Effects of biphasic waveforms on outcomes of cardiopulmonary resuscitation in a porcine model of prolonged cardiac arrest.
OBJECTIVE
The effects of two clinically available biphasic waveforms on the success of defibrillation and postresuscitation myocardial dysfunction after prolonged ventricular fibrillation were compared with two newly designed dual-path sequential and simultaneous rectilinear biphasic waveforms. Defibrillation via sequential pulses and encircling, overlapping multiple pathway may depolarize a larger myocardial mass and facilitate transthoracic defibrillation.


METHODS
Animal study.


METHODS
Experimental laboratory.


METHODS
Thirty-two 40 +/- 3 kg pigs.


METHODS
Ventricular fibrillation was ischemically induced in 32 pigs. After 7 mins of untreated ventricular fibrillation, cardiopulmonary resuscitation was initiated and continued for 5 mins. Animals were then randomized to receive up to three shocks with a) single-path rectilinear biphasic waveform; b) single-path biphasic truncated exponential waveform; c) dual-path rectilinear biphasic sequential defibrillation; or d) dual-path rectilinear biphasic simultaneous defibrillation.


RESULTS
Rectilinear biphasic, dual-path sequential defibrillation, and simultaneous defibrillation had significantly fewer shocks (1.1 +/- 0.4, 1.4 +/- 0.5, 1.3 +/- 0.7, respectively) before restoration of spontaneous circulation than biphasic truncated exponential waveform (2.6 +/- 1.4, p < .005) and less postresuscitation myocardial dysfunction (p < .05). Also, dual-path sequential defibrillation had higher postresuscitation ejection fraction than rectilinear biphasic and dual-path simultaneous defibrillation (p < .005).


CONCLUSIONS
The energy requirements for terminating ischemically induced ventricular fibrillation were significantly lower and minimized early postresuscitation myocardial dysfunction in the rectilinear biphasic, dual-path sequential defibrillation, and simultaneous defibrillation than the biphasic truncated exponential waveform. Dual-path sequential defibrillation had less postresuscitation myocardial dysfunction than rectilinear biphasic and dual-path simultaneous defibrillation, but at 72 hrs these differences were no longer significant.
Chang
Yun-Te
YT
Weil Institute of Critical Care Medicine, Rancho Mirage, CA, USA.
Tang
Wanchun
W
Wang
Jinglan
J
Brewer
James E
JE
Freeman
Gary
G
Sun
Shijie
S
Weil
Max Harry
MH
D000818:Animals; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D004195:Disease Models, Animal; D004554:Electric Countershock / Q000295:instrumentation; D006323:Heart Arrest / Q000150:complications*; D013552:Swine; D014693:Ventricular Fibrillation / Q000209:etiology / Q000628:therapy*