无创正压通气时呼气时间常数和呼气阻力的测算分析  

Estimated calculation of expiratory time constants for expiratory resistance evaluation during noninvasive positive pressure ventilation

作　　者：陈宇清 袁越阳 张海[1] 李锋 李兴旺[3] Chen Yuqing;Yuan Yueyang;Zhang Hai;Li Feng;Li Xingwang(Department of Respiratory and Critical Care Medicine,Shanghai Chest Hospital,Chest Hospital Affiliated to Shanghai Jiaotong University,Shanghai 200030,China;School of Mechanical and Electrical Engineering,Hunan City University,Yiyang 413049,Hunan,China;Bio-X Institute,Shanghai Jiaotong University,Shanghai 200030,China)

机构地区：[1]上海市胸科医院,上海交通大学附属胸科医院呼吸与危重症医学科,200030 [2]湖南城市学院机械与电气工程学院,湖南益阳413049 [3]上海交通大学Bio-X研究院,200030

出　　处：《中华生物医学工程杂志》2020年第5期385-391,共7页Chinese Journal of Biomedical Engineering

基　　金：科技部国家重点研发计划"重大慢性非传染性疾病防控研究"重点专项项目(2018YFC1313600);上海交通大学"交大之星"医工交叉研究基金(YG2019ZDB08)。

摘　　要：目的通过测算呼气时间常数(τE)监测无创正压通气(NPPV)时不同肺力学模型的呼气阻力(Rexp)。方法使用ASL 5000机械模拟肺模拟体质量为65~70 kg的半卧位健康成年人、高气道阻力及高气道阻力合并低胸肺顺应性(混合性通气障碍)患者,设置系统顺应性(C_(rs))为25(混合性通气障碍)和50 ml/cmH_(2)O(1 cmH_(2)O=0.098 kPa),R_(exp)为5(健康成年人)和20 cmH_(2)O·L^(-1)·s^(-1),吸气时间为1.6 s,呼吸频率为15次/min。Respironics V60呼吸机以S/T模式运行,呼气末正压(PEEP)为5 cmH_(2)O,调整吸气压力水平使呼吸机输出潮气量(VT)分别达到5、7和10 ml/kg,后备通气频率为10次/min。收集系统泄漏量为25~28 L/min时的通气参数吸入潮气量(VTI)、呼出潮气量(VTE)、漏气量(Vleak)、吸气峰压(PIP)、吸气峰流量(PIF)、呼气峰流量(PEF)和呼气时75%潮气量处的流量(TEF_(75))变化并测算τE、Crs和Rexp。结果随着VTI、VTE的增大,Vleak、PIP、PIF和PEF逐渐增高,VT为10 ml/kg时混合性通气障碍模型的PIP达到28 cmH2O,3种肺力学模型的PIF和PEF较VT为5 ml/kg时增高近一倍(均P<0.01)。呼气时,PEF随着VTE排出而逐渐减低,VT为7~10 ml/kg时TEF75与PEF差异无统计学意义(均P>0.01)。不同VT对高气道阻力模型的τE值测算无明显影响。3种肺力学模型的Crs测算值均随VT增大而逐渐减小,高气道阻力条件下Crs值测算误差在VT为7 ml/kg时可<20%。随着通气支持水平的增高,3种肺力学模型的Rexp测算值均逐渐增高,VT为7 ml/kg时Rexp测算值与预设值的差异更低(<10%)。结论通过测算τE,可实现在不阻断自主呼吸连续监测接受NPPV支持患者的Rexp。适宜的VT(7 ml/kg)是减少测算误差的关键,同时也保证有效的通气支持。Objective To evaluate the expiratory resistance(Rexp)in different lung mechanics models during noninvasive positive pressure ventilation(NPPV)according to estimated calculation of expiratory time constants(τE).Methods ASL 5000 mechanical lung simulator was used to mimic a semi-recumbent subject with a body mass of 65-70 kg,either being a healthy adult or a patient with high airway resistance with or without low thoraco-pulmonary compliance(mixed ventilatory disorder).The system settings included:compliance(Crs),25(for mixed ventilatory disorder)or otherwise 50 ml/cmH_(2)O(1 cmH_(2)O=0.098 kPa);Rexp,5(for healthy adult)or otherwise 20 cmH_(2)O·L^(-1)·s^(-1);inspiratory time,1.6 s;respiratory rate,15 times/min.The Respironics V60 ventilator was set to operate in S/T mode with a positive end-expiratory pressure(PEEP)of 5 cmH_(2)O.Inspiratory pressure was adjusted to maintain a tidal ventilator output(VT)of 5,7 and 10 ml/kg,respectively,and a backup ventilation frequency of 10 times/min.Ventilation parameters[inspiratory tidal volume(VTI),expiratory tidal volume(VTE),system leakage(Vleak),peak inspiratory pressure(PIP),peak inspiratory flow(PIF),peak expiratory flow(PEF)and the expiratory flow at 75%expiratory tidal volume(TEF_(75))]were recorded at the Vleak level of 25-28 L/min.TherebyτE,Crs and Rexp were estimated and evaluated.Results With increasing VTI and VTE,Vleak,PIP,PIF and PEF gradually increased.At the VT of 10 ml/kg,the PIP in the mixed ventilatory disorder model reached 28 cmH_(2)O,and the PIF and PEF values in all of the three lung mechanics models were nearly two times higher than those at the VT of 5 ml/kg(all P<0.01).During expiration,the PEF gradually decreased with the discharge of VTE.When VT was 7-10 ml/kg,there was no statistically significant difference between TEF75 and PEF(all P>0.01).The level of VT did not interfere obviously with the calculatedτE value in the high airway resistance model.In all of the three lung mechanics models,the estimated Crs values gradually decreased with incre

关 键 词：无创通气 连续气道正压通气 呼气时间常数 呼气阻力 肺疾病 慢性阻塞性 

分 类 号：R563.9[医药卫生—呼吸系统]