Effective Fraction of Inspired Oxygen in Premature Infants Receiving Support Via Nasal Cannula

During routine nasal cannula (NC) use in the newborn ICU, the actual fraction of oxygen inspired by the infant, i.e. the effective FiO2 (Effective-FiO2) that reaches the infant's airways, cannot be easily determined. The effective FiO2 during NC use is generally lower than the FiO2 in the gas delivered by NC at the infant's nose due to dilution with ambient gas entrained by the infants during spontaneous inspiration. The factors influencing effective FiO2 include the set FiO2 of the gas delivered by NC (NC-FiO2), the NC-flow rate, and the entrainment of ambient gas by the infant during each spontaneous inspiration. The individual contribution of each of these factors to the variability in effective-FiO2 in extreme premature infants has not been systematically evaluated.

The objective of this study is to determine the multifactorial relationship between the effective fraction of inspired oxygen (Effective-FiO2) and the FiO2 in the gas delivered by the nasal cannula (NC-FiO2), NC flow rate, spontaneous minute ventilation and other patient characteristics in premature infants who receive supplemental oxygen via nasal cannula (NC).