High Discharge Survival Rate After Out-of-Hospital Ventricular Fibrillation With Rapid Defibrillation by Police and Paramedics,☆☆,

Presented at the Society for Academic Emergency Medicine Annual Meeting, Denver, May 1996.
https://doi.org/10.1016/S0196-0644(96)70109-9Get rights and content

Abstract

Study objective: To assess outcome in patients with ventricular fibrillation (VF) treated by defibrillator-equipped police and emergency medical technician-paramedics in an advanced life support (ALS) emergency medical services (EMS) system. Methods: We carried out a retrospective observational outcome study of all consecutive adult patients with atraumatic cardiac arrest treated from November 1990 through July 1995. The study was carried out in a city with a population of 76,865 in an area of 32.6 square miles. Central 911 dispatched police and an ALS ambulance simultaneously. Accurate intervals were obtained with the synchronization of all defibrillator clocks with the 911 dispatch clock. The personnel who arrived first delivered the initial shock. After shocks delivered by police, paramedics provided additional treatment if needed. Main outcome measures were time elapsed before delivery of the first shock, restoration of spontaneous circulation (ROSC), and survival to discharge home. Results: Of 84 patients, 31 (37%) were first shocked by police. Thirteen of the 31 demonstrated ROSC, without need for ALS treatment. All 13 survived to discharge. The other 18 patients required ALS; 5 (27.7%) survived. Among the 53 patients first shocked by paramedics, 15 had ROSC after shocks only, and 14 survived. The other 38 needed ALS treatment; 9 survived. Call-to-shock time for all patients was less in the police group than in the paramedic group (5.6 versus 6.3 minutes, P=.038). For all patients, call-to-shock time was less in those with ROSC after shocks only than in those who needed ALS (5.4 versus 6.3 minutes, P=.011). Survival to discharge was 49% (41 of 84), with 18 of 31 (58%) in the police group and 23 of 53 (43%) in the paramedic group. Call-to-shock time for survivors was 5.8 minutes; it was 6.4 minutes for the nonsurvivors (P=.020). Neither ROSC nor discharge survival was significantly different between police- and paramedic-shocked patients. ROSC after initial shock and call-to-shock time were major determinants of survival, whether the first shocks were administered by police or by paramedics. With ROSC after shocks only, 27 of 28 (96%) survived, whereas 14 of 56 (25%) needing ALS survived (P<.001). Conclusion: A high discharge-to-home survival rate was obtained with early defibrillation by both police and paramedics. When shocks resulted in ROSC, the overwhelming majority of patients survived (96%). Even brief time decreases (eg, 1 minute) in call-to-shock time increase the likelihood of ROSC from shocks only, with a consequent decrease in the need for ALS intervention. Short call-to-shock time and ROSC response to shocks only are major determinants of a high rate of survival after VF.

[White RD, Asplin BR, Bugliosi TF, Hankins DG: High discharge survival rate after out-of-hospital ventricular fibrillation with rapid defibrillation by police and paramedics. Ann Emerg Med November 1996;28:480-485.]

Section snippets

INTRODUCTION

Rapid defibrillation after out-of-hospital cardiac arrest (OHCA) caused by ventricular fibrillation (VF) is the single most important determinant of outcome.1, 2 Other variables such as witnessed arrest, rapid access to emergency medical services (EMS), prompt bystander CPR, and initial VF maximum amplitude have been shown to improve survival.3, 4, 5, 6, 7, 8, 9, 10 However, the interval between collapse and delivery of defibrillatory shocks is the most critical variable influencing outcome.1

MATERIALS AND METHODS

The city of Rochester, Minnesota (1993 population, 76,865; area, 32.6 square miles), is served by a private ambulance service (Gold Cross Ambulance Service, Incorporated). Patient care personnel are nationally registered EMT-Ps. Rochester Police Department police officers are trained as first responders in accord with the US Department of Transportation First Responder Training Program.23 All officers are trained to operate automated external defibrillators (AEDs) with the American Heart

RESULTS

During the 57-month study period, 84 OHCA patients presented with VF as the initial rhythm. Seventy-four patients in non-VF arrest (40 in asystole and 34 in pulseless electrical activity) were encountered but were excluded from this analysis for obvious reasons. All arrests included in the study occurred before the arrival of police or paramedics. None of the 74 survived. No patients were excluded because of insufficient, inaccurate, or unavailable data.

Thirty-one patients were first shocked by

DISCUSSION

Our observations extend and affirm the conclusions of our earlier preliminary study.22 In that study, as in this one, we chose to use the call-to-shock interval rather than the collapse-to-shock interval because the latter is almost always, at best, an estimate. We prefer to use an interval that is precise and quantitative and can be correlated with outcome. The call-to-shock interval also can be used for accurate intersystem data comparisons, provided all EMS system clocks are synchronized at

Acknowledgements

The authors are grateful to Kimberly Sankey for assistance in preparation of the manuscript; to Elizabeth Atkinson, Section of Biostatistics, Mayo Clinic; to the City of Rochester Police Department; to Gold Cross Ambulance Service personnel; and to law enforcement and Gold Cross dispatch staff for their commitment to synchronization of times.

References (33)

  • LB Becker et al.

    Outcome of CPR in a large metropolitan area: Where are the survivors?

    Ann Emerg Med

    (1991)
  • RD White et al.

    Early defibrillation by police: Initial experience with measurement of critical time intervals and patient outcome

    Ann Emerg Med

    (1994)
  • RA Swor et al.

    Bystander CPR, ventricular fibrillation, and survival in witnessed, unmonitored out-of-hospital cardiac arrest

    Ann Emerg Med

    (1995)
  • H Stueven et al.

    Bystander/first responder CPR: Ten years experience in a paramedic system

    Ann Emerg Med

    (1986)
  • Emergency Cardiac Care Committee and Subcommittees, American Heart Association

    Guidelines for cardiopulmonary resuscitation and emergency cardiac care. IX. Ensuring effectiveness of communitywide emergency cardiac care

    JAMA

    (1992)
  • WD Weaver et al.

    Improved neurologic recovery and survival after early defibrillation

    Circulation

    (1984)
  • Cited by (0)

    From the Mayo Clinic and Medical School* and May Gold Cross Ambulance Service, Incorporated, Rochester, Minnesota; and the Affiliated Residency in Emergency Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.§

    ☆☆

    Address for reprints: Roger D White, MD, Department of Anesthesiology, Mayo Clinic, 200 First Street Southwest, Rochester, Minnesota 55905, 507-255-4235, Fax 507-255-6463, E-mail [email protected]

    Reprint no. 47/1/76895

    View full text