The Postoperative Analgesic Effects of Epidural Clonidine during General Anesthesia

Choi, So Yong; Chung, Chong Dal; Lee, Jung Tae; Yu, Byung Sik; So, Keum Young

Abstract

BACKGROUND
Epidurally administered clonidine produces analgesia by an alpha 2-adrenergic mechanism and may provide postoperative analgesia without nausea, pruritus and respiratory depression associated with opioid administration. Many studies have shown the beneficial effects of epidural clonidine in postoperative pain management. Pre-administered epidural analgesic agent before the skin incision may prevent the nociceptive input. We provided the pre-emptive analgesia and compared the postoperative analgesic effects of epidural clonidine when used as the sole analgesic agent with epidural fentanyl and epidural bupivacaine.
METHODS
Thirty-nine gynecologic patients, ASA physical status 1, 2, undergoing elective lower abdominal surgery under general anesthesia, were studied. They were not taking any premedications. Before anesthesia, an epidural catheter was inserted at the L2~3 interspace. Patients were divided into 3 groups randomly. Group 1 received 0.125% bupivacaine 20 ml through the epidural catheter, group 2 received 100 microgram fentanyl in normal saline 20 ml, and group 3 received 150 microgram clonidine in normal saline 20 ml. During the operation, we recorded the vital signs and side effects. Just before suturing peritoneum, we injected the corresponding drugs on individual groups through the epidural catheter. In the recovery room, the postoperative analgesia was assessed by VAS (visual analogue scale). Vital signs, sedation score and side effects were also checked.
RESULTS
VAS and systolic blood pressure were significantly lower in group 3 than group 1 or group 2 at the recovery room. The diastolic blood pressure, heart rate and sedation score were not significantly different between three groups at the recovery room. Also the vital signs during the operation were notsignificantly different between three groups. The incidence of hypotension was 3 out of 13 in group 3 and 1 out of 13 in group 1.
CONCLUSION
Epidural bolus clonidine 150 microgram produces more profound and longer postoperative analgesic effects than fentanyl 100 microgram or 0.125% bupivacaine at the lower abdominal surgery. But hypotension may occur more frequently. So, if we select the patient cautiously, epidural clonidine is a good alternative analgesic agent for the postoperative analgesia.