摘要目的 评估经面罩内鼻导管给氧及经面罩给氧对吸入氧浓度的影响,寻找一种提高无创正压机械通气(NPPV)时吸入氧浓度的给氧方法.方法 采用人面部模型模拟人面部,双腔气管内导管模拟人双侧鼻腔及气管,连接模拟肺,建立模拟人无创通气模型,测定不同压力(潮气量恒定)及不同潮气量(压力恒定)条件下经面罩给氧及经面罩内鼻导管给氧时吸入氧浓度变化;观察同一给氧方式时不同压力(潮气量恒定)及不同潮气量(压力恒定)对吸入氧浓度的影响.结果 固定潮气量(500 ml)和氧流量(5 L/min),不同吸气压力条件下,经面罩内鼻导管给氧时的吸入氧浓度为(52.4±2.1)％,明显高于经面罩给氧(31.2±0.8)％(P＜0.05);固定呼吸机压力和氧流量(5 L/min),不同潮气量条件下,经面罩内鼻导管给氧时的吸入氧浓度为(55.9 ±0.7)％,明显高于经面罩给氧(35.4±1.7)％(P＜0.05).经面罩给氧时,潮气量恒定,氧浓度随IPAP增高有下降趋势,IPAP为16 cmH2O(1 cmH2O =0.098 kPa)时高于IPAP为8 cmH2O时,IPAP为20 cmH2O时高于IPAP为8和12 cmH2O时(均P＜0.05).吸气压固定,氧浓度随潮气量增加有增加趋势,潮气量为600 ml时高于潮气量为400 ml时(P＜0.05).然而在经面罩内鼻导管给氧时,潮气量及压力变化对吸入氧浓度无明显影响.结论 无创通气时采用经面罩内鼻导管给氧的方式可提高吸入氧浓度,节约氧气,适应家庭NPPV.

abstractsObjective We evaluated the effects of administering oxygen through nasal catheter inside the mask or through the mask on inspired oxygen concentration in order to find better ways of administering oxygen to improve the inspired oxygen concentration in non-invasive positive pressure ventilation (NPPV).Methods A human face model was used to simulate the human face,and the model of the double lumen endotracheal tube was used to simulate the bilateral nasal cavity and trachea,and then a model was constructed to allow simulated NPPV.The changes of FIO2 were measured in different pressure (constant tidal volume) and different tidal volume (constant pressure) conditions under the way of administering oxygen through nasal catheter inside the mask or through the mask.The effects on FIO2 were measured in different pressure (constant tidal volume) and different tidal volume (constant pressure) conditions under same way of administering oxygen.Results The FIO2 was (35.4 ± 1.7) ％ when oxygen was administered through the mask,but a higher FIO2 was achieved with the oxygen injected into the mask [(52.4 ±2.1) ％,and oxygen flow of 5 L/min,P ＜ 0.05].The oxygen concentration declined with the increase of inspiratory positive airway pressure (IPAP) on the condition of administering oxygen through the mask on constant tidal volume.The FIO2 at IPAP 16 cmH2O (1 cmH2O =0.098 kPa) was higher than that at IPAP 8 cmH2O,and the FIO2 at IPAP 20 cmH2O was higher than those at IPAP 8 cmH2O and 12 cmH2O,P ＜ 0.05.The oxygen concentration increased with the tidal volume increase on the condition of administering oxygen through the mask on constant IPAP.The changes of tidal volume and IPAP had no effects on FIO2 on the condition of administering oxygen through nasal catheter inside the mask.Conclusions Administering oxygen through nasal catheter inside the mask during NPPV can increase FIO2 and conserve oxygen.This study provides theoretical basis for the development of newer masks.