Comparison of Delivered Distending Pressures in the Oropharynx in Preterm Infant on Bubble CPAP and on Three Different Nasal Interfaces

Objective: To compare the level of continuous positive airway pressure (CPAP) delivered by three different CPAP delivery interfaces (RAM cannula system, Hudson prongs, and nasal mask) in preterm neonates with respiratory distress.

Methods: Preterm neonates with gestation between 28 weeks and 34 weeks and birth weight more than or equal to 1000 g and requiring nasal CPAP for respiratory distress were eligible for the study. During the study period, consecutive infants requiring CPAP were started on Hudson prongs or RAM cannula or nasal mask in that order. We measured the mean oropharyngeal pressure, which approximates the applied CPAP level. Oropharyngeal pressures in the recruited neonates were measured between 24 and 48 hours of postnatal age, when stable and in sleep or quiet awake state. Comparison of the delivered oropharyngeal pressures when on three different nasal interfaces at the same set flow rate and at set CPAP of 5 cm or 6 cm of H O was the primary outcome.

Results: Data was analyzed from 30 neonates in each group. We found that measured oropharyngeal pressures were less than set CPAP level in all three studied interfaces. Maximum drop in oropharyngeal pressure was observed with use of RAM cannula with measured oropharyngeal pressures being 1.1 and 1.2 cm H O less than set CPAP of 5 and 6 cm H O respectively. Pharyngeal pressure best correlated to set CPAP level with the use of nasal mask.

Conclusion: None of the nasal interfaces delivered oropharyngeal pressure equivalent to the set CPAP. However, nasal mask delivered oropharyngeal pressure best matched to the set CPAP.