Résumé
Preemptive analgesia is one of the pain sedative methods which is based on the blocking of pain receptor before any painful stimulation. Ketamine is a NMDA [N-Methyl D-Aspartate] receptor blocker, which has been used to reduce central sensitization. This study was performed to evaluate the preemptive effect of low dose ketamine [0.5 mg/kg, i.v.] on postoperative pain of cholecystectomy. In this study, sixty patients aged 30-60 years, with Anesthesia Society of America Scoring I or II [ASA I or II], candidate for elective cholecystectomy were randomly divided into two groups. The same operation and general anesthetic methods were used for the two groups. The patients in group 1 received 0.5 mg/kg ketamine, 20 min. before surgical incision and normal saline [the same volume], 20 min. after the operation. The patients of group 2, received normal saline [0.5 mg/kg] 20 min. before surgical incision and ketamine [0.5 mg/kg] 20 min. after that. In the postoperative period, analgesia was maintained with pethidine Using Visual Analogue Scale [VAS], pain was measured at 0 [arousal], 6, 12 and 24 hrs after the operation. The time interval for the first request of analgesia and the total amount of analgesic consumption during 24 hrs were reported. The data was analyzed using t and x2 tests. The mean value of pain intensity at 0, 6, 12 and 24 hrs after the operation in group 1 [3.24 +/- 0.97] was significantly less than that of the group 2 [4.18 +/- 1.09] [p<0.05]. The time interval to request the first analgesic supplement was longer in the group 1 than that in the group 2 [31.12 min versus 18.12 min; p<0.05]. Also, the total pethidine consumption was significantly different between two groups [p<0.05]. Based on our results, using pre-incisional ketamine [1 mg/kg] has more preemptive effect on reducing pain and analgesia requirement after cholecystectomy compared to those of post-operative ketamine