呼出气C02容积曲线对肺部疾病换气功能障碍的诊断与评价

Diagnosis and evaluation of volumetric capnography for pulmonary gas exchange dysfunction in patients with pulmonary disease

目的评价无创肺换气功能诊断技术即呼出气CO2容积曲线（VCap）对肺部疾病慢性阻塞性肺疾病（chronic obstructive pulmonary disease，COPD）、支气管哮喘（简称哮喘）和间质性肺疾病（ILD）患者换气功能障碍的诊断价值及临床意义。方法对照组（医院对照）94人，平均年龄（61．59±8．73）岁。COPD组287例，平均年龄（64．31±11．71）岁。根据COPD肺功能分级标准分4级：COPDI级（9例）、COPDII级（141例）、COPDⅢ级（75例）、COPDIV级（62例）。哮喘组251例，平均年龄（57．86±13．54）岁。根据气道阻塞程度分4级（分级标准同COPD）：轻度阻塞（6例）、中度阻塞（儿3例）、重度阻塞（100例）、极重度阻塞（32例）。ILD组45例，平均年龄（56．42±13．97）岁。主要分析变量：最大呼出气二氧化碳浓度、Ⅲ相斜率（dC／dV3）、呼出气最高CO。浓度的25％～50％时的容积与潮气容积的比值（Vm25-50／VT）、呼出气最高CO2浓度的50％～75％时的容积与潮气容积的比值（Vm50-75／VT）。结果①ILD、哮喘和COPD分别与对照组比较：Vm25-50／VT、Vm50-75／VT、FeC02max、dC／dV3，差异有统计学意义（P〈0．01）；②轻度哮喘和轻度COPD组比较：Vm50-75／VT，dC／dV3差异无统计学意义；中、重度组比较：Vm50-75／VT，dC／dV3差异有统计学意义（P〈O．01）；哮喘合并肺气肿和COPD（肺气肿）组比较差异无统计学意义；③Vm50-75／VT和dC／dV3用于COPD（肺气肿）的评价敏感度分别为98．3％和96．5％，特异度分别为91．4％和86．1％。结论①COPD、哮喘和ILD患者VCap形态异常，dC／dV3增高并且与疾病的严重程度有关，示肺内气体分布不均，系气道阻力增高和（或）肺顺应性改变导致吸人气体分布不均和呼出气体非同步排空所致，ILD相对于COPD和哮喘则气体分布不均更为突出；②变量Vm50-75／VT间接反映肺泡死腔量，相对受生理因素及通气量的影响小，与常规肺功能指标均有较好的相关性，可作为评价肺部疾病换气功能障碍即肺泡死腔增大，通气血流／灌注失调间接指标。③Vm50-75／VT％≥10％和dC／dV3≥1．3％／L用于评价肺气肿有较高敏感度和特异度。

Objective To evaluate the diagnostic and clinical value of volumetric capnography（VCap） for pulmonary gas exchange dysfunction in patients with pulmonary disease. Methods VCap was performed on all patients with pulmonary disease, including 287 chronic obstructive pulmonary disease （COPD） patients,251 asthma patients, 45 interstitial lung diseases （ILD） patients and 94 control subjects. Main variables., maximum CO2 concentration（CO2 max）, the slope of phase3 （dC/dV3）, volume between 25% and 50V0 of CO2 max （Vm25-50）,volume between 50% and 75% of CO2 max （Vm50-75）,Vm25-50/VT,Vn50-75/VT. Results ① Four variatblos of Vcap exhibited statistical differences （ P〈0.01） between three disease groups （ILD,asthma,COPD） and control group; ②Vm50-75/VT and dC/dV; had no statistical differences between light asthma and light COPD, but showed statistical differences （P〈0.01） between moderate, severe asthma and COPD, and had no statistical d iiJerences between COPD（emphysema） and asthma combining with emphysema;③Vm50-75/VT and dC/dV3 had high sensitivity（98.3%,96.5%） and specificity（91.4%, 86.1%） in estimating COPD（emphysema）. Conclusions ①The values and pattern of VCap are obviously abnormal,which can be used for diagnosing pulmonary gas exchange dysfunction of patients with COPD. dC/dV3 （91.3G） has a prominent rise in COPD patients and relates to the severity of COPD, showing an unequal pulmonary gas distributing; ②Vm50-75/VT and Vm255o/VT are less affected by physiological factors and expired volume, Vm25-50/VT （ ≥7% ）, Vm50-75/VT （ ≥10%） indirectly reflects alveolar dead space increasing and unequal ventilation-perfusion ratio commendably; ③VCap is simple, rapid, non-invasive, and secure and can be repeated well.