Yamanouchi Y, Mowrey K A, Kroll M W, Brewer J E, Donohoo A M, Niebauer M J, Wilkoff B L, Tchou P J
Department of Cardiology, Cleveland Clinic Foundation, Ohio 44195, USA.
Pacing Clin Electrophysiol. 1998 Jun;21(6):1216-24. doi: 10.1111/j.1540-8159.1998.tb00180.x.
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.
除颤通路的阻抗是心室除颤效果的重要决定因素。本研究的假设是，呼吸阶段（吸气末与呼气末）可能会改变“热罐”电极系统中的阻抗和/或除颤效果。通过双相波形，以随机顺序在10只麻醉猪（体重：19.1±2.4 kg；心脏重量：97±10 g）的呼气末和吸气末阶段评估除颤阈值（DFT）参数。猪通过带套囊的气管内导管插管，并通过德尔格SAV呼吸机进行通气，潮气量为400 - 500 mL。将一根经静脉除颤导线（6 cm长，6.5 Fr）插入右心室心尖。将一个钛罐电极（表面积92 cm²）置于左胸区域。右心室导线在第一阶段为阳极，在第二阶段为阴极。DFT通过“降-升-降-升”方案确定。采用Wilcoxon配对检验进行统计分析。呼气期和吸气期DFT时的中位阻抗分别为37.8±3.1Ω和39.3±3.6Ω（P = 0.02）。呼气期和吸气期DFT时的储存能量分别为5.7±1.9 J和6.0±1.0 J（P = 0.594）。在“热罐”电极系统中，吸气末施加的电击显示电极阻抗有统计学显著增加。两个呼吸阶段的DFT能量无显著差异这一发现表明，呼吸阶段对除颤能量需求无显著影响。
