Gill R M, Sweeney R J, Reid P R
Department of Electrophysiology Research, Lilly Research Laboratories Division, Eli Lilly and Company, Indianapolis, Indiana 46285.
Pacing Clin Electrophysiol. 1993 Apr;16(4 Pt 1):708-14. doi: 10.1111/j.1540-8159.1993.tb01649.x.
In 18 open-chested mongrel dogs (18.0 +/- 1.7 kg) we compared three anesthetics and three methods for measuring the defibrillation threshold. Six animals were anesthetized with pentobarbital (30 mg/kg) and maintained with a pentobarbital infusion (4 mg/kg per hour). All other animals were anesthetized with sodium brevital (10 mg/kg) and maintained with either halothane gas (1.5%, N = 6) or isoflurane gas (1.8%, N = 6). In each dog, we measured the energy required for 50% successful defibrillation (E50) with: (A) a 3 reversal--up/down method; (B) a 15 shock--up/down method; and (C) a percent success method. Anesthetics and methods were selected in a balanced random order. Ventricular fibrillation was induced with 50 Hz electrical pacing. After 15 seconds, monophasic truncated exponential shocks were delivered by way of a spring-patch electrode configuration. The animal was rescued (if needed) and fibrillation/defibrillation episodes were repeated at 3 minute intervals. After each determination of the E50, the E50 was delivered in ten successive defibrillation trials to determine its actual success rate. We found no significant difference in E50 among anesthetics; a significant difference (P < 0.05) in E50 between method C (9.7 +/- 2.6 joules) and method B (8.2 +/- 1.6 joules); no significant difference among anesthetics or methods for the actual success rate of the E50 (45 +/- 21% successful); and method A required significantly fewer fibrillation episodes and number of shocks and less cumulative energy than the other methods. We concluded that the anesthetics tested had little effect on E50 but that the method used to determine E50 could have an effect.(ABSTRACT TRUNCATED AT 250 WORDS)
在18只开胸杂种犬（体重18.0±1.7千克）中，我们比较了三种麻醉剂以及三种测量除颤阈值的方法。6只动物用戊巴比妥（30毫克/千克）麻醉，并用戊巴比妥输注（每小时4毫克/千克）维持麻醉。所有其他动物用速眠新钠（10毫克/千克）麻醉，并用氟烷气体（1.5%，N = 6）或异氟烷气体（1.8%，N = 6）维持麻醉。在每只犬中，我们用以下方法测量50%成功除颤所需的能量（E50）：（A）3次反转——上下法；（B）15次电击——上下法；（C）成功率法。麻醉剂和方法按平衡随机顺序选择。用50赫兹电起搏诱发心室颤动。15秒后，通过弹簧贴片电极配置给予单相截断指数电击。如果需要，对动物进行抢救，颤动/除颤发作每隔3分钟重复一次。每次测定E50后，在连续十次除颤试验中给予E50以确定其实际成功率。我们发现麻醉剂之间的E50没有显著差异；方法C（9.7±2.6焦耳）和方法B（8.2±1.6焦耳）之间的E50有显著差异（P<0.05）；E50实际成功率的麻醉剂或方法之间没有显著差异（45±21%成功）；并且方法A比其他方法所需的颤动发作次数、电击次数和累积能量显著更少。我们得出结论，所测试的麻醉剂对E50影响很小，但用于确定E50的方法可能有影响。（摘要截断于250字）
