Role of volume expansion in severe pre-eclampsia.

Fifteen primigravid patients with severe pregnancy-induced hypertension were studied by catheterization of the right side of the heart. A hemodynamic protocol was implemented that required maintaining colloid osmotic pressure above 17 millimeters of mercury, pulmonary capillary wedge pressure below 15 millimeters of mercury and the mean arterial pressure in a very narrow range throughout labor and delivery and for 48 hours postpartum. The initial colloid osmotic pressures and pulmonary capillary wedge pressures were 18.0 +/- 2.6 and 10.5 +/- 4.0 millimeters of mercury, respectively, and remained essentially unchanged throughout the post partum period. The only benefit derived from volume expansion in these patients appeared to be the absence of acute fetal distress after the initiation of antihypertensive therapy. Six of 15 patients had late fetal stress develop during labor, suggesting that aggressive volume repletion and colloid osmotic pressure correction in pregnancy-induced hypertension does not effect the over-all incidence of fetal distress. We recommend that correction of colloid osmotic pressure be restricted to instances in which extremely low values (less than 12 millimeters of mercury) or a prolonged negative colloid osmotic pressure to pulmonary capillary wedge pressure gradient are identified. Finally, the benefit of volume expansion in pregnancy-induced hypertension appears to be the prevention of sudden and profound drops in blood pressure with antihypertensive therapy--not the prevention of fetal distress during labor.