Placental blood flow during caesarean section performed under subarachnoid blockade.

Subarachnoid blockade using 0.5% bupivacine after a "preload" of Ringer's lactate solution 1500-2000 ml i.v. was studied in nine patients undergoing elective Caesarean section. Ephedrine infusion 50 mg in 500 ml was instituted at the first signs of maternal hypotension in seven patients. Although significant decreases in mean maternal systolic, mean and diastolic arterial pressures were recorded, the individual decreases in pressure were less than 30 mm Hg in all except two patients. In general placental blood flow did not change, although there was a marked increase in one patient with toxaemia and a decrease in one woman with diabetes mellitus. The babies were unaffected at delivery. Preventive measures, especially the "preload" infusion, are important in the maintenance of adequate placental perfusion in patients undergoing Caesarean section under subarachnoid blockade.