Atelectasis is a collapse in part of the lungs. Normally, air passes through the airways into small sacs of the lungs. Oxygen from the air passes through these sacs into the blood. Carbon dioxide also passes from the blood to the sacs to leave the body. With atelectasis, these sacs are collapsed. Oxygen and carbon dioxide cannot pass through the collapsed sacs.

A collapse over large areas of the lungs can lead to serious problems. In infants, atelectasis may be:

  • Congenital—present at birth
  • Acquired—caused by an acquired condition

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Atelectasis is not a disease. It is the result of a disease or abnormality in the body. It can be caused by:

  • Blockage in airways—as a result of an inhaled stool during birth, inhaled object, or a mucus plug that keeps air from moving into sacs
  • Lung infections—may cause fluid build-up that blocks air to lung sacs
  • Lack of surfactant (common in premature infants)—surfactant is a fluid that lines the inside of the lungs and helps them function properly
  • Impaired breathing—air is not pulled deep enough into the lungs to open all sacs
  • Damage to nerve and muscles that control breathing—may prevent coughing, deep breathing, or yawning