February 1, 1983Critical Care Medicine
Efficacy and safety of defibrillation with rectangular waves of 2− to 20-milliseconds duration
Why the study?
Does the duration of rectangular electrical waveforms affect the safety margin for functional depression during defibrillation in isolated canine hearts?
Population
8 isolated, perfused, contracting canine hearts
Comparison
Defibrillation with rectangular electrical… vs Comparison among the 4 different waveform…
Design
Preclinical
Follow-up
immediately after the shocks
Authors
Discussion
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Member takes
Implication
Shorter 2-msec waveforms reduce safety margin for cardiac depression in canine hearts; leaves open optimal duration for clinical defibrillation.
Structured PICO
Does the duration of rectangular electrical waveforms affect the safety margin for functional depression during defibrillation in isolated canine hearts?
P
Population
8 isolated, perfused, contracting canine hearts
I
Intervention
Defibrillation with rectangular electrical waveforms of 2-, 5-, 10-, and 20-msec durations, including overdose shocks of 3, 4.5, 6, and 9 times threshold current density
C
Comparator
Comparison among the 4 different waveform durations (2, 5, 10, and 20 msec)
O
Outcome
Defibrillation threshold and safety factor (current overdose ratio required to produce a 50% decrease in left ventricular isovolumic systolic pressure immediately after the shock)safety
In an isolated canine heart model, a 2-msec rectangular defibrillation waveform had a significantly lower margin of safety for functional cardiac depression compared to 5-, 10-, and 20-msec waveforms.
Cite This Study
Niebauer et al. (1983) studied this question.