Work of breathing tests will be performed on premature infants who required oxygen for at least 28 days during their time in NICU. These same work of breathing tests will be performed in another group of premature infants who did not require oxygen for at least 28 days during their time in the NICU. The two groups will be compared.
The purpose of this study is to compare how premature infants who required oxygen for at least 28 days during their time in the NICU (Neonatal Intensive Care Unit) breathe at discharge compared to premature infants who did not require oxygen for at least 28 days during their time in the NICU.