Epidural Ketamine for Postopertive Analgesia: Comparison with Epidural Morphine

Kim, Han Soo; Baik, Seong Wan; Kim, Inn Se; Chung, Kyoo Sub

Abstract

Sixty patients, of ASA physical status class I for elective operations in the lower abdomen, perineum, or lower extremities, were studied in a comparative prospective trial to evaluate the efficacy of epidural morphine and ketamine for postoperative analgesia. They were divided into two groups: an epidural morphine sulfate group (EMS group; 30 patients), and an epidural ketamine hydrochloride group (EKH group; 30 patients). Indwelling epidural catheters were placed in the patients' lumber areas (L3-4) and then all patients were anesthetized with thiopental, nitrous oxide, and halothane. After the patients had fully recover- ed from the anesthesia, the analgesic agents were administered epidurally via the catheter when the patients complained of pain in the postoperative period. The groups were given either 0.1 mg/kg of morphine sulfate or 0.5 mg/ kg of ketamine hydrochloride administered in a volume of 10 ml of normal saline. Patients were observed for the onset and duration of postoperative analgesia and for other effects. Total doses were 5.70+/-0.6 mg of morphine sulfate in the EMS group and 27.9+/-3.3 mg of ketamine hydrochloride in the EKH group. The onset of analgesia was detectable within 35 min. (23.5+/-6.3 min) in 86.7% (26 cases) of the EMS group and within 10 min. (7.83+/-3.7 min) in 76.7% (23 cases) of the EKH group. Mean duration of postoperative analgesia was 22.3 +/- 2.1 hr, in the EMS group. ln the EKH gruup, the duration of analgesia was shorter and variable. the range of duration was from 2 hr, to 24 hr. Cardiopulnulmeary changes were statistically insignificant in both groups. Side effects such as nausea, vomiting, urinary retention, pruritus, dizziness, and headache were observed in EMS group. In the EKH group, there was no discomfort except dizziness (3 cases) and headache (1 case). Epidural ketamine was a safe technique for postoperative analgesia, but because of the variability and relative shortness in the duration of analgesia the use of this technique will require further clinical trials.