to January 2018 we surveyed community PADs available for public use on the 'Save a Life' AED locator mobile application in and around Southampton, UK. Location and signage characteristics were collected, and the distance from the furthest sign to the AED was measured. RESULTS: Researchers evaluated 201 separate PADs. All devices visited were included in the final analysis. No signage at all was present for 135 (67.2%) devices. Only 15/201 (7.5%) AEDs had signage at a distance from AED itself. In only 5 of these cases (2.5%) was signage mounted more than 5.0 m from the AED. When signage was present, 46 used 2008 ILCOR signage and 15 used 2006 Resuscitation Council (UK) signage. Signage visibility was partially or severely obstructed at 27/66 (40.9%) sites. None of the 45 GP surgeries surveyed used exterior signage or an exterior 24/7 access box. CONCLUSIONS: Current signage of PADs is poor and limits the device effectiveness by impeding public awareness and location of AEDs. Recommendations should promote visible signage within the operational radius of each AED.

Public knowledge and confidence in the use of public access defibrillation.

INTRODUCTION: Growing numbers of public access defibrillators aim to improve the effectiveness of bystander cardiopulmonary resuscitation prior to ambulance arrival. In the UK, however, public access defibrillators are only deployed successfully in 1.7% of out-of-hospital cardiac arrests. We aimed to understand whether this was due to a lack of devices, lack of awareness of their location or a reflection of lack of public knowledge and confidence to use a defibrillator. METHODS: Face-to-face semistructured open quantitative questionnaire delivered in a busy urban shopping centre, to identify public knowledge relating to public access defibrillation. RESULTS: 1004 members of the public aged 9-90 years completed the survey. 61.1% had been first aid trained to a basic life support level. 69.3% claimed to know what an automatic external defibrillator was and 26.1% reported knowing how to use one. Only 5.1% knew where or how to find their nearest public access defibrillator. Only 3.3% of people would attempt to locate a defibrillator in a cardiac arrest situation, and even fewer (2.1%) would actually retrieve and use the device. CONCLUSIONS: These findings suggest that a lack of public knowledge, confidence in using a defibrillator and the inability to locate a nearby device may be more important than a lack of defibrillators themselves. Underused public access defibrillation is a missed opportunity to save lives, and improving this link in the chain of survival may require these issues to be addressed ahead of investing more funds in actual defibrillator installation.