Restrictive lung diseases are chronic lung conditions that limit the ability of a person’s lungs to expand during inhalation. Most cases of restrictive lung diseases are not curable, but they are often manageable with medication and exercise regimes.
What are restrictive lung diseases?
Obstructive lung diseases, such as asthma, prevent normal exhalation. In contrast, restrictive lung diseases prevent normal inhalation. Long-term lung conditions are traditionally separated into two main categories based on how they affect a person’s breathing. These categories are either obstructive or restrictive. A third category, called mixed lung disease, is smaller and has characteristics of both obstructive and restrictive lung diseases. Mixed lung disease most commonly occurs in people with chronic obstructive pulmonary disease (COPD), who also have congestive heart failure. In cases of obstructive lung diseases, such as asthma, bronchiectasis, COPD, and emphysema, the lungs are unable to expel air properly during exhalation. Restrictive lung diseases, on the other hand, mean the lungs are unable to fully expand, so they limit the amount of oxygen taken in during inhalation. This limitation also restricts what can be exhaled when compared to an average person. Restrictive lung diseases cause a decreased lung capacity or volume, so a person’s breathing rate often increases to meet their oxygen demands. Most restrictive lung diseases are progressive, meaning they worsen over time. One study estimated that, from 2007 to 2010, 6.5 percent of Americans aged 20 to 79 had restrictive lung disease.
Restrictive lung diseases are often divided into two groups, depending on whether their cause is intrinsic or extrinsic. Intrinsic restrictive lung disorders cause an internal abnormality, usually leading to the stiffening, inflammation, and scarring of the lung tissues. Types of diseases and conditions involved in intrinsic restrictive lung disease can include:
- idiopathic pulmonary fibrosis
- interstitial lung disease
- lung cancers
- fibrosis caused by radiation
- rheumatoid arthritis
- infant and acute respiratory distress syndrome
- inflammatory bowel disease (IBD)
- systemic lupus
Extrinsic restrictive lung disease is caused by complications with tissues or structures outside of the lungs, including neurological conditions. External factors that cause an extrinsic restrictive lung disease are often associated with weakened muscles, damaged nerves, or the stiffening of the chest wall tissues. Types of diseases and conditions involved in extrinsic restrictive lung disease can include:
- pleural effusions, or the build-up of excessive fluid between tissue layers surrounding the lungs
- scoliosis, or twisting of the spine
- neuromuscular disease or conditions, such as Lou Gehrig’s disease (ALS), multiple sclerosis, and muscular dystrophy
- myasthenia gravis, or intermittent muscle weakness
- malignant tumours
- rib damage, especially fractures
- ascites, or abdominal swelling connected with liver scarring or cancer
- diaphragm paralysis
- kyphosis, or hunching of the upper back
- diaphragmatic hernia
- heart failure
Most people with restrictive lung diseases have similar symptoms, including:
- shortness of breath, especially with exertion
- inability to catch their breath or get enough breath
- chronic or a long-term cough, usually dry, but sometimes accompanied by white sputum or mucus
- weight loss
- chest pain
- wheezing or gasping breath
- fatigue or extreme exhaustion without a logical reason
Diagnosis will be based on a variety of tests, and in some cases scans such as x-rays. A doctor will normally perform or order a pulmonary function test to assess total lung capacity (TLC), or the total amount of air the lungs take in when a person inhales. The total lung capacity is usually decreased in restrictive lung disease. Other tests may be necessary for a full diagnosis and to ensure the correct treatment plan is arranged. The specific tests used are usually determined by whether the suspected cause of the restrictive lung disease is intrinsic or extrinsic. Tests that show reduced lung functioning may indicate that scarring, stiffening, or inflammation is affecting a large portion of the lungs.
Commonly used tests for restrictive lung disease include:
- Forced vital capacity (FVC) test, which involves inhaling and filling the lungs with as much air as possible, then exhaling with as much force as possible. The FVC of those with restrictive lung diseases is typically decreased. A FVC value of less than or equal to 80 percent of what is expected can be a sign of a restrictive disease.
- Forced expiratory volume in 1 second (FEV1) test, which measures the amount of air exhaled during the first second of the FVC test. Most people expel about three-quarters of the air inhaled during this initial period of exhalation. In restrictive disease, because the FVC is usually reduced, the FEV1 will be lower, proportionally.
- FEVI to FVC ratio test, which compares the amount of air expelled during the first second of exhalation (FEV1) to the total amount of air exhaled during an FVC test. This ratio is often normal or even increased in those with restrictive lung disease.
- Chest X-ray, which creates images of the entire chest and lung area for evaluation.
- Computed tomography (CT) scans, which create more detailed images of the chest and lung area compared to chest X-rays.
- Bronchoscopy, where a flexible tube with a camera is inserted through the nose or mouth into the airways of the lung for examination.
Treatment plans depend on the cause or the type of restrictive lung disease. In some cases, delivering oxygen to a person using oxygen therapy may be necessary to help them breathe properly. In severe cases, lung transplant surgery, corrective surgery, or stem cell therapy may be options. Medications commonly used to treat restrictive lung diseases include:
- corticosteroids, usually in an inhaler form
- other immunosuppressing and anti-inflammatory medications
- anti-scarring medications, such as pirfenidone or nintedanib
Unfortunately, a majority of the scarring, thickening, or loss of elasticity associated with restrictive lung diseases is irreversible. There are ways, however, to reduce the symptoms or impact of restrictive lung diseases. Doing at-home exercises and making some lifestyle changes have been shown to reduce the severity of restrictive disease symptoms.
Commonly recommended methods include:
- breath conditioning, often 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, or allergens that may worsen symptoms
Following a treatment plan and sticking to certain lifestyle changes can help alleviate the symptoms of a restrictive lung disease and improve a person’s quality of life.
Medical News Today, 13 August 2017 ;