THE MATERNAL HEMODYNAMIC-EFFECTS OF BUPIVACAINE-EPINEPHRINE MIXTURE USED FOR OBSTETRICAL-ANESTHESIA

The maternal hemodynamic effects of bupivacaine (0.5%)‐epinephrine (5 μg/ml) mixture used for lumbar epidural anesthesia were studied with an impedance cardiograph and an automated blood pressure device in term gravidas undergoing elective cesarean section. Following i.v. hydration with 2000 ml Ringer' s lactate solution, 16 patients received bupivacaine‐epinephrine mixture and 16 patients plain bupivacaine in 5‐ml increments to a T4 level. Measurements were made before anesthesia, at T10 and at T4 sensory levels. Results were analyzed using analysis of variance (ANOVA) and the least significant difference method at P<0.05. In the epinephrine group, at T10 level, the diastolic (D) and mean (M) pressures decreased significantly 11 ± 3, and 10 ± 1 % (mean ± s.e.mean) respectively with no significant change in the S pressure. No significant changes were seen in the plain group. At T4, the S, D and M pressures decreased significantly 8 ± 2, 18 ± 4 and 16 ± 2% in the epinephrine group. In the plain group the decrease in each one of these pressures was less than 5% and was not significant. In the epinephrine group, S, D and M pressures decreased significantly more than they did in the plain group at T10 and T4. Systemic vascular resistance decreasd significantly from control values by 19 ± 6% at T4 in the epinephrine group with no significant changes in the plain group. No significant differences were seen in cardiac output (CO), stroke volume and heart rate (HR) in either group at T10 or T4 levels, compared to the baseline value or compared to the other group. It is concluded that epidurally administered epinephrine produces mainly a β‐2 mediated vasodilatation without any evidence of u‐agonism or changes in CO or HR. © 1990 Acta Anaesthesiologica Scandinavica Fonden