AIMS: This study aims to determine if there is a difference in the pharyngeal 
pressure, measured as a surrogate for continuous positive distending airway 
pressure, delivered to premature infants between two commonly used heated, 
humidified high-flow nasal cannulae (HHHFNC) devices: Fisher & Paykel Healthcare 
HHHFNC and Vapotherm 2000i.
METHODS: Pharyngeal pressure measurements were taken from stable premature 
infants receiving HHHFNC for respiratory support. Flow rates of 2-8 L/min were 
studied.
RESULTS: Nine infants had pharyngeal pressure measurements recorded with both 
HHHFNC devices at flow rates of 2-8 L/min. There was no difference in pharyngeal 
pressures recorded between devices at flow rates of 2-6 L/min; measured pressure 
was linearly associated with flow (R(2) = 0.9). At flow rates of 7 L/min, 
Vapotherm delivered a mean (standard deviation) pharyngeal pressure of 4.7 (2.2) 
cmH2 O compared with 4.23 (2.2) cmH2 O by the Fisher & Paykel device (P = 0.04). 
At a flow of 8 L/min, the mean pharyngeal pressure via Vapotherm was 4.9 (2.2) 
cmH2 O compared with 4.1 (2.3) cmH2 O with the Fisher & Paykel device (P = 
0.05).
CONCLUSIONS: Both HHHFNC delivered similar pharyngeal pressures at flow rates of 
2-6 L/min. The pressure limiter valve of the Fisher & Paykel device attenuated 
the pharyngeal pressures at flows of 7 and 8 L/min. Vapotherm trended towards 
higher delivered pharyngeal pressure at flow rates 7 and 8 L/min, but the 
clinical significance of the difference remains unclear.