Cardiorespiratory pathology and pathophysiology

Patients with severe pre-eclampsia are predisposed to the development of pulmonary edema because of low oncotic pressure and altered capillary permeability with or without left ventricular dysfunction (systolic or diastolic) (Belfort et al., 1991; Visser and Wallenberg, 1991). Left ventricular diastolic dysfunction increases the risk of pulmonary edema following rapid plasma volume expansion; even small aliquots of intravenous fluids have been shown to cause a sharp rise in left-sided filling pressures, usually without any changes in central venous pressure. Iatrogenic fluid overload is consequently a frequent cause of pulmonary edema among these patients. Undiagnosed occult valvular disease may also increase the risk of pulmonary edema in hypertensive patients.

Other causes of respiratory distress include atelectasis and aspiration pneumonia. Atelectasis giving rise to respiratory distress may follow surgery and is also seen among patients with HELLP syndrome, who often splint the right hemi-diaphragm because of pain associated with hepatic ischemia. Aspiration pneumonia may develop as a result of eclampsia.

Adult respiratory distress syndrome (ARDS) is often cited as a complication of pre-eclampsia but is an unlikely primary complication of the disease although it may follow aspiration pneumonia or prolonged ventilation. Reporting the occurrence of ARDS in an obstetric intensive care unit, Mabie et al. found only 16 cases of respiratory distress attributable to ARDS over a 6-year period (Mabie et al., 1992). Only 4 of these 16 cases were linked to pre-eclampsia/eclampsia. Three of these four cases had additional complications that may have contributed to the development of ARDS (including aspiration pneumonia, lupus nephritis, sepsis and a ruptured liver hematoma with massive blood transfusion). The fourth case had pulmonary edema that developed into ARDS after the patient had a respiratory arrest. These observations are important because most cases of respiratory distress will have a cardiogenic component amenable to intervention. ARDS should never be accepted as a primary diagnosis in pre-eclampsia/eclampsia.

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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