Glucose-dependent hepatic membrane transport in nonbacteremic and bacteremic thermally injured patients

Abstract

Hepatic clearance of indocyanine green was measured in 106 studies in 25 thermally injured patients with an average total body surface burn of 59% and a mean age of 35 years. Seventeen patients subsequently developed positive blood cultures and were restudied. Fourteen serial measurements of dye concentration taken over a 70-min period were computer fitted to describe each disappearance curve, and the two rate constants, k 1 and k 2 were determined (all r 2 > 0.94). ICG plasma disappearance was unimpaired in nonbacteremic patients when glucose or glucose plus amino acids were part of the parenteral regimen (− k 1 = 0.241 ± 0.023 and 0.255 ± 0.009 min −1) but significantly decreased when near isocaloric amounts of glucose-free amino acid solutions were administered (− k 1 = 0.150 ± 0.016 min −1, P < 0.001). Bacteremic patients had markedly impaired ICG hepatic clearance irrespective of the hypocaloric dietary regimen. Both exclusion of glucose from the nutrient infusates in nonbacteremic patients and bacteremia result in a marked reduction in the maximal velocity of the ICG dye transport reaction. Septic patients infused with glucose and insulin improved their clearance of the dye (from k 1 = 0.169 ± 0.029 to 0.183 ± 0.028 min −1, P < 0.01). These alterations could not be related to changes in circulation or perfusion. Urea production varied inversely and endogenous insulin levels directly with the k 1 suggesting that membrane transport is related to the ornithine cycle and/or is influenced by insulin. Optimal metabolic integrity of the hepatocyte is substrate specific and dependent upon the provision of exogenous energy. Hepatic transport function is limited in bacteremic patients as well as burn patients who are deprived of glucose. Restoration of hepatic transport processes may be achieved by providing sufficient energy in the form of glucose.