Acute respiratory failure in pregnancy. An analysis of 19 cases.

We studied 19 peripartum patients with acute respiratory failure associated with pregnancy. Although it is an uncommon event, noncardiogenic pulmonary edema is the most common cause of respiratory failure in the peripartum period. This acute lung injury syndrome was observed to be associated with a variety of complications of pregnancy including premature labor, the use of tocolytics, infection, hypertension, leukoagglutinin reactions, aspiration, abruptio placentae, and amniotic fluid embolism. From 1989 through 1992 there were 10,852 deliveries and 19 patients with noncardiogenic pulmonary edema at our institution. Analyzing these cases has led us to favor the hypothesis that the respiratory failure associated with the various complications of pregnancy primarily represents the fatal and nonfatal cases of amniotic fluid embolism that Steiner and Lushbaugh initially believed undoubtedly to exist. Moreover, we suggest, as have others, that the nonspecific symptom complex of inflammation, coagulopathy, and cardiopulmonary failure represents the release of soluble mediators into the maternal circulation. It is not clear what the predominant mediator is, but we have focused on platelet activating factor. It is also not established whether the mediator(s) is of amniotic fluid origin or a result of maternal anaphylactoid-type of response to a fetal or amnioplacental antigen. In conclusion, monitoring maternal oxygenation either directly or indirectly by oximetry should be considered routinely in the peripartum period, especially in complicated pregnancies, to detect at an early stage "asymptomatic" or preclinical cases of noncardiogenic pulmonary edema, in hopes of then modifying management to prevent their progression.