PT - JOURNAL ARTICLE AU - Li-Li Li AU - Bing Dai AU - Jie Lu AU - Xin-Yu Li TI - Effect of Different Interfaces on F<sub>IO<sub>2</sub></sub> and CO<sub>2</sub> Rebreathing During Noninvasive Ventilation AID - 10.4187/respcare.07444 DP - 2021 Jan 01 TA - Respiratory Care PG - 25--32 VI - 66 IP - 1 4099 - http://rc.rcjournal.com/content/66/1/25.short 4100 - http://rc.rcjournal.com/content/66/1/25.full AB - BACKGROUND: Improving FIO2 and reducing CO2 rebreathing (V̇ICO2) are the key means to improve the therapeutic efficacy of noninvasive ventilation (NIV). This study aimed to investigate the impact of interface design on FIO2 and V̇ICO2 during NIV.METHODS: A simulated lung model was established to analyze 17 different interfaces. CO2 was injected into the outlet of the simulated lung, and the noninvasive ventilator was connected to the simulated lung to simulate the application of NIV in patients with COPD with hypercapnia. FIO2 and V̇ICO2 were calculated by mathematical integration of synchronously collected data pertaining to real-time pressure, flow, oxygen concentration, and CO2 concentration in the breathing circuit. Comparisons were performed between different types (nasal vs oronasal) and models of interfaces as well as between interfaces with different leak positions. Correlation of FIO2 and V̇ICO2 with inner volume and leakage, respectively, and the correlation between FIO2 and V̇ICO2 were analyzed.RESULTS: FIO2 levels were significantly different with a nasal or an oronasal mask (0.45 ± 0.05% vs 0.41 ± 0.08%, respectively; P &lt; .001). FIO2 levels associated with different models of interfaces varied significantly (all P &lt; .001); V̇ICO2 did not differ significantly among the different interfaces (P = .19). Leak position significantly affected FIO2 and V̇ICO2 (all P &lt; .001). Both inner volume and leakage significantly correlated with FIO2 (r = −0.23, P &lt; .001; r = −0.08, P = .02). There was a significant correlation between FIO2 and V̇ICO2 (r = 0.43, P &lt; .01); the general linear equation was y = 0.17 + 0.02x (r = 0.43, R2 = 0.19).CONCLUSIONS: The design of the interface had a significant impact on FIO2 and V̇ICO2 during NIV. FIO2 and V̇ICO2 showed a significant positive correlation, although the effect size of correlation was moderate.