Application Of Central Venous Oxygen Saturation Monitoring During Off-Pump Coronary Artery Bypass Graft Surgery

Objective:To analyze the alterations of ScvO2and SvO2and the hemodynamic changes during off-pump coronary artery bypass graft (OPCABG) surgery, detect the correlation and consistency between ScvO2and SvO2, and the correlation between ScvO2/SvO2and CI, respectively. To investigate the possibility of replace SvO2with ScvO2,and to guide the management of the mismatch of oxygen demand and consumption during OPCABG.Methods:37patients undering selective OPCABG were included in this study. The central venous catheter and pulmonary artery catheter were inserted into the right internal jugular vein after anesthesia induction. The variables were measured after the anesthesia induction (basic value, T1),5min after the tissue stabilization was positioned for the LAD, LCX and RCA anastomosis (T2, T3and T4, respectively) and after the sternum was closed (T5). Follo wing datas were collected:central venous oxygen saturation (ScvO2), mixed venous oxygen saturation (SvO2), oxygen delivery (DO2), oxygen consumption (VO2), oxygen extraction rate (O2ER), heart rate (HR), cardiac output (CO), cardiac index (CI), mean arterial pressure (MAP), mean pulmonary arterial pressure (MPAP), central venous pressure (CVP), pulmonary arterial wedge pressure (PAWP), right ventricular end-diostolic volume index (RVEDVI), right ventricular ejection fraction (RVEF), systemic vascular resistance index (SVRI), pulmonary vascular resistance index (PVRI), left ventricular stroke work index (LVSWI), right ventricular stroke work index (RVSWI), stroke volume index (SVI). The ECG changes and the using of positive inotropic drug were recorded at each time pointResults:The tendencies of ScvO2and SvO2during OPCABG were same, the values of ScvO2were lower than the SvO2at each time point. When LAD was anastomosed, oxygen metabolism was changed with significant increase of CI, VO2, O2ER, significant decrease of ScvO2(P<0.05), DO2and SvO2changed unsignificantly (P>0.05). When LCX and PDA were anastomosed, oxygen metabolism was changed with significant decrease of ScvO2, SvO2, DO2, PvO2, CI, Hb, significant increase of O2ER, and significant increase of VO2during LCX (P<0.05). After the sternum was closed, oxygen metabolism was changed significantly:ScvO2and Hb were increasing, but still lower than the basic value; SvO2, DO2and VO2were increasing and higher than both basic value and PDA;O2ER was decreasing, but still higher than basic value(P<0.05). Correlation index of ScvO2and SvO2were0.35,0.169,0.568,0.311and0.446, respectively. The correlation of SvO2and CI was better compared to ScvO2, the correlation of ScvO2and Hb was better compared to SvO2。The bias range between ScvO2and SvO2were (-5.46±4.97)%,(-7.84±6.50)%,(-8.52±5.62)%,(-9.73±7.96)%and (-10.5±5.96)%respectively.When LCX and PDA were anastomosed, the hemodynamics changed with significant increase of MPAP, CVP and PAWP, significantly decrease of CI, RVEF, LVSWI、RVSWI and SVI. The various hemodynamic parameters tended becoming stable gradually after the sternum closed.Conclusion:When LAD, LCX and PDA were anastomosed, DO2, ScvO2and SvO2decreased significantly, and CI and Hb decreased simultaneously, O2ER increased significantly, VO2was nearly unchangeable. The tendencies of ScvO2and SvO2during OPCABG were unanimous, their correlation and consistency were moderate. There is some feasibility to replace SvO2with ScvO2for patients undergoing OPCABG.