Kozek-Langenecker S, Chiari A, Semsroth M
Department of Anesthesiology and General Intensive Care, University of Vienna, Austria.
Anesthesiology. 1996 Aug;85(2):277-80. doi: 10.1097/00000542-199608000-00008.
An epidural test dose containing epinephrine does not reliably produce hemodynamic responses in children under halothane anesthesia. The purpose of this study was to determine hemodynamic responses to intravenous isoproterenol in both awake and halothane-anesthetized children.
After obtaining institutional review board approval and parental informed consent, 72 ASA physical status 1 or 2 children (2.8 +/- 1.7 yr) undergoing elective minor surgery were studied before and during anesthesia with 1.2 minimum alveolar concentration halothane. A bolus containing 0.25 mg/ kg bupivacaine and 0.05 microgram/kg, 0.075 microgram/kg, or 0.1 microgram/kg isoproterenol, or bupivacaine and saline was injected via a peripheral arm vein to simulate intravascular injection of an epidural test dose.
Before induction of anesthesia, all patients showed a positive test response after isoproterenol injection (heart rate increase > or = 20 beats/min). During anesthesia, 79% of patients receiving 0.05 microgram/kg, 89% of patients receiving 0.075 microgram/kg, and 100% of patients receiving 0.1 microgram/kg met the criterion of a positive test response. Among each treatment group, all infants showed a positive test response. Blood pressure did not differ among the groups at any time. Transient benign dysrhythmias occurred in only one patient under halothane anesthesia receiving 0.075 microgram/kg isoproterenol.
Isoproterenol at a dose of 0.1 microgram/kg is a sensitive indicator for intravascular injection of a test dose in children anesthetized with halothane and nitrous oxide. Isoproterenol at a dose of 0.05 microgram/kg approximates a minimal effective dose in awake children and in infants. After detailed studies on neural toxicity, isoproterenol could be of value as an epidural test agent in children.
含肾上腺素的硬膜外试验剂量在氟烷麻醉下的儿童中不能可靠地产生血流动力学反应。本研究的目的是确定清醒和氟烷麻醉儿童对静脉注射异丙肾上腺素的血流动力学反应。
在获得机构审查委员会批准和家长知情同意后，对72例接受择期小手术的ASA身体状况1或2级儿童（2.8±1.7岁）在麻醉前和麻醉期间使用1.2最低肺泡浓度的氟烷进行研究。通过外周手臂静脉注射含0.25mg/kg布比卡因和0.05μg/kg、0.075μg/kg或0.1μg/kg异丙肾上腺素的推注剂量，或布比卡因和生理盐水，以模拟硬膜外试验剂量的血管内注射。
麻醉诱导前，所有患者在注射异丙肾上腺素后均显示阳性试验反应（心率增加≥20次/分钟）。麻醉期间，接受0.05μg/kg的患者中有79%、接受0.075μg/kg的患者中有89%、接受0.1μg/kg的患者中有100%符合阳性试验反应标准。在每个治疗组中，所有婴儿均显示阳性试验反应。各治疗组间血压在任何时候均无差异。仅1例接受0.07μg/kg异丙肾上腺素氟烷麻醉的患者出现短暂性良性心律失常。
0.1μg/kg剂量的异丙肾上腺素是氟烷和氧化亚氮麻醉儿童血管内注射试验剂量的敏感指标。0.05μg/kg剂量的异丙肾上腺素接近清醒儿童和婴儿的最小有效剂量。在对神经毒性进行详细研究后，异丙肾上腺素可能作为儿童硬膜外试验药物具有价值。
