[Spinal anesthesia for cesarean section with 0.5% isobaric bupivacaine plus fentanyl and morphine: prospective study with different volumes].

BACKGROUND AND OBJECTIVES

Spinal block for cesarean section was described few years after the first report of spinal anesthesia by Bier in 1899. It was not until the last 5 years that spinal anesthesia has become the most frequent anesthetic method for cesarean section at our hospital. This prospective study aimed at evaluating 0.5% spinal isobaric bupivacaine for cesarean section, injected after fentanyl and morphine, in the lateral position, and at correlating the incidence of hemodynamic changes and cephalad spread with different volumes.

METHODS

Participated in this study 100 patients undergoing spinal anesthesia for elective cesarean delivery who were randomly allocated into three groups to receive: 4 ml (20 mg), 3 ml (15 mg) or 2.5 ml (12.5 mg) of 0.5% isobaric bupivacaine after 25 microg fentanyl plus 50 microg morphine. The following parameters were evaluated and compared: analgesia and motor block onset, cephalad spread of analgesia, cardiovascular changes and the incidence of nausea and vomiting.

RESULTS

The three volumes of 0.5% isobaric bupivacaine produced comparable effects. Onset was longer for the lowest dose. There were no differences in cephalad spread, number of patients with high cervical levels, cardiovascular changes and post dural puncture headache. Maximum analgesic level was T4 (range: T3-T6) with 4 ml, T4 (range: T4-T11) with 3 ml and T4 (range: T4-T8) with 2.5 ml. No patient required ephedrine to treat arterial hypotension. Motor block was incomplete for all patients. One patient developed post dural puncture headache.

CONCLUSIONS

Results of this study confirm that 0.5% isobaric bupivacaine, following fentanyl and morphine injected with separate syringes and in the lateral position, in doses of 2.5, 3 and 4 ml provides a fast and effective anesthesia for cesarean section.