Effects Of Methoxamine On Blood Pressure And Coronary Artery Blood Flow In Elderly Patients With Post Volume Treatment Hypotension After Cardiopulmonary Bypass Undergoing Coronary Artery Bypass Grafting

Objective To investigate the effects of intravenous infusion of methoxamine and phenylephrine on blood pressure and coronary artery blood flow in elderly patients with post volume treatment hypotension after cardiopulmonary bypass（CPB）undergoing coronary artery bypass grafting（CABG）.Methods Forty patients,physical status ASA II or III,>65 years old,undergoing CABG,who following CPB,mean arterial pressure（MAP）<70%of baseline,despite adequate volume replacement（based on achieving a normal CVP）,were randomly assigned to methoxamine group（group M,n=28）or phenylephrine group（group P,n=28）.The initial infusion rate was 3μg·kg^-1·min^-1 in group M and 0.24μg·kg^-1·min^-11 in group P,respectively.The rate was increased or decreased by one third of initial dose in order to maintain the MAP at the target level（±20%of baseline MAP）.MAP,HR,CVP,stroke volume index（SVI）,systemic vascular resistance index（SVRI）,pulmonary vascular resistance index（PVRI）,left ventricular ejection fraction（LVEF）,coronary sinus（CS）systolic blood flow velocity time integral（SVTI）,diastolic velocity time integral（DVTI）,CS blood flow（CSBF）were recorded before administration,at 3,5,10,15,30 min after administration.Results Compared with pre-administration,MAP,SVRI,SVTI,DVTI,CSBF were increased at each point in two groups（P<0.05 or 0.01）,SVI,LVEF at 15,30min was higher in group M（P<0.05）.Compared with group P,DVTI and CSBF at 5,10,15 min and 30 min was higher in group M（P<0.05 or 0.01）.Conclusion Intravenous infusion of methoxamine and phenylephrine both can correct post volume treatment hypotension after CPB in elderly patients undergoing CABG,but methoxamine increases cardiac output and coronary blood flow more significantly and may be more beneficial to patients with coronary heart disease.