[Addition of sodium bicarbonate and/or clonidine to mepivacaine: influence on axillary brachial plexus block characteristics].

BACKGROUND AND OBJECTIVE

The axillary brachial plexus block is a frequently performed anesthetic technique. Adding a variety of coadjuvant drugs has been shown to improve results. This study evaluated the addition of sodium bicarbonate (NaHCO3) and/or clonidine to mepivacaine for performing the block.

MATERIAL AND METHODS

Sixty patients between 18 and 70 years old, ASA 1-3 in stable condition received axillary brachial plexus blocks in a randomized controlled study. Four groups of 15 patients each were formed: group I (control group) received 40 mL of 1% mepivacaine with adrenaline plus 5 mL of saline; group II, 40 mL of 1% mepivacaine with adrenaline plus 4 mL of NaHCO3 and 1 mL of saline; group III, 40 mL of 1% mepivacaine with 150 microg of clonidine plus 4mL of saline; and group IV, 40 mL of 1% mepivacaine with adrenaline plus 4 mL of NaHCO3 and 150 microg of clonidine.

RESULTS

The onset time was significantly shorter in groups 2 and 4. The duration of the block was longer in group 3 and the analgesic effect was significantly better.

CONCLUSIONS

Adding NaHCO3 to mepivacaine shortens the time of onset of an axillary brachial plexus block. Including clonidine prolongs the duration of anesthesia and analgesia. The addition of both NaHCO3 and clonidine shortens time to onset but does not prolong duration of anesthesia or analgesia.