Resuscitation After Prolonged Ventricular Fibrillation With Use of Monophasic and Biphasic Waveform Pulses for External Defibrillation

Abstract

Background-Survival after prolonged ventricular fibrillation (VF) appears severely limited by 2 major factors: (1) low defibrillation success rates and (2) persistent post-countershock myocardial dysfunction. Biphasic (BP) waveforms may prove capable of favorably modifying these limitations. However, they have not been rigorously tested against monophasic (MP) waveforms in clinical models of external defibrillation, particularly where rescue from prolonged VF is the general rule. Methods and Results-We randomized 26 dogs to external countershocks with either MP or BP waveforms.Hemodynamics were assessed after shocks applied during sinus rhythm, after brief VF (Ͼ10 seconds), and after resuscitation from prolonged VF (Ͼ10 minutes). Short-term differences in percent change in left ventricular ϩdP/dt max (MP Ϫ16Ϯ28%, BP ϩ9.1Ϯ24%; Pϭ0.03) and left ventricular ϪdP/dt max (MP Ϫ37Ϯ26%, BP Ϫ18Ϯ20%; Pϭ0.05) were present after rescue from brief VF, with BP animals exhibiting less countershock-induced dysfunction. After prolonged VF, the BP group had lower mean defibrillation thresholds (107Ϯ57 versus 172Ϯ88 J for MP, Pϭ0.04) and significantly shorter resuscitation times (397Ϯ73.7 versus 488Ϯ74.3 seconds for MP, Pϭ0.03). Conclusions-External defibrillation is more efficacious with BP countershocks than with MP countershocks. The lower defibrillation thresholds and shorter resuscitation times associated with BP waveform defibrillation may improve survival after prolonged VF arrest.

The efficacy and safety of external biphasic defibrillation in toy breed dogs

“…BP waveforms may rescue victims who might otherwise have failed defibrillation with conventional MP waveforms. In addition, the lower energy BP countershocks may produce less myocardial injury and mechanical dysfunction than equally effective MP countershocks 18 . We found that the shock energy level for E80 of a BP waveform was 30% less than that of an MP waveform, implying that BP defibrillation was more effective than MP defibrillation.…”

The efficacy and safety of external biphasic defibrillation in toy breed dogs

“…BP waveforms may rescue victims who might otherwise have failed defibrillation with conventional MP waveforms. In addition, the lower energy BP countershocks may produce less myocardial injury and mechanical dysfunction than equally effective MP countershocks 18 . We found that the shock energy level for E80 of a BP waveform was 30% less than that of an MP waveform, implying that BP defibrillation was more effective than MP defibrillation.…”

Successful biphasic transthoracic defibrillation of a dog with prolonged, refractory ventricular fibrillation

“…The dog in this report received appropriate resuscitative interventions; yet spontaneous circulation was not restored with delivery of monophasic shocks of increasing energy, including a 200 J monophasic shock, the highest recommended energy dose. Even though defibrillation efficacy is known to decrease with fibrillation of long duration, 12,18,19 a single 200 J biphasic shock was immediately successful at reestablishing sinus rhythm in this dog following 12 minutes of sustained ventricular fibrillation.…”

Ventricular fibrillation in a dog with refractory hyperkalaemia due to uroabdomen following extradural anaesthesia

“…36 Biphasic defibrillation also achieves ROSC quicker and causes less myocardial damage than monophasic and was thus utilised in the reported case. 41,42 In summary, the presented case was highly compromised by multiple electrolyte and acid-base disturbances, most notably a refractory hyperkalaemia. Extradural local anaesthetic administration was likely the final insult in causing CPA.…”

“…A suggested range for external biphasic defibrillation is 2–6 J/kg 36 . Biphasic defibrillation also achieves ROSC quicker and causes less myocardial damage than monophasic and was thus utilised in the reported case 41,42 …”

The efficacy and safety of external biphasic defibrillation in toy breed dogs

“…BP waveforms may rescue victims who might otherwise have failed defibrillation with conventional MP waveforms. In addition, the lower energy BP countershocks may produce less myocardial injury and mechanical dysfunction than equally effective MP countershocks 18 . We found that the shock energy level for E80 of a BP waveform was 30% less than that of an MP waveform, implying that BP defibrillation was more effective than MP defibrillation.…”

Successful biphasic transthoracic defibrillation of a dog with prolonged, refractory ventricular fibrillation

“…The dog in this report received appropriate resuscitative interventions; yet spontaneous circulation was not restored with delivery of monophasic shocks of increasing energy, including a 200 J monophasic shock, the highest recommended energy dose. Even though defibrillation efficacy is known to decrease with fibrillation of long duration, 12,18,19 a single 200 J biphasic shock was immediately successful at reestablishing sinus rhythm in this dog following 12 minutes of sustained ventricular fibrillation.…”

Ventricular fibrillation in a dog with refractory hyperkalaemia due to uroabdomen following extradural anaesthesia

“…36 Biphasic defibrillation also achieves ROSC quicker and causes less myocardial damage than monophasic and was thus utilised in the reported case. 41,42 In summary, the presented case was highly compromised by multiple electrolyte and acid-base disturbances, most notably a refractory hyperkalaemia. Extradural local anaesthetic administration was likely the final insult in causing CPA.…”

“…A suggested range for external biphasic defibrillation is 2–6 J/kg 36 . Biphasic defibrillation also achieves ROSC quicker and causes less myocardial damage than monophasic and was thus utilised in the reported case 41,42 …”

The efficacy and safety of external biphasic defibrillation in toy breed dogs

“…BP waveforms may rescue victims who might otherwise have failed defibrillation with conventional MP waveforms. In addition, the lower energy BP countershocks may produce less myocardial injury and mechanical dysfunction than equally effective MP countershocks 18 . We found that the shock energy level for E80 of a BP waveform was 30% less than that of an MP waveform, implying that BP defibrillation was more effective than MP defibrillation.…”

Successful biphasic transthoracic defibrillation of a dog with prolonged, refractory ventricular fibrillation

“…The dog in this report received appropriate resuscitative interventions; yet spontaneous circulation was not restored with delivery of monophasic shocks of increasing energy, including a 200 J monophasic shock, the highest recommended energy dose. Even though defibrillation efficacy is known to decrease with fibrillation of long duration, 12,18,19 a single 200 J biphasic shock was immediately successful at reestablishing sinus rhythm in this dog following 12 minutes of sustained ventricular fibrillation.…”

Ventricular fibrillation in a dog with refractory hyperkalaemia due to uroabdomen following extradural anaesthesia

“…36 Biphasic defibrillation also achieves ROSC quicker and causes less myocardial damage than monophasic and was thus utilised in the reported case. 41,42 In summary, the presented case was highly compromised by multiple electrolyte and acid-base disturbances, most notably a refractory hyperkalaemia. Extradural local anaesthetic administration was likely the final insult in causing CPA.…”

“…A suggested range for external biphasic defibrillation is 2–6 J/kg 36 . Biphasic defibrillation also achieves ROSC quicker and causes less myocardial damage than monophasic and was thus utilised in the reported case 41,42 …”