A Restrictive lung disease is any lung disease or condition that causes a reduction in the size and capacity of the lung to hold and utilize air.
Restrictive lung diseases are a diverse set of pulmonary disorders defined by restrictive patterns on spirometry; these restrictive lung patterns as shown on a spirometer are the revelation of a dysfunction in the respiratory ability of the lung(s) which is caused by restrictive lung disease.
Restrictive lung diseases cause the air-holding capacity of the lungs to reduce drastically, thereby limiting the ability of the lungs to expand during inhalation.
Unlike obstructive lung diseases such as asthma, COPD, bronchiectasis, emphysema, and bronchiolitis which are characterized by increased resistance to the airflow due to partial or complete obstruction at any level of the respiratory tract, restrictive lung disease comprises of reduced lung distensibility and reduced lung expansion which results in a reduction of lung volumes.
Restrictive lung diseases accounts for about fifth of reported pulmonary syndromes, it is mostly caused by the destruction of distal internal lung tissues due to penetrating damages from inflammation, toxins and other mechanisms yet to be revealed (intrinsic factors), as well as abnormal destructive conditions outside the lungs (extrinsic factors).
The total numerical statistics of the restrictive lung diseases is difficult to correlate, solely because this heterogeneous set of lung conditions involve so many pathological conditions, of which each pathological condition can occur in numerous clinical stages.
However, it has been estimated that about 3 to 6 cases per 100,000 persons are suffering from intrinsic restrictive lung disorders in the United States. The prevalence of sarcoidosis in North America amind others has been estimated as 10 to 40 cases per 100,000 persons and the numbers tend to increase in Sweden (64/100,000 persons).
Risk Factor for Restrictive Lung Disease
Studies on the global population and deductions from reported clinical cases so far have revealed that some particular categories of persons are prone to developing a restrictive lung pattern on spirometry.
This population of persons with higher risk of restrictive lung patterns includes:
- Old Aged Individuals: The case of restrictive lung conditions increases from 2.7 cases per 100,000 persons (in individuals aged 35-44 years) to 175 cases per 100,000 persons (in individuals above age 75 years). Although it is rare, some restrictive conditions such as sarcoidosis, pulmonary Langerhans, and collagen-vascular associated disease might occur in younger aged individuals (aged 20 to 40 years).
- African Americans: Unlike the Whites (10.9 cases per 100,000 persons), the case of restrictive conditions is higher in this group of individuals, reaching up to 35.5 cases per 100,000 persons.
- Smokers: patients of Idiopathic pulmonary fibrosis (IPF), a type of chronic scarring lung disease characterized by a progressive and irreversible decline in lung function, are usually present or past smokers.
- Females: restrictive lung condition like sarcoidosis slightly occurs more in women than men. Moreover, females have been reported to have an increased risk for a restrictive pattern. Also, IPF is more common in men than women.
- Obese individuals: Restrictive lung pattern is closely related to the elevated body mass index (BMI) of an individual, with a reduction in lung volume attributed to the increased amount of central obesity.
- Occupational standards: Persons having specific environmental and occupational exposures are at higher risk. The continuous encountering of harmful substances in line with an occupation such as asbestos, coal dust, soil dust, spray dust, iron dust, and several other dangerous specks of dust can in time result in abnormal lung tissue change leading to inflammation, scarring, and a restrictive pattern on a spirometer.
- Pregnancy: restrictive lung diseases are very rare in pregnant women, but if it occurs, it may be due to extrinsic conditions such as neuromuscular disease or kyphoscoliosis (abnormal curvature of the spine).
Causes of Restrictive Lung Disease
The cause of restrictive lung disease can be linked to numerous conditions. An acronym “PAINT” is used to memorize the causes of restrictive lung disease; Pleural, Alveolar, Interstitial, Neuromuscular and Thoracic cage abnormalities.
Recently, in order to consider the pathogenic mechanisms of these abnormalities, the causes of restrictive lung diseases have medically been grouped into two categories:
- Intrinsic causes (Pulmonary parenchyma diseases)
- Extrinsic causes (Extra-pulmonary diseases)
The parenchyma is the functional part of an organ, thereby, intrinsic factors or causes include all conditions that affect the parenchyma of the lungs.
While extrinsic causes originating from outside-parenchyma conditions (complications with tissues outside the lungs). In both conditions, however, the lung volume becomes reduced due to restrictions in pulmonary functions.
Intrinsic restrictions are caused by diseases that result in inflammations within the lung tissues; they are mostly interstitial lung diseases.
- Acute Interstitial Pneumonia (AIP)
- Idiopathic Pulmonary Fibrosis (IPF)
- Cryptogenic organizing pneumonia (COP)
- Hypersensitivity pneumonitis
- Non-specific interstitial pneumonia (NSIP)
- Systemic Sclerosis
- Rheumatoid arthritis
- Infant and acute respiratory distress syndrome
- Adult respiratory distress syndrome
- Inflammatory bowel disease
- Pulmonary vasculitis
- Pulmonary Langerhans
- Radiation therapy
- Inorganic dust exposure such as silicosis, asbestosis, talc, hard metal fibrosis, coal worker’s pneumoconiosis, berylliosis, pneumoconiosis
- Organic dust exposure such as farmer’s lung, bagassosis, bird fancier’s lung, humidifier lung, hot tub pneumonitis and mushroom worker’s lung
- Drugs such as nitrofurantoin, gold, phenytoin, amindarone, thiazides, hydralazine, bleomycin, carmustine, cyclophosphamide, methotrexate and Medications such as Lobectomy and pneumonectomy (lung cancer surgery).
The above conditions can also be grouped as disease provoked by the occupation of alveolar spaces such as pneumonia and diseases that lead to an increased elastic return such as interstitial diseases, and infiltrative pneumopathies.
Extrinsic conditions can be result of diseases associated with the chest wall, such as weakened muscles, damaged nerves or stiffening of tissues.
Diseases and conditions involved in extrinsic restrictive causes include:
- Pleural diseases such as trapped lungs, pleural scarring, effusions, chronic emphysema
- Neuromuscular disorders like amyotrophic lateral sclerosis, muscular dystrophy, polio, Lou Gehrig’s disease (ALS) and phrenic neuropathies.
- Malignant tumors
- Myasthenia gravis
- Rib damage or fractures
- Diaphragm paralysis
- Kyphosis (hunching of the upper back)
- Diaphragmatic hernia
- Heart failure
Extrinsic pulmonary causes can also be grouped into pathologies that produce a decreased muscle tone of the respiratory pump such as neurological deficits and myopathies, deformations of the rib cage for instance kyphoscoliosis, and space occupation such as pleural effusions, pneumothorax.
Symptoms of Restrictive Lung Disease
Symptoms of restrictive lung diseases are very similar, most cases reported presents the following symptoms:
- Shortness of breath, especially with exertion
- Weight loss
- Inability to get enough breath.
- Cough, usually long-term and dry, but sometimes accompanied by white sputum.
- Chest pain
- Wheezing (to breath hard)
- Extreme fatigue
Diagnosis of Restrictive Lung Disease
Diagnosis of restrictive lung disease begins with a thorough investigation of the medical history and physical examination of the patient-presented symptoms.
Pulmonary function tests and imaging tests are also conducted to confirm the diagnosis and reveal if more than one condition is present at the same time, especially if a mixed pattern is found. Tests include:
Pulmonary Function Tests
- Spirometry is a common desk test used to determine how well the lung(s) work, by measuring how much air a person inhales and how much air is exhaled and how quickly the air is exhaled. This test helps to determine the severity of these diseases and it measures the:
- FVC (Forced vital capacity): the amount of air a person can breathe out forcefully after taking a breath as deep as possible.
- FEV1 (Forced expiratory volume in 1 second): the total amount of air that can be forcibly exhaled in the first second of the FVC test. Healthy individuals generally expel around 75% to 85% in this time while it is minimally decreased I restrictive conditions.
- TLC (Total lung capacity): this is the summation of the volume of air left in the lungs after exhalation (residual volume) with the FVC. In restrictive conditions, this sum is decreased compared to healthy lungs.
The above are the main desk test conducted during diagnosis, other pulmonary functions tests may also be recommended for further study and confirmation, such as:
- Lung plethysmography
- Diffusing capacity: this measure how well oxygen and carbon dioxide can diffuse between the alveoli and blood vessels in the lungs.
- Laboratory test to indicate the severity of the lung disease may be conducted; however, these tests are not very helpful in determining the nature of the disease. for instance:
- Oximetry: measure the oxygen content in the blood, which is usually low in any case of lung disease (both restrictive and obstructive). It sometimes reveals an elevated carbon dioxide level (hypercapnia).
- Hemoglobin level tests in chronic lung disease are often elevated in an attempt of the body to carry more oxygen to the cells of the body.
Imaging Studies and tests such as chest x-ray or chest computed tomography (CT) scan and Bronchoscopy which may reveal clues to if the lung disease is obstructive or restrictive and if any underlying conditions like rib fracture or pneumonia is present.
Treatment of Restrictive Lung Disease
There are series of treatments that clinicians can recommend helping ease some symptoms and tangle the disease. These treatments are mainly dependent on the type and severity of the restrictive lung disease and also on factors like medical history, age and overall health status are considered.
Treatments primarily focus on easing breathing and slowing down the progression of the disease.
Some treatments involve the use of:
This is a handheld device that can deliver quick blasts of corticosteroids and other medications into the bronchial tracts in order to dilate or relax them. In cases of restrictive lung diseases due to inflammation, inhalers may be effective in controlling these inflammations and if used in the long-term can reverse the condition.
Examples of medications (corticosteroids) that are inhaled include flunisolide, ciclesonide, and budesonide.
Restrictive lung disease automatically limits the amount of oxygen flowing through the blood to the organs, muscles and other tissues of the body.
This treatment helps provide extra amount of oxygen for inhalation by pumping oxygen from a portable tank through a tube to either a mask worn by the patient or through oxygen tiny tubes placed in the nostril. Many restrictive lung diseases are treated with oxygen therapy; larger non-portable tanks are also available for home and clinic use.
Some types of restrictive lung diseases such as rheumatoid arthritis (RA), scleroderma and Sjogren’s syndrome are caused by autoimmune connective tissue disorder.
An autoimmune disease that causes the body to attack its own tissues, it can affect the lungs, heart, or any other organ, scaring them and making them harder.
Immunosuppressants functions by blocking this autoimmune action of the body’s immune system. Also, individuals who suffered from advanced long-term lung diseases, after undergoing a lung transplant take immunosuppressant to prevent their body from attacking the cells of the new lung thereby causing a rejection of the organ.
Some frequently used immunosuppressants include azathioprine, basiliximab, cyclosporine and daclizumab.
Expectorants are medications that come in pills or liquid form, the medications work by clearing up the airways of built-up mucus. Restrictive lung disease such as pneumoconiosis can result to build up of mucus in the airways.
Also, the continuous inhaling of some kinds of dust particles can lead to pneumoconiosis, especially in factory and mine workers. Examples of expectorants are potassium iodide, carbocysteine, and guaifenesin.
When restrictive lung disease reaches an advance irreversible stage, it might be advisable to have a lung transplant. This approach is only recommended by doctors when medications and other approaches appear ineffective. Usually new health lungs are gotten from recently deceased donors.
The transplant might involve one lung, both lungs or lungs, and heart transplants. After the transplant, in order to prevent organ rejection which can result in serious health complications in the body of the recipients, the doctors administer immunosuppressants drugs either intravenously or by oral capsules.
Not all restrictive lung disease are product of inflammation or tissue scarring, some restrictive lung disease occurs as a result of infections, mostly bacterial infection.
For instance, pleural effusion causes a buildup of fluid in the lungs, in such cases, antibiotics are used for treatment until the infection clears and effusion buildup symptoms pass.
Obesity hypoventilation syndrome is one other condition that can restrict breathing. This condition frequently occurs in individuals that are morbidly obese (when an individual is 100 pounds over the ideal body weight).
When fatty tissues surrounding the chest muscles become too much, it makes it harder for chest movement and this restricts the expansion of the lungs.
Complications of Restrictive Lung Disease
Chronic restrictive lung diseases can result in hypoxemia, which is characterized and compensated by elevations in respiratory rate. Increased energy expenditure due to excessive short breaths can lead to muscle wasting and weight loss.
Once compensatory mechanisms fail, hypoxia worsens, and the patient develops chronic respiratory failure. Chronic respiratory failure and anatomical lung distortion lead to pulmonary hypertension and cor-pulmonale.
Due to increased occupational safety precautions and falling rate of cigarette smoking, an epidemiological study by Kurth et al. revealed that restrictive patterns on spirometry were discovered to fall from 7.2% to 5.4% from 1988-1994 and 2007-2010.
Restrictive lung disease and other lung-related disorders can be treated with pulmonary rehabilitation. This is usually an outpatient program; it enlightens the patients about his/her condition, effective exercise options, breathing techniques, nutrition, safe ways to conserve energy, and tips on how to emotionally deal with the disease. Pulmonary rehabilitation is usually recommended for restrictive lung disease patients alongside another treatment approach.
Following a treatment dialogue and sticking to certain better lifestyle can greatly improve the quality of life and alleviate the symptoms of restrictive lung disease in a person.
- Respiratory system and chest wall dis see; http://www.sciencedirect.com/topics/nursing-and-health-professions/restrictive-lung-disease
- Obstructive Lung Disease; https://www.aastweb.org/blog/obstructive-lung-disease-vs-restrictive-lung-disease-causes-diagnosis-and-treatment-options?hs_amp=true
- Restrictive Lung Disease; https://www.google.com/amp/s/www.hopkinsmedicine.org/health/conditions-and-diseases/restrictive-lung-disease%3famp=true
- Pulmonary Rehabilitation in Intrinsic Restrictive Lung Diseases; https://now.aapmr.org/pulmonary-rehabilitation-in-instrinsic-restrictive-lung-diseases/