Intravenous lidocaine suppresses dexamethasone-induced perineal pruritus during anesthesia induction: a randomized controlled, double blind study.

Previous studies have found that intravenous dexamethasone may produce perineal pruritus in some patients when administered as premedicant in the preoperative period. This randomized controlled, double-blind study evaluated the efficacy of pretreatment of lidocaine on the incidence and severity of dexamethasone-induced perineal pruritus. 400 patients were enrolled in this study and allocated randomly into four groups (n=100, in each). Then, patients received intravenously anesthesia induction as the following sequence of medications: injecting 0.9% sodium chloride (placebo) 10 mL in group I, lidocaine 0.5mg/kg in group II, lidocaine 1mg/kg in group III, and lidocaine 1.5mg/kg in group IV, 1 minute later, injecting 10mg dexamethasone in all groups. The severity of perineal pruritus was graded based on the VAS as none (VAS 0), mild (VAS 1-3), moderate (4-6), or severe (VAS 7 to 10), and recorded the occurrence, the severity and the duration of perineal pruritus. Occurrence of perineal pruritus was significantly reduced in group III and group IV (8%, 9% vs 40% and 33% in Groups I and II, respectively, p<0.05). The incidence of perineal pruritus of females was higher than males in groups I and II (P<0.05). The duration of perineal pruritus was shorter in group IV compared to groups I, II and III (p<0.05). We conclude that pretreatment 1mg/kg or 1.5mg/kg lidocaine may effectively reduce the incidence of perineal pruritus.