Colloid vs. crystalloid preloading to prevent maternal hypotension during spinal anesthesia for elective cesarean section

Background:  Hypotension associated with spinal anesthesia for cesarean section is still a clinical problem. Colloid solutions seem preferable to crystalloid solutions for preloading. In most studies the overall rate of hypotension is reported. Few studies have, however, investigated the maternal and neonatal consequences of different levels of maternal hypotension.
Methods:  In this randomized, double-blinded study 110 patients presenting for elective cesarean section received either 1000 ml acetated Ringer's solution or 1000 ml 3% dextran 60 solution immediately before spinal anesthesia. The effect on overall hypotension, clinically significant hypotension (hypotension associated with maternal discomfort defined as nausea, retching/vomiting, dizziness or chest symptoms) and severe hypotension (systolic arterial pressure <80 mmHg) was studied.
Results:  Dextran reduced the incidence of overall hypotension from 85 to 66% ( P =  0.03), reduced the incidence of clinically significant hypotension from 60 to 30% ( P =  0.002) and reduced the incidence of severe hypotension from 23 to 3.6% ( P =  0.004) compared to Ringer's solution. There were neither differences in neonatal outcome between treatment groups nor between neonates grouped after severity of maternal hypotension.
Conclusion:  Clinically significant hypotension seems to be a more suitable outcome variable than overall hypotension. The protective effect of the colloid solution increased with increased severity of hypotension.