ZOLL M Series Defibrillator Rev E BiPhasic - Manual (Page 4)

OPTION INSERT
9650-0209-01 Biphasic- 4
Clinical Trials Results for the M Series
Biphasic Waveform
:
The Efficacy of ZOLL’s Rectilinear Biphasic Waveform has
been clinically verified during various studies for defibrillation
of Ventricular Fibrillation (VF) / Ventricular Tachycardia (VT)
and for synchronized cardioversion of Atrial Fibrillation (AF).
Feasibility studies were performed initially for defibrillation of
VF/VT (n=20) and synchronized cardioversion of AF (n=21)
on two separate groups of patients to ensure waveform
safety and energy selection. Subsequently two separate,
multi-center, randomized clinical trials were performed to
verify the waveform’s efficacy. Descriptions of these studies
are provided below. All studies were performed using ZOLL
defibrillation systems consisting of ZOLL defibrillators, the
ZOLL Rectilinear Biphasic Waveform and ZOLL Multi-
Function Pads.
A) Randomized Multi-Center Clinical Trial for
Defibrillation of Ventricular Fibrillation (VF) and
Ventricular Tachycardia (VT):
Overview: The defibrillation efficacy of ZOLL’s Rectilinear
Biphasic Waveform was compared to a monophasic damped
sine waveform in a prospective, randomized, multi-center
study of patients undergoing ventricular defibrillation for
VF/VT during electro-physiological studies, ICD implants and
tests. A total of 194 patients were enrolled in the study. Ten
(10) patients who did not satisfy all protocol criteria were
excluded from the analysis.
Objectives: The primary goal of this study was to compare
the first shock efficacy of the 120J Rectilinear Biphasic
Waveform with a 200J monophasic waveform. The
secondary goal was to compare all shock (three consecutive
120, 150, 170J) efficacy of the Rectilinear Biphasic
Waveform with that of a monophasic waveform (three
consecutive 200, 300, 360J). A significance level of p=0.05
or less was considered statistically significant using Fischer’s
Exact test. Also, differences between the two waveforms
were considered statistically significant when the customary
95% or AHA recommended 90%* confidence interval
between the two waveforms was greater than 0%.
Results: The study population of 184 patients had a mean
age of 63
±
14 years. 143 patients were males. 98 patients
were in the biphasic group (ventricular fibrillation/flutter,
n=80, ventricular tachycardia, n=18) and 86 patients were in
the monophasic group (ventricular fibrillation/flutter, n=76,
ventricular tachycardia, n=10). There were no adverse
events or injuries related to the study.
The first shock, first induction efficacy of biphasic shocks at
120J was 99% versus 93% for monophasic shocks at 200J
(p=0.0517, 95% confidence interval of the difference of
–2.7% to 16.5% and 90% confidence interval of the
difference of –1.01% to 15.3%).
Monophasic Biphasic
1 st Shock Efficacy 93% 99%
p-value 0.0517
95% Confidence. Interval -2.7% to 16.5%
90% Confidence Interval -1.01% to 15.3%
Successful defibrillation with rectilinear biphasic shocks was
achieved with 58% less delivered current than with
monophasic shocks (14
±
1 vs. 33
±
7 A, p=0.0001).
The difference in efficacy between the rectilinear biphasic
and the monophasic shocks was greater in patients with high
transthoracic impedance (greater than 90
Ω). The first shock,
first induction efficacy of biphasic shocks was 100% versus
63% for monophasic shocks for patients with high
impedance (p=0.02, 95% confidence interval of the
difference of –0.021% to 0.759% and 90% confidence
interval of the difference of 0.037% to 0.706%).
Monophasic Biphasic
1
st
Shock Efficacy (High
Impedance Patients)
63% 100%
p-value 0.02
95% Confidence. Interval -0.021% to 0.759%
90% Confidence Interval 0.037% to 0.706%
A single patient required a second biphasic shock at 150J to
achieve 100% efficacy versus six patients for whom shocks
of up to 360J were required for 100% total defibrillation
efficacy.
Conclusion: The data demonstrate the equivalent efficacy
of low energy rectilinear biphasic shocks compared to
standard high energy monophasic shocks for transthoracic
defibrillation for all patients at the 95% confidence level. The
data also demonstrate the superior efficacy of low energy
rectilinear biphasic shocks compared to standard high
energy monophasic shocks in patients with high
transthoracic impedance at the 90% confidence level. There
were no unsafe outcomes or adverse events due to the use
of the rectilinear biphasic waveform
.
* Kerber, R., et. al., AHA Scientific Statement, Circulation,
1997; 95: 1677-1682:
“… the task force suggests that to demonstrate superiority of
an alternative waveform over standard waveforms, the upper
boundary of the 90% confidence interval of the difference
between standard and alternative waveforms must be < 0%
(i.e., alternative is greater than standard).”