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.