ACCELERATED SPLANCHNIC AMINO-ACID-UPTAKE AFTER CARDIAC-SURGERY

Energy expenditure increases after cardiac surgery, but changes in per ipheral tissue metabolism do not explain this increase. We hypothesize d that the splanchnic region is a major contributor to the postoperati ve hypermetabolism, and this should be reflected in the exchange of am ino acids across the splanchnic bed. We measured systemic and regional (splanchnic and leg) amino acid exchange, oxygen uptake and hemodynam ics in 22 elective coronary bypass grafting patients postoperatively a fter arrival to the intensive care unit, 2 h later, and after stabiliz ation of hemodynamics. Splanchnic uptake of glutamine (50 +/- 37 mu mo l/min/m(2) to 78 +/- 37 mu mol/min/m(2), P < 0.05) and three of the gl uconeogenetic amino acids, alanine (115 +/- 52 mu mol/min/m(2) to 183 +/- 70 mu mol/min/m(2), P < 0.05), serine (18 +/- 10 mu mol/min/m(2) t o 26 +/- 13 mu mol/min/m(2)) and threonine (20 +/- 8 mu mol/min/m(2) t o 28 +/- 8 mu mol/min/m(2)) increased during the observation period. S imilarly, the oxygen consumption by the splanchnic region increased wh ile splanchnic blood flow remained stable. A correlation between oxyge n and amino acid uptake by the splanchnic bed was observed during the study period. Femoral exchange of glutamine and alanine did not change , although femoral blood flow and oxygen consumption increased during rewarming. High metabolic activity was observed in the splanchnic regi on during the early postoperative phase after hypothermic cardiac surg ery. The increased plasma amino acid concentration indicates a release of amino acids from other sources than the peripheral muscle.