Clonidine Added to Lidocaine Prolongs the Duration of Anesthesia and Analgesia during Brachial Plexus Block

Kim, Tae Hwan

Abstract

BACKGROUND: Clonidine, a selective alpha2 adrenergic agonist, increases the duration of anesthesia and analgesia when it is used with local anesthetics. This study was undertaken to evaluate whether clonidine, which was mixed with lidocaine for the brachial plexus block (BPB), has a local (peripheral) or a systemic (central) anesthetic effect.
METHODS
Seventy patients scheduled for upper extremity surgery were randomly allocated to two groups. In group IV (n = 35) an axillary perivascular BPB was performed with 40 ml of 1% lidocaine and 1:200,000 epinephrine, and just after BPB clonidine 2microgram/kg was administered intravenously. In group BPB (n = 35) the same BPB was performed with 40 ml of 1% lidocaine, 1:200,000 epinephrine and clonidine 2microgram/kg. The following variables were recorded: onset time, duration of anesthesia and analgesia, and adverse effects.
RESULTS
Onset time was comparable in both groups. The duration of anesthesia and analgesia significantly increased to 306 min and 354 min in group BPB, when compared to 119 min and 151 min in group IV, respectively. No side effects such as hypotension, bradycardia, and sedation were reported.
CONCLUSIONS
The duration of anesthesia and analgesia is prolonged by adding clonidine to lidocaine during brachial plexus block, which suggests that its effect is local rather than systemic.