Restrictive lung disease

Restrictive lung disease
Classification and external resources
ICD-9-CM	518.89
eMedicine	article/301760
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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.

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.

The main symptoms are shortness of breath and cough.

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, the FEV1/FVC is less than 0.7, indicating that both FEV1 and FVC are reduced. This indicates that the FVC is also reduced, but not by the same ratio as FEV1.

One definition requires a total lung capacity which is 80% or less of the expected value.

Restrictive lung diseases may be due to specific causes which can be intrinsic to the parenchyma 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.

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