Key result
End-inspiration significantly increased electrode impedance but did not significantly affect defibrillation energy requirements compared to end-expiration (6.0 J vs 5.7 J; P=0.594).
Why the study?
Does respiration phase alter defibrillation threshold energy or impedance in a hot can electrode system in an anesthetized pig model?
RCT (n=10)
random order
Does respiration phase alter defibrillation threshold energy or impedance in a hot can electrode system in an anesthetized pig model?
While respiration phase significantly affects electrode impedance, it does not significantly alter defibrillation energy requirements in a hot can electrode system.
Answers are grounded in this paper and cite their sources.
Should not alter defibrillation protocols; leaves open human validation of respiration effects.
The impedance of defibrillation pathways is an important determinant of ventricular defibrillation efficacy. The hypothesis in this study was that the respiration phase (end-inspiration versus end-expiration) may alter impedance and/or defibrillation efficacy in a "hot can" electrode system. Defibrillation threshold (DFT) parameters were evaluated at end-expiration and at end-inspiration phases in random order by a biphasic waveform in ten anesthetized pigs (body weight: 19.1 +/- 2.4 kg; heart weight: 97 +/- 10 g). Pigs were intubated with a cuffed endotracheal tube and ventilated through a Drager SAV respirator with tidal volume of 400-500 mL. A transvenous defibrillation lead (6 cm long, 6.5 Fr) was inserted into the right ventricular apex. A titanium can electrode (92-cm2 surface area) was placed in the left pectoral area. The right ventricular lead was the anode for the first phase and the cathode for the second phase. The DFT was determined by a "down-up down-up" protocol. Statistical analysis was performed with a Wilcoxon matched pair test. The median impedance at DFT for expiration and inspiration phases were 37.8 +/- 3.1 omega, and 39.3 +/- 3.6 omega, respectively (P = 0.02). The stored energy at DFT for expiration and inspiration phases were 5.7 +/- 1.9 J and 6.0 +/- 1.0 J, respectively (P = 0.594). Shocks delivered at end-inspiration exhibited a statistically significant increase in electrode impedance in a " hot can" electrode system. The finding that DFT energy was not significantly different at both respiration phases indicates that respiration phase does not significantly affect defibrillation energy requirements.
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Yamanouchi et al. (1998) conducted an RCT in Ventricular defibrillation (n=10). End-inspiration phase vs. End-expiration phase was evaluated on Stored energy at defibrillation threshold (p=0.594). End-inspiration significantly increased electrode impedance but did not significantly affect defibrillation energy requirements compared to end-expiration (6.0 J vs 5.7 J; P=0.594).
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