INSULIN AND AMINO-ACID INFUSION AFTER CARDIAC OPERATIONS - EFFECTS ONSYSTEMIC AND RENAL PERFUSION

Objective: The purpose of this study was to answer two questions: (1) Does a mixed amino acid infusion enhance systemic and renal perfusion in the early postoperative period after heart operations? (2) Does the addition of insulin (glucose-insulin-potassium solution) provide addi tional effects to those of an amino acid infusion? Methods: Thirty-thr ee male patients undergoing coronary artery bypass grafting (mean age 65.9 +/- 1.2 years) were included in a prospective, controlled, random ized study, Eleven patients (AA group) received infusion of mixed amin o acids (11.4 gm), 11 patients (AA + GIK group) received infusion of m ixed amino acids (11.4 gm) and insulin solution (225 IU insulin, gluco se with glucose clamp technique, and potassium), and 11 patients serve d as control subjects. Results: Amino acid infusion alone had no effec t on systemic vascular resistance or cardiac index but increased renal blood flow 51% +/- 11% (from 114 +/- 13 to 172 +/- 24 ml . min(-1). m (-2) in one kidney, p < 0.05 vs the control group). Insulin solution i n addition to amino acid infusion reduced systemic vascular resistance 24% +/- 3% (from 1280 +/- 85 to 960 +/- 57 dyn . sec . cm(-5), p < 0. 05 vs the control and AA groups) and increased cardiac index 13% +/- 3 % (from 2.3 +/- 0.2 to 2.6 +/- 0.2 L . min(-1). m(-2), p < 0.05 vs the control and AA groups), Insulin had no significant additive effect on renal blood flow, Conclusions: Our data imply that (1) infusion of mi xed amino acids enhances renal blood flow after cardiac operations but has no effect on systemic perfusion and (2) the addition of insulin s olution improves systemic perfusion, The combined treatment may potent ially reduce the risk of renal hypoperfusion injury in the postoperati ve period after coronary artery bypass grafting.