Use of automated external defibrillator by first responders in out of hospital cardiac arrest: prospective controlled trial

Abstract

Objective: To test the hypothesis that the use of an automated external defibrillator by police and fire fighters results in higher discharge rates for out of hospital cardiac arrest.

Design: Controlled clinical trial with initial random allocation of automated external defibrillators to first responders in four of the eight participating regions; each region switched from control to experimental, and vice versa, every four months.

Setting: Amsterdam and surroundings, the Netherlands.

Participants: Patients with witnessed out of hospital cardiac arrests, identified by the emergency medical system between January 2000 and January 2002.

Main outcomes measures: Survival to hospital discharge; return of spontaneous circulation; admission to hospital.

Results: 243 patients (65% in ventricular fibrillation) were included in the experimental area and 226 patients (67% in ventricular fibrillation) in the control area. The median time interval between collapse and first shock was 668 seconds in the experimental area and 769 seconds in the control area (P < 0.001). 44 (18%) patients in the experimental area versus 33 (15%) patients in the control area were discharged (odds ratio 1.3 (95% confidence interval 0.8 to 2.2), P = 0.33), 139 (57%) experimental versus 108 (48%) control patients had return of spontaneous circulation (1.5 (1.0 to 2.2), P = 0.05), and 103 (42%) experimental versus 74 (33%) control patients were admitted (1.5 (1.1 to 1.6), P = 0.02). The median delay from receipt of call to dispatch of the ambulance was 120 seconds, and the delay to dispatch of the first responder was 180 seconds.

Conclusions: Use of automated external defibrillators by first responders did not significantly increase survival to discharge from hospital, although it did improve return of spontaneous circulation and admission to hospital. Improved dispatch procedures should increase the success of programmes of first responders using external defibrillators.

Fig 1

Primary and secondary outcomes according to treatment group, stratified according to initial rhythm. Admission denotes admission to hospital after leaving the emergency room; ROSC=return of spontaneous circulation

Fig 2

Cumulative time intervals from collapse to call, dispatch, and arrival of ambulance and first responders in the experimental group. Delays in placing the call by the witness and handling the call by the dispatcher contributed to over half of the total delay to arrival at the scene. Delay in dispatching the first responder eliminated much of the benefit of the shorter travel time of the first responder

Fig 3

Cumulative time intervals from collapse to first shock for experimental and control groups. In the experimental group the first shock was delivered by first responders or ambulance personnel, depending on who arrived first; this was the first responders in 72 cases and the ambulance in 85 cases. In the control group all shocks were delivered by the ambulance personnel. The difference between the two groups in the median time to first shock was 101 seconds