INHIBITION OF EPIDURAL MORPHINE-INDUCED PRURITUS BY INTRAVENOUS DROPERIDOL

Background and Objectives. our objective was to study in more detail o ur previous finding that intravenous droperidol inhibits pruritus indu ced by epidural morphine. Methods. In a double blind study, 107 ASA I or II patients undergoing cesarean section received epidural anesthesi a with 150 mg (30 ml) of 0.5% bupivacaine with 1:200,000 epinephrine a nd 2 mg of morphine hydrochloride in a single injection. They were ran domly allocated to either receive (treated group, n = 54) or not recei ve (control group, n = 53) an intravenous injection of 2.5 mg of drope ridol just after delivery. During the postoperative period, the patien ts were assessed for the occurrence and severity of pruritus or other possible untoward symptoms. Pruritus was classified as absent, mild, m oderate, or severe. Results. The incidence of pruritus in control grou p was absent, 26.4%; mild, 39.6%; moderate, 28.3%; severe, 5.7%; for t he treated group, the incidences were, respectively: 59.2; 27.8; 13.0; and 0.0% (p = 0.0003; Mann-Whitney test). As for other side effects o f morphine, nausea and vomiting had a similar incidence in the two gro ups; urinary retention could not be analyzed because of bladder cathet erization, and constipation, herpes labialis and clinical evidence of respiratory depression were never observed. Droperidol produced a grea ter incidence of somnolence (2% in control and 17% in treated group - p < 0.02; Fisher's exact test), but it was never incapacitating. The i ncidence of hypotension was similar in the two groups. Conclusion. Int ravenous droperidol reduces the incidence and severity of pruritus cau sed by epidural injection of morphine without inducing important side effects.