A 53 year-old woman presents with increasing dyspnea on exertion. She denies cough, fevers, hemoptysis, weight loss or sweats. She was previously an active runner but has had to cut back significantly because of the worsening dyspnea. She does note occasional chest pain with exercise but has not had any syncope or palpitations. Her pulmonary function tests are as follows:
DLCO is measured in ml/min/mmHg
Corr = Corrected for hemoglobin concentration
1 (L) 1.95
Based on the results of this testing, what would be the most appropriate next diagnostic or therapeutic step for this patient?
Start an inhaled corticosteroid
Start a short-acting inhaled beta-agonist
Refer for bronchoscopy with bronchoalveolar lavage
Order a High Resolution chest CT scan
Order an echocardiogram
Question 10.1 Explanation
1/FVC ratio is above 0.8, her FEV 1 and FVC are both above 80% and her TLC is normal. She therefore has no evidence of obstruction or restriction. She does, however, have an isolated decrease in her DLCO. An isolated decrease in the DLCO is highly suggestive of some form of pulmonary vascular disease, such as pulmonary arterial hypertension, and the next most appropriate diagnostic test to work up this issue would, therefore, be an echocardiogram. Anemia is another process that can result in a normal flow-volume loop and normal pulmonary function tests.
In terms of the other answer choices, the patient does not have any evidence of an obstructive process that would warrant either inhaled corticosteroids or inhaled bronchodilators. In the absence of a restrictive process, neither bronchoscopy nor a CT scan would be indicated.
This patient was referred for echocardiography and found to have pulmonary hypertension. Subsequent work-up revealed that she had chronic thromboembolic disease as the source of her elevated pulmonary artery pressures.
How would you characterize the severity of the reduction in her DLCO?
Question 10.2 Explanation
The severity of abnormalities in DLCO can be characterized as follows:
< DLCO <80% predicted: Mild 50%
< DLCO < 65% predicted: Moderate DLCO < 50% predicted: Severe
Her DLCO is 43% predicted and, therefore, is considered to be severely decreased.