Tseng Hui-Yun, Yang Shih-Hsing, Chiang Han-Sun
Department of Chemistry, Fu Jen Catholic University, New Taipei City 242062, Taiwan.
Graduate Institute of Biomedical and Pharmaceutical Science, Fu Jen Catholic University, New Taipei City 242062, Taiwan.
Healthcare (Basel). 2021 Sep 19;9(9):1235. doi: 10.3390/healthcare9091235.
Measuring the fraction of inspired oxygen (FiO) is challenging in spontaneously breathing patients with impaired respiratory mechanics during low-flow nasal cannula. Our study investigates the FiO with varied tidal volume (V) and respiratory rate (RR) among different lung mechanics and provides equations to estimate the FiO.
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 (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 FiO was measured at the carina.
The lowest and highest FiO were evident during high (700 mL) and low V (300 mL), respectively, among normal, restrictive, and obstructive lung models. As RR increases, this decreases the FiO. However, we found that V and oxygen flow rate are the principal factors influencing measured FiO by multiple linear regression analysis.
Our data suggest that the actual FiO is never as high in spontaneously breathing patients as that estimated. V and oxygen flow rate had a substantial impact on the FiO.
在低流量鼻导管给氧期间，对于呼吸力学受损的自主呼吸患者，测量吸入氧分数（FiO）具有挑战性。我们的研究调查了不同肺力学情况下，潮气量（V）和呼吸频率（RR）变化时的FiO，并提供了估算FiO的公式。
本研究使用了两个训练肺和测试肺，并设计了三种肺力学情况（正常（R5/C60）、限制性（R20/C80）、阻塞性（R5/C40））。模拟了V（300、500和700毫升）和RR（10、20和30次/分钟）的自主呼吸。鼻导管的流速设置为每分钟1、3和5升（LPM），并在隆突处测量FiO。
在正常、限制性和阻塞性肺模型中，分别在高V（700毫升）和低V（300毫升）时，FiO最低和最高。随着RR增加，FiO降低。然而，通过多元线性回归分析，我们发现V和氧流速是影响测量FiO的主要因素。
我们的数据表明，自主呼吸患者的实际FiO从未达到估算值那么高。V和氧流速对FiO有重大影响。
