Cardiac arrest & resuscitation
Does transthoracic impedance influence termination and recurrence of ventricular fibrillation during impedance-compensated shocks for out-of-hospital cardiac arrest? A retrospective study
Authors' conclusion
Despite impedance-compensated defibrillation, TTI ≥100 Ω remains associated with reduced likelihood of VF/pVT termination in OHCA. In contrast, TTI does not appear to influence the risk of recurrent VF/pVT following successful termination.
Study context
- Population
- Non-traumatic out-of-hospital cardiac arrest (OHCA), patients aged ≥16 years with initial shockable rhythm, January 2019–October 2022, impedance-compensated shocks8,333 analysable shocks
- Participants
- 1,880 participants
- Exposure
- Transthoracic impedance <100 Ω vs ≥100 Ω, per 1-Ω increase
- Outcome
- Termination of VF/pVT (no shockable rhythm within 5 s after shock, resulting in asystole or organised rhythm)
Methodological detailsmixed-effects logistic regression, shock-level analysis
- Mixed-effects logistic regression
- Shock-level analysis
Main finding
As reported in the abstract
VF/pVT termination
Adjusted odds ratio per 1-Ω increase (95% CI)P value
TTI <100 Ω
0.999(0.993–1.006)
P = 0.860TTI ≥100 Ω
0.994(0.988–0.999)
P = 0.016Observational data: associations, not effects.
Further findings
Recurrent VF/pVT after termination
| aOR per 1-Ω increase (95% CI) | P value | ||
|---|---|---|---|
| TTI | 1.003 (0.999–1.006) | P = 0.082 | |
| 0.512Adjusted odds ratio per 1-Ω increase (log scale) |
Original publication
Does transthoracic impedance influence termination and recurrence of ventricular fibrillation during impedance-compensated shocks for out-of-hospital cardiac arrest? A retrospective study. Resuscitation. Published 25 May 2026. doi:10.
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