Prediction of Nasal-HFO Characteristics of Nasal-CPAP using Air-curtain and Entrainment

Abstract

High-frequency oscillatory (HFO) is a commonly used therapy applied to preterm infant who require ventilatory support for open lung. The authors have been developing a generator for Nasal-CPAP (HNCPAP) using an air-curtain capable controlling nasal-HFO. This paper describes Nasal-HFO pressure waveforms synchronized with spontaneous breathing from Nasal-HFO results. Experiments were conducted using a breathing mode simulating healthy lungs of a spontaneous breathing simulator for neonates, with MAP (mean airway pressure) constant, and without HFO and with HFO for each of tidal volume. The experimental conditions are MAP 500 Pa, respirator frequency 50 times/min, stroke volume 15 ml, tidal volume 2 ml, 5 ml, 7 ml. The results obtained were as follows: (1) HFO amplitude should not be attenuated in the airways, (2) HFO amplitude increased during inhalation further reduced alveolar pressure, and (3) Adding HFO in first half of exhalation halved the entrainment effect. From these results, Nasal-HFO pressure waveform were predicted.

・ By adding HFO during inhalation, the alveolar pressure was further reduced, and the lung recruitment effect was improved.

・ By eliminating HFO in the first half of exhalation, exhalation flow can be discharged without resistance using entrainment.

Finally, prediction of Nasal-HFO synchronized with spontaneous breathing showed the possibility of new use of HNCPAP.