Ultrasonography for Fluid Assessment in Parturients With Preeclampsia Undergoing Cesarean Section

Overview

Preeclampsia is a multifocal syndrome reported in 2-8 % of pregnancies. It is diagnosed in the second half of pregnancy by two separate measurements of systolic blood pressure ≥140 mmHg and/or a diastolic blood pressure ≥ 90 mmHg in the same arm and proteinuria \>300 mg in 24 h urine collection. The risk for serious complications such as pulmonary edema, cerebrovascular accidents, coagulopathy, and hemorrhage is 10 to 30 fold higher among parturients with severe preeclampsia. Severe preeclampsia is defined by one or more of the following clinical features: severe hypertension (systolic arterial pressure 160 mmHg and/or diastolic arterial pressure 110 mmHg on more than one occasion at least 4 h apart while the patient is on bed rest, renal dysfunction (serum creatinine \>1.1mg/dl or doubling of serum creatinine in the absence of another renal disease, platelet count less than \<100,000 mm3, acute pulmonary edema, epigastric pain not responding to medical treatment, new-onset cerebral and visual manifestation, hemolysis, elevated liver enzymes and low platelet count syndrome (HELLP syndrome)

Fluid resuscitation is a key determinant in the management of these parturients. Hypovolemia exacerbates organ failure, whereas volume overload results in pulmonary edema. In this setting, the use of noninvasive hemodynamic monitoring is associated with reduced mortality. Point-of-care lung ultrasonography is used in many critical care settings as the initial diagnostic imaging study for patients with respiratory symptoms. It is highly sensitive for the diagnosis of pulmonary edema which may occur even without cardiomyopathy or heart failure. The IVC is a highly compliant vessel that changes its diam¬eter in parallel with changes in blood volume and central venous pressure. Measurement of IVC diameter and col¬lapsibility index using ultrasound through a subcostal approach has been investigated in patients of various settings. The IVC-CI imaging technique may be used to assess the volume status in healthy parturients undergoing routine cesarean delivery as well as in high-risk parturients as preeclampsia. Cerebral edema is predominantly vasogenic and may be related to the failure of cerebral autoregulation with subsequent hyperperfusion, blood-brain barrier disruption, and endothelial cell dysfunction. Ultrasonographic measurements of the optic nerve sheath diameter (ONSD) correlate with signs of raised ICP.