[The effects of a dose of epidural clonidine combined with intrathecal morphine for postoperative analgesia].

Objective: To evaluate the effectiveness of a single bolus of epidural (ED) clonidine (C) associated with intrathecal morphine (M) on postoperative analgesia after cesarean section (CS).

Design: Prospective double-blind randomized study.

Setting: Obstetric department.

Patients: Fourty patients ASA 1-2 submitted to combined spinal-epidural block (CSE) for CS.

Interventions: A needle through needle set for CSE was used. The intrathecal block was induced with 2.7-3 ml of isobaric 0.5% bupivacaine (B) and 250 micrograms of M. After ED test with 0.5% B, a single bolus of C 150 micrograms in NS 10 ml (group C, n 20) or NS 10 ml as placebo (group P, n 20) was given through the ED catheter.

Methods: The observation for 36 hours evaluated analgesia (VAS until the first dose of additional analgesic, total amount of analgesic and time of first analgesic request) and side effects (variations of arterial pressure and heart rate, motor block, sedation, nausea, vomiting, itching, respiratory depression). Groups were statistically compared.

Results: In group C lower analgesic request (significantly between 12th and 18th hour) and significant delay of first request (22.5 +/- 4.1 h) were registered. VAS showed significant trend to opposite sign variations (downwards in group C, upwards in group P) at 1, 2 and 12 hours. In group C lower sistolic arterial pressure at 1 and 4 hours, denser motor block at 2 and 4 hours and mild sedation were observed.

Conclusions: A single ED bolus of C 150 micrograms after CS significantly enhances and prolongs the analgesic effect of M 250 micrograms without important side effects.