Results of a Double Blind Study on Small Doses of Ketamine for Postoperative Pain

• Published in: Journal of Japan Society of Pain Clinicians Vol. 5; no. 2; pp. 125 - 133
• Main Authors: DAN, Kenjiro, MATSUNAGA, Matsuko, GOTOH, Hiroto
• Format: Journal Article
• Language: English; Japanese
• Published: Japan Society of Pain Clinicians 1998; 一般社団法人 日本ペインクリニック学会
• ISSN: 1340-4903; 1884-1791
• DOI: 10.11321/jjspc1994.5.125

Objective of the study: Pre- and postoperative small doses of ketamine, NMDA blocking agent (C13H16CINO-HCl) were included in perioperative pain control together with epidural local anesthetics and opioid administration, and effects on postoperative pain were compared. Patients and methods: 43 male and female Japanese patients (30 upper abdomen and 13 lower abdomen) were divided into two groups, group 1 (23 patients; 61.7±7.8 years old) received ketamine 10mg given preoperatively and 25mg/day for 3 days postoperatively and group 2 (20 patients; 56.5±9.5 years old) given a placebo (saline). Subjects in the two groups' were selected in a double blind manner, and all procedures were approved by the Local Ethics Committee. Epidural analgesia plus general anesthesia (N2O+O2) were administered. In the recovery room, both groups of patients were given epidural bolus of buprenorphine 0.2mg, and epidural infusion of 0.25% bupivacaine 144ml+buprenorphine 0.6mg was given continuously for 3 days. At 6, 12, 24, 36, 48, 72 hours after surgery, the intensity of pain was evaluated using the Visual Analogue Scale (VAS). The required frequency of analgesics was also recorded to aid an evaluation of control of postoperative pain. Results: VAS values at rest and with physical movements in group 1 were significantly lower than those of group 2. The Mann-Whitney U-test was used to compare group 1 with group 2. Group 1 required smaller amounts of analgesics than did group 2. For events recorded 2 weeks after surgery, the untoward effects of ketamine were nil. Conclusion: In a double blind, randomized study, small doses of ketamine which did not produce frank anesthesia, led to control of postoperative pain, especially, pain related to physical movement. These findings strongly suggest that pre- and postoperative ketamine given in small doses pre- and postoperatively attenuate the hyperalgesia and allodynia caused by sensitization of NMDA receptors in the dorsal horn.