Lack of enteral nutrition during critical illness is associated with profound decrements in biliary lipid concentrations

Background: Food in the intestine drives the enterohepatic circulation of b ile components. Objective: We investigated whether parenteral or enteral delivery of nutrie nts alters serum and biliary lipids in critically ill patients. Design: Eight intensive care unit (ICU) patients who had received greater t han or equal to 5 d of total parenteral nutrition (TPN) were compared with 8 ICU patients who had fasted for greater than or equal to 5 d. Both groups were studied before and after 5 d of enteral nutrition (EN). Each patient served as his or her own control. Duodenal bile was analyzed for biliary li pid content and serum lipids were determined simultaneously. Duodenal bile samples from 18 healthy persons served as controls. Results: Bile salt concentrations in all ICU patients were 17% of control v alues before EN (P < 0.005) and 34% of control values after 5 d of EN (P < 0.005). Phospholipid concentrations were 12% of control before EN (P < 0.00 05) but increased almost 4-fold after EN (P < 0.0005). Biliary cholesterol concentrations were 20% of control values before EN (P < 0.001) and did not improve afterward. No difference in bile composition was observed between fasted ICU patients and those who received TPN. The inverse correlation bet ween the severity of illness and biliary lipid concentrations observed befo re EN disappeared with enteric stimulation. The low serum concentrations of HDL cholesterol and apolipoprotein A-I increased significantly with EN in all ICU patients. Conclusion: Lack of EN during critical illness was associated with profound decrements in biliary lipid concentrations that normalized partially after 5 d of EN. We hypothesize that loss of enteric stimulation in ICU patients impairs hepatic lipid metabolism.