Reversible respiratory failure due to intravascular leukostasis in chronic myelogenous leukemia. Relationship of oxygen transfer to leukocyte count.

In a 49 year old man with blast crisis and massive leukocytosis due to chronic myelogenous leukemia, severe hypoxic respiratory failure developed despite a normal chest film. Correction of hypoxemia was observed after reduction of the white blood cell count by hydroxy-urea therapy. A similar episode occurred prior to death, and necropsy examination revealed extensive plugging of the pulmonary vasculature by leukemic blast cells but no infection or pulmonary edema. An inverse linear correlation was demonstrated between the peripheral white blood cell count and the efficiency of oxygen transfer in the lung as determined by the arterial to alveolar oxygen tension ratio. We postulate that mechanical obstruction and/or leukocyte mediated capillary endothelial injury caused the severe leukocyte mediated capillary endothelial injury caused the severe hypoxemia. Abnormalities of pulmonary gas exchange may be common in leukemic patients with markedly increased leukocyte counts.