Pseudopulmonary embolism: acute respiratory distress in the syndrome of heparin-induced thrombocytopenia.

A 73-year-old man with myasthenia gravis was treated with daily plasmapheresis. During the course of treatment, the patient developed progressive thrombocytopenia and an episode of severe acute respiratory distress suggesting pulmonary embolism. The thrombocytopenia and respiratory impairment improved after discontinuation of heparin, and both recurred on heparin rechallenge. The presence of heparin-specific antibodies was confirmed by in vitro assay. The time frame of clinical events suggests a heparin-mediated mechanism for both the thrombocytopenia and respiratory compromise. We conclude that acute respiratory distress may be the presenting manifestation of the syndrome of heparin-associated thrombocytopenia in patients treated with dialysis or apheresis.