Spinal anesthesia with tetracaine--effect of added vasoconstrictors

The effect of adding 0.2 ml of 1:1000 epinephrine or 0.5 ml of 1% phenylephrine to 1.5 ml of 1% tetracaine for spinal anesthesia was assessed in 30 patients in a double-blind study. Phenylephrine but not epinephrine produced a significant prolongation of sensory loss in the T12 dermatome. Both vasoconstrictors produced a significant prolongation of the total duration of sensory and motor blockade. These findings differ from those in previous studies in which lidocaine and bupivacaine were used.