Comparative effects of subarachnoid hyperbaric bupivacaine and tetracaine-procaine for cesarean delivery.

Hyperbaric solutions of 0.75% bupivacaine (8.25% dextrose), and 1% tetracaine mixed with an equal volume of 10% procaine were compared in a double-blind study of 22 parturients undergoing elective cesarean delivery and spinal anesthesia. The onset of sensory anesthesia and motor block was similar in the two groups. The maximal level of sensory anesthesia to pinprick was significantly higher after the use of the tetracaine-procaine mixture. The adequacy of anesthesia was similar in both groups as indicated by the lack of differences with regard to anesthetic supplementation between the groups. However, a significantly shorter duration of sensory anesthesia and motor blockade occurred in the group in which bupivacaine was employed. The incidence of hypotension was higher in those patients receiving the tetracaine-procaine mixture as indicated by the use of significantly higher total doses of ephedrine to maintain baseline blood pressure in this group. No differences in Apgar scores or blood gases were noted between the two groups of patients. This study suggests that hyperbaric 0.75% bupivacaine offers certain advantages over hyperbaric tetracaine-procaine when used in equal volumes for spinal anesthesia cesarean delivery.