容积二氧化碳图在气道反应性测定中的应用

目的 探讨容积二氧化碳图(volumetric capnography,Vcap)参数在组胺激发试验中的反应性变化并与肺通气测定法做比较.方法 对60例门诊慢性咳嗽,疑诊咳嗽变异性哮喘患者进行组胺支气管激发实验,于基础状态、每次吸入组胺后,及吸入支气管扩张药后,先进行Vcap测定,再进行肺通气功能测定.使用Vcap来评价气道反应性.结果 60例患者气道高反应性的阳性率为50%.激发试验阳性组第1秒用力呼气容积(FEV1)、最大用力呼气峰流量(PEF)及Vcap参数Threshold死腔(VDT)、Fowler死腔(VDF)、Wolff死腔(VDW)、Ⅲ期斜率(dC3/DV)在基础值和激发后值之间差异均有统计学意义(P<0.01),激发后和舒张后值之间差异也有统计学意义(P<0.05).阴性组FEV1、PEF在基础值和激发后值之间、激发后和舒张后值之间差异无统计学意义(P>0.05),VDT、VDF、VDW激发后和舒张后值之间差异有统计学意义(P<0.05).所有患者的基础值、激发后、舒张后数据,FEV1均与PEF、Vcap各参数(除dC2/DV、dC3/DV、SR23外)呈显著直线相关(P<0.05).激发试验过程中各死腔参数的下降提前于FEV1和PEF的下降.激发试验终止时,ROC曲线提示VDT、VDF为最敏感指标,VDT较基础值增加28%、VDF较基础值增加20%,可作为Vcap气道高反应性阳性判断标准.结论 Vcap是一种定量评估支气管阻塞严重性的有效方法,可应用于气道反应性测定.

Application of volumetric capnography in the measurement of bronchial hyperresponsiveness

Objective To investigate the sensitivity and specificity of volumetric capnography (VCap) parameters in the measurement of bronchial hyperresponsiveness (BHR) and bronchodilator responsiveness,and compared with the routine spirometry method. Methods Sixty chronic cough suspect cough variation asthmatic outpatients were selected randomly to perform bronchial challenge test with VCap and spirometry respectively, VCap were measured firstly every step. Results Positive rate of BHR was 50%. In the posifive group, FEV1 ,PEF and VDT, VDF, VDW,dC3/DV were significantly changed between the postchallenge value and the baseline value(P<0.01). In the negative group, FEV1 , PEF were not significantly changed between the postchallenge value and the baseline value, but VDT, VDF,VDW were significantly changed between the postchallenge value and the baseline value (P<0.05). Of all subjects,FEV1 was close linear correlated with PEF and VCap parameters (except for dC2/DV,dC3/DV,SR23) in the baseline value, the postchallenge value and the postbonchodilator value ( P<0.05). Changes in dead space preceded changes in PEF and FEV1 during histamine challenge. The diagnostic criteria of BHR was that VDT decreased by 28% ,or VDF increased decreased by 20% or compared with the baseline value at the postchallenge value. Conclusions VCap is a quantitative method for evaluating the severity of airflow obstruction. It can be used in bronchial asthma diagnosis and therapy.