Propofol and intralipid cause creaming of serum from critically ill patients.

The aim of this in-vitro study was to investigate the incidence of propofol agglutination with serum from critically ill patients. Serum (400 microliters) from 58 critically ill patients and 30 healthy volunteers was incubated with 10 microliters of either propofol, Intralipid 10% or Intralipid 20%. Control incubations contained serum only. At 24 h, the serum was examined macroscopically and microscopically for agglutination. Agglutination was seen with Intralipid 20% in serum from all critically ill patients and 13.3% of volunteers. Serum from 91.4% of critically ill patients was agglutinated with Intralipid 10% and only 3.3% of the healthy volunteers. In comparison, propofol produced agglutination in 74.1% of critically ill patients and in none of the serum from healthy volunteers (p < 0.05 propofol versus Intralipid 10%, p < 0.0001 propofol versus Intralipid 20%). No correlation was seen between agglutination and age, sex, APACHE II score or plasma concentration of acute phase proteins. However, agglutination of propofol and Intralipid 10% was more frequent (p < 0.001) in serum from patients with pulmonary disease, than in patients with normal lungs. The clinical implications of these in-vitro findings are unclear and need further investigation.