Elsevier

Resuscitation

Volume 65, Issue 3, June 2005, Pages 309-314
Resuscitation

Method for determining automatic external defibrillator need at mass gatherings

https://doi.org/10.1016/j.resuscitation.2004.09.016Get rights and content

Abstract

Objectives:

A method for determining the number of automatic external defibrillators (AEDs) required for a 3-min response at mass gatherings has been described previously. Our study sought to modify the method, replicate it, then validate the results.

Methods:

Emergency medical technicians (EMTs) were timed walking defined courses in a football stadium. Velocities were obtained for a horizontal distance and ascending/descending upper and lower decks. This was replicated in a basketball arena. To validate, actual response times were compared to predicted times for predetermined distances in each venue. Predicted response times were calculated using the second standard deviation velocities as the most pessimistic. Numbers of AEDs needed were calculated using predicted response times for each venue's longest distance.

Results:

Average velocities in m/s (football) were horizontal 1.7, lower deck 1.6 ascending and 1.4 descending, upper deck 1.0 ascending and 1.1 descending. Average velocities (basketball) were horizontal 1.7, lower deck 1.2 ascending and descending, upper deck 0.9 ascending and descending. In the validation phase, every EMT completed the four predetermined courses within the predicted intervals. Predicted response times were 363 s for the longest football stadium distance, and 187 s for the basketball arena. For a 3-min (180 s) response, the number of AEDs required can be calculated.

Conclusion:

This method was easily replicated and appears to be useful for determining the number of AEDs at mass gatherings. The number of AEDs needed for any desired response interval can be calculated using the predicted response time for the longest distance within an arena.

Introduction

Despite advances in medical technologies and treatments, survival from out-of-hospital cardiac arrest remains poor. The American Heart Association has identified early defibrillation as one of the most important links in the chain of survival [1], a ventricular fibrillation arrest survival decreases by 10% for each minute without defibrillation [2], [3]. With the development of automated external defibrillators (AEDs), personnel with minimal training are able to deliver early defibrillation. Thus, AEDs are becoming more commonplace on fire trucks, police cars, airplanes, and in settings where large numbers of people congregate, so that defibrillation may be performed prior to EMS arrival.

A previous study by Crocco et al. [4] derived a method for determining the number of AEDs needed to provide a 3-min response interval in settings of mass gathering. This method divided the setting into areas of different slopes, and used these areas and volunteer response times and distances to calculate the number of AEDs needed. The Crocco method used responders who ran to the designated area. In many systems, including our own, running is not permitted for responders within a mass gathering, due to the tendency for running to cause panic and unexpected crowd movements. In addition, Crocco's formulae were somewhat complicated, and the method was only tested in a single venue. Therefore, the purposes of our project were to modify the Crocco method, to replicate our new method in a second venue, and to validate the results.

Section snippets

Setting

Kenan Memorial Stadium and The Dean E. Smith Center (Fig. 1, Fig. 2) are the venues for football and basketball games at The University of North Carolina. Capacity seating is 60,000 and 21,444, respectively. Approximately 6 football games and 18 basketball games are held at these locations each year, along with various other activities, including concerts, band competitions, and graduations. Three cardiac arrests have occurred in these locations over the last four years (two in Kenan Memorial

Derivation data

Ten EMTs participated in data acquisition in Kenan Memorial Stadium. Average times were obtained and “worst-case” velocities calculated for each surface (Table 1; Formula 1 in Appendix A).

Replication of method in second venue

Ten EMTs participated when the study was replicated at The Dean E. Smith Center. Their times and velocities are listed in Table 2.

Validation

In the validation phase of the study, five EMT volunteers were timed responding to two pre-determined locations in each coliseum. Knowing the distance to each location, the

Discussion

Since the 1992 American Heart Association guidelines identified early defibrillation as one of the four interventions in the “chain of survival” [1], many methods to shorten the time to defibrillation have been explored. It is commonly accepted that survival decreases by approximately 10% for each minute that defibrillation is delayed [2], [3], and multiple studies have demonstrated improved survival with earlier defibrillation [5], [6], [7], [8], [9]. One of the most promising methods for

Conclusion

AEDs are becoming increasingly more common in settings of mass gatherings. Our method was easily replicated and appears to be valid for determining the required number of AEDs in these types of settings. To calculate the number of AEDs needed, first calculate the “worst-case” response velocities over each of the different slopes of the location. Then, using the velocities, determine the time necessary to traverse the longest response distance. This maximum response time can be used to figure

Acknowledgements

The authors wish to thank Orange County Emergency Management for their continued support of our research, the volunteers of Orange EMS and Rescue Squad for their participation, and The University of North Carolina Athletic Office for permission to perform the study in Kenan Memorial Stadium and The Dean E. Smith Center during athletic events. The authors report no financial or personal relationships with people or organizations related to this field of study that might serve as conflicts of

Cited by (0)

A Spanish and Portuguese translated version of the Abstract and Keywords of this article appears at doi: 10.1016/j.resuscitation.2004.09.016.

1

Huntsville Hospital Emergency Physicians Group, 903 Madison Street, Huntsville, AL 35801, USA.

2

Department of Emergency Medicine, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, NC 27157-1089, USA

3

Pikeville College School of Osteopathic Medicine, 147 Sycamore Street, Pikeville, KY 41501, USA.

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