Access to automatic external defibrillators limited at night time


A retrospective study has indicated that although the majority of out-of-hospital cardiac arrests occur in the evening, in the night, or at the weekend, accessibility to automatic external defibrillators (AEDs) during these times is limited. 

Carolina Malta Hansen (Department of Cardiology, Copenhagen University Hospital Gentofte, Denmark) and others write in Circulation that current guidelines recommend that AEDs are placed in areas with a high incidence of cardiac arrest but do not mention how accessible the devices should be. They comment: “Once deployed, AEDs need to be accessible at the right time.” In their study, they performed a retrospective analysis of the time and location of all cardiac arrests in public locations in Copenhagen between 1991 and 2011 and also reviewed the location and accessibility (as identified by the Emergency Dispatch Center) of AEDs on 31st December 2011.

Of 1,864 cardiac arrests that occurred during the study time period, 61.8% occurred on the weekends, in the evenings, or at night time. Malta Hansen et al note that similar to the arrests that occurred during the day, 27.5% of these events occurred within 100 metres of an AED. They add: “Assuming all AEDs were accessible 24 hours a day, seven days a week, nearly 30% of all historic cardiac arrests in public locations could be reached by an AED within a few minutes on weekdays and weekends.”

However, while most AEDs were accessible during daytime on weekdays, only 9.1% were accessible 24 hours a day, seven days a week. The authors report: “When AED accessibility and time of historic cardiac arrest were taken into account, AED coverage of cardiac arrest was 29.8% for those occurring the daytime on weekdays, but only 12.9% for cardiac arrests occurring during the evening, night time or weekends.” Of the 537 cardiac arrests that occurred within 100 metres of an AED device, 180 occurred when there was no access to a device. For these events, the overall loss of AED potential was 33.5% but this rose to 53.4% for events that occurred during evening, night time, or weekends.

According to Malta Hansen et al, their findings indicated that “limited AED accessibility is a major limitation to AEDs’ potential in community settings.” They add that different approaches should be considered to promote an increase in AED accessibility and thus facilitate its use. The authors suggest that such approaches could include using multimedia campaigns to raise awareness of the problem of limited AED accessibility, ensuring Danish recommendations to provide AED accessibility 24 hours a day, seven days a week in municipal or governmental buildings are strictly followed, identifying areas with a high incidence of cardiac arrests where 24/7 AED coverage is not available, and placing AEDs in vending machines or protective cabinets in strategic locations. 

Malta Hansen told
Cardiovascular News: “The Danish AED network provides citizens and emergency dispatch centres from the whole country with unique and validated information on AEDs accessible to anyone. However, in order to benefit from this set up, it is necessary that the AEDs are accessible when people need them. Our study shows that it is necessary to remember that cardiac arrests happen at all hours and since AEDs are meant for treating them, they require 24-hour accessibility.”