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Lung diseases

Decreased breathing capacity

11/20/2007

Question:

I recently had a breathing tests. The results showed breathing capacity of 57%. What is the impact or restrictions I may experience generally? to daily living?

Answer:

"Breathing capacity" is not a value that is actually reported on a pulmonary function test, so your question is difficult to answer specifically. In general, complete pulmonary function testing evaluates for three things: 1. obstruction to airflow (such as with asthma or emphysema), 2. restriction to lung expansion (such as stiffening which occurs with pulmonary fibrosis or obesity), and 3. the ability to exchange gases such as oxygen or carbon dioxide. The answer to your question depends a little on which of these categories you are actually describing. In general, we describe each of these parameters as a percentage of what would be expected for your gender, race, and age. In most cases, 80% or greater is considered normal, 70-80% is considered a mild reduction in function, 60-70% a moderate reduction, 50-59% a moderately severe reduction, 34-49% severe, and less than 34% is very severe. These parameters vary a little depending on the actual test performed. The numbers are most useful to physicians as we decide when and what medications to prescribe. In addition, a change in your level of function overtime may be more important than the actual number today.

Although you would fall near the "moderate" reduction in function, it is not possible to predict you limitations based on this alone. In many people, the impact on daily living and functional status for each level of function is different, and no number firmly predicts the response. Your limitations will also be affected by your general health, the presence of other medical conditions, and overall level of physical conditioning and weight.

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Response by:

Jennifer  McCallister, MD Jennifer McCallister, MD
Clinical Assistant Professor of Pulmonary, Allergy, Critical Care & Sleep
College of Medicine
The Ohio State University