The Effects of Epidural Clonidine Added to Bupivacaine , Fentanyl and Epinephrine after Total Abdominal Hysterectomy

Choi, Sung Soo; So, Geum Young; Chung, Chong Dal

Abstract

Epidurally administered clonidine, a selective alpha2-adrenergic agonist, has been reported to produce postoperative analgesia. The aim of this study was to see if the addition of a small dose of clonidine to a mixture of bupivacaine, fentanyl and epinephrine prolonged the duration of analgesia and reduce the number of injections or the total bupivacaine requirement and the incidence of side effects. Forty patients presenting for TAH in ASA physical status 1 or 2, were randomly divided into two groups group 1 was given a 10 ml epidural solution of bupivacaine 12.5 mg combined with fentanyl 50 pg and epinephrine 50ug ; group 2 was given the same solution with clonidine 75 ug. Changes in the systolic and diastolic blood pressure and the pulse rate were recorded at 5, 10, 20, 30, 45, 60, 75, 90, 105 and 120 minutes after drug administration, and the analgesic effects were assessed by measuring pain score (Prince Henry Score), analgesic duration, total bupivacaine requirement for 24 hours and side effect. The results were as follows; 1) Heart rate changed little in group 1 and decreased significantly in group 2. 2) Systolic and diastolic blood pressure decreased significantly in all groups (earlier in group 2 than in group 1). 3) The mean duration of analgesia was significantly prolonged in group 2, compared with group 1 (437 min in group 2; 229 min in group 1). For 24 hours after the first injection, numbers of injections (6 in group 1; 3.15 in group 2) and total bupivacaine requirements (75.0 mg in group 1 ; 39.1 mg in group 2) were significantly reduced. 5) The side effects including hypotension, nausea and vomiting, pruritus, and respiratory depression were not significantly different from each other. These results show that epidurally administered clonidine helps to prolong analgesic duration, and decreased need for supplemental bupivacaine, after lower abdominal surgery.