ZOLL R Series Monitor Defibrillator Rev K Operators Guide - Manual (Page 188)

A PPENDIX A S PECIFICATIONS
A–26 www.zoll.com 9650-0904-01 Rev. K
Successful defibrillation with rectilinear biphasic shocks was achieved with 58% less delivered
current than with monophasic shocks (14±1 amperes versus 33±7 amperes, 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 ohms). 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 –0.0217%
to 0.759% and 90% confidence interval of the difference of 0.037% to 0.706%).
A single patient required a second biphasic shock at 150 joules to achieve 100% efficacy versus
six patients for whom monophasic shocks of up to 360 joules 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 rectilinear biphasic waveform.
Randomized Multi-Center Clinical trial for Cardioversion of Atrial
Fibrillation (AF)
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 cardioversion of their atrial fibrillation. A total of 173 patients
entered the study. Seven (7) patients who did not satisfy all protocol criteria were excluded
from the analysis. ZOLL disposable gel electrodes with surface areas of 78 cm
2
(anterior) and
113 cm
2
(posterior) were used exclusively for the study.
Objective: The primary goal of the study was to compare the total efficacy of four consecutive
rectilinear biphasic shocks (70J, 120J, 150J, 170J) with four consecutive monophasic shocks
(100J, 200J, 300J, 360J). The significance of the multiple shocks efficacy was tested
statistically via two procedures, the Mantel-Haenszel statistic and the log-rank test, significance
level of p=0.05 or less was considered statistically significant. The data are completely
analogous to the comparison of two "survival" curves using a life-table approach where shock
number plays the role of time.
The secondary goal was to compare the first shock success of rectilinear biphasic and
monophasic waveforms. A significance level of p=0.05 or less was considered statistically
significant using Fisher Exact tests. Also, differences between the two waveforms were
considered statistically significant when the 95% confidence interval between the two
waveforms was greater than 0%.
Results: The study population of 165 patients had a mean age of 66±12 years with 116 male
patients.
Monophasic Biphasic
First 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%