Physio Control LIFEPAK 20, Manual

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Append
ix B
Clinical Summaries
LIFEPAK 20e Defibrillator/Monitor Operating Instructions B-9
©2006-2015 Physio-Control, Inc.
Guidance for Selection of Shock Energy
Biphasic waveform technology is a standard in cardiac defibrillators. The results of this study
1
provide specific guidance for three possible strategies in developing a dosing regimen.
• To optimize for lower initial and cumulative energy using a step-up protocol, select 5 J for the
first shock and use small incremental increases in energy if further shocks are needed. In this
study, biphasic shocks of 5 J were successful in approximately half of the patients.
• To optimize for more rapid defibrillation and fewer shocks, select the same BTE energy level
used previously with MDS (e.g., 20 J BTE instead of 20 J MDS), which can be expected to
increase the success rate yet decrease by approximately 30% the peak current of the first and
subsequent shocks.
• To maintain an equivalent degree of efficacy as previously observed with MDS shocks, a BTE
energy level one-half of that previously used for MDS shocks (e.g., 10 J BTE instead of 20 J
MDS) would be an appropriate choice.
Each of these strategies should provide effective defibrillation therapy while substantially
reducing the amount of peak current to which the heart is exposed.
Fibrillation may persist for a variety of reasons unrelated to the type of waveform used for
defibrillation. In cases where fibrillation is persistent, physicians continue to have the option to
either increase shock intensity or switch to a larger paddle size. Larger paddle size is known to
decrease energy requirements for successful defibrillation.
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1
B. Schwarz et al., Biphasic shocks compared with monophasic damped sine wave shocks for direct ventricular
defibrillation during open heart surgery. Anesthesiology . 2003;98(5):1063-1069.
2
Y. Zhang et al., “Open chest defibrillation: biphasic versus monophasic waveform shocks,” J Am Coll Cardiol ,
2001, 37(2 supplement A):320A.