A 31-year-old primiparous female gave birth 10 hours ago after preterm labor. The delivery was vaginal and proceeded without complications under epidural analgesia. The baby is a 25-week gestational age female and weighs 1780 g. Terbutaline administration failed in delaying the delivery. The mother has a history of anaphylaxis triggered by NSAIDs, past history of deep venous thrombosis, hypertension, and hypothyroidism. She has had a dry cough with mild fever and malaise for the past 10 days treated with amoxicillin. The patient now develops acute onset dyspnea and cannot speak in full sentences. She denies pain. Vitals are:
Bilateral rales and wheezing at the left base is heard on auscultation, cardiac sounds are normal, no jugular distension is observed, the skin is warm and well perfused. Blood gas analysis:
What is the MOST likely cause of the patient’s respiratory failure?a. Pulmonary embolism
Correct Answer: C
Although infrequent, tocolytic pulmonary edema is triggered by drugs such as beta-agonists and calcium antagonists, with symptoms occurring within 12 hours after delivery. It is a purely hydrostatic edema occurring in the presence of normal cardiac function and results in a marked increase in the arterial-alveolar gradient and a hypoxic-nonhypercapnic respiratory failure. Pulmonary embolism (PE) is an important differential, especially with high alveolar-arterial gradient and history of deep venous thrombosis. However, PE with this degree of shunt would typically be accompanied by some degree of right heart failure. This patient does not have clinical signs of right cardiac failure (no gallop, jugular distension, or hypotension). The acuity of presentation makes pneumonia a less likely diagnosis. Peripartum cardiomyopathy and heart failure is another important differential. Although the respiratory signs and symptoms are compatible with cardiac failure, stable hemodynamics and adequate peripheral perfusion poorly fit with that clinical scenario.