High-Velocity Nasal Insufflation Increases Nasopharyngeal Pressure with Flow-Dependent Manner Compared with High Flow Nasal Cannula in Adult Volunteers - A Single-Center Prospective Observational Study.

Background: High flow nasal cannula (HFNC) can produce positive airway pressure, and the pressure increases in proportion to the gas flow. Recently, high-velocity nasal insufflation (HiVNI) was developed as a new system of HFNC. However, it is still unclear whether HiVNI can increase the airway pressure. The purpose of our study was to evaluate whether the HiVNI can increase the airway pressure compared to HFNC, under various gas flows.

Methods: This single-center prospective observational study recorded nasopharyngeal pressures in fifteen healthy volunteers who received both normal HFNC and HiVNI. After a 10 Fr catheter was inserted via the nose, the catheter was connected to the manometer and high flow oxygen therapy was performed using both systems. The measurements were carried out at flows of 20, 30, and 40 L/min, and the pressures were recorded at 50 Hz. The measurements were repeated with the mouth in the open and closed positions for each high-flow system.

Results: With the mouth open, the mean nasopharyngeal pressure was low in both systems, and the difference between the two systems was not significant. However, with the mouth closed, a significantly higher nasopharyngeal pressure was recorded with the HiVNI system compared to the HFNC system at all flows (P < .01). Furthermore, the difference between HiVNI and HFNC at each flow became significantly greater with the increase of flow (P < .01).

Conclusion: In healthy volunteers, HiVNI can produce higher nasopharyngeal pressure than normal HFNC in a flow-dependent manner.