The Virtual Hospital: ElectricPE: The Diagnosis of Pulmonary Embolism: Interstitial Lung Disease

ElectricPE: The Diagnosis of Pulmonary Embolism: Case Study 6

Interstitial Lung Disease

Jeffrey R. Galvin, M.D. and James J. Choi, B.S.
Peer Review Status: Internally Reviewed

This case was a 75 year old male, with known idiopathic pulmonary fibrosis (IPF) who was transferred from his local hospital with rapidly progressing shortness of breath. He was tapered off of his steroid medication 2 weeks prior to admission and now was breathless at rest. His pulmonary functions demonstrated restrictive lung volumes with a diffusing capacity that was 50% of predicted. His arterial blood gases on admission were: PH 7.39 Pco2 41 Po2 61 on 2 liter of oxygen.

His chest radiograph demonstrated decreased lung volumes and reticular-nodular densities predominantly in the lower lung fields. He was presumed to be suffering from rapidly progressive IPF and a High resolution CT of the chest was ordered to confirm the diagnosis.

The lung windows of the high resolution CT show the typical peripheral honeycombing associated with IPF. In addition, large filling defects were found in the right main pulmonary artery consistent with the diagnosis of pulmonary embolus.

Multiple segmental and subsegmental defects were present in both lungs.

Posterior ventilation images obtained after the inhalation of Xenon 133 demonstrate remarkably even distribution of ventilation. The wash-out phase was normal.

The Nuclear Medicine diagnosis was High probability ventilation/perfusion scan.

Case Assessment
This is a 75 year old male with interstitial lung disease who presents with progressive dyspnea. The reason for his precipitous decline was related to pulmonary emboli and not to his underlying disease. He improved substantially with anticoagulation.

1. The diagnosis of pulmonary embolus may be particularly difficult to make when the process is superimposed on a chronic lung disease. A high index of suspicion is required.

2. Computed tomography can be helpful in suggesting the diagnosis. The appearance of pleural based, wedge shaped abnormalities should raise the possibility of PE. The clots themselves can sometimes be visualized with a modern CT scanner.

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