Noninvasive high frequency oscillatory ventilation through nasal prongs: bench evaluation of efficacy and mechanics.

BACKGROUND: Noninvasive high frequency oscillatory ventilation through nasal prongs (nHFOV) has been proposed as a new respiratory support in neonatology. We studied the effect of ventilation parameters and nasal prongs on nHFOV efficacy and mechanics.

METHODS: Customized sealed circuits connecting a SM3100A oscillator to a neonatal lung model were developed to evaluate the effect of applying HFOV via two different sized nasal prongs on delivered tidal volume and pressure. Measurements were made across a range of frequencies and pressures; amplitude was set to obtain visible lung oscillation.

RESULTS: Volume delivered by peak-to-peak oscillation, ventilation, and pressure significantly differed among the interfaces, being higher for large cannulae and the control circuit (p < 0.0001). The interposition of a large or small nasal prong reduced volume to 56 and 26%, ventilation to 32 and 9%, and mean pressure to 83 and 79%, respectively, of the values measured for the direct connection of the oscillator to the test lung. Volume and ventilation were inversely related to frequency, which was particularly evident with larger diameter circuits due to higher delivered tidal volume (R (2) > 0.9). Increasing ventilation was associated with larger tidal volume and nasal prong diameter (adjusted R (2) = 0.97).

CONCLUSIONS: nHFOV using common nasal prongs is technically possible. Efficiency of tidal volume delivery is significantly affected by prong diameter.