Effect Of Different Interfaces On CO₂ Rebreathing And FiO₂ During Noninvasive Positive Pressure Ventilation

Objective:To investigate the effect of different interfaces on CO₂ rebreathing?ViCO₂?and FiO₂ 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 CO₂ gas from the closest to the outlet of simulated lung to maintain end-tidal carbon dioxide partial pressure in 80mmHg,and oxygen delivery during NPPV was simulated by means of injection 5L/min oxygen through the hole of interface.ViCO₂ and FiO₂ were integral calculated though the synchronous collection real-time of pressure,flow rate,oxygen concentration and CO₂concentration.The effect of different type and models interfaces on ViCO₂ and FiO₂ were compared,and the correlation of bivariate correlation analysis was applied to investigate the correlation of ViCO₂ and FiO₂.Results:The inner volume,leak volume and leak position of different interfaces were different.The ViCO₂ of the oral-nasal mask and nasal mask were not significantly different?P=0.19?,which were 13.23±1.49ml and13.31±1.91ml,respectively.The ViCO₂of the different models of interfaces was significantly different?P<0.05?,the ViCO₂ of the No.10 nasal mask was lowest?11.01±0.29%?,and the ViCO₂ of the No.12 nasal mask was highest?16.78±0.46%?.The FiO₂ of the oral-nasal mask and nasal mask were significantly different?P<0.05?,which were 40.85±8.73%and 44.96±5.21%,respectively.The FiO₂ of the different models of interfaces was significantly different?P<0.05?,the FiO₂ of the No.6 oral-nasal mask was lowest?28.29±0.08%?,and the FiO₂of the No.7 oral-nasal mask was highest?54.24±0.16%?.The different leak position of interface has a significant effect on ViCO₂ and FiO₂?P<0.05?.The inner volume and leak volume?CPAP=4cmH2O?are significantly correlated with FiO2,respectively?r=-0.33,P=0.00;r=-0.23,P=0.00?.There is a significant correlation between ViCO₂and FiO₂?r=0.41,P=0.00?,and the general linear equation is y=14.51+1.82X?R²=0.168?.Conclusion:Different interface have significant effects on ViCO₂ and FiO₂ during NPPV,The ViCO₂ of the oral-nasal mask and nasal mask were not significantly different.The FiO2 of the oral-nasal mask and nasal mask were significantly different.The different leak position of interface has a significant effect on ViCO₂ and FiO₂,The inner volume and leak volume are significantly correlated with FiO2,respectively.ViCO₂ and FiO₂ are positively correlated.