[Prevention of the acute tolerence with fentanyl by ketamine].

Introduction: The objective of this study is to evaluate in under developed country where post operative pain management inadequate the efficiency of the prevention of this acute tolerance with opioids by the ketamine.

Materials and methods: We did a prospective study on months period (January 2004 to June 2004). The setting was the HPD surgical unit recovery room. The patients of more than 15 years and less than 60 years who underwent painful or fairly painful surgical operation under general anaesthesia were included. The patients intubés,ventilated and sedated in the recovery room were excluded from the study .The patients were divided into two groups: in group 1 the patients were given 100 microg/kg of ketamine 15 mn before induction. In group 2 the patients where given a placebo 15 mn before induction. The fentanyl was used systematically during induction at the dosage of 5 microg/kg. The quality of per-operative analgesia was evaluated by the appreciation of the heart rate and the blood pressure. The DPO was evaluated by the analogical visual scale (EV A) at the entrance and the exit of the recovery room, and at the 4th, 8th, 12th and 24th hour after the surgery.

Results: Hundred and thirteen (113) patient were included in the study (groupel with ketamine: 56 patients, groupe 2 without ketamine: 57). The average age was 30 years with extremes from 16 to 60 years. In group 1 and preoperatively 5.9% of the patients receided additional fentanyl ranging from 50 to 100 microg/kg against 47.7% in group 2. In the post-operative period, the morphine consumption was 22.02% for the Group 1 and 43.37% for Group 2. The difference between the two groups is statistically significant. A case of restlessness was noted in group 1.

Conclusion: The low dose ketamine seems to be effective for the prevention of the postoperative severe pain induced by the fentanyl. It allows also an improvement of the quality of per-operational analgesia.