Spinal anesthesia with hyperbaric bupivacaine: effect of added vasoconstrictors

The effect of adding 0.2 ml of 1:1000 epinephrine or 0.5 ml of 1% phenylephrine to 3 ml of 0.5% bupivacaine in 8% dextrose for spinal anesthesia was assessed in 30 patients in a double-blind study. The addition of phenylephrine gave a small prolongation of the block which was not statistically significant. Although epinephrine produced a greater prolongation, this only reached statistical significance with regard to total duration. Three patients who received solutions that contained a vasopressor had prolonged blocks, but these solutions could not be relied upon to produce consistently a clinically significant increase in duration in individual patients.