Intralipid disappearance in critically ill patients.

Intralipid elimination patterns were compared in 25 healthy controls, 12 patients recovering from uncomplicated cholecystectomy, and 25 critically ill patients. The intravenous fat tolerance test revealed a similar fractional removal rate (k2) in healthy controls and critically ill patients, but k2 was increased in cholecystectomy patients. The concentration of cross-reactive protein (CRP) correlated positively to the concentration of total triglyceride and low-density lipoprotein-triglyceride, and negatively to low-density lipoprotein-cholesterol and high-density lipoprotein-cholesterol. The extrapolated zero-time concentration of Intralipid in the critically ill patients was only one-third of the value in healthy controls. After this initial loss, however, Intralipid was removed from the circulation after first-order kinetics. These low concentrations of Intralipid were not correlated with concentrations of CRP. Possible explanations for this phenomenon include a change in the configuration of the lipid particles, the so-called creaming phenomenon, and/or immediate and substantial uptake of the emulsion by certain organs.