Influence of barbotage on block characteristics during spinal anesthesia with hyperbaric tetracaine and bupivacaine.

Barbotage is the aspiration of the injected volume back into the syringe followed by reinjection twice, with 0.5 ml increases in each aspirated volume. The effects of this technique versus injection without barbotage, on the spinal anesthetic spread of 0.5% tetracaine or 0.5% bupivacaine in 5% glucose 4 ml each, were investigated in 80 men undergoing urologic surgery. The local anesthetic solutions were randomly injected into four groups of 20 patients each, and the anesthetic profile of each solution was then evaluated in a double-blind fashion for the two techniques (barbotage/without barbotage) by an independent observer. In the tetracaine groups, barbotage was associated with a higher dermatome level and shorter time to reach this compared with tetracaine without barbotage. Barbotage caused the latency of bupivacaine to be shorter, but the actual time difference was small and clinically not relevant. Comparing tetracaine and bupivacaine, tetracaine with barbotage achieved a higher segmental level. Time to highest dermatome, however, was shorter for bupivacaine with barbotage compared with tetracaine with barbotage. Barbotage shortened the onset of 3+ motor block with bupivacaine. This difference was statistically significant. Results suggest that barbotage is useful to shorten the time for full development of analgesia when using 0.5% hyperbaric tetracaine. Barbotage with 0.5% hyperbaric bupivacaine, however, has the advantage of intensifying and shortening the onset time of a complete motor block.