What are common restrictive lung diseases and their management options?

Common Restrictive Lung Diseases

Restrictive lung diseases are divided into intrinsic (parenchymal) and extrinsic (extraparenchymal) categories, with the most common intrinsic types being interstitial lung diseases (ILDs) including idiopathic pulmonary fibrosis, hypersensitivity pneumonitis, occupational lung diseases (asbestosis, silicosis), and connective tissue disease-related ILD, while common extrinsic types include chest wall disorders, pleural diseases, obesity-related respiratory disease, and neuromuscular conditions. 1

Intrinsic (Parenchymal) Restrictive Lung Diseases

Interstitial Lung Diseases

• Idiopathic pulmonary fibrosis represents a chronic progressive interstitial pneumonia with fibrosis that accounts for a significant portion of ILD cases 2
• Hypersensitivity pneumonitis and lymphangioleiomyomatosis are recognized ILD subtypes by the European Respiratory Society 1
• Occupational lung diseases including asbestosis and silicosis result from inhalational exposures to mineral dusts 1
• Connective tissue disease-related ILD occurs in conditions like systemic sclerosis, systemic lupus erythematosus, and rheumatoid arthritis 1
• Sarcoidosis presents with granulomatous inflammation and is generally not altered by pregnancy, though prognosis worsens with parenchymal lesions on chest radiography and advanced staging 3

Diagnostic Characteristics of Intrinsic Disease

• These conditions demonstrate restrictive pattern on spirometry with reduced total lung capacity (TLC < -1.96 SD of reference) 2, 4
• Peak expiratory flow (PEF) and mid-expiratory flows (MEF75/50/25) remain relatively preserved or elevated compared to extrapulmonary restriction because conducting airways are tethered in stiffened parenchyma and resist compression during forced expiration 4
• Reduced diffusing capacity for carbon monoxide (DLCO) is characteristic, particularly in more severe disease 2
• Asbestosis specifically shows irregular opacities predominantly in lower lung fields on chest radiograph, with profusion of 1/0 or greater indicating abnormality by ILO classification 5

Extrinsic (Extraparenchymal) Restrictive Lung Diseases

Chest Wall and Pleural Disorders

• Kyphoscoliosis is relatively common and can progress during pregnancy, particularly in unstable curves 3
• Post-tuberculosis syndrome with pleural thickening represents chronic sequelae of infection 1
• Pleural effusion and pleural thickening mechanically restrict lung expansion 1

Obesity-Related Conditions

• Obesity hypoventilation syndrome presents with snoring, daytime somnolence, difficulty concentrating, witnessed apneas, and morning headaches 2
• Serum bicarbonate serves as a screening biomarker for subclinical obesity hypoventilation syndrome 2
• Obstructive sleep apnea frequently coexists with obesity-related restriction 2

Neuromuscular Disorders

• These conditions impair respiratory muscle function and chest wall mechanics 1
• Treatment focuses on addressing the underlying neuromuscular condition when possible 1

Diagnostic Approach

Pulmonary Function Testing

• Spirometry showing FEV1/FVC ratio > 70% with FVC ≤ 80% predicted defines restrictive pattern 6
• Total lung capacity measurement via body plethysmography or washout technique confirms true restriction 5
• DLCO measurement helps differentiate parenchymal from extraparenchymal disease and assess severity 5
• Maximum inspiratory and expiratory pressures evaluate respiratory muscle strength, particularly important in neuromuscular and chest wall disorders 5

Imaging

• Chest radiograph identifies anatomic restriction, chronic lung disease patterns, and pleural abnormalities 5
• High-resolution CT (HRCT) reveals characteristic parenchymal abnormalities and bilateral pleural changes highly suggestive of asbestos exposure when radiographic findings are indeterminate 5

Additional Testing

• Peak cough flow < 160 L/min indicates inadequate cough response and risk of insufficient sputum clearance, though values < 270 L/min may be ineffective 5
• FEF25-75% assesses small airway function, which may be abnormal even with normal FEV1 in some restrictive conditions 5

Management Strategies

General Supportive Care

• Oxygen therapy for hypoxemia is fundamental supportive treatment 1, 2
• Pulmonary rehabilitation improves respiratory muscle forces, exercise tolerance (6-minute walk distance), health-related quality of life, and dyspnea perception in restrictive lung disease patients to the same extent as COPD patients 1, 6
• Pneumococcal and influenza immunizations are recommended by the American Thoracic Society 1
• Regular monitoring with chest imaging and pulmonary function tests tracks disease progression 1

Disease-Specific Treatments

Inflammatory ILDs

• Corticosteroids benefit inflammatory conditions like sarcoidosis and hypersensitivity pneumonitis 1

Idiopathic Pulmonary Fibrosis

• Pirfenidone and nintedanib slow disease progression in IPF 2
• Lung transplantation evaluation should be pursued for appropriate candidates 2

Asbestosis

• Immediate removal from further asbestos exposure is critical 1
• Smoking cessation prevents additional lung injury 1
• Management is primarily supportive as no specific therapy reverses fibrosis 1

Severe Disease Considerations

• Patients with vital capacity < 1 L should be counseled to avoid pregnancy or consider therapeutic abortion due to high maternal and fetal risk 3
• Cesarean section delivery should be considered for pregnant patients with severe restrictive disease who continue pregnancy 3
• Preoperative optimization includes weight loss, pulmonary rehabilitation, oxygen therapy, and respiratory support before elective surgery 2

Key Clinical Pitfalls

• Do not rely solely on spirometry—total lung capacity measurement is required to confirm true restriction versus pseudorestriction from poor effort 2
• Mixed obstructive-restrictive patterns do not exclude asbestosis—asbestos can cause small airway disease with increased upstream resistance at low lung volumes 5
• Progression after exposure cessation is common in asbestosis, particularly in those with existing radiographic abnormalities and high cumulative exposure 5
• Normal spirometry does not exclude early restrictive disease—chronic respiratory symptoms may precede airflow limitation development 7