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Evaluation of Biphasic Transthoracic Defibrillation in an Animal Model of Prolonged Ventricular Fibrillation
Author(s) -
Scheatzle Mark D.,
Menegazzi James J.,
Allen Todd L.,
Durham S. Bryan
Publication year - 1999
Publication title -
academic emergency medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.221
H-Index - 124
eISSN - 1553-2712
pISSN - 1069-6563
DOI - 10.1111/j.1553-2712.1999.tb01234.x
Subject(s) - medicine , ventricular fibrillation , defibrillation , cardiology , anesthesia
. Objectives: To determine whether a biphasic defibrillation waveform (BDW) would produce a superior rate of converting prolonged ventricular fibrillation (VF) into a perfusing rhythm and delay the occurrence of asystole and/or pulseless electrical activity (PEA) during the resuscitation attempt, when compared with a monophasic defibrillation waveform (MDW). Methods: The authors performed a prospective, randomized, blinded experiment using an established swine model of prolonged VF. Thirty‐four mixed‐breed domestic swine (mean mass 22.9 kg) were sedated (ketamine/xylazine), anesthetized (isoflurane), and intubated. Aortic and femoral venous catheters were placed. ECG was monitored continuously. The animals were shocked into VF (3‐s, 100‐mA, 60‐Hz shock), and were untreated for 8 minutes. Advanced Cardiac Life Support (ACLS) began with 1 minute of standardized (Thumper) chest compressions and ventilation. The animals were randomized to treatment with either BDW or MDW. Standard ACLS protocols were followed. The energy sequence was 2.5 J/kg first, 3.5 J/kg second, and 4.5 J/kg for all subsequent shocks. Outcome variables were time to event of asystole/PEA, return of spontaneous circulation (ROSC), and one‐hour survival. Data were analyzed with two‐tailed Fisher's exact test and Kaplan‐Meier survival plots (alpha = 0.05). Results: ROSC occurred more frequently in the BDW group (7/17) compared with the MDW group (1/17); p = 0.04. Survival analysis showed that the BDW significantly delayed the occurrence of asystole/PEA during the resuscitation attempt when compared with the MDW; log‐ranked p = 0.02. One‐hour survival rates (5/17 BDW and 1/17 MDW, p = 0.17) did not differ. Conclusions: BDW resulted in a superior rate of ROSC and delay in the occurrence of asystole/PEA during the resuscitation attempt when compared with MDW.