Badgwell J M, Heavner J E, Kytta J
Department of Anesthesiology, Texas Tech University Health Sciences Center, Lubbock 79430.
Anesthesiology. 1990 Aug;73(2):297-303. doi: 10.1097/00000542-199008000-00018.
The influence of age and volatile anesthetic agents on plasma concentrations and toxic effects of bupivacaine were studied in 2-day-old, 2-week-old, and 2-month-old pigs. Bupivacaine was infused at a constant rate while the pigs' ECGs and EEGs were recorded. Six pigs in each age group were lightly anesthetized with 70% N2O/30% O2 during the bupivacaine infusion, and twelve 2-day-old pigs were anesthetized with 70% N2O/30% O2 plus either 0.5 X MAC halothane or isoflurane. Two-day-old pigs were more resistant than older pigs to the toxic effects of bupivacaine despite higher plasma concentrations at all sample times. All pigs given N2O alone or N2O plus halothane had ventricular dysrhythmias, but only one pig in the N2O plus isoflurane group had a ventricular dysrhythmia. Threshold doses of bupivacaine for dysrhythmias in the N2O alone and N2O plus halothane groups did not differ. Seizures occurred in all pigs in the N2O alone group, in none of the N2O plus halothane group, and in two of the N2O plus isoflurane group. The doses required to depress cardiac index and cause asystole were less in the groups receiving halothane and isoflurane. It was concluded that N2O plus halothane and N2O plus isoflurane increase the lethality of bupivacaine while preventing early warning signs of toxicity.
在2日龄、2周龄和2月龄的猪身上研究了年龄和挥发性麻醉剂对布比卡因血浆浓度及毒性作用的影响。以恒定速率输注布比卡因，同时记录猪的心电图和脑电图。在输注布比卡因期间，每个年龄组的6头猪用70%N₂O/30%O₂轻度麻醉，12头2日龄猪用70%N₂O/30%O₂加0.5倍最低肺泡有效浓度（MAC）的氟烷或异氟烷麻醉。尽管在所有采样时间2日龄猪的血浆浓度较高，但它们比年长的猪对布比卡因的毒性作用更具抵抗力。所有单独给予N₂O或N₂O加氟烷的猪都出现了室性心律失常，但N₂O加异氟烷组只有1头猪出现室性心律失常。单独使用N₂O组和N₂O加氟烷组中布比卡因致心律失常的阈剂量没有差异。单独使用N₂O组的所有猪都发生了惊厥，N₂O加氟烷组无一发生惊厥，N₂O加异氟烷组有2头猪发生惊厥。接受氟烷和异氟烷的组中，降低心脏指数和导致心搏停止所需的剂量较小。得出的结论是，N₂O加氟烷和N₂O加异氟烷增加了布比卡因的致死率，同时掩盖了毒性的早期预警信号。
