Alveolar-arterial oxygen gradient in acute pulmonary embolism in pregnancy.

Abstract

Our goal was to determine the prevalence of normal alveolar-arterial gradients in pregnant patients with documented pulmonary embolism. A retrospective chart review was performed on all pregnant women with pulmonary embolism at two large obstetric centers between 1990 and 1995. Alveolar-arterial gradients were calculated from room air arterial blood gas values and compared with values from patients who had been established as normal. Ten of 17 patients with pulmonary embolism identified had alveolar-arterial gradients that were normal. In our study 58% of pregnant women with documented pulmonary embolism had a normal alveolar-arterial gradient. This markedly differs from the published data in nonpregnant patients, in which the incidence of normal alveolar-arterial gradients in pulmonary embolism has ranged from 1.9% to 20%. This suggests that the alveolar-arterial gradient should not be used to determine the likelihood of pulmonary embolism in pregnant women because this could lead to the withholding of appropriate treatment for this life-threatening condition.