What is pulmonary restriction in physiology and what diseases can stem from issues with it, specifically regarding conditions such as restrictive lung disease (RLD)?

From the Guidelines

Pulmonary restriction is a physiological condition characterized by decreased lung volumes and capacities, particularly reduced total lung capacity, which can lead to significant morbidity and mortality if left untreated or poorly managed. This condition occurs when the lungs themselves become stiff or when the chest wall or respiratory muscles cannot expand properly. According to a recent study published in 2024 in Autoimmunity Reviews 1, pulmonary function tests can reveal restrictive lung physiology, which is very useful for monitoring the progression of interstitial lung disease (ILD). Several diseases can stem from pulmonary restriction, including:

• Pulmonary fibrosis, which involves scarring of lung tissue
• Sarcoidosis, characterized by inflammatory cell clusters in the lungs
• Pneumoconiosis, caused by inhalation of dust particles
• Scleroderma, an autoimmune disease affecting connective tissue
• Obesity hypoventilation syndrome, where excess weight impairs breathing
• Kyphoscoliosis, involving spinal deformities that affect chest expansion
• Pleural diseases like effusions or thickening
• Neuromuscular disorders such as myasthenia gravis or muscular dystrophy that weaken respiratory muscles. The diagnosis of pulmonary restriction is confirmed by measuring total lung capacity (TLC) and is typically monitored through regular spirometry and measurement of diffusion capacity. Treatment depends on the underlying cause but may include medications like corticosteroids or immunosuppressants for inflammatory conditions, oxygen therapy for hypoxemia, pulmonary rehabilitation to improve breathing efficiency, and in severe cases, mechanical ventilation or lung transplantation, as suggested by the study 1.

From the Research

Definition of Pulmonary Restriction

Pulmonary restriction refers to a condition where the lungs are unable to expand fully, resulting in a reduction in total lung volume [ 2 ]. This can be caused by intrinsic factors, such as lung parenchymal involvement, or extrinsic factors, such as obesity and neuromuscular disorders.

Diseases Associated with Pulmonary Restriction

Some diseases that can stem from issues with pulmonary restriction include:

• Interstitial lung disease (ILD), which consists of a group of pulmonary disorders characterized by inflammation and/or fibrosis of the lung parenchyma [ 3 ]
• Idiopathic pulmonary fibrosis (IPF), a chronic progressive interstitial pneumonia with fibrosis [ 2 ]
• Sarcoidosis, a multiorgan, granulomatous disease of unknown etiology that can lead to pulmonary fibrosis [ 4 ]
• Progressive fibrosing interstitial lung diseases, a group of rare and chronic respiratory disorders [ 5 ]

Characteristics and Symptoms

Pulmonary restriction can present with symptoms such as:

• Dyspnea on exertion [ 3 ]
• Cough [ 3 ]
• Reduced diffusing capacity of the lung for carbon monoxide [ 2 ]
• Snoring, daytime somnolence, difficulty concentrating, fatigue, witnessed apneas, and morning headaches in cases of obstructive sleep apnea and obesity hypoventilation syndrome [ 2 ]

Diagnosis and Treatment

Diagnosis of pulmonary restriction can be confirmed by a reduction in total lung volume and a restrictive pattern on spirometry [ 2 ]. Treatment options may include:

• Antifibrotic therapy with nintedanib or pirfenidone [ 3 ]
• Immunomodulatory therapy, such as tocilizumab, rituximab, and mycophenolate mofetil [ 3 ]
• Oxygen therapy [ 3 ]
• Pulmonary rehabilitation [ 3 ]
• Lung transplant [ 3 ]