Acute pulmonary edema requires emergency care. Furosemide is given in 20-to 40-mg intravenous doses along with therapy to control severe hypertension. Further treatment depends on whether a woman is ante-or postpartum. A live fetus prohibits the use of cardioactive drugs that might rapidly lower peripheral resistance and in turn severely diminish uteroplacental circulation. he cause of cardiogenic failure is determined by echocardiography, which will help direct further therapy. Acute pulmonary edema is not, per se, an indication for emergency cesarean delivery.
Acute lung injury that causes a form of severe permeability pulmonary edema and respiratory failure is termed acute respiratory distress syndrome (ARDS). This is a pathophysiological continuum from mild pulmonary insuiciency to dependence on high inspired oxygen concentrations and mechanical ventilation. Uniform criteria for its diagnosis are lacking, and thus the incidence is variably reported for pregnancy. In one survey of the Nationwide Inpatient Sample, 2808 pregnant women with ARDS were identified (Rush, 2017). he incidence ranged from 36 to 60 cases per 100,000 births, and the maternal mortality rate was 9 percent. In its most extreme form, requiring ventilatory support, the associated mortality rate is 45 percent. This rate can be as high as 90 percent if caused or complicated by sepsis (Phua, 2009). Although gravidas are younger and usully healthier thn the overall population, they still have mortality rates of 25 to 40 percent (Catanzarite, 2001; Cole, 2005). Finally, if ARDS develops antepartum, the perinatal mortality rate is correspondingly high.
Most investigators define ARDS as radiographically documented pulmonary iniltrates, a ratio of arterial oxygen tension to the fraction of inspired oxygen (Pao2:Fio2) <200, and no evidence of heart failure (Mallampalli, 2010; hompson, 2017). Revised by international consensus, the Berlin Dinition was described by the ARDS Definition Task Force (2012) and includes categories of mild, moderate and severe. To date, for most interventional studies, a working diagnosis of acute lung injuy is made when the Pao2:Fio2 ratio is <300 and is coupled with dyspnea, tachypnea, oxygen desaturation, and radiographic pulmonary infiltrates (Wheeler, 2007).
ARDS is a pathophysiological description that begins with an acute lung injury from various causes (Table 47-5). In pregnant
TABLE 47-5. Some Causes of Acute Lung Injury and Respiratory Failure in Pregnant Women
Pneumonia: bacterial, viral, aspiration
Sepsis syndrome: chorioamnionitis, pyelonephritis, puerperal infection, septic abortion
Hemorrhage: shock, massive transfusion, transfusion-
Embolism: amnionic fluid, trophoblastic disease, air, fat
Data from Cole, 2005; Duarte, 2014; Golombeck, 2006; Lapinsky, 2015; Martin, 2006; Sheffield, 2005; Sibai, 20104; Snyder, 201n3; Zeeman, 2003, 2006.