Progressive exertional dyspnea of interstitial origin

Specialty: Respiratory.

• progressive dyspnea in collagen diseases
• progressive shortness of breath due to fibrosis

Why it occurs

• Idiopathic pulmonary fibrosis (IPF) (progressive loss of lung elasticity due to collagen deposition in the alveolar interstitium that limits expansion capacity and decreases gas transfer)
• Chronic hypersensitivity pneumonitis (prolonged exposure to organic antigens such as bird dust or molds that generates interstitial granulomatous inflammation and subsequent fibrosis)
• Interstitial pneumopathy associated with systemic sclerosis (scleroderma) or rheumatoid arthritis (autoimmune inflammatory and fibrotic lung disease)
• Advanced-stage sarcoidosis (presence of diffuse non-caseating granulomas in the lung parenchyma and mediastinal lymph nodes)
• Pneumoconiosis (chronic occupational exposure to silica, asbestos or coal that generates a diffuse nodular fibrotic reaction)

Initial workup

High-resolution chest computed tomography (CT) (HRCT) without contrast; Complete respiratory function testing with plethysmography (to document restrictive pattern with decreased total lung capacity) and carbon monoxide diffusing capacity (low DLCO); 6-minute walk test (to evaluate effort-induced desaturation); Transthoracic echocardiogram (estimate pulmonary arterial pressure).

Standard management

• Nintedanib — 150 mg orally every 12 hours to slow the progression of idiopathic pulmonary fibrosis and other progressive fibrosing interstitial lung diseases
• Pirfenidone — 801 mg orally three times a day with initial titration
• Mycophenolate mofetil — 1-1.5 g orally every 12 hours in case of interstitial lung disease secondary to connective tissue diseases such as scleroderma
• Prednisone (0.5 mg/kg/day in inflammatory phases of sarcoidosis or hypersensitivity pneumonitis).