Background

From the point of view of machine construction and hydrodynamics, this paper innovatively proposes that the essence of high-flow nasal cannula (HFNC) is a constant-flow mode of non-invasive ventilator (NIVCFM). This study enrolled healthy adults as study subjects to assess the subjective comfort assessed by visual analog scoring scale of NIVCFM/HFNC and objective comfort measured by the noise level generated by NIVCFM/HFNC. Aiming to provide a scientific basis for the rational clinical application of NIVCFM/HFNC.

Methods

44 healthy adults participated in this study. The noise generated by NIVCFM/HFNC is measured and the comfort is evaluated during NIVCFM delivery at flow rates of 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60L/min.

Results

When the ventilator flow rate is 60 L/min, the maximum noise is 65.9dB, increasing noise by 23.7dB from a baseline of 42.2dB at the flow rate of 0L/min. There was a strong nonlinear positive correlation between the noise level and the flow rates. The median score for dry mouth, nose or throat, dysphagia, sore throat and other discomfort was 0. The median score for dyspnea was 0 at 0-30L/min,1 at 35-55L/min and 2 at 60L/min.

Conclusions

The grater the flow rate, the greater the noise generated by NIVCFM/HFNC (<65.9dB). The maximum flow rate that most healthy adults can able to tolerate is 30 L/min, and the main discomfort is dyspnea.