[Ephedrine administration for cesarean section under spinal anesthesia].
Prophylactic ephedrine was administered to healthy parturients undergoing elective cesarean section under spinal anesthesia. The methods of ephedrine administration were as follows: intramuscular injection of 0.3 mg/kg, 15 minutes before the block (20 cases: group M), infusion of 0.02% solution immediately after the block (20 cases: group D), premedication with atropine 0.5 mg and infusion immediately after the block (20 cases: group AD). The mean ephedrine dosage was 18.8 +/- 2.2 gm (SD) in group M, 12.6 +/- 6.2 mg in group D and 5.2 +/- 0.7 mg in group AD, and there were significant differences among the three groups. The base line (a), the minimal postanesthetic (b) and the maximal postpartum systolic blood pressures (c) revealed no significant difference among the three groups, and 'b' was significantly higher than 'a' and lower than 'c' in all groups. Only one case (group M) was transiently hypotensive, while hypertension was not found in any of the subjects. One- and 5-minute Apgar scores were 8 or more in all, and umbilical acid-base values were within normal limits in all of them, though the base deficit in group AD was significantly lower than that in group M. Atropine premedication makes it possible to retrench the ephedrine dosage without any harmful effect on either mother or fetus, and ephedrine infusion makes it easy to cope with changes in maternal blood pressure. Consequently, for healthy parturients receiving elective cesarean section under spinal block, we recommend atropine premedication and minimal infusion of ephedrine immediately following the block.