RESUMO
INTRODUCTION: Total knee replacement is usually a very painful procedure. A single-dose of femoral nerve block has been shown to provide similar analgesia to an epidural, with fewer side effects, but limited in time. OBJECTIVE: To compare the analgesia provided by dexamethasone used at perineural level in the femoral nerve block after total knee replacement with the one used at intravenous level, and with that of a control group. MATERIAL AND METHODS: A prospective, randomised, double-blind controlled trial was conducted on 81 patients randomly assigned to one of three groups: 1)IV dexamethasone (8mg); 2)perineural dexamethasone (8mg), and 3)placebo. All patients received 20ml of ropivacaine 0.5% for femoral nerve block. The primary outcome was the duration of the sensory-analgesic block of the femoral nerve block. The secondary outcomes included pain intensity measurements, patient satisfaction, and incidence of complications. RESULTS: Randomisation was effective. Analgesia duration was significantly higher (P<.0001) in the perineural dexamethasone group (mean 1152.2min, 95% confidence interval [95% CI]: 756.9-1547.6) in comparison with the control group (mean 186min, 95%CI: 81.2-292) and dexamethasone IV group (mean 159.4min, 95%CI: 109.8-209). Postoperative pain, complications and side effects were also lower in this group. CONCLUSIONS: Dexamethasone prolongs sensory block of single dose of femoral nerve block using ropivacaine. It also provides better analgesia and patient satisfaction, with fewer side effects.
