正常人在静态和运动状态下“死腔/潮气”估测值和实测值的比较

Comparison of the Estimated and Actual Values of Dead Space/Tidal Volume Ratios at Rest and during Exercise in Health Adults

目的:研究正常人静态及运动状态下死腔/潮气(VD/VT)估测值和实测值的关系。方法:23名受试者行心肺运动试验,同步实时测定摄氧量和二氧化碳排出量,分别在运动前及运动高峰时抽取动脉血,根据Bohr的公式,得出VD/VT实测值,同时再用呼气末CO2分压(PetCO2)代替PaCO2,计算VD/VT,得出VD/VT估测值。结果:根据病史、体检、肺功能和运动前后的心电图判断23名受试者均为正常受试者。静态时的VD/VT估测值和VD/VT实测值分别为0.359±0.109和0.354±0.106,两者无显著性差异(P=0.710),相关分析显示两者高度相关(r=0.911,P<0.001)。运动高峰时的VD/VT估测值和VD/VT实测值分别为0.234±0.070和0.248±0.094,两者无显著性差异(P=0.748),相关分析表明两者显著相关(r=0.783,P<0.001)。与静态时比较,运动时估测和实测VD/VT均明显下降。结论:对于正常成人,无论是在静态或最大运动状态下,可用无创方法计算VD/VT代替VD/VT实测值。

Objective To investigate the association between the estimated and the actual dead space/tidal volume ratios （VD/VT） at rest and during exercise in healthy adults. Methods Cardiopulmonary exercise testing was performed in 23 health adults. Oxygen uptake and carbon dioxide output were measured continuously with the breath - by - breath mode. Arterial blood samples were drawn both at rest and maximal exercise. The actual VD/VT was measured according to Bohr＇s equation, and the estimated VD/VT was calculated using PCO2 at the end of expiration instead of arterial PCO2. Results All subjects were judged to be normal based on the clinical history, physical examination, pulmonary function and electrocardiogram, as well as blood gas at rest and during exercise. There were no significant differences between the estimated VD/VT and actual VD/ VT both at rest （0.359 ± 0.109 vs 0.354 ± 0.106） or at maximal exercise （0.234 ± 0.070 vs 0.248 ± 0.094）. There are significant correlations between the estimated and actual VD/VT both at rest （ r = 0.911, P 〈 0.001） and maximal exercise （r = 0.783, P 〈 0.001 ）. Both the estimated and actual VD/VT decreased significantly during exercise. Conclusion The estimated VD/VT can be used instead of actual VD/VT in healthy adults both at rest and during exercise.