Diagnosis and Management of Interstitial Lung Disease

Initial Diagnostic Approach

The American Thoracic Society recommends obtaining high-resolution CT chest imaging and pulmonary function testing with DLCO to establish the diagnosis and assess disease severity in patients with suspected interstitial lung disease 1, 2
A thorough exposure history is critical to diagnose hypersensitivity pneumonitis, and the American College of Chest Physicians suggests systematically inquiring about occupational exposures, environmental exposures at home, and hobbies that may cause hypersensitivity pneumonitis 3
The American College of Cardiology recommends excluding cardiac causes of dyspnea by asking about orthopnea, paroxysmal nocturnal dyspnea, peripheral edema, and number of pillows needed for sleep 4

The American Thoracic Society suggests auscultating for fine bibasilar crackles ("Velcro rales") as this finding is highly suggestive of pulmonary fibrosis and present in most interstitial lung disease patients 3
The American College of Chest Physicians recommends assessing for digital clubbing, which is present in 25-50% of idiopathic pulmonary fibrosis cases 3

High-resolution CT chest (HRCT) without contrast is the single most important test to diagnose interstitial lung disease, and the American Thoracic Society recommends looking for ground-glass opacities, reticulation, honeycombing, or traction bronchiectasis that define fibrotic vs. non-fibrotic disease 3
Pulmonary function testing with spirometry and DLCO is essential to assess disease severity, and the American College of Chest Physicians expects a restrictive pattern (reduced FVC) with reduced DLCO in interstitial lung disease 1, 2

The American Thoracic Society states that if HRCT shows a fibrotic pattern, the prognosis is significantly worse, with fibrotic hypersensitivity pneumonitis patients having a 4.35 times increased risk of death compared to non-fibrotic hypersensitivity pneumonitis 3
The extent of fibrosis predicts mortality, with patients having >40% lung involvement having 83% mortality vs. 21% with <10% involvement, according to the American College of Chest Physicians 3

The American Thoracic Society recommends addressing the underlying cause first, and for hypersensitivity pneumonitis, antigen avoidance is paramount, with complete removal from exposure leading to disease resolution in non-fibrotic cases 3
The American College of Chest Physicians suggests optimizing any disease-modifying therapy, and for fibrotic interstitial lung disease, antifibrotic agents reduce disease progression 5

The American Thoracic Society strongly recommends pulmonary rehabilitation and exercise training for all patients with chronic dyspnea and reduced functional capacity 1, 2, 5
The American College of Chest Physicians suggests providing supplemental oxygen if hypoxemic, with the goal of maintaining SpO2 >90% 5

The American College of Chest Physicians recommends treating the underlying interstitial lung disease, as cough often improves with disease-specific therapy 6, 7
The American Thoracic Society suggests excluding upper airway cough syndrome, asthma, and GERD, as these are common causes of chronic cough and may coexist with interstitial lung disease 6, 7