What are the differences between obstructive lung disease (OLD) and restrictive lung disease (RLD) in terms of definition, classification, etiology, pathophysiology, clinical features, diagnosis, and treatment?

From the Guidelines

Obstructive lung diseases (OLD) and restrictive lung diseases (RLD) are two distinct categories of respiratory disorders with different definitions, classifications, etiologies, pathophysiologies, clinical features, diagnoses, and treatments, with OLD characterized by airway narrowing and RLD by limited lung expansion. The key differences between OLD and RLD are:

• Definition: OLD involves airway narrowing that impedes airflow, while RLD limits lung expansion and reduces total lung capacity 1.
• Classification: OLD includes conditions like asthma, chronic obstructive pulmonary disease (COPD), bronchiectasis, and cystic fibrosis, while RLD includes interstitial lung diseases, pneumoconioses, sarcoidosis, and neuromuscular disorders.
• Etiology: OLD is often caused by environmental exposures like smoking and occupational irritants, while RLD is caused by lung parenchyma scarring, chest wall abnormalities, or neuromuscular weakness.
• Pathophysiology: OLD features bronchial smooth muscle constriction, mucus hypersecretion, airway inflammation, and eventual airway remodeling, while RLD involves reduced lung compliance, decreased lung volumes, and impaired gas exchange.
• Clinical features: OLD presents with symptoms like wheezing, cough, dyspnea, and prolonged expiration, while RLD presents with nonproductive cough, progressive dyspnea, and fine crackles on auscultation.
• Diagnosis: OLD is diagnosed using pulmonary function tests showing reduced FEV1/FVC ratio, increased residual volume, and normal or increased total lung capacity, while RLD is diagnosed using tests showing reduced FEV1 and FVC with normal or increased FEV1/FVC ratio, decreased total lung capacity, and often reduced diffusion capacity.
• Treatment: OLD treatment focuses on bronchodilators, anti-inflammatories, and oxygen therapy, while RLD treatment addresses underlying causes with immunosuppressants, antifibrotics, oxygen supplementation, and lung transplantation in advanced cases 1.

The management of both OLD and RLD requires a comprehensive approach, including:

• Smoking cessation
• Vaccination
• Pulmonary rehabilitation to optimize respiratory function and quality of life
• Treatment of underlying causes and symptoms to improve morbidity, mortality, and quality of life 1.

It is essential to prioritize the most recent and highest-quality studies when making treatment decisions, and the 2017 Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Lung Disease report provides the most up-to-date guidance on the management of OLD 1.

From the Research

Definition and Classification

• Obstructive lung disease (OLD) is characterized by chronic airway inflammation and airway obstruction, with asthma and chronic obstructive pulmonary disease (COPD) being the most common types 2, 3.
• Restrictive lung disease (RLD) is not explicitly defined in the provided studies, but it can be inferred that it is a separate category of lung diseases with different pathophysiological characteristics.
• The definition and classification of COPD are not uniform, with different criteria based on symptoms, physiological impairment, and pathological abnormalities 4.

Etiology

• Asthma and COPD have different etiologies, with asthma being a serious global health problem affecting an estimated 300 million individuals, and COPD being one of the major causes of chronic morbidity and mortality worldwide 5.
• Tobacco smoking is a major risk factor for COPD, with a definition of COPD that includes tobacco smoking greater than 10 pack years, symptoms, and airway obstruction on spirometry 4.
• The etiology of RLD is not discussed in the provided studies.

Pathophysiology

• Asthma and COPD have different pathophysiological characteristics, with asthma being characterized by reticular basement membrane thickening and cellular infiltration with eosinophils and T-helper (CD4+) lymphocytes, and COPD being characterized by epithelial squamous metaplasia, airway wall fibrosis, emphysema, bronchoalveolar lavage (BAL) neutrophilia, and (CD8+) T-cytotoxic lymphocyte infiltrations in the airway wall 6.
• The pathophysiology of RLD is not discussed in the provided studies.

Clinical Features

• Asthma and COPD have different clinical features, with asthma being characterized by intermittent and reversible airway obstruction, and COPD being characterized by progressive and largely irreversible airway obstruction 2.
• The clinical features of RLD are not discussed in the provided studies.

Diagnosis

• Spirometry is generally used to detect early COPD in smokers and to evaluate patients with respiratory symptoms 3.
• The diagnosis of RLD is not discussed in the provided studies.

Treatment

• The treatment goals of obstructive airway diseases are similar, driven primarily by the need to control symptoms, optimize health status, and prevent exacerbations 2.
• The treatment of RLD is not discussed in the provided studies.
• Asthma and COPD have different responses to therapy, with asthma being more responsive to bronchodilators and COPD being more responsive to combination therapy 5.