KETAMINE ANESTHESIA CAUSES GREATER MUSCLE CATABOLISM IN RABBITS THAN DOES PROPOFOL

Whereas ketamine and propofol are popular anesthetics in the intensive care unit and trauma/burn surgery, their metabolic effects are not kn own. Because traumatized patients are under catabolic state and may ne ed multiple operations over the acute period of treatment, the knowled ge of metabolic effects of anesthetics should hale clinical relevance. We have compared muscle protein kinetics in rabbits under ketamine or propofol anesthesia. Because propofol is given in a fat emulsion (Int ralipid), we have also tested the Effect of Intralipid in an additiona l group of animals under ketamine anesthesia by giving the same dose o f Intralipid as in the propofol group. In all animals, xylazine was us ed as a supplemental anesthetic and a balanced amino acid infusion (10 % Travasol) was infused at 2 mg.kg(-1).min(-1).L-[ring-C-13(6)]phenyla lanine tons infused as a tracer and the arteriovenous balance method w as applied to the hindlimb for determination of muscle protein kinetic s. Results: the rate of muscle protein breakdown was significantly gre ater in the ketamine group than in the propofol group and intermediate in the lipid group. These results were consistent with whole body pro tein breakdown rates reflected by total phenylalanine flux. Rates of m uscle protein synthesis were not significantly different among the gro ups. Consequently, the ketamine group had significantly greater net lo ss of muscle protein. We conclude that in relation to propofol, ketami ne has a greater catabolic effect on muscle protein, which can be atte nuated by lipid infusion. Therefore, ketamine is not an optimal anesth etic for catabolic patients. (C) Elsevier Science Inc. 1997.