The hemodynamic derangement in severe pre-eclampsia (reduced plasma volume and low to normal cardiac output) increases the likelihood of oliguria and fetal distress, particularly following vasodilatation. Endothelial damage, low colloid osmotic pressure, and excessive fluid administration increase the risk of pulmonary edema. The principles of fluid management in severe pre-eclampsia are maintenance of strict fluid balance, selective hemodynamic monitoring, and selective plasma colloid expansion. Diuretic therapy should be limited to women with pulmonary edema.
The place of central venous and pulmonary artery wedge pressure monitoring in the management of women with severe pre-eclampsia is controversial. These procedures, particularly pulmonary artery catheterization, are not without risks, especially with concurrent coagulopathy. Therefore they should be instituted only when the benefits are thought to outweigh the hazards. Central venous pressure monitoring should be reserved for women with oliguria (defined as a urine output of less than 100 ml over 4 h) or hemorrhage (blood loss of more than 500 ml) and those having a Cesarean section. All women should receive maintenance crystalloid fluid, with subsequent management determined by urine output ( Fig, 2). Oliguria with a low central venous pressure (< 4 mmHg) is an indicator of hypovolemia, and a reasonable indication for colloid (400-500 ml of 5 per cent albumin solution or an appropriate alternative). The role of colloid in women with oliguria, a normal central venous pressure, and normal serum creatinine is unproven, and conservative management appears justified. Women who are hypovolemic secondary to hemorrhage require transfusion with the aim of keeping the hemoglobin level above 10 g/dl. Dopamine (1-5 ^g/kg/min) has been shown to increase urine output in euvolemic women.
Fig. 2 Fluid regimen for management of severe pre-eclampsia: CVP, central venous pressure; CXR, chest radiography.
Pulmonary artery catheterization should be considered in the following circumstances ( Clark and Cotton 1988).
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