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Truncated exponential versus damped sinusoidal waveform shocks for transthoracic defibrillation
J C Behr1, L L Hartley, D K York
1Department of Internal Medicine and the Emergency Medical Services Learning Resource Center, University of Iowa Hospitals and Clinics, Iowa City 52242, USA.
The American Journal of Cardiology
|December 1, 1996
Summary
Damped sinusoidal (DS) waveforms were more effective at terminating ventricular fibrillation (VF) than truncated exponential (TE) waveforms. However, neither waveform significantly improved survival rates in witnessed cardiac arrest patients.
Area of Science:
- Cardiology
- Emergency Medicine
- Biomedical Engineering
Background:
- Transthoracic defibrillators utilize either damped sinusoidal (DS) or truncated exponential (TE) waveforms.
- Concerns exist that the long pulse duration of TE waveforms during high transthoracic impedance may reduce defibrillation efficacy.
Purpose of the Study:
- To compare the effectiveness of DS versus TE waveform shocks in terminating ventricular fibrillation (VF).
- To assess the impact of DS and TE waveforms on survival from witnessed cardiac arrest.
Main Methods:
- Retrospective analysis of field-recorded electrocardiograms from 86 patients with witnessed VF.
- Patients were treated by prehospital personnel using either DS or TE waveform defibrillators.
- Comparison of shock outcomes, including rhythm conversion and survival to hospital discharge.
Main Results:
- DS waveforms terminated VF more frequently (42% vs. 65% persistent VF for TE, p < 0.01).
- No significant difference was observed in the resumption of organized rhythm (22% DS vs. 12% TE).
- Survival to hospital discharge showed no significant difference between the two waveforms (19% DS vs. 11% TE).
Conclusions:
- DS waveforms demonstrated a higher success rate in terminating VF compared to TE waveforms.
- Despite improved VF termination, neither waveform significantly impacted overall survival rates.
- A prospective study is recommended to definitively compare the clinical outcomes of DS and TE waveforms.