February 3, 2004Circulation
Ventricular Fibrillation Scaling Exponent Can Guide Timing of Defibrillation and Other Therapies
Key result
Immediate countershock proves ineffective for prolonged VF and delays time to ROSC.
- n=72
Why the study?
The scaling exponent of the ventricular fibrillation waveform correlates with VF duration and predicts defibrillation outcome, but optimal therapy timing based on ScE is unclear.
Does the scaling exponent of the ventricular fibrillation waveform guide the optimal choice of first intervention (immediate shock vs CPR/drugs) in a swine model?
Comparison
Immediate countershock vs CPR vs CPR with drugs vs drugs plus CPR at varying ScE levels
Design
Randomized controlled trial with 9 groups
Follow-up
1 hour
Authors
Discussion
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Overview
May support CPR-first sequencing for high scaling-exponent VF; hypothesis-generating for human resuscitation trials.
Study Design
Type
RCT (n=72)
Randomization
randomly assigned
Structured PICO
Does the scaling exponent of the ventricular fibrillation waveform guide the optimal choice of first intervention (immediate shock vs CPR/drugs) in a swine model?
P
Population
72 swine weighing 19.5 to 25.7 kg with induced ventricular fibrillation, randomized to different resuscitation strategies based on scaling exponent.
I
Intervention
Immediate countershock (IC); 3 minutes of CPR before the first countershock (CPR); CPR for 2 minutes, then drugs given with 3 more minutes of CPR before the first shock (CPR-D); or drugs given at the start of CPR with 3 minutes of CPR before the first shock (Drugs+CPR)
C
Comparator
Comparison between the 4 therapeutic approaches across different VF durations (ScE levels)
O
Outcome
Return of spontaneous circulation (ROSC) and 1-hour survivalhard clinical
The scaling exponent of the ventricular fibrillation waveform can predict the failure of immediate countershock in prolonged VF, potentially guiding the decision to initiate CPR or drugs first.
Cite This Study
Menegazzi et al. (2004) conducted an RCT in Ventricular fibrillation (n=72). Immediate countershock, CPR, CPR-D, or Drugs+CPR vs. Comparison among the 4 therapeutic approaches at different scaling exponents was evaluated on Return of spontaneous circulation (ROSC) and 1-hour survival. Immediate countershock was ineffective for prolonged ventricular fibrillation (scaling exponent ≥1.3) and significantly delayed time to return of spontaneous circulation (P=0.0006).