Correct!
3. Spiral thoracic CT angiography
The patient’s chest x-ray shows bilateral areas of lung consolidation and he is hypoxic (SpO2 81%). At this juncture the etiology is unclear. Both an urinanalysis and complete blood count are indicated in the presence of diffuse lung consolidation and hypoxia since many lung diseases are also associated with abnormalities in the blood count and urinanalysis. A spiral thoracic CT angiogram is usually done for pulmonary embolism. However, the pre-test probability of pulmonary embolism is low in this case and spiral CT thoracic angiogram should not be performed (1). He has had a 2 week long history of progressive dyspnea and has not known risk factors for pulmonary embolism.
His arterial blood gases showed a PaO2 of 46 mm Hg, PaCO2 of 28 mm Hg, pH of 7.53 and a HCO3- of 23 mEq/L on a non-rebreather mask. His hemoglobin is 6.0 g/dL, white blood cell count of 293,000 cells/mm3 and a normal urinanalysis other than a specific gravity of 1.030.
Which of the following is the best next step in the management of this patient?