Correct!
4. Pulmonary irradiation
The goal in this patient was to reduce his white blood cell count. In general, pulmonary leukostasis improves with a reduction of the white count (2,3). Leukapheresis will rapidly move white blood cells and was begun the night of admission. In addition, he was begun on chemotherapy consisting of daunorubicin, cytarabine, and hydroxyurea. Pulmonary irradiation is not helpful in resolving the pulmonary consolidation from pulmonary leukostasis (2). A major complication of treating very high white blood cell counts is tumor lysis syndrome (4). This occurs as a complication when large numbers of cancer cells die resulting in hyperkalemia, hyperphosphatemia, hyperuricemia and hyperuricosuria, hypocalcemia, and consequent acute uric acid nephropathy and acute renal failure. Large amounts of fluid were given along with xanthine oxidase inhibitors as prophylaxis against uric acid nephropathy. In addition he was treated empirically with broad-spectrum antibiotics as well as anti-fungals and anti-virals.
His white blood cell count decreased to 30,000 cells/mm3 and he remained relatively stable and afebrile. His platelet count was low but he was given intermittent platelet transfusions and vitamin K for intermittent mild hemoptysis. Although his FiO2 was high 0.60, he demanded to be extubated on hospital day 3. After extubation he was given oxygen by high flow nasal cannula. His arterial blood gases were PaO2 of 72 mm Hg, PaCO2 of 32 mm Hg, pH of 7.48, and a HCO3- of 24 mEq/L. A repeat portable chest x-ray was performed (Figure 3).
Figure 3. Portable AP of chest after extubation.
A thoracic CT scan was performed because of his continuing hypoxia (Figure 4).
Figure 4. Representative static views from the thoracic scan (Panels A-D, left). Movie of thoracic CT scan (right).
Which of the following is the best explanation for his failure to resolve his ongoing pulmonary process?