The optimal dose of hyperbaric tetracaine spinal anesthesia for cesarean section

Seventy-five term parturients undergoing cesarean section were anesthetized with 9 mg, 12 mg, 15 mg and 18 mg of tetracaine in 1.5 cc of 10% using a standardized spinal anesthetic technique. The four groups were compared for their maximal spread of anesthesia, quality of analgesia, incidence of hypotension, mgs of ephedrine used to correct hypotension, and the Apgar scores of the infant. It was found that maximal segmental spread of analgesia for 9 mg. 12 mg and 15 mg groups were not different significant regardless of height or weight. But with the 18 mg-group there was significant excessive spread of analgesia. While there was no difference in maximal spread of analgesia, there was a progressive increase in good quality of analgesia with increasing dosages. There were 67%, 81%, 96%, 100% of the patients had good analgesia for their operation in the four respective group. The percentages of hypotension were significanly more in the 15 mg and 18 mg groups. However, we did not find the hypotension in the 15 mg and 18 mg group need more ephedrine to correct than the lower dosages. In addition, all babies had good Apgar scores and there was no statistical difference among the four groups.