Restrictive lung diseases are chronic conditions that limit the ability of the lungs to expand during inhalation. This reduces the amount of air that the person can breathe in.
A range of chronic health issues can restrict lung performance. For most of these conditions, there is no cure, but a person can manage the symptoms with medication and physical therapy. It is crucial for a doctor to identify the root cause of any lung-related symptoms.
In this article, we describe the types of restrictive lung disease and their symptoms. We also look into how a doctor diagnoses these diseases and what the treatment plan might involve.
Long-term lung conditions fall into two general categories: restrictive and obstructive lung diseases.
Restrictive diseases stop the lungs from fully expanding. This limits the volume of air and amount of oxygen that a person breathes in. To meet the body’s oxygen needs, the person’s breathing rate often increases.
Restrictive lung diseases account for around
By contrast, obstructive lung diseases block or narrow the airways. This stops the lungs from expelling air at optimum levels.
A smaller, third category, called mixed lung disease, has characteristics of obstructive and restrictive lung diseases.
Medical professionals classify restrictive lung diseases into
Intrinsic restrictive lung diseases affect the functional tissue of the lung, including the alveoli, capillaries, and the interstitium. The alveoli are small branches of air tubes in the lungs. Capillaries are blood vessels, and the interstitium refers to a group of tissues within the lung that provide support.
Intrinsic restrictive lung diseases usually result from inflammation and scarring of lung tissue.
The cause may be interstitial lung disease. This is an umbrella term for a large group of diseases that cause scarring of the lungs. The scarring leads to stiffness that makes it difficult to breathe and get oxygen to the bloodstream. Damage from interstitial lung disease is often irreversible and gets worse over time.
One example of intrinsic restrictive lung disease is idiopathic pulmonary fibrosis. Some other health issues that may be involved in intrinsic restrictive lung disease include:
- connective tissue diseases, such as scleroderma
- drug-induced lung disease
- exposure to toxins
Extrinsic restrictive lung diseases involve the chest wall, pleura, and respiratory muscles. The pleura is a membrane that covers the inside surface of the rib cage and spreads over the lungs. Diseases of these structures result in lung restriction, impaired function, and respiratory failure.
Some other health issues that can be involved in extrinsic restrictive lung disease include:
People with different restrictive lung diseases may share some symptoms, including:
A doctor who suspects a restrictive lung disease typically orders a pulmonary function test (PFT). This noninvasive test shows how well the lungs are working by measuring lung volume, capacity, rates of flow, and gas exchange. This information can help the doctor identify the type of lung disorder.
An important part of a PFT involves measuring total lung capacity — the gold standard for diagnosing restrictive lung disease. This is the total volume of air that the lungs take in on maximum inhalation. A person with restrictive lung disease has a low total lung capacity.
Another important measurement in a PFT is the diffusing capacity of the lungs for carbon monoxide (DLCO).
This measurement determines whether the restrictive lung disease is intrinsic or extrinsic. Restrictive lung diseases such as pulmonary fibrosis tend to decrease the DLCO due to scarring and thickening of the area between the alveoli and the capillaries.
Other tests are necessary for a confirmed diagnosis and to ensure the most effective treatment plan. The specific tests involved depend on whether the suspected cause is intrinsic or extrinsic.
Some other common tests for restrictive lung disease include:
- Forced vital capacity (FVC) test: This is part of the PFT and involves inhaling as much air as possible, then exhaling with as much force as possible.
- Forced expiratory volume in 1 second (FEV1) test: This measures how much air is exhaled in the first second of the FVC.
- FEV1 to FVC ratio test: This compares the FEV1 reading to the total amount of air exhaled during an FVC test. The resulting ratio may be normal or high in a person with restrictive lung disease, depending on whether the disease is extrinsic or intrinsic.
- Chest X-rays: These create images of the entire chest and lung area.
- CT scans: These create more detailed images than chest X-rays.
- Bronchoscopy: In this test, a medical professional inserts a flexible tube with an attached camera through the nose or mouth into the airways of the lungs for examination.
The best treatment plan depends on the cause and the type of restrictive lung disease.
In some cases, a person may need oxygen therapy, lung transplant surgery, or corrective surgery.
Drug-based treatments for restrictive intrinsic lung disease, particularly interstitial lung disease, may
- mycophenolate mofetil
- other immunosuppressing and anti-inflammatory medications
- antifibrotic medications, such as pirfenidone or nintedanib
Often, the scarring, thickening, and loss of muscle elasticity caused by restrictive lung diseases are irreversible. However, there are still ways to reduce the symptoms and their impact.
Doing exercises and making some lifestyle changes, for example, may help. Doctors often recommend:
- breath conditioning techniques, such as pursed-lip breathing, slow, deep breathing, or diaphragmatic breathing
- upper and lower limb strengthening and conditioning exercises
- respiratory muscle strengthening exercises
- level walking
- relaxation or visualized meditation
- eating a balanced, nutritious diet
- quitting smoking
- avoiding environments with toxins, irritants, and allergens that may worsen symptoms
Restrictive lung diseases keep the lungs from expanding fully, limiting how much air a person can breathe in.
The term covers several chronic conditions, including pulmonary fibrosis and various neuromuscular diseases. Many restrictive lung diseases are incurable, but a range of treatments and management strategies can reduce the symptoms and enhance the quality of life.