Some Lung Problems in Premature Infants Resolve After a Week

Premature infants born before 32 weeks’ gestation have immature lungs that do not produce enough surfactant, a slippery substance that helps the lungs expand. But even though lung disease may not entirely resolve, surfactant composition and function normalizes after the first week of life, according to a new study.

Infants born premature, before 32 weeks’ gestation, have immature lungs that do not produce enough surfactant, a slippery substance that aids in the expansion of the lungs. But even though lung disease may not ever be entirely resolved, surfactant composition and function returns to normal levels within the first few weeks of life, according to a new study. Normal pregnancy runs its course over 40 weeks. When infants are born before the 32nd week, their lives are threatened because their lungs are unable to draw enough oxygen from the blood because lung surfactant is abnormal and present at very low levels. Because very premature infants do not secrete enough surfactant, their lungs collapse during each exhalation, thereby endangering the preemies’ already fragile state of health. “Although premature infants are known to be deficient in pulmonary surfactant, there is limited information regarding surfactant protein composition,” Dr. Phillip L. Ballard and colleagues from Children’s Hospital of Philadelphia, Pennsylvania, write in the November 1st issue of the American Journal of Respiratory and Critical Care Medicine. t The researchers collected windpipe secretions from 35 intubated infants (23 to 31 weeks’ gestation) between 8 and 80 days of age. When tested in a lab, the samples had normal surfactant function. Samples from additional infants who received only synthetic replacement surfactant were analyzed in order to assess surfactant proteins in the first week of life. On the second day of life, contents of three different surfactant proteins were 13.4%, 8.4%, and 0.1%, of the levels observed in samples from days 8 to 80. “The major postnatal increases for SP-A, SP-B, and SP-C occurred during the first, second, and third weeks, respectively,” Dr. Ballard and colleagues explain. “Our findings indicate that premature infants have both surfactant deficiency and dysfunction at birth and that normal surfactant composition and function can occur after the first week despite lung disease,” they conclude. (Source: Reuters, MEDline Plus November 2003)