Thermogenic and hormonal responses to amino acid infusion in septic humans

Metabolic effects of a commercially available amino acid infusate were investigated in five preoperative patients with abdominal sepsis and five healthy subjects. Oxygen consumption (VO2) was measured continuously during the 3-h study, and blood samples were taken regularly for hormone and metabolite analyses. During 1 h of preinfusion measurements, VO2 was 15% higher (P less than 0.05) in the septic patients. Preinfusion plasma cortisol, glucagon, and catecholamines were also significantly elevated in the septic group. The amino acid solution (9 g nitrogen; 950 kJ; 227 kcal) was infused into each subject through their central venous catheter during the 2nd and 3rd h of the study. VO2 increased similarly in both groups by approximately 21% during the infusion (P less than 0.05), whereas respiratory quotient increased significantly in only the controls (P less than 0.05). Plasma insulin and glucagon concentrations rose significantly in both groups during the infusion, despite little change in glucose levels. Plasma norepinephrine increased in both groups, although the response was significant in only the control subjects. In summary, the amino acid infusate stimulated metabolic rate similarly in the septic and nonseptic subjects.