Clinical Effects of Ketamine on Ropivacaine in Brachial Plexus Blockade

Lee, In Ho; Lee, Il Ok; Kong, Myoung Hoon; Lee, Mi Kyoung; Kim, Nan Sook; Choi, Young Seok; Lim, Sang Ho

Abstract

BACKGROUND: Ketamine enhances local anesthetic and analgesic effects of bupivacaine by peripheral mechanisms. We evaluated the additive effects of ketamine (30 mg) on 0.5%, and 0.75% ropivacaine (total 30 ml) for an interscalene brachial plexus blockade (IBPB).
METHODS
Thirty five adult patients scheduled for major forearm or hand surgery were prospectively randomized to receive one of the following solutions. Group 1 received 0.75% ropivacaine 28 ml with normal saline 2 ml, group 2 received 0.75% ropivacaine 28 ml with 5% ketamine 0.6 ml and normal saline 1.4 ml, group 3 received 0.75% ropivacaine 20 ml with normal saline 10 ml, and group 4 received 0.75% ropivacaine 20 ml with 5% ketamine 0.6 ml and normal saline 9.4 ml. At 1 minute intervals after IBPB, patients were assessed to determine loss of shoulder abduction, elbow flexion, wrist flexion and loss of pinprick in the deltoid, radial, median, and ulnar dermatomes. At 5 minute intervals after IBPB, pulse rate, blood pressure, sedation score and level of discomfort were assessed. Before discharge, patients were asked to document when incisional discomfort began and when full sensation and motor control returned to the arm.
RESULTS
The onset time of loss of pinprick and motor blockade were similar. Duration of sensory and motor blockade were similar in all groups. Hemodynamic changes and sedation scores were not significantly different in all groups.
CONCLUSIONS
We demonstrated that 30 mg of ketamine didn't enhance the onset and duration of sensory or motor blockade of ropivacaine during the 0.75% or 0.5% ropivacaine IBPB.