Restrictive lung disease
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Restrictive lung diseases (or restrictive ventilatory defects[1]) are a category of extrapulmonary, pleural, or parenchymal respiratory diseases that restrict lung expansion,[2] 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.
Pathophysiology
In disorders that are intrinsic to the lung parenchyma, the underlying process is usually pulmonary fibrosis (scarring of the lung).[3] 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 cough.[citation needed]
Diagnosis
In restrictive lung disease, both forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) are reduced, however, the decline in FVC is more than that of FEV1, resulting in a higher than 80% FEV1/FVC ratio. In obstructive lung disease however, FEV1 is reduced while FVC remains stable, consequentially depicting a lower FEV1/FVC ratio.[citation needed]
One definition requires a total lung capacity which is 80% or less of the expected value.[4]
Causes and classification
Restrictive lung diseases may be due to specific causes which can be intrinsic to the parenchyma of the lung, or extrinsic to it.[5]
Intrinsic
- Pneumoconiosis caused by long-term exposure to dusts, especially in mining. For example, Asbestosis.
- Radiation fibrosis, usually from the radiation given for cancer treatment.
- Certain drugs such as amiodarone, bleomycin and methotrexate.
- As a consequence of another disease such as rheumatoid arthritis.
- Hypersensitivity pneumonitis due to an allergic reaction to inhaled particles.
- Acute respiratory distress syndrome (ARDS), a severe lung condition occurring in response to a critical illness or injury.
- Infant respiratory distress syndrome due to a deficiency of surfactant in the lungs of a baby born prematurely.
- Tuberculosis[6]
Many cases of restrictive lung disease are idiopathic (have no known cause). Still, there is generally pulmonary fibrosis.[3] Examples are:
- Idiopathic pulmonary fibrosis
- Idiopathic interstitial pneumonia, of which there are several types
- Sarcoidosis
- Eosinophilic pneumonia
- Lymphangioleiomyomatosis
- Pulmonary Langerhans' cell histiocytosis
- Pulmonary alveolar proteinosis
Conditions specifically affecting the interstitium are called interstitial lung diseases.
Extrinsic
- Nonmuscular diseases of the upper thorax such as kyphosis , pectus carinatum and pectus excavatum.[7]
- Diseases restricting lower thoracic/abdominal volume (e.g. obesity, diaphragmatic hernia, or the presence of ascites).[7]
- Pleural thickening.
See also
References
- ^ Johns Hopkins School of Medicine's Interactive Respiratory Physiology > Restrictive Ventilatory Defect Retrieved on February 25, 2010
- ^ Sharma, Sat. "Restrictive Lung Disease". Retrieved 2008-04-19.
- ^ a b PULMONARY FUNCTION TESTS A Workshop on Simple Spirometry & Flow Volume Loops. Dr. S. Osborne, Dept. Cellular & Physiological Sciences. Mars 2009
- ^ Brack T, Jubran A, Tobin MJ (May 2002). "Dyspnea and decreased variability of breathing in patients with restrictive lung disease". Am. J. Respir. Crit. Care Med. 165 (9): 1260–4. doi:10.1164/rccm.2201018. PMID 11991875.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ "eMedicine - Restrictive Lung Disease : Article by Sat Sharma". Retrieved 2008-11-21.
- ^ Amaral, André F.S.; Coton, Sonia; Kato, Bernet; Tan, Wan C.; Studnicka, Michael; Janson, Christer; Gislason, Thorarinn; Mannino, David; Bateman, Eric D.; Buist, Sonia; Burney, Peter G.J. (October 2015). "Tuberculosis associates with both airflow obstruction and low lung function: BOLD results". European Respiratory Journal. 46 (4): 1104–1112. doi:10.1183/13993003.02325-2014. PMID 26113680.
- ^ a b eMedicine Specialties > Pulmonology > Interstitial Lung Diseases > Restrictive Lung Disease Author: Lalit K Kanaparthi, MD, Klaus-Dieter Lessnau, MD, Sat Sharma, MD. Updated: Jul 27, 2009