Dexamethasone reduces postoperative pain after thyroidectomy

A Barros1, CP Vale1, FC Oliveira1, C Ventura1, JP Assun çã o1, CA Fontes Ribeiro0,2, FC Pereira0,2. 1Hospital S ã o Teot ó nio, E.P.E - Viseu, Department of Anaesthesiology,, Portugal, 2Faculty of Medicine, University of Coimbra, Pharmacoloy and Therapeutics/IBILI, 3000-354 Coimbra, Portugal

Introduction: Tramadol is a central acting analgesic which has been shown to be effective in the management of moderate to severe postoperative pain, in spite of its administration might be sometimes associated with nausea and vomiting. We and others demonstrated that its analgesic efficacy is decreased by co-administration of anti-emetics like ondansetron. On the other hand, a possible clinical indication is its co-use with dexamethasone included in an anti-emetic strategy. Pre-clinical studies showed that this corticosteroid increased the analgesic effect of tramadol. Additionally clinical studies demonstrated that glucocorticoids have analgesic and antiemetic effects when administered perioperatively.

Objectives: The aim of this study is to test the hypothesis that co-administration of tramadol and dexamethasone decreases both postoperative pain and tramadol requirement by patient-controlled analgesia (PCA).

Methods: ortFy patients undergoing thyroidectomy under general anesthesia (sevoflurane) and mechanical ventilation were enrolled in a double-blind, controlled study. The patients were randomly allocated to receive dexamethasone 4 mg i.v. (dexamethasone group, n=20) or saline (control group, n=20) immediately after induction. At 0, 1, 2, 4 and 22 hours of PCA, tramadol consumption, pain, nausea, vomiting, sedation and shivering were evaluated. Statistical analysis was performed using the Mann-Whitney U-test, which significance level was set at P<0.05. Data were presented as mean SD.

Results: Pain (NRS 0-10) was significantly lower in the dexamethasone group than in the control group (2.88 ± 1.4 vs. 3.8 ± 1.2, P=0.02) at the beginning of patient-controlled analgesia. However, this positive effect was lost throughout the remaining observation periods. Moreover, there were no significant differences in tramadol consumption in all observation periods (P>0.05). The incidence of nausea and vomiting requiring anti-emetic rescue was 29% in each group. The other endpoints evaluated were not significantly different between groups.

Conclusions: Pain scores were significantly smaller in the dexamethasone group at the beginning of PCA but tramadol demand was not significantly different between groups. This shows a possible beneficial effect of a preoperative single low dose of 4 mg dexamethasone on postoperative pain but doesn ’ t support the hypothesis of decreasing tramadol requirements. Whether an increase in dexamethasone (8 mg) would further have a beneficial effect on tramadol consumption warrants investigation.