Dalzell G W, Cunningham S R, Anderson J, Adgey A A
Regional Medical Cardiology Center, Royal Victoria Hospital, Belfast, Northern Ireland.
Am J Cardiol. 1989 Oct 1;64(12):741-4. doi: 10.1016/0002-9149(89)90757-1.
Electrode pad size is an important determinant of transthoracic current flow during external countershock. Self-adhesive, dual function electrocardiogram/defibrillator pads were used to assess the effect of electrode pad size on defibrillation success with low energy (200 J) shocks. The study analyzed 123 cardiac arrests due to primary ventricular fibrillation (VF) in 105 patients (74 men, 31 women) ages 40 to 84 years (mean 64). Transthoracic impedance was measured before defibrillation using a low amplitude 30-kHz current passed through the chest by way of the electrocardiogram/defibrillator pads applied anteroanteriorly. Pad diameters were small (8/8 cm) in 26 cardiac arrests, intermediate (8/12 cm) in 63 arrests and large (12/12 cm) in 34 cardiac arrests. Transthoracic impedance decreased with increasing pad size (112 +/- 17 vs 92 +/- 22 vs 72 +/- 14 omega, respectively, p = 0.0001). Only the first episode of primary VF during a cardiac arrest was analyzed. A single shock of 200 J (delivered energy) was successful in 8 of 26 (31%) arrests using small pads, in 40 of 63 (63%) with intermediate pads and in 28 of 34 (82%) with large pads (p = 0.0003). A second 200-J shock increased the cumulative defibrillation rates to 12 of 26 (46%), 50 of 63 (79%) and 33 of 34 (97%), respectively (p less than 0.0001). In primary VF, larger self-adhesive electrocardiogram/defibrillator pads are associated with a lower transthoracic impedance and improved defibrillation success rates with low energy shocks.
电极板尺寸是体外除颤时经胸电流流动的一个重要决定因素。使用自粘性、具有双重功能的心电图/除颤器电极板来评估电极板尺寸对低能量（200焦耳）电击除颤成功率的影响。该研究分析了105例年龄在40至84岁（平均64岁）患者（74名男性，31名女性）中因原发性心室颤动（VF）导致的123次心脏骤停。在除颤前，通过经胸前放置的心电图/除颤器电极板，利用低幅度30千赫兹电流测量经胸阻抗。26次心脏骤停使用的电极板直径小（8/8厘米），63次骤停使用的电极板直径中等（8/12厘米），34次心脏骤停使用的电极板直径大（12/12厘米）。经胸阻抗随着电极板尺寸增大而降低（分别为112±17、92±22和72±14欧姆，p = 0.0001）。仅分析心脏骤停期间原发性VF的首次发作情况。使用小电极板时，26次骤停中有8次（31%）单次200焦耳（输送能量）电击成功，使用中等电极板时，63次中有40次（63%）成功，使用大电极板时，34次中有28次（82%）成功（p = 0.0003）。第二次200焦耳电击使累计除颤率分别提高到26次中的12次（46%）、63次中的50次（79%）和34次中的33次（97%）（p＜0.0001）。在原发性VF中，更大的自粘性心电图/除颤器电极板与较低的经胸阻抗以及低能量电击时更高的除颤成功率相关。
