The key difference between obstructive and restrictive lung disease is that obstructive lung diseases feature blocked airways, while restrictive lung diseases feature an inability to expand or loss of elastic recoil of lungs.
Asthma, bronchitis, bronchiectasis, and chronic obstructive pulmonary disease (COPD) are common obstructive lung diseases. Meanwhile, common restrictive lung diseases include cystic fibrosis and other causes of pulmonary scarring. Cystic fibrosis shares some features with obstructive lung diseases but is considered a restrictive lung disease according to pathophysiology. Though both obstructive and restrictive lung diseases share some symptoms, signs, diagnosis, and treatment methods, there are slight variations too. This article will talk about those in detail.
CONTENTS
1. Overview and Key Difference
2. What is Obstructive Lung Disease
3. What is Restrictive Lung Disease
4. Obstructive vs Restrictive Lung Disease in Tabular Form
5. Summary – Obstructive vs Restrictive Lung Disease
What are Obstructive Lung Diseases?
Asthma, bronchitis, bronchiectasis, and COPD are common obstructive lung diseases. Their main feature is blocked airways.
Asthma
Asthma affects 5-8% of the population. Most asthmatic children grow out of it or suffer much less as adults. It is characterized by recurrent episodes of dyspnea, cough, and wheezing caused by reversible airway obstruction. Three factors contribute to airway narrowing: bronchial muscle contraction triggered by a variety of stimuli, mucosal swelling/inflammation caused by mast cells, and basophil degranulation resulting in the release of inflammatory mediators and increased mucus production. Cold air, exercise, emotion, allergens, infection, and drugs trigger the episodes. Airway diameter changes throughout the day and is at its smallest during morning and evening. Therefore, most attacks occur during this time of day. Acid reflux is associated with asthma. Spirometry, skin prick tests for allergens, and chest X-rays are commonly done. Bronchodilators and steroids as inhalers, tablets, or, in an emergency, intravenous preparations may be administered as treatment.
Bronchitis
Bronchitis is inflammation of larger airways. It is most commonly viral or bacterial. The patient presents with cough, shortness of breath, sputum production, and sometimes fever. There is airway obstruction due to mucus production and bronchial muscle contraction. Bronchitis is treated with steam inhalation, bronchodilators, and antibiotics.
Bronchiectasis
Bronchiectasis is due to chronic infections of the bronchi and bronchioles, leading to permanent dilatation of these airways. Heamophilus influenza, Streptococcus pneumonia, Staphylococcus aureus, and Pseudomonas aeruginosa are the usual culprits. Young syndrome, primary ciliary dyskinesia, cystic fibrosis, Kartergener syndrome, bronchial obstruction due to tumors, and foreign bodies, and allergic broncho-pulmonary aspergillosis can lead to bronchiectasis. Bronchiectasis features persistent cough, sputum production, shortness of breath, and finger clubbing. It is treated with postural drainage of sputum, antibiotics, bronchodilators, and steroids.
COPD
Chronic obstructive pulmonary disease (COPD) consists of two closely related clinical entities; chronic bronchitis (long-standing inflammation of large airways characterized by cough and sputum most days of 3 months of two successive years) and emphysema (loss of elastic recoil of lung and histologically, enlargement of airway smaller than terminal bronchioles and destruction of walls of alveoli). Patients may have either asthma or COPD but not both. If the patient is above 35 years of age, has a history of smoking, long-standing production of sputum, cough, and shortness of breath without clear variations throughout the day, COPD is likely. NICE (National Institute for Healthcare Excellence) recommends the name COPD. Smoking is the main risk factor for COPD. The tendency to develop COPD rises with the number of cigarettes smoked, and all lifelong smokers get COPD.
Individuals who work in gold mines, coal mines, and textile plants may also get COPD due to the chemicals, and dust exposure causes an elevated state of reactivity in airways. Similar to cigarette smoke, these molecules increase airway secretions and cause constriction of airways. There is no cure for COPD, although it is manageable. Acute exacerbations are treated at emergency units with bronchodilators, steroids, and antibiotics.
What are Restrictive Lung Diseases?
Restrictive lung diseases feature an inability to expand or loss of elastic recoil of lungs. The common restrictive lung diseases are cystic fibrosis and other causes of pulmonary scarring.
Cystic Fibrosis
Cystic fibrosis is one of the commonest life-threatening autosomal recessive conditions affecting Caucasians. It is caused by mutations in the cystic fibrosis trans-membrane conductance regulator gene. This leads to a combination of defective chloride secretion and increased sodium absorption across airway epithelium. The changes in the composition of airway surface liquid predispose the lung to infections and bronchiectasis. Patients present with cough, wheeze, failure to thrive, pancreatic insufficiency, intestinal obstruction, cirrhosis, and osteoporosis. Chest physiotherapy, pancreatic enzyme replacement, fat-soluble vitamin replacement, and lowering blood sugar are important treatment methods for cystic fibrosis. The average survival of patients with cystic fibrosis is now over 30 years.
What is the Difference Between Obstructive and Restrictive Lung Disease?
Obstructive lung diseases feature airway blockage, while restrictive diseases feature a failure of lung expansion. This is the key difference between obstructive and restrictive lung disease. Moreover, in obstructive lung diseases, there is increased mucus formation, while there’s no increased mucus formation in restrictive diseases. Restrictive diseases are due to lung scarring, while no scarring exists in obstructive diseases.
The following table summarizes the difference between obstructive and restrictive lung disease.
Summary – Obstructive vs Restrictive Lung Disease
The key difference between obstructive and restrictive lung disease is that obstructive lung diseases feature blocked airways, while restrictive lung diseases feature an inability to expand or loss of elastic recoil of lungs.
Image Courtesy:
1. “Asthma: Mild and Chronic” By NIAID (CC BY 2.0) via Flickr
2. “Cysticfibrosis01” By National Heart Lung and Blood Institute (NIH) – National Heart Lung and Blood Institute (NIH) (Public Domain) via Commons Wikimedia