What’s Typical?

Lung diseases are usually divided into two categories: Obstructive and Restrictive. A third category that should also be considered is a Diffusion Defect.

Obstructive refers to Airway Obstruction, or a reduction in the speed that air can flow in and out of the lungs. Examples of Obstructive lung diseases include Asthma, Chronic Bronchitis and Emphysema.

Restriction refers to a reduction in the amount of air the lung can hold. Examples of Restrictive lung disease include Pulmonary Fibrosis and Sarcoidosis.

A Diffusion Defect refers to a reduction in the ability of the lung to transfer oxygen and carbon dioxide to and from the circulation. An example of Diffusion Defects include Pulmonary Emboli, Emphysema and Pulmonary Fibrosis.

A problem in determining what is typical for a given lung disease is that there is often overlap between categories and diseases. Pure examples tend to be rare. For example, when looking at obstructive lung diseases:


Asthma, bronchitis and emphysema can overlap and share characteristics. This can make it difficult to say how much the diagnosis of asthma or bronchitis or emphysema applies to given individual. This is a problem that is common to one degree or another for all lung diseases and this needs to be taken into consideration when trying to determine what’s typical.

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