Rate of elimination of the intralipid fat emulsion from the circulation in ICU patients.

The rate of removal of Intralipid was studied in 2 groups of intensive care patients by analysis of the fractional removal rate after a single iv dose and by analysis of the removal rate during a constant infusion of Intralipid which immediately followed. The patients in group I were moderately ill after uncomplicated surgery whereas group 2 patients were critically ill and had a mortality of 44%. The fractional removal rate was 2-fold greater in group 1 than group 2 and controls; the 2 latter groups had similar rates of removal. During the constant infusion of Intralipid, 0.42 g/min for 3 h, group 1 patients were found to have a first order removal rate with a constant plasma concentration of Intralipid. The rate constants were not different during the entire infusion from those obtained by the single injection. In all of the group 2 patients, a zero order removal rate was present as the concentration of Intralipid particles increased linearly with time. Group 2 patients had cleared all Intralipid within 6 h after the end of the infusion. Some patients were treated with heparin and/or insulin for clinical reasons. The removal rates were not influenced in either group by these drugs. Thus, moderately traumatized patients were found to clear plasma from Intralipid at recommended infusion rates. However, in critically ill patients, the infusion rate of Intralipid may have to be adjusted below the maximal elimination capacity to avoid Intralipid accumulation in plasma.