Restrictive lung disease
Encyclopedia
Restrictive lung diseases (or restrictive ventilatory defects) are a category of extrapulmonary, pleural, or parenchymal respiratory diseases that restrict lung expansion, resulting in a decreased lung volume, an increased work of breathing, and inadequate ventilation and/or oxygenation. Pulmonary function test demonstrates a decrease in the forced vital capacity.
(scarring of the lung). As the disease progresses, the normal lung tissue is gradually replaced by scar tissue interspersed with pockets of air. This can lead to parts of the lung having a honeycomb-like appearance.
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In obstructive lung disease however, FEV1 is reduced while FVC remains stable, concequentially depicting a lower FEV1/FVC ratio.
One definition requires a total lung capacity which is 80% or less of the expected value.
of the lung, or extrinsic to it.
Many cases of restrictive lung disease are idiopathic
(have no known cause). Still, there is generally pulmonary fibrosis
. Examples are:
Conditions specifically affecting the interstitium are called interstitial lung diseases.
Pathophysiology
In disorders that are intrinsic to the lung parenchyma, the underlying process is usually pulmonary fibrosisPulmonary fibrosis
Pulmonary fibrosis is the formation or development of excess fibrous connective tissue in the lungs. It is also described as "scarring of the lung".-Symptoms:Symptoms of pulmonary fibrosis are mainly:...
(scarring of the lung). As the disease progresses, the normal lung tissue is gradually replaced by scar tissue interspersed with pockets of air. This can lead to parts of the lung having a honeycomb-like appearance.
Presentation
The main symptoms are shortness of breath and coughCough
A cough is a sudden and often repetitively occurring reflex which helps to clear the large breathing passages from secretions, irritants, foreign particles and microbes...
.
Diagnosis
In restrictive lung disease, forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) are reduced, resulting in a normal FEV1/FVC ratioFEV1/FVC ratio
The FEV1/FVC ratio, also called Tiffeneau index, is a calculated ratio used in the diagnosis of obstructive and restrictive lung disease.It represents the proportion of the forced vital capacity exhaled in the first second....
.
In obstructive lung disease however, FEV1 is reduced while FVC remains stable, concequentially depicting a lower FEV1/FVC ratio.
One definition requires a total lung capacity which is 80% or less of the expected value.
Causes and classification
Restrictive lung diseases may be due to specific causes which can be intrinsic to the parenchymaParenchyma
Parenchyma is a term used to describe a bulk of a substance. It is used in different ways in animals and in plants.The term is New Latin, f. Greek παρέγχυμα - parenkhuma, "visceral flesh", f. παρεγχεῖν - parenkhein, "to pour in" f. para-, "beside" + en-, "in" + khein, "to pour"...
of the lung, or extrinsic to it.
Intrinsic
- AsbestosisAsbestosisAsbestosis is a chronic inflammatory and fibrotic medical condition affecting the parenchymal tissue of the lungs caused by the inhalation and retention of asbestos fibers...
caused by long-term exposure to asbestos dust. - Radiation fibrosis, usually from the radiation given for cancer treatment.
- Certain drugs such as amiodaroneAmiodaroneAmiodarone is an antiarrhythmic agent used for various types of tachyarrhythmias , both ventricular and supraventricular arrhythmias. Discovered in 1961, it was not approved for use in the United States until 1985...
, bleomycinBleomycinBleomycin is a glycopeptide antibiotic produced by the bacterium Streptomyces verticillus. Bleomycin refers to a family of structurally related compounds. When used as an anticancer agent, the chemotherapeutical forms are primarily bleomycin A2 and B2. It works by causing breaks in DNA...
and methotrexateMethotrexateMethotrexate , abbreviated MTX and formerly known as amethopterin, is an antimetabolite and antifolate drug. It is used in treatment of cancer, autoimmune diseases, ectopic pregnancy, and for the induction of medical abortions. It acts by inhibiting the metabolism of folic acid. Methotrexate...
. - As a consequence of another disease such as rheumatoid arthritisRheumatoid arthritisRheumatoid arthritis is a chronic, systemic inflammatory disorder that may affect many tissues and organs, but principally attacks synovial joints. The process produces an inflammatory response of the synovium secondary to hyperplasia of synovial cells, excess synovial fluid, and the development...
. - Hypersensitivity pneumonitisHypersensitivity pneumonitisHypersensitivity pneumonitis is an inflammation of the alveoli within the lung caused by hypersensitivity to inhaled organic dusts. Sufferers are commonly exposed to the dust by their occupation or hobbies.-Pathophysiology:Hypersensitivity pneumonitis involves inhalation of an antigen...
due to an allergic reaction to inhaled particles. - Acute respiratory distress syndromeAcute respiratory distress syndromeAcute respiratory distress syndrome , also known as respiratory distress syndrome or adult respiratory distress syndrome is a serious reaction to various forms of injuries to the lung....
(ARDS), a severe lung condition occurring in response to a critical illness or injury. - Infant respiratory distress syndromeInfant respiratory distress syndromeInfant respiratory distress syndrome , also called neonatal respiratory distress syndrome or respiratory distress syndrome of newborn, previously called hyaline membrane disease, is a syndrome in premature infants caused by developmental insufficiency of surfactant production and structural...
due to a deficiency of surfactantSurfactantSurfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid...
in the lungs of a baby born prematurely.
Many cases of restrictive lung disease are idiopathic
Idiopathic
Idiopathic is an adjective used primarily in medicine meaning arising spontaneously or from an obscure or unknown cause. From Greek ἴδιος, idios + πάθος, pathos , it means approximately "a disease of its own kind". It is technically a term from nosology, the classification of disease...
(have no known cause). Still, there is generally pulmonary fibrosis
Pulmonary fibrosis
Pulmonary fibrosis is the formation or development of excess fibrous connective tissue in the lungs. It is also described as "scarring of the lung".-Symptoms:Symptoms of pulmonary fibrosis are mainly:...
. Examples are:
- Idiopathic pulmonary fibrosisIdiopathic pulmonary fibrosisIdiopathic pulmonary fibrosis is a chronic, progressive form of lung disease characterized by fibrosis of the supporting framework of the lungs...
- Idiopathic interstitial pneumoniaIdiopathic interstitial pneumoniaIdiopathic interstitial pneumonia , or noninfectious pneumoniaare a class of diffuse lung diseases. Is a term used for a type of diffuse parenchymal lung disease , also called interstitial lung disease .There are seven distinct subtypes of IIP.-Histologic classification:Classification can be...
, of which there are several types - SarcoidosisSarcoidosisSarcoidosis , also called sarcoid, Besnier-Boeck disease or Besnier-Boeck-Schaumann disease, is a disease in which abnormal collections of chronic inflammatory cells form as nodules in multiple organs. The cause of sarcoidosis is unknown...
- Eosinophilic pneumoniaEosinophilic pneumoniaEosinophilic pneumonia is a disease in which a certain type of white blood cell called an eosinophil accumulates in the lung. These cells cause disruption of the normal air spaces where oxygen is extracted from the atmosphere. Several different kinds of eosinophilic pneumonia exist and can occur...
- LymphangioleiomyomatosisLymphangioleiomyomatosisLymphangioleiomyomatosis is a rare lung disease that results in a proliferation of disorderly smooth muscle growth throughout the lungs, in the bronchioles, alveolar septa, perivascular spaces, and lymphatics, resulting in the obstruction of small airways and lymphatics...
- Pulmonary Langerhans' cell histiocytosis
- Pulmonary alveolar proteinosisPulmonary alveolar proteinosisPulmonary alveolar proteinosis is a rare lung disease in which abnormal accumulation of surfactant occurs within the alveoli, interfering with gas exchange. PAP can occur in a primary form or secondarily in the settings of malignancy , pulmonary infection, or environmental exposure to dusts or...
Conditions specifically affecting the interstitium are called interstitial lung diseases.
Extrinsic
- Neuromuscular diseases, including Myasthenia gravisMyasthenia gravisMyasthenia gravis is an autoimmune neuromuscular disease leading to fluctuating muscle weakness and fatiguability...
, and Guillain barre - Nonmuscular diseases of the chest wall, e.g. kyphosisKyphosisKyphosis , also called roundback or Kelso's hunchback, is a condition of over-curvature of the thoracic vertebrae...
and obesityObesityObesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems...
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