Placement of automated external defibrillators and logistics to facilitate early defibrillation in sudden cardiac arrest

Abstract

Background and aim: Out-of-hospital cardiac arrest (OHCA) is a leading cause of death in many western countries. Much effort is put in to measures to improve survival. Early cardiopulmonary resuscitation (CPR) and the use of an automated external defibrillator (AED) significantly increase the chance of survival. In 2016, 5,312 cases of OHCA were reported to the Swedish Register for Cardiopulmonary Resuscitation (SRCR), but only 577 (11%) survived to 30-days. The bystander CPR rate in Sweden is high (73%), and AEDs are widely spread in all parts of the country; however, the use of public AEDs is low. If the use of AEDs could be increased, more patients could be saved. The aim of this thesis was to investigate, in four separate studies, how logistics and placement of AEDs can help facilitate early defibrillation.

Methods and results: Study 1. A prospective study at five emergency dispatch centres in Sweden where dispatchers were given access to the Swedish AED registry and had instructions to refer callers to nearby AEDs in cases of suspected OHCA. Of 3,009 suspected OHCA calls over seven months, only 200 occurred within 100 metres of an AED, and in only two cases did dispatchers referred callers to a nearby AED. AED accessibility (opening hours of the venue) and the fact that the callers often were alone on the scene, were identified as barriers for referral. Study 2. A retrospective analysis of AED installation sites and locations of OHCA in public locations in Stockholm. We used renowned geographic information system (GIS) analyses and a freely available dataset of land use (Urban Atlas). Incidence of OHCA in public locations in “residential areas” was similar to “non-residential” but AED installation was significantly higher in “non-residential areas”. Study 3. An explorative study to investigate the feasibility of using unmanned aerial vehicles (UAV)/Drones to transport AEDs to decrease time to defibrillation. The study included live test flights of a UAV system as well as retrospective GIS analysis of suitable locations for installation of UAVs equipped with AEDs for maximum coverage of OHCA. Study 4. An overview of the Swedish AED registry (SAEDREG) shows a two-fold increase of registered AEDs since 2013 and that the majority (45%) of the n=15,849 AEDs are placed in offices/workplaces. In a select region of Sweden, a survey was directed to the owners of all n=218 AEDs that focused on AED functionality and reasons for not registering the AED in SAEDREG. An additional n=94 AEDs were found through customer registries from AED vendors. AED functionality was high in both groups. Owners of AEDs not registered in SAEDREG was often unaware of the national AED registry or stated difficulties with the registration process as the main cause for not registering AEDs in SAEDREG.

Conclusions: Dispatch centres have the potential to refer callers to nearby AEDs at an early stage in OHCA but may need supporting training and software. There is a mismatch between where public OHCA occur and where AEDs are located. Most AEDs are found in offices and workplaces whereas most OHCA occur in residential areas. Drones have the potential to transport AEDs and compensate for prolonged ambulance response time, especially in rural areas. A high quality national AED register is important for increasing general awareness within the community, thus facilitating early defibrillation in OHCA; however, many AEDs are nonregistered or discarded in the validation process.