Abstract & Commentary
Synopsis: Establishing a dual system with AEDs available to both police and EMS yields improved response times and survival for victims found to be in VT or VF. Unfortunately, more than 60% of patients have nonshockable rhythms and do not benefit from this system.
Source: Myerburg RJ, et al. Circulation. 2002;106: 1058-1064.
This paper describes the results of community-wide deployment of automatic external defibrillators (AEDs) to police officers. Beginning in early 1999, AEDs were given to Miami Dade County police officers. Distribution was phased in more than a 5-month period with training and deployment carried out in 9 police districts in an ordered sequence. The emergency response system during this time was modified so that medical emergency calls were dispatched both to the emergency medical services (EMS) and to the police in a dual dispatch program. Data for the dual dispatch system were compared to dispatches to the EMS system only in districts waiting for deployment and to historical controls in the previous 2-year period.
In the period of study, there were more than 2 million calls to 911 and of these, 56,321 triggered dual police-AED and EMS dispatches for possible or definite medical emergencies. There were 420 true cardiac arrests among the police-AED medical emergency runs. The police arrived first to 237 of the 420 (56%) cardiac arrests. EMS arrived first in 138 cases (33%) and police and EMS arrived simultaneously in 45 (11%). The initial rhythm recorded at the scene of cardiac arrest was a shockable rhythm, ventricular tachycardia or ventricular fibrillation (VT or VF) in 39% of the police-AED responses and 38% of the EMS responses. The mean response time for police arrival at the cardiac arrest was 6.16 ± 4.27 minutes. The mean response time by the EMS teams was 7.56 ± 3.6 minutes (P < 0.001 compared with police). The time to arrival of any first responder was 4.8 ± 2.88 minutes with the dual dispatch system. This was an improvement over the historical control of 7.64 ± 3.66 minutes with the EMS-only system. Overall, the first responder time was less than five minutes in 41% of the runs compared with 11% for EMS deployments during the historical control period.
Survival data were also analyzed. There were 163 patients in ventricular tachycardia or ventricular fibrillation at first contact. Of these, 28 (17.2%) survived to hospital discharge using the dual dispatch system compared to the EMS survival rate of 9.0%. However, survival among cardiac arrest victims who were in a nonshockable rhythm at the time of police or EMS arrival was very low and was not benefited by the police-AED program. For all cardiac arrest victims, the survival rate during the police-AED program was 7.6% vs 6.0% with the standard EMS program.
Myerburg and associates conclude that establishing a dual system with AEDs available to both police and EMS yields improved response times and survival for victims found to be in VT or VF. Unfortunately, more than 60% of patients have nonshockable rhythms and do not benefit from this system.
Comment by John P. DiMarco, MD, PhD
Out-of-hospital cardiac arrest remains a major health problem. Although certain high-risk groups can be targeted for implantable cardioverter defibrillators (ICD), these patients account for a minority of all sudden deaths in the general population and widespread extension of ICD therapy to low or moderate risk populations is not practical. Increased availability of early defibrillation is now possible through the development of the AED. Successful resuscitation and increased survival rates have been reported after deployment of AEDs in airports, airliners, and casinos. This paper documents the effectiveness of AED deployment to police officers in a large metropolitan area.
In most large cities, survival to hospital discharge for victims of out-of-hospital cardiac arrest remains poor. A major factor is the ability to deliver defibrillation within the required brief period of time. Even though distances may not be great, traffic problems can greatly delay the arrival of the unit at the victim’s side. As shown in this paper, a simple training program for police and widespread distribution of AED units can cut this response time and increase survival rates. Unfortunately, the data here also are in agreement with other national trends. Out-of-hospital cardiac arrest victims are increasingly older and a larger portion are found by first responders to have nonshockable rhythms. At least some of these patients probably started off with VT or VF that degenerated to asystole or electromechanical dissociation relatively rapidly, but it is also possible that cardiac arrest is now a later manifestation of severe heart disease and a ventricular arrhythmia was not involved. Further improvements in survival for those who do at least start with VT or VF will require either defibrillation that does not depend on professional police or EMS services or targeting of high-risk groups for therapy with implantable devices. AED programs in casinos where virtually all individuals are continuously observed have proven very effective with high survival rates. Trials of home AEDs are now beginning. ICDs are highly effective and their implantation is now relatively simple, but the cost of such an approach remains a major issue.
The data presented here from Dade County, Fla, are very encouraging. All police and public safety agencies should look at this program to see if it would be applicable in their area.
Dr. DiMarco is Professor of Medicine Division of Cardiology University of Virginia, Charlottesville.
This paper describes the results of community-wide deployment of automatic external defibrillators (AEDs) to police officers.
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