ABSTRACT
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,undergo-ing CABG,following CPB,with a mean arterial pressure (MAP)<70% of baseline,despite adequate volume replacement (based on achieving a normal CVP),were randomly assigned to me-thoxamine group (group M,n=20)or phenylephrine group (group P,n=20).The initial infusion rate was 3 μg·kg-1·min-1in group M and 0.24 μg·kg-1·min-1in 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).Coronary sinus (CS),systolic blood flow velocity time integral (SV-TI),diastolic velocity time integral (DVTI),CS blood flow (CSBF)were recorded before adminis-tration,at 3,5,10,15,30 min after administration.Results Compared with pre-administration,SV-TI,DVTI,CSBF were increased at each point in the two groups (P<0.05 or P<0.01).SVI was in-creased at 15 min and 30 min in group M (P<0.05).Compared with group P,DVTI and CSBF at 10,15 min and 30 min was higher in group M (P<0.05 or P<0.01).There were 2 cases of atrial fibrillation and 1 case of frequent ventricular premature beat after operation in group M;1 case of bradycardia and 1 case of frequent ventricular premature beats after operation in group P.Conclusion Intravenous infusion of methox-amine and phenylephrine both can correct post volume treatment hypotension after CPB in elderly patients undergoing CABG,but methoxamine increases coronary blood flow more significantly and may be more ben-eficial to patients with coronary heart disease.