Effect of high frequency oscillatory high flow nasal cannula on carbon dioxide clearance in a premature infant lung model: A bench study.

ObjectiveThis study compared CO2 clearance in a premature infant lung model connected to a high flow nasal cannula (HFNC) system supplied with oscillatory versus non-oscillatory flow. Design/MethodsThe lung model was set to compliance 1.0mL/cmH(2)O, RR 60 breaths/min, and 6mL tidal volume. A 100% CO2 was injected at a constant 15mL/min. To create oscillation, HFNC flow was interrupted at rates of 4-6-8 and 10Hz. equilibrated end-tidal CO2 (ETCO2) was recorded with and without oscillation at set flows of 2-8L/min and repeated for each oscillation frequency. ResultsOverall ETCO2 decreased significantly (P<0.001) during both non-oscillatory and oscillatory HFNC as set flow increased from 2 to 8L/min by 26.3% and 60.8%, respectively. Oscillatory ETCO2 levels decreased linearly compared to non-oscillatory HFNC with negligible difference at 2L/min and a 48.4% difference at 8L/min (P<0.001). There were no differences in ETCO2 levels between oscillation frequencies at any flow except at 6Hz for which ETCO2 was significantly lower (P<0.01) than at 4, 8, and 10Hz for 5-8L/min HFNC flows. Amplitude of volume oscillations increased with increasing flow from 0.5mL at 2L/min to 4.0mL at 8L/min (P<0.001), and decreased with increasing oscillation frequency. ConclusionOscillatory HFNC as compared to non-oscillatory was associated with significantly improved CO2 clearance in this premature infant lung model. This simple modification of the HFNC system may prove to be a useful enhancement to this mode of non-invasive respiratory support for preterm infants at high risk for respiratory failure.