OBJECTIVE: The aim of this study was to measure pharyngeal pressures in preterm 
infants receiving high-flow nasal cannulae.
STUDY DESIGN: A total of 18 infants were studied (median gestational age 34 
weeks, weight 1.619 kg). A catheter-tip pressure transducer was introduced into 
the nasopharynx. Flow was sequentially increased to a maximum of 8 l min(-1) and 
decreased to a minimum of 2 l min(-1).
RESULT: There was a strong association between pharyngeal pressure and both flow 
rate and infant weight (P<0.001, r (2)=0.61), but not mouth closure. This 
relationship could be expressed as pharyngeal pressure (cm H(2)O)=0.7+1.1 F 
(F=flow per kg in l min(-1) kg(-1)).
CONCLUSION: High-flow nasal cannulae at flow rates of 2 to 8 l min(-1) can lead 
to clinically significant elevations in pharyngeal pressure in preterm infants. 
Flow rate and weight but not mouth closure are important determinants of the 
pressure transmitted.