Abstract

The anesthetic properties of hyperbaric bupivacaine and tetracaine administered intrathecally were compared in a double-blind, randomized study involving 40 healthy surgical patients. This investigation employed solutions of the two agents that contained equal doses (15 mg), concentration (0.375%), volumes (4 ml), and glucose concentration (5%). No statistically significant difference in onset and duration of surgical anesthesia was observed between the two solutions. However, the maximum spread of sensory anesthesia was greater in the bupivacaine group, while the total duration of sensory anesthesia was longer in the tetracaine group. Tourniquet pain or inadequate anesthesia occurred in 35% of the patients in the tetracaine group compared to 10% of the bupivacaine-treated patients. This difference, however, was not statistically significant. The onset and intensity of motor block were similar in both groups. However, tetracaine produced a significantly longer duration of motor blockade of the lower limbs than did bupivacaine. The results suggest that equal concentrations and dosages of hyperbaric tetracaine and bupivacaine possessed similar anesthetic qualities following subarachnoid administration.