Does Epidural Clonidine Decrease the Sevoflurane Concentration for Maintaining the BIS 50? / 대한마취과학회지

BACKGROUND: The aim of this study was to investigate the influence of epidural clonidine on the BIS, and its potential dose-sparing effect on the sevoflurane requirement for maintaining the BIS 50. METHODS: Forty ASA I or II patients aged 20 to 65, undergoing lower abdominal, gynecologic surgery under general anesthesia, were randomly allocated to either a 10 ml epidural normal saline injection group (n = 20) or a 10 ml epidural clonidine 3microgram/kg mixed with normal saline injection group (n = 20). They received 5 mg/kg thiopental sodium and 0.1 mg/kg vecuronium bromide for induction, with no premedication. After surgical incision, the sevoflurane concentration was controlled to maintain the BIS 50. Epidural saline or clonidine was then injected and end-tidal sevoflurane concentration to maintain the BIS 50, the heart rate (HR) and mean arterial pressure (MBP) were measured every 5 min over a 20 minute period. RESULTS: The end-tidal sevoflurane concentration in the clonidine group decreased by 27.5% after the epidural clonidine injection (1.49 +/- 0.23 vol% vs. 1.08 +/- 0.27 vol%; P0.05). There were no changes in the heart rate and mean blood pressure in either group. CONCLUSIONS: Epidural clonidine causes a significant decrease in the BIS, and lowers the end-tidal sevoflurane concentration required for maintaining the BIS 50.

Cardiovascular Response, Analgesic and Sedative Effect according to the Dose of Epidural Clonidine / 대한마취과학회지

The subarachnoidal or epidural opioid reveals excellent analgesic effect for postoperative pain and intractable cancer pain, but its side effects such as nausea, vomiting, voiding difficulty, pruritus and respiratory failure limit its use. There were many studies for decreasing frequency and severity of side effects and reinforcing the analgesic effect of opioid by administrating other drugs. Clonidine is one of such drugs which is able to be administered epidurally with opioids for that purpose. We studied the changes of cardiovascular response, analgesic and sedative effect according to the dose of epidural clonidine. The analgesic effect of epidural clonidine was investigated in 30 patients who underwent anal surgery with epidural anesthesia using 15 ml of 1.5~2 % lidocaine.The time of maximal intensity of pain after disapperance of injected lidocaine was checked. Thirty patients were divided into three groups randomly. In group 1 (n=10), the dose of epidural clonidine was 50 ug; Group 2 (n=10) was 150 ug; Group 3 (n=10) was 450 ug. Changes in the arterial pressure, pulse rate, sedation state and SpO2 were observed before and during 60 minutes after epidural clonidine administration. And the analgesic effect was assessed by measuring VAS pain score. Blood pressures and pulse rates decreased according to increase of dosage of clonidine. Group 1 showed the analgesic effect of 34%, group 2 showed 77% and group 3 showed 81% at 60 minutes after administration. Sedation effect was seen in group 2 and 3 but SpO2 was not decreased significantly. We thought that the respiratory depression of epidural clonidine was not so significant to limit the use for the postoperative pain control. We conclude that it is better to administer clonidine with opioids epidurally than clonidine slone to get better analgesic effect and less sedative effect, because the analgesic effect of epidural clonidine increases according to increase of dosage but the sedative effect increases also.

The Effects of Epidural Clonidine with Morphine or Bupivacaine after Upper Abdominal Surgery / 대한마취과학회지

Epidural narcotics has been most widely used for the control of postoperative pain. However, patients have been treated insufficiently because of the fear of respiratory depression. Urinary retension, nausea and vomiting, pruritus are other complications of epidural narcotics. Epidural local anesthetics may be an alternative to epidural narcotics. But the duration of action is usually too short, although epinephrine can prolong the analgesic effect. Clonidine, an a2-adrenergic agonist has its own analgesic effect and can prolong the effects of epidurally administered drugs. Therefore epidural clonidine may be expected to lessen the requirement of epidural narcotics and hence reduce the complications of narcotics. 75 ug or 150ug of clonidine was added to 0.125% bupivacaine or 2 mg of morphine. 6ml of mixed solution was administered epidurally during and after operation for the control of pain following upper abdominal surgery. Clonidine caused increase in the analgesic duration of epidural bupivacaine and morphine. Clonidine also cause decrease in systolic pressure in dose-dependent manner, especially during anesthesia without significant alterations in heart rate. Clonidine may be an useful adjunct to epidural narcotics, provided the dosage is carefully titrated in the range of modest hemodynamic change.