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Updated June 18, 2014

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Definition: Pulmonary surfactant is a chemical found in the lungs. Surfactant helps the alveoli, the tiny air sacs where oxygen and carbon dioxide are exchanged in the blood, to stay open.

Babies don't have enough surfactant to keep their alveoli open until they are close to term. When the alveoli don't have enough surfactant, they collapse, and gas exchange cannot occur.

A lack of surfactant can cause respiratory distress syndrome (RDS) in premature babies, so doctors will often give very premature babies one or more doses of synthetic surfactant.

Pronunciation: sur-FAC-tent
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