Validation Of Arterial Pressure-based Cardiac Output Measurement In Patients Undergoing Off-pump Coronary Artery Bypass Graft Surgeries

Objective:To evaluate the validation of arterial pressure-based cardiac output measurement in patients undergoing off-pump coronary artery bypass graft surgeries.Methods:Fifteen patients undergoing elective OPCABG.were included in this study. A radial artery catheter was inserted before anesthesia and connected to an arterial pressure-based cardiac output(APCO) measurement device(FloTrac^TM/Vigileo^TM, Edwards Lifesciences),meanwhile a thermodilution pulmonary artery catheter (744HF75,Edwards Lifesciences) for continuous monitoring of cardiac output (CCO) was placed through internal jugular vein.The hemodynamic variables were recorded after the induction of anesthesia,dissecting the internal mammarian artery (baseline),exposing and stabilizing the following coronary arteries(LAD,OM,PDA), before and after the sternum was closed.Results:The mean age of this group was(67.8±5.6) years,and the average LVEF was (61±10)%.Hemodynamic parameters changed significantly except heart rate for exposing all three target coronary arteries.The most extensive changes were observed when anastomosing the graft to OM.Mean arterial pressure(MAP),arterial pressure-based cardiac output index(APCI),stroke volume index(SVI) dropped from (90±16) mmHg,(2.7±0.4) L/min/m²,(37.9±6.5) ml/bpm/m² to(66±14) mmHg, (1.9±0.7)L/min/m²,(26.4±8.1)ml/bpm/m²,respectively(P＜0.05).The lowest APCI was obtained during OM anastomosis,while the lowest CCI was obtained during PDA anastomosis.Compared to baseline,stroke volume variation(SVV) increased from(6.4±2.8)%to(15.7±13.0)%(P＜0.05).In a Bland-Altman plot,APCO correlated well with CCO.The bias and the precision were 0.02L/min/m² and 1.13L/min/m²,respectively.During the process of displacement,the magnitudes of changes in APCI and in MAP were closely related(r=0.687,P＜0.001).A significant correlation was also observed between magnitudes of SVV change and APCI change (r=0.468,P＜0.005). Conclusion:Cardiac output measurement based on uncalibrated pulse contour analysis is able to reflect cardiac output measured with the continuous thermodilution method in patients undergoing OPCABG.Compared to the latter,it provides a quicker response to hemodynamic changes.Arterial pressure-based cardiac output measurement can be widely used for continuous cardiac output monitoring and volume status evaluating.