Aim: We evaluated muscle-visceral interorgan flux of substrates in 8 critically ill patients in the flow phase after injury.
Setting: This study was conducted on critically ill patients admitted in ICU.
Patients: 8 patients were studied immediately after injury.
Results: We measured leg flux for oxygen, amino acids, glucose, lactate pyruvate, keton bodies, free fatty acids (FFA), free and total carnitine, and whole body oxygen consumption, nitrogen (N) balance and 3-methyl hystidine (3MEH) excretion during fasting and the second day of metabolic treatment (10.7 +/- 0.06 g x N x m-2 e 1035.5 +/- 3.9 kcal x m-2 x die). During fast the leg shows a net release of N, pyruvate, FFA and free carnitine while glucose, lactate and keton bodies fluxes are not different from zero. The energy balance of the leg is markedly negative (substrate for 79 kcal x m-2 burned for leg energy requirement and 347 kcal x m-2 released as a such). Assuming the body muscle tissue 4.5 times the leg tissue and knowing whole body energy balance, we were able to assess that the non muscular (visceral) part of the body resulted in a consistently positive energy balance. The metabolic treatment is able to match the energy expenditure and the substrate efflux of the leg (and the whole body muscle tissue). In fact the efflux of amino acids and FFA is reduced pyruvate blunted while glucose is remarkably taken up (the uptake of the whole muscle tissue accounted for 72% of the daily load). At the same time, the treatment blunts leg free carnitine and reduces body 3MEH output. Moreover, the caloric balance of the non muscular part of the body remains positive even if the qualiquantitative uptake of substrates is different from fasting.
Conclusion: Substrates for energy requirements of visceral tissue came from muscular tissue. The metabolic treatment is able to modulate this process.