Restrictive lung disease

Restrictive lung disease
Classification and external resources
ICD-9	518.89
eMedicine	med/2012

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.

Pathophysiology

In disorders that are intrinsic to the lung parenchyma, the underlying process is usually pulmonary fibrosis (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 cough.^{[citation needed]}

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 ratio. In obstructive lung disease however, FEV1 is reduced while FVC remains stable, consequentially 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 parenchyma of the lung, or extrinsic to it.

Intrinsic

• Asbestosis caused by long-term exposure to asbestos dust.
• 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.

Many cases of restrictive lung disease are idiopathic (have no known cause). Still, there is generally pulmonary fibrosis. 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

• Neuromuscular diseases, including Myasthenia gravis, and Guillain barre
• Nonmuscular diseases of the chest wall, e.g. kyphosis and obesity.

See also

• Obstructive lung disease
• Chronic obstructive pulmonary disease