Hypothermia improves defibrillation success and resuscitation outcomes from ventricular fibrillation

Kimberly A Boddicker; Yi Zhang; M Bridget Zimmerman; Loyd R Davies; Richard E Kerber

doi:10.1161/circulationaha.104.492108

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Hypothermia improves defibrillation success and resuscitation outcomes from ventricular fibrillation

Journal article

Open access

Peer reviewed

Hypothermia improves defibrillation success and resuscitation outcomes from ventricular fibrillation

Kimberly A Boddicker, Yi Zhang, M Bridget Zimmerman, Loyd R Davies and Richard E Kerber

Circulation (New York, N.Y.), Vol.111(24), pp.3195-3201

06/21/2005

DOI: 10.1161/circulationaha.104.492108

PMID: 15956132

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Abstract

Induced hypothermia is recommended to improve neurological outcomes in unconscious survivors of out-of-hospital ventricular fibrillation (VF) cardiac arrest. Patients resuscitated from a VF arrest are at risk of refibrillation, but there are few data on the effects of already existing hypothermia on defibrillation and resuscitation. Thirty-two swine (mean+/-SE weight, 23.0+/-0.6 kg) were divided into 4 groups: normothermia (n=8), mild hypothermia (35 degrees C) (n=8), moderate hypothermia (33 degrees C) (n=8), and severe hypothermia (30 degrees C) (n=8). Hypothermia was induced by surrounding the animal with ice, and VF was electrically induced. After 8 minutes of unsupported VF (no CPR), the swine were defibrillated (biphasic waveform) with successive shocks as needed and underwent CPR until resumption of spontaneous circulation or no response (> or =10 minutes). First-shock defibrillation success was higher in the moderate hypothermia group (6 of 8 hypothermia versus 1 of 8 normothermia; P=0.04). The number of shocks needed for late defibrillation (> or =1 minute after initial shock) was less in all 3 hypothermia groups compared with normothermia (all P<0.05). None of the 8 animals in the normothermia group achieved resumption of spontaneous circulation compared with 3 of 8 mild hypothermia (P=NS), 7 of 8 moderate hypothermia (P=0.001), and 5 of 8 severe hypothermia (P=0.03) animals. Coronary perfusion pressure during CPR was not different between the groups. When VF was induced in the setting of moderate or severe hypothermia, resuscitative measures were facilitated with significantly improved defibrillation success and resuscitation outcome. The beneficial effect of hypothermia was not due to alteration of coronary perfusion pressure, which suggests that changes in the mechanical, metabolic, or electrophysiological properties of the myocardium may be responsible.

Hemodynamics

Blood Pressure

Cardiopulmonary Resuscitation - adverse effects

Cardiopulmonary Resuscitation - methods

Temperature

Ventricular Fibrillation - mortality

Survival Rate

Treatment Outcome

Electric Countershock - adverse effects

Animals

Swine

Hypothermia, Induced

Nervous System Diseases - etiology

Ventricular Fibrillation - therapy

Disease Models, Animal

Electric Countershock - methods

Details

Title: Subtitle: Hypothermia improves defibrillation success and resuscitation outcomes from ventricular fibrillation
Creators: Kimberly A Boddicker - Cardiovascular Center, College of Medicine, University of Iowa, Iowa City, USA
Yi Zhang - University of Iowa
M Bridget Zimmerman
Loyd R Davies
Richard E Kerber
Resource Type: Journal article
Publication Details: Circulation (New York, N.Y.), Vol.111(24), pp.3195-3201
DOI: 10.1161/circulationaha.104.492108
PMID: 15956132
NLM abbreviation: Circulation
ISSN: 1524-4539
eISSN: 1524-4539
Publisher: United States
Language: English
Date published: 06/21/2005
Academic Unit: Biostatistics
Record Identifier: 9983997342702771

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