Schnaider Taylor Brandão, Vieira Antonio Mauro, Brandão Antonio Carlos Aguiar, Lobo Marcos Vinicius Tonante
Departamento de Clínica Cirúrgica, FCM de Pouso Alegre, MG.
Rev Bras Anestesiol. 2005 Oct;55(5):525-31. doi: 10.1590/s0034-70942005000500007.
Low dose ketamine decreases nociception by blocking NMDA receptor channels. Alpha2-adrenergic receptor activation triggers intense analgesic response. This study aimed at evaluating the effects of epidural ketamine, clonidine and dexmedetomidine, in patients undergoing upper abdominal surgery.
Participated in this randomized double-blind study 70 patients of both genders, aged 18 to 50 years, physical status ASA I or II, submitted to subcostal cholecystectomy under general anesthesia associated to lumbar epidural anesthesia. Lumbar epidural anesthesia was randomly induced as follows:
20 mL of 0.75% ropivacaine and 1 mL of 0.9% saline solution (n = 10); Ketamine group: 20 mL of 0.75% ropivacaine and 0.5 mg.kg-1 ketamine (n = 20); Clonidine group: 20 mL of 0.75% ropivacaine and 1 mL clonidine (150 microg) (n = 20); Dexmedetomidine group: 20 mL of 0.75% ropivacaine and 2 microg.kg-1 dexmedetomidine (n = 20). Anesthesia was induced with etomidate, alfentanil and rocuronium and was maintained with isoflurane and alfentanil. Analgesia was evaluated by clinical signs and inhalational anesthetic inspired concentration was evaluated by anesthetic gases analysis during surgery.
All patients receiving ketamine, clonidine or dexmedetomidine had heart rate and systemic blood pressure decrease and have not required perioperative analgesic complementation. For the same patients, isoflurane inspired concentration varied from 0.5vol% to 1vol% and there were no clinical signs or responses suggesting inadequate anesthetic levels.
Epidural ketamine, clonidine or dexmedetomidine decreases alfentanil consumption and isoflurane inspired concentration in the intraoperative period of upper abdominal surgery.
低剂量氯胺酮通过阻断N-甲基-D-天冬氨酸（NMDA）受体通道来降低痛觉。α2肾上腺素能受体激活会引发强烈的镇痛反应。本研究旨在评估硬膜外给予氯胺酮、可乐定和右美托咪定对接受上腹部手术患者的影响。
70例年龄在18至50岁之间、身体状况为美国麻醉医师协会（ASA）I或II级的男女患者参与了这项随机双盲研究，他们在全身麻醉联合腰段硬膜外麻醉下接受肋下胆囊切除术。腰段硬膜外麻醉随机诱导如下：
20毫升0.75%罗哌卡因和1毫升0.9%生理盐水（n = 10）；氯胺酮组：20毫升0.75%罗哌卡因和0.5毫克/千克氯胺酮（n = 20）；可乐定组：20毫升0.75%罗哌卡因和1毫升可乐定（150微克）（n = 20）；右美托咪定组：20毫升0.75%罗哌卡因和2微克/千克右美托咪定（n = 20）。采用依托咪酯、阿芬太尼和罗库溴铵诱导麻醉，并用异氟烷和阿芬太尼维持麻醉。通过临床体征评估镇痛效果，在手术期间通过麻醉气体分析评估吸入麻醉药的吸入浓度。
所有接受氯胺酮、可乐定或右美托咪定的患者心率和全身血压均下降，且无需围手术期镇痛补充。对于相同的患者，异氟烷吸入浓度在0.5%体积至1%体积之间变化，且没有临床体征或反应提示麻醉水平不足。
在接受上腹部手术的患者术中，硬膜外给予氯胺酮、可乐定或右美托咪定可减少阿芬太尼的用量和异氟烷的吸入浓度。
