Endothelial activation is the common denominator that is associated with preeclampsia, sepsis syndrome, and acute hemorrhage-or frequently combinations thereof-and they are the most common predisposing factors to pulmonary edema (T able 47-4). As discussed, these clinical scenarios are often associated with corticosteroids given to induce fetal lung
TABLE 47-4. Some Causes and Associated Factors for Pulmonary Edema in Pregnancy
Noncardiogenic permeability edema: endothelial activation with capillary-alveolar leakage
Sepsis syndrome: pyelonephritis, metritis
Tocolytic therapy: �-mimetics, MgS04
Cardiogenic pulmonary edema: myocardial failure with maturation along with vigorous luid replacement and tocolytic therapy (Thornton, 2011). Parenteral 3-agonists are indisputably linked to pulmonary edema. Studies have also associated magnesium sulfate given for preeclampsia (Gandhi, 2014; Wilson, 2014; Xiao, 2014). Combined therapy is also causative. In one study of nearly 800 women given magnesium sulfate for preterm labor, 8 percent developed pulmonary edema, and half of this afected group had also received terbutaline (Samol, 2005).
Ventricular failure causing pulmonary edema in pregnancy is usually associated with some form of gestational hypertension. Although it can be due to congenital or acquired anatomical defects, diastolic dysfunction is frequently from chronic hypertension, obesity, or both (Jessup, 2003; Kenchaiah, 2002). In these women, acute systolic hypertension exacerbates diastolic dysfunction and causes pulmonary edema (Dennis, 2012; Gandhi, 2001). Of note, concentric and eccentric hypertrophy is two-to threefold more common in black women compared with white women (Drazner, 2005). In a case-control study of 28 gravidas with preeclampsia and pulmonary edema, half of them were undelivered (Gandhi, 2014).
In women with an underlying cardiomyopathy, heart failure is commonly precipitated by preeclampsia, hypertension, hemorrhage and anemia, and puerperal sepsis (Cunningham, 1986; Sibai, 1987). In many of these, when echocardiography is done later, systolic function is normal as measured by ejection fraction, but evidence for diastolic dysunction can often be found (Aurigemma, 2004). The use of brain natriuretic peptide (BNP) has not been evaluated extensively in pregnancy (Seror, 2014). his neurohormone is secreted from ventricle myocytes and fibroblasts with distention seen in heart failure. In nonpregnant patients, values < 100 pgl mL have an excellent negative-predictive value, and levels >500 pg/mL have an excellent positivepredictive value. It is problematic that levels frequently are 100 to 500 pg/mL, and thus nondiagnostic (Ware, 2005). Values for N-terminal BNP and atrial natriuretic peptide (ANP) are both elevated with preeclampsia (Szabo, 2014; Tihtonen, 2007). his is discussed in greater detail in Chapter 4 (p. 63), and normal values for pregnancy are given in the Appendix (p. 1259).