无创测定人体PCO2变化对平均动脉血压的影响

目的 无创测定PCO2变化对人体平均动脉血压的影响.方法 研究对象为16例健康志愿者,用经颅超声多普勒仪、无创血压监测仪持续记录人体正常呼吸、低碳酸血症和高碳酸血症时的大脑中动脉的血流流速和桡动脉血压,用潮气末二氧化碳监测仪持续监测呼出气体的二氧化碳分压.低碳酸血症由试验对象过度换气获得;高碳酸血症通过经面罩吸入混合气体(5%CO2、21%O2和74%N2)获得.结果 低碳酸血症阶段大脑中动脉的平均流速较正常呼吸时明显下降,高碳酸血症阶段大脑中动脉(MCA)的平均流速则较正常呼吸时明显增快,三个阶段的平均流速比较差异均有显著性意义(F=42.411,P=0.000).MAP在低碳酸血症阶段有轻度下降,在高碳酸血症阶段MAP则有轻度上升,两者比较差异有显著性意义(F=3.784,P=0.030),但两者与正常呼吸时的MAP比较差异均无显著性意义.结论 PCO2的波动可导致MAP变化,且MAP的变化的程度与PCO2的变化幅度相关.

Noninvasive Estimating the Correlation of Mean Blood Pressure and Varying Carbon Dioxide in Human

Objective Noninvasive estimating the correlation of the mean blood pressure (MAP) and varying partial pressure of carbon dioxide (PCO2)in human.Methods The study was conducted in 16 healthy volunteers. During the courses of hypocapnia, baseline and hypercapnia, Transcranial Doppler velocities of middle cerebral artery and noinvasive blood pressure in radial artery were continuous recorded in subjects, respectively. End-tidal CO2 was also measured by a monitor. Hypocapnia was induced by voluntary hyperventilation, and hypercapnia was gained by conducting subjects breath a gas mixture of 5%CO2,21%O2,74% nitrogen.Results The Velocities of middle cerebral artery decreased significantly during hypocapnia, and increased obviously during hypercapnia, there were significant changes among hypocapnia, hypercapnia and basline (F=42.411,P=0.000). Hypocapnia caused a small fall in MAP, and hypocapnia had the opposite effect, there were significant difference in MAP in hypocapnia phrase and hypercapnia phrase (F=3.784,P=0.030), but both of them had not significant differences according with baseline.Conclusion Varying carbon dioxide produces significant changes in MAP,there is a correlation between the MAP and the amplitude of varying carbon dioxide.