[Analgesic effect of continuous intravenous nefopam after urological surgery]

Abstract

Objectives: To evaluate the efficacy of continuous infusion of nefopam. Indeed this analgesic is commonly used by continuous infusion by many anaesthetists to reduce its adverse effects. However whether the analgesic effect of an intermittent administration of nefopam has been proven, the efficacy of continuous infusion has not been established.

Study design: Double-blind placebo controlled prospective randomised study.

Patients and methods: Sixty patients ASA 1 to 3 undergoing planned urological surgery with laparotomy were included. At the end of surgery, bolus doses of placebo (Group 3) or nefopam 20 mg (Group 1 and 2) were administered to all the patients. Placebo (Group 3), nefopam 80 mg (Group 1) or 120 mg (Group 2) was thereafter continuously infused over 24 hours. All patients received additional analgesia with PCA morphine. We measured pain at rest and on cough with VAS. Adverse side effects such as nausea and vomiting, sedation and respiratory depression were evaluated. Mental performance was measured with mini mental status tests.

Results: Patients were older in the placebo group by approximately six years but anesthetic and surgical variables were not different between groups. Pain at rest and on cough was not statistically different between groups. In the placebo group, the median (interquartile range) morphine consumption reached 29 mg (13-53) whereas in patients receiving 80 and 120 mg nefopam, it levelled to 44 mg (11-54) and 35 mg (9-82) respectively (p > 0.05). Patients needed morphine during the same time period whether they received nefopam or not. Patients suffering from adverse effects were similar between groups.

Conclusion: In this study, continuous administration of nefopam did not reduce morphine consumption nor ameliorate analgesia and thus may not be recommended in urological surgery. Nefopam pharmacokinetics when used with continuous infusion as well as surgery types and differences in age between groups may explain these results.