Effect of different interfaces on FiO_2 and CO_2 rebreathing during noninvasive positive pressure ventilation / 中国实用内科杂志

ABSTRACT

OBJECTIVE: To investigate the effect of different interfaces on FiO_2 and CO_2 rebreathing(ViCO_2) during noninvasive positive pressure ventilation. METHODS: The Active Servo Lung respiratory simulation system was used to simulate a hypercapnia COPD patient received NPPV through injection of CO_2 gas from the place closest to the outlet of simulated lung to maintain end-tidal carbon dioxide partial pressure at 80 mmHg,and oxygen delivery during NPPV was simulated by means of injection of 5 L/min oxygen through the hole of interface. FiO_2 and ViCO_2 were integral calculated through the synchronous collect real-time pressure, flow rate, oxygen concentration and CO_2 concentration. The effect of different type and models of interfaces on FiO_2 and ViCO_2 were compared, and the bivariate correlation analysis was applied to investigate the correlation of FiO_2 and ViCO_2. RESULTS: The inner volume, leak volume and leak position of different interfaces were different. The FiO_2 of the oral-nasal mask and nasal mask were significantly different(P<0.05), which were(39.81±9.06)% and(43.91±6.33)%,respectively. The FiO_2 of the different models of interfaces was significantly different(P<0.05), the FiO_2 of the No.4 oral-nasal mask was the lowest(28.29±0.08)%, and the FiO_2 of the No. 10 oral-nasal mask was the highest(53.83±0.63)%. The ViCO_2 of the oral-nasal mask and nasal mask wasn't significantly different(P=0.19), which was(15.26±1.27)mL and(14.79±2.21)mL, respectively. The ViCO_2 of the different models of interfaces was significantly different(P<0.05), the FiO_2 of the No.8 nasal mask was the lowest(12.48±0.29%), and the ViCO_2 of the No. 10 nasal mask was the highest(18.38±0.31)%. There was a significant correlation between FiO_2 and ViCO_2(r=0.41, P<0.05), and the general linear equation was Y=14.51+1.82 X(R~2=0.168). CONCLUSION: Different interfaces have significant effects on FiO_2 and ViCO_2 during NPPV,and FiO_2 and ViCO_2 are positively correlated.