Impact of Oxygen Concentration Delivered via Nasal Cannula on Different Lung Conditions: A Bench Study

Hui-Yun Tseng; Shih-Hsing Yang; Han-Sun Chiang

doi:10.3390/healthcare9091235

Impact of Oxygen Concentration Delivered via Nasal Cannula on Different Lung Conditions: A Bench Study

Healthcare (Basel). 2021 Sep 19;9(9):1235. doi: 10.3390/healthcare9091235.

Authors

Hui-Yun Tseng^{1

2

3

4}, Shih-Hsing Yang³, Han-Sun Chiang²

Affiliations

¹ Department of Chemistry, Fu Jen Catholic University, New Taipei City 242062, Taiwan.
² Graduate Institute of Biomedical and Pharmaceutical Science, Fu Jen Catholic University, New Taipei City 242062, Taiwan.
³ Department of Respiratory Therapy, Fu Jen Catholic University, New Taipei City 242062, Taiwan.
⁴ Department of Respiratory Therapy, Chang Gung University, Taoyuan 33302, Taiwan.

Abstract

Background: Measuring the fraction of inspired oxygen (FiO₂) is challenging in spontaneously breathing patients with impaired respiratory mechanics during low-flow nasal cannula. Our study investigates the FiO₂ with varied tidal volume (V_T) and respiratory rate (RR) among different lung mechanics and provides equations to estimate the FiO₂.

Methods: Two training and test lungs were used in this study, and the three lung mechanics (normal (R5/C60), restrictive (R20/C80), obstructive (R5/C40)) were designed. Spontaneous breathing with V_T (300, 500, and 700 mL) and RR (10, 20, and 30 breaths/min) was simulated. The flow rate of the nasal cannula was set to 1, 3, and 5 L per minute (LPM), and the FiO₂ was measured at the carina.

Results: The lowest and highest FiO₂ were evident during high (700 mL) and low V_T (300 mL), respectively, among normal, restrictive, and obstructive lung models. As RR increases, this decreases the FiO₂. However, we found that V_T and oxygen flow rate are the principal factors influencing measured FiO₂ by multiple linear regression analysis.

Conclusions: Our data suggest that the actual FiO₂ is never as high in spontaneously breathing patients as that estimated. V_T and oxygen flow rate had a substantial impact on the FiO₂.

Keywords: delivered oxygen concentration; nasal cannula; normal lung model; obstructive lung model; oxygen therapy; restrictive lung model; simulation study.