Apnea of prematurity (AOP) is frequently managed with nasal continuous positive 
airway pressure (NCPAP). Nasal cannula (NC) are used at low flows (<0.5 L/min) 
to deliver supplemental oxygen to neonates. A number of centers use high-flow 
nasal cannula (HFNC) in the management of AOP without measuring the positive 
distending pressure (PDP) generated. Objective. To determine the NC flow 
required to generate PDP equal to that provided by NCPAP at 6 cm H(2)O and to 
assess the effectiveness of HFNC as compared NCPAP in the management of AOP. 
Method. Forty premature infants, gestation 28.7 +/- 0.4 weeks (mean +/- standard 
error of mean), postconceptual age at study 30.3 +/- 0.6 weeks, birth weight 
1256 +/- 66 g, study weight 1260 +/- 63 g who were being managed with 
conventional NCPAP for at least 24 hours for clinically significant apnea of 
prematurity, were enrolled in a trial of ventilator-generated conventional NCPAP 
versus infant NC at flows of up to 2.5 L/min. End expiratory esophageal pressure 
was measured on NCPAP and on NC, and the gas flow on NC was adjusted to generate 
an end expiratory esophageal pressure equal to that measured on NCPAP. Two 
6-hour periods were continuously recorded and the data were stored on computer. 
Results. The flow required to generate a comparable PDP with NC varied with the 
infant's weight and was represented by the equation: flow (L/min) = 0.92 + 
0.68x, x = weight in kg, R = 0.72. There was no difference in the frequency and 
duration of apnea, bradycardia or desaturation per recording between the 2 
systems. Conclusion. NC at flows of 1 to 2.5 L/min can deliver PDP in premature 
neonates. HFNC is as effective as NCPAP in the management of AOP.