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9
Rescue Life
– Instruction For Use
Rev.0.5 – 30/03/2022
The difference between monophasic and biphasic waveform is qualitatively similar but varies quantitatively
for different parameter values. The fundamental difference is that first phase of the biphasic pulse acts as a
pre-pulse to remove inactivation from the heart cell, accelerating its recovery, and thereby lowering the
activation threshold for defibrillation prior to second phase of biphasic pulse which is reversed current
flow.
ENOUGH ENERGY FOR RESTORING HEART RHYTHM
The Biphasic Truncated Exponential waveform uses lower energy than the Monophasic waveform. But the
lower energy of biphasic shock is more efficient than high energy of the monophasic shock for defibrillation
to restore heart rhythm.
In a multicenter, randomized, controlled trial of 150J biphasic waveform compared with 200J and 360J
monophasic waveforms done in humans, Schneider et al [5] showed that "the 150-J biphasic waveform
defibrillated at higher rates, resulting in more patients who achieved a return of spontaneous circulation.
Although survival rates to hospital admission and discharge did not differ, discharged patients who had
been resuscitated with biphasic shocks were more likely to have good cerebral performance."
Positive evidence for safety and clinical effectiveness of biphasic truncated exponential waveforms for
internal and external use was ascertained by the AHA ECC committee [8], [9].
THE EFFECT OF TIME TO DEFIBRILLATION AND TARGETED TEMPERATURE MANAGEMENT ON
FUNCTIONAL SURVIVAL AFTER OUT-OF-HOSPITAL CARDIAC ARREST
Cardiac arrest physiology can be divided into three phases: electrical, circulatory and metabolic. Survival
from cardiac arrests in the electrical phase are dependent upon rapid defibrillation, whereas cardiac arrests
in the circulatory phase may benefit from an initial method of oxygen delivery (chest compressions and
ventilations) prior to defibrillation. Cardiac arrests that enter the metabolic phase generally have poor
survival.
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