Onset Time of Brachial Plexus Block Using Local Anaesthetic Diluted With 0.9% Saline vs 5% Dextrose
Status:
Completed
Trial end date:
2012-10-01
Target enrollment:
Participant gender:
Summary
Regional anesthesia employs the use of local anesthetics (LA) to block specific nerves to
enable pain free surgery to be performed, or for intra and post operative pain relief.
Dilution of local anesthetics with normal saline (NS) is a common practice to enable larger
volumes of LA to be given, for example, in instances where multiple nerve blocks are needed
to be performed for optimal pain relief while avoiding toxic doses.
A high sodium concentration is known to antagonize the analgesic effect of local anesthetics.
5% dextrose (D5W) on the other hand is painless on injection and does not cause any long-term
effects in animals or humans when injected around neurological tissue. In the literature,
only one study using dextrose 5% as diluent to produce 0.5% ropivacaine for axillary brachial
plexus block showed a statistically significant reduction in the onset time for sensory
blockade when compared with dilution with NS.
In this study, 0.5% ropivacaine diluted with D5W or NS is used for ultrasound guided
supraclavicular brachial plexus block, and the time for complete sensory and motor blockade
was compared. 0.5% ropivacaine is easily diluted and is a common concentration used at our
centre for nerve blocks. The aim of this study is to assess if 0.5% ropivacaine diluted with
D5W results in a shorter onset time for sensory block which may change the current practice
of dilution with NS