Correct!
1. A normal chest x-ray in a hospitalized hypoxic patient should prompt a search for a pulmonary embolism.

The post-operative portable chest x-ray is fairly unremarkable. There is loss of the left diaphragm shadow which would be expected from left lower lung atelectasis and/or pleural effusion which usually occurs with a Nissen. However, they are relatively mild and unlikely to explain the hypoxemia seen with a FiO2 of 100%. The endotracheal tube is in satisfactory position about 2-3 cm above the main carina. The lungs are relatively clear and although the diaphragms are somewhat elevated, but paralyzed diaphragms require a sniff test for diagnosis. Furthermore, hypoxia from paralyzed diaphragms would be accompanied by pCO2 retention and relieved by mechanical ventilation.

Pulmonary embolism is common and frequently misdiagnosed in hospitalized patients. In patients who do not have a good explanation of their hypoxemia a search for pulmonary embolism would be a logical next step. A chest CT angiography was performed (Figure 2).

Figure 2. Representative images from the thoracic CT scan. (Click here for a movie of the CT angiogram)

Which of the following is true regarding the CT scan?

1. There is a large saddle embolism which should be surgically removed.
2. There is a filling defect in the pulmonary artery and the patient should be anticoagulated.
3. There is a filling defect in the pulmonary artery and the patient should have an inferior vena cava filter inserted.
4. There is a large pleural effusion which should be drained.
5. There is no pulmonary embolism.

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