ZOLL M Series Defibrillator Rev E BiPhasic - Manual (Page 5)

RECTILINEAR BIPHASIC WAVEFORM
9650-0209-01 Biphasic - 5
B). 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.
The total efficacy of consecutive rectilinear biphasic shocks
was significantly greater than that of monophasic shocks.
The following table displays the Kaplan-Meier (product-limit)
“survival” curves for each of the two waveforms. As all
patients begin in the failure mode, the estimated life-table
probabilities refer to the chance of still being in failure after
the k
th
shock (k=1,2,3,4):
Shock #
Kaplan-Meier Estimate for the
Probability of Shock Failure
Biphasic Monophasic
0 1.000
1.000
1 0.318 0.792
2 0.147 0.558
3 0.091 0.324
4 0.057 0.208
As can be seen from the table, the Biphasic experience is
superior over the entire course of shocks delivered. The one
degree of freedom chi-square statistic for the Mantel-
Haenszel test is 30.39 (p<0.0001). Similarly, the log-rank
test, also a one degree of freedom chi-square statistic, is
30.38 (p<0.0001). The residual number of patients not
successfully treated after four shocks is 5.7% for biphasic
compared to 20.8% for monophasic.
There was a significant difference between the first shock
efficacy of biphasic shocks at 70J of 68% and that of
monophasic shocks at 100J of 21% (p=0.0001, 95%
confidence interval of the difference of 34.1% to 60.7%).
Successful cardioversion with rectilinear biphasic shocks
was achieved with 48% less delivered current than with
monophasic shocks (11
±
1 vs. 21
±
4 A, p<0.0001).
One half of the patients who failed cardioversion after four
consecutive escalating monophasic shocks were
subsequently successfully cardioverted using a biphasic
shock at 170J. No patient was successfully cardioverted
using a 360J monophasic shock after the patient had failed
cardioversion with biphasic shocks.
Conclusion: The data demonstrate the superior efficacy of
low energy rectilinear biphasic shocks compared to high
energy monophasic shocks for transthoracic cardioversion of
atrial fibrillation. There were no unsafe outcomes or adverse
events due to the use of Rectilinear Biphasic Waveform.
Synchronized Cardioversion of Atrial
Fibrillation
Cardioversion of Atrial Fibrillation (AF) and overall clinical
effectiveness is enhanced by proper pad placement. Clinical
studies (refer to above) of the M Series Biphasic Defibrillator
Waveform Option demonstrated that high conversion rates
are achieved when defibrillation pads are placed as shown in
the diagram below.
Front/
Apex
Recommended Anterior/Posterior Placement
Back/
Posterior
Place the Front (Apex) pad on the third intercostal space,
mid clavicular line on the right anterior chest. The
Back/Posterior Pad should be placed in the standard
posterior position as shown.
Defibrillation and Cardioversion
Performance
Caution: The clinical results for the ZOLL Biphasic
Defibrillator Waveform Option are based upon the use of
ZOLL Multi-Function Pads. The combination of waveform,
electrode properties and gel characteristics is essential to
achieving efficacy results similar to those described above.
For synchronized cardioversion of Atrial Fibrillation, the
combination of waveform, electrode properties, gel
characteristics and pad placement is essential to achieving
efficacy results similar to those above.
WARNING: Unnecessary skin damage can result from
incorrect application or use of a defibrillation pad other than
the type recommended.