[Use of ketamine combined with local anesthetics in epidural anesthesia]

Postoperative pain relief and sedation with epidural ketamine were studied. Twenty-four patients for elective upper abdominal surgery were divided into 4 groups. Epidural catheter was inserted into thoracic epidural space before induction of general anesthesia. In each group, either 0.25% bupivacaine 5 ml only, ketamine 0.1 mg.kg-1 + bupivacaine 5 ml, or ketamine 0.3 mg.kg-1 + bupivacaine 5 ml, or ketamine 0.5 mg.kg-1 + bupivacaine 5 ml was injected into epidural catheter for complaint of pain in recovery room. In ketamine injected groups, blood pressure and heart were unchanged, but respiration rate increased significantly. Patients in ketamine 0.3 or 0.5 mg.kg-1 injected groups, pain relief and sedation score were significantly intensified, but patients in ketamine 0.5 mg.kg-1 injected group, incidence of pain in the back during injection and headache was high. We conclude that epidural ketamine is useful for postoperative pain relief, and the superior dose of epidural ketamine is 0.3 mg.kg-1.