Correlation Between Central Venous Pressure And Superior Vena Cava Diameter Of The Patients Undergoing Mechanical Ventilation

OBJECTIVE:To evaluate the effect of positive end-expiratory pressure(PEEP) on central venous pressure(CVP) and superior vena cava diameter(SVCD) of the patients undergoing mechanical ventilation in dynamic diversify,and to find the correlation between CVP and SVCD.To verify the theory of monitoring CVP with non-invasive method.METHODS:22 patients(14 male and 8 female)undergoing mechanical ventilation for acute respiratory failure were enrolled in the study,and SVCD was measured by Doppler ultrasonography. SVCD,CVP,heart rate(HR),mean arterial pressure(MAP) and oxygen saturation of arterial blood (SaO₂) at various PEEP levels were recorded.Data were processed by F test and correlation analysis. There was statistical difference when P＜0.05 and significant statistical difference when P＜0.01.RESULTS:(1) There were decreases of SVCD accompanied with PEEP increment,and there was a significant negative correlation between SVCD and PEEP(r=-0.981,P＜0.01).(2) There were increases of CVP accompanied with PEEP increment,and there was a significant positive correlation between CVP and PEEP(r=0.997,P＜0.01).(3) There was a significant negative correlation between CVP and SVCD(r=-0.961,P＜0.01).(4) No significant effects of PEEP on HR and MAP were found. (5)There was a significant positive correlation between SVCD and SaO₂(r=-0.971,P＜0.01).CONCLUSION:Monitoring SVCD by Doppler ultrasonography was an effective method directing fluid theraphy in patients undergoing mechanical ventilation.