From the Guidelines
In preeclampsia, cardiac output may be either reduced or increased, while peripheral vascular resistance is typically increased, and fluid balance should aim for euvolemia to avoid risks of pulmonary edema and ensure adequate organ perfusion. The changes in cardiac output and peripheral vascular resistance in preeclampsia are complex and can vary depending on the stage of the disease. According to the most recent and highest quality study 1, preeclamptic women may have either reduced or increased cardiac output, and the goal of fluid management should be to achieve euvolemia, replacing insensible losses and anticipated urinary losses to avoid risks of pulmonary edema.
Key Hemodynamic Changes
- Cardiac output may be reduced or increased in preeclampsia
- Peripheral vascular resistance is typically increased
- Fluid balance should aim for euvolemia to avoid risks of pulmonary edema and ensure adequate organ perfusion
- Insensible losses should be replaced (30 mL/h) along with anticipated urinary losses (0.5–1 mL/kg per hour)
The increased peripheral vascular resistance in preeclampsia results from widespread vasoconstriction caused by endothelial dysfunction, increased sensitivity to vasopressors, and release of anti-angiogenic factors. The endothelial damage leads to capillary leak, edema, and reduced plasma volume, further compromising cardiac function. Understanding these hemodynamic alterations is crucial for appropriate management of preeclampsia, as they differ significantly from the normal pregnancy state of increased cardiac output and decreased peripheral vascular resistance. The use of intravenous antihypertensives may be needed to control blood pressure, particularly if it becomes severe, as reduced gastrointestinal motility may decrease absorption of antihypertensives after oral administration 1.
Clinical Implications
- Preeclamptic women are at risk of capillary leak and reduced plasma volume, which can compromise cardiac function
- Fluid management should aim for euvolemia to avoid risks of pulmonary edema and ensure adequate organ perfusion
- Intravenous antihypertensives may be needed to control blood pressure, particularly if it becomes severe
- Close maternal and fetal surveillance are essential to promptly identify worsening of the maternal condition, laboratory evidence of end-organ dysfunction, or fetal distress, which may require prompt delivery.
From the Research
Changes in Cardiac Output
- In preeclampsia, cardiac output is decreased 2, but a more recent study found that early and late preeclampsia are characterized by high cardiac output 3.
- However, when preeclampsia presents with fetal growth restriction, cardiac output is low 3.
- Another study found that women with preeclampsia had significantly elevated cardiac outputs before clinical diagnosis, but total peripheral resistance was not significantly different during this latent phase 4.
Changes in Peripheral Vascular Resistance
- Peripheral vascular resistance is increased in preeclampsia 2.
- A study found that women with preeclampsia had lower peripheral vascular resistance Z scores, while those with fetal growth restriction had higher peripheral vascular resistance Z scores 3.
- In the clinical phase of preeclampsia, there is a marked increase in peripheral resistance 4.
Relationship between Cardiac Output and Peripheral Vascular Resistance
- The relationship between cardiac output and peripheral vascular resistance in preeclampsia is complex and may depend on the presence of fetal growth restriction 3.
- A study found that preeclampsia is associated with high cardiac output, but if preeclampsia presents with fetal growth restriction, the opposite is true; both conditions are nevertheless defined by hypertension 3.
- Fetal growth restriction without preeclampsia is associated with high peripheral vascular resistance 3.