Physio-Control LIFEPAK 20e - Manual (Page 171)

Append
ix B
Clinical Summaries
LIFEPAK 20e Defibrillator/Monitor Operating Instructions B-5
©2006-2013 Physio-Control, Inc.
Figure B-1 Cumulative Shock Success for Cardioversion of Atrial Fibrillation with Monophasic (MDS) and
Biphasic (BTE) Shocks: Observed Rates (n) Plotted with Estimated Dose Response Curves
Compared to monophasic shocks, biphasic shocks cardioverted atrial fibrillation with less peak
current (14.0 ± 4.3 vs. 39.5 ± 11.2 A, p<0.0001), less energy (97 ± 47 vs. 278 ± 120 J,
p<0.0001), fewer shocks (1.7 vs. 3.5 shocks, p < 0.0001) and less cumulative energy (146 ± 116
vs. 546 ± 265 J, p<0.0001). Patients treated with the biphasic protocol, as compared to those
treated with the monophasic protocol, reported significantly less post-procedure pain just after
(0.4 ± 0.9 vs. 2.5 ± 2.2, p<0.0001) and 24 hours after the procedure (0.2 ± 0.4 vs. 1.6 ± 2.0,
p<0.0001).
All patients with atrial flutter were cardioverted with the first shock (70 J), whether that shock was
monophasic (n=4) or biphasic (n=3).
Anterior-lateral electrode placement was used for treatment of most (96%) of the patients
studied. Reports in the literature differ on whether anterior-posterior electrode placement
provides better shock efficacy than anterior-lateral placement. If there is a benefit to anterior-
posterior electrode placement, it may be possible to obtain modestly higher cardioversion
success rates with both waveforms than those observed in this study. However, placement is not
likely to affect the observed relationship between the efficacies of monophasic and biphasic
waveforms.
Conclusions
The data demonstrate the Physio-Control biphasic waveform is clinically superior to the
conventional monophasic damped sine waveform for cardioversion of atrial fibrillation.
Specifically, compared to monophasic shocks, biphasic shocks cardioverted atrial fibrillation with
less peak current, less energy, fewer shocks and less cumulative energy. Patients undergoing
elective cardioversion with the biphasic protocol, as compared to those receiving the monophasic
protocol, reported significantly less post-procedure pain just after and 24 hours after the
procedure. This may be due to fewer required shocks, less cumulative energy, less delivered
peak current or other characteristics of this biphasic waveform.
% Success
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Energy Setting (J)
0 50 100 150 200
MDS
BTE
350 300 400 250