Effects of small dose of dopamine on renal blood flow in elderly patients undergoing cardiac valve replacement under cardiopulmonary bypass / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effects of small dose of dopamine on the renal blood flow in the elderly patients undergoing cardiac valve replacement under cardiopulmonary bypass (CPB).Methods Sixty elderly patients,of ASA physical status Ⅱ or Ⅲ,aged 65-74 yr,weighing 52-77 kg,scheduled for elective cardiac valve replacement under CPB,were randomized to receive either normal saline (group C,n =30) or dopamine (group D,n =30).After beginning of surgery,CPB was established routinely.In group D,dopamine was continuously infused for 20 min at a rate of 2 μg· kg-1 · min-1 starting from 10 min after the hearts were perfused with cardioplegic solution for the first time,while the equal volume of normal saline was given in group C.The left renal blood flow velocity was measured by transesophageal echocardiography and mean arterial pressure was recorded before and after dopamine infusion.Blood samples were obtained before surgery and at 24 h after surgery for determination of blood urea nitrogen concentrations.Results Blood urea nitrogen concentrations were significantly increased at 24 h after surgery than that before surgery in the two groups.There was no significant difference in mean arterial pressure and the left renal blood flow velocity before and after dopamine infusion between the two groups.Conclusion Small dose of dopamine (2 μg· kg-1· min-1) dose not increase the renal blood flow or improve the postoperative renal function in the elderly patients undergoing cardiac valve replacement under CPB.