MATERNAL AND FETAL COLLOID OSMOTIC-PRESSURE FOLLOWING FLUID EXPANSIONDURING CESAREAN-SECTION

Objectives: To characterize the changes in colloid osmotic pressure du ring delivery and to determine the relationship between maternal and f etal colloid osmotic pressures. Design: Clinical, prospective study. S etting: Obstetrical operating theater in a tertiary care university ho spital.Patients: Thirty healthy parturient patients, at term gestation receiving spinal anesthesia for: elective cesarean section. Intervent ions: None. Measurements and Main Results: Maternal colloid osmotic pr essure samples were obtained at the time of intravenous insertion and delivery, Fetal umbilical vein and umbilical artery colloid osmotic pr essure samples were measured from the umbilical cord at delivery. The volume of intravenous infusion and dose of ephedrine were recorded for each patient, Maternal colloid osmotic pressure at delivery was signi ficantly less than that value measured at the time of intravenous cath eter insertion in each patient (15.8 +/- 0.3 vs. 23.1 +/- 0.3 mm Hg; p < .0001). Umbilical artery colloid osmotic pressure was consistently higher than umbilical vein colloid osmotic pressure (21.0 +/- 0.4 vs. 19.4 +/- 0.3 mm Hg; p < .0001), Both umbilical artery colloid osmotic pressure and umbilical vein colloid osmotic pressure were significantl y higher than maternal colloid osmotic pressure at delivery (p < .0001 ). The volume of intravenous infusion and the dose of ephedrine both c orrelated inversely with maternal colloid osmotic pressure measured at delivery (p < .05). Conclusions: The reduction in maternal colloid os motic pressure during delivery is, in part, related to intravenous flu id expansion and the amount of vasopressor administered, Despite the s ignificant fluctuations in maternal colloid osmotic pressure, the plac enta and fetus possess the capability to alter colloid osmotic pressur e.