| Minimal Effective Dose of Clonidine Added to Local Anesthetics for Increasing Duration of Anesthesia and Analgesia after Brachial Plexus Block. |
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Soo Kyung Lee, Ho Yeong Kil |
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Department of Anesthesiology, School of Medicine, Hallym University, Seoul, Korea. |
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| Abstract |
BACKGROUND
Clonidine has been shown to increase the duration of anesthesia and analgesia when mixed with the local anesthetic used to perform a regional block, but it has side effects such as hypotension, excessive sedation when used large amounts.
The aim of this study was to determine the minimal effective dose of clonidine increasing anesthesia and analgesia time without any significant side effects after brachial plexus block.
METHODS
One-hundred and twenty patients scheduled for upper extremity surgery, ASA physical status I and II, were randomly allocated into six groups(n=20 for each group) including group A(no clonidine) and group B-F(clonidine 0.25~1.25 mcg/kg at interval of 0.25 mcg/kg for each group).
A parascalene brachial plexus block was performed with admixture of 20ml of 2% lidocaine and 20ml of 0.5% bupivacaine with or without clonidine. Duration of anesthesia and analgesia, also side effects were checked for each clonidine group and compared with group A.
RESULTS
Duration of anesthesia increased significantly in group E(442+/-137 min) and F(472+/-143 min), and duration of analgesia increased significantly in group D(466+/-140 min), E(540+/-144 min) and F(561+/-196 min) compared with group A.
More rapid onset time is noted in group C, D, E, and F.
There were no differences in vital signs among groups.
Sedative effect was evident in group D, E, and F, especially 60 minute after injection of drug, and the onset and duration of sedation depended on dosage.
CONCLUSIONS
Minimal effective dose of clonidine for increasing anesthesia and analgesia time without any significant side effects was 1.0 mcg/kg. |
| Key Words:
Anesthetic techniques brachial plexus block; Pharmacology clonidine |
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