How is chronic lung disease in infants diagnosed?

There is no one test to diagnose chronic lung disease. A doctor may first suspect it if your baby has trouble breathing. The diagnosis is confirmed when one of the following is present:

• The baby needs extra oxygen for at least 28 days after birth.
• At 36 weeks of gestational age, the baby needs more oxygen than is present in ordinary air. Gestational age is the number of weeks and days a baby has developed since the beginning of the pregnancy, or gestation.

Babies with chronic lung disease usually have regular blood tests (including a blood gas test) to monitor how well their lungs are working. These tests may be done until the baby can breathe without extra oxygen.

A number of tests may be done to rule out other causes of difficulty breathing and to learn whether complications of chronic lung disease are present.

• A baby may have an electrocardiogram and an echocardiogram to see how well the heart is working. Echocardiograms are usually repeated every 2 to 3 months until 4 to 6 months after oxygen therapy has stopped.
• A baby may have a lung function test to find out how much damage has been done to the lungs. This test is repeated regularly as the child gets older. After results are normal, a child may no longer need lung function tests.