Effect of high-frequency oscillation on pressure delivered by high flow nasal cannula in a premature infant lung model.

Objective This study describes the effect of high-frequency oscillation on airway pressure generated by high flow nasal cannula (HFNC) in a premature infant lung model. Design/Methods A premature in 0.5 or 1.0 mL/cmH(2)O, respiratory rate (RR) of 40 or 60 breaths per min, and tidal volume of 6 mL. Oscillation was achieved by passing the HFNC supply flow through a 3-way solenoid valve operating at 4, 6, 8, or 10 Hz. Airway pressure at the simulated trachea was recorded following equilibration of end-tidal CO2 both with and without oscillation. Results Superimposing high-frequency oscillations onto HFNC resulted in an average decrease in mean airway pressure of 17.9% (P = .011). The difference between the maximum and minimum airway pressures, increment P-min-max,P- significantly increased as oscillation frequency decreased (P < .001). Airway pressure during oscillation was 12.8% greater with the 1.0 vs the 0.5 mL/cmH(2)O compliance at flows > 4 L/min (P = .031). CO2 clearance was 13.1% greater with the 1.0 vs 0.5 mL/cmH(2)O compliance at oscillation frequencies less than 8 Hz (P = .015). Conclusion In this in-vitro study we demonstrate that delivered mean airway pressure decreases when applying high-frequency oscillation to HFNC, while still improving CO2 clearance. The combination of improved CO2 clearance and reduced pressure delivery of this novel noninvasive modality may prove to be a useful improvement in the respiratory care of infants in respiratory distress.