With the advent of new technologies, it has become routine to offer supplemental oxygen to neonates via nasal prongs rather than by increasing the ambient oxygen in the incubator. The rationale for use of nasal prongs is that it provides more constant inspired O2 concentration whereas ambient oxygen is subject to fluctuations due to opening of the incubator doors. Nasal prongs, however, have significant disadvantages including i) nasal trauma, ii) increased restlessness, and iii) increased upper airway resistance with increased work of breathing. It remains subject to inspired O2 fluctuation due to prong dislodgement, which is common. Furthermore, we observed substantial clinical improvement in two preterm infants who had fewer apneas and appeared more comfortable after removing the nasal prongs and increasing the ambient O2 concentration. We hypothesized, therefore, that infants would have less apnea, less desaturation and less bradycardia with increased ambient O2 concentration compared with the nasal canulae. To test this hypothesis we studied 8 preterm infants[birthweight 1160±587g (mean ± SE), study weight 1240±534g, gestational age 28±3wk, postnatal age 28 + 4 d] on 9 occasions. Each study consisted of two consecutive 4 hour epochs where FiO2, hypopharyngeal O2, episodes of desaturation < 90%, bradycardias < 90 bpm, and apneas > 10 s duration were measured while the infant was given O2 by either nasal prongs or into the isolette to maintain saturations at about 95%. Hypopharyngeal FiO2 was measured using a 10F suction catheter inserted via the nares and through which a 60 cc sample of gas was aspirated and its FiO2 measured with a Miniox O2 analyzer. Although hypopharyngeal O2 concentrations were similar (24 ± 4 vs 23 ± 5%, p = 0.55), we observed significantly greater number of apneas 13.2 ± 3 vs 2.8 ± 7 (p < 0.008) and desaturations 14 ± 3 vs 9 ± 3 (p < 0.008) when using nasal prongs. There was no difference in the number of bradycardias. We conclude that administration of O2 into the isolette is associated with fewer apneas and less desaturations and, for this reason, it may be a superior method of O2 administration in preterm infants. Supported by Children's Hospital Research Foundation & Canadian Lung Association.
