Impact of CPAP Level on V/Q Mismatch in Premature Infants

Inclusion Criteria: 1. Born at 27-35 weeks gestational age (GA) by best obstetric estimate, determined by the clinical obstetric team during antepartum admission. 2. Age limits: 24 hours of age - 35 weeks corrected gestational age. 3. On continuous CPAP support between 4-8 cm H2O for greater than 24 hours, as document on the bedside infant flow sheet. 4. Supplemental oxygen requirement, with a fraction of inspired oxygen (FiO2) 0.25 for at least 2 consecutive hours, as documented on the bedside infant flow sheet. Exclusion Criteria: 1. Congenital anomalies, as determined by the clinical supervising physician. 2. Current or prior air leak syndrome, as determined by the clinical supervising physician.