Chapter 83 Care of the Critically Ill Pregnant Patient
2 How does pregnancy affect hemodynamics?
Cardiovascular physiology changes significantly during pregnancy, characterized by an increase in blood volume, an elevation in cardiac output, and a small decrease in blood pressure, resulting in a number of changes in the normal hemodynamic values in the third trimester (Table 83-1). In the supine position, the gravid uterus may produce significant mechanical obstruction of the inferior vena cava, reducing venous return and resulting in a decrease in cardiac output and hypotension. Maternal syncope or fetal distress may result. Supine hypotension syndrome may be avoided by positioning the patient on her left side, or at least with the right hip slightly elevated.
Parameter | Change from nonpregnant value |
---|---|
Central venous pressure | No change |
Pulmonary capillary wedge pressure | No change |
Cardiac output | 30%-50% increase |
Systemic vascular resistance | 20%-30% decrease |
Pulmonary vascular resistance | 20%-30% decrease |
Oxygen consumption | 20%-40% increase |
Oxygen extraction ratio | No change |
4 Are there any special concerns to be considered when inserting an endotracheal tube in a critically ill pregnant patient?
5 Describe the principles of management of severe preeclampsia
Patients with preeclampsia usually have volume depletion and require volume expansion, but excessive fluid administration may result in pulmonary or cerebral edema.
Hypertension is managed to prevent maternal vascular damage and does not alter the pathologic process of preeclampsia. Commonly used regimens include small boluses of hydralazine (5–10 mg intravenous [IV]), boluses or infusion of labetalol, or oral calcium antagonists.
Seizure prophylaxis should be undertaken with magnesium sulfate, with use of a loading IV bolus of 4 g over a 20-minute period followed by an infusion of 2 to 3 g/hour. Toxic levels (usually > 5 mmol/L) can cause respiratory muscle weakness and cardiac conduction defects and are usually seen in a patient with associated renal failure. Hypocalcemia is common and should not be treated unless symptomatic. The effects of magnesium sulfate (toxic as well as therapeutic) can be reversed with IV calcium.
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