Conclusion
Our study assessed FO2 insp. and FO2pre-insp. during nasal cannula oxygen therapy in a spontaneous breathing
lung model and suggested that multiple factors influence the measured
FO2 insp. and FO2 pre-insp. under
low-flow nasal cannula, such as respiratory patterns, additional
VT, f and inspiratory or expiratory time, which indicate
the short-term storage of oxygen in an anatomic space between the
end-expiratory period and the next inspiratory period, as in the normal,
restrictive and obstructive lung models. As such, an increased
VT cause a decrease in FO2 insp. and
FO2 pre-insp. measured in the carina. As
VT and f decrease, there is less difference between
FO2 pre-insp. and FO2 insp.; therefore,
any variation in the total expiratory time will affect the oxygen
reservoir in the next inspiration. The results of this bench study
provide a reference for clinicians and researchers regarding various
lung mechanics and respiratory patterns under low flow nasal cannula.