INVITED COMMENTARY

Abstract

Removal of lipid particles has become of interest after the alarming results of Moody and colleagues [1Moody D.M. Brown W.R. Challa V.R. Stump D.A. Reboussin D.M. Legault C. Brain microemboli associated with cardiopul-monary bypass a histologic and magnetic resonance imaging study.Ann Thorac Surg. 1995; 59: 1304-1307Abstract Full Text PDF PubMed Scopus (169) Google Scholar] on lipid embolization in brain arterioles after cardiac surgery. It resulted in various attempts to reduce lipids in retransfusion blood, which would be beneficial after cardiac surgery, but also after orthopedic surgery. Despite the known side effects of retransfusion from the wound area, autologous blood transfusion is increasingly used to reduce the use of allogenic blood. A major problem in justifying the efforts, time, and costs to clear retransfusion blood from lipid particles is to obtain evidence of clinically relevant brain damage and evidence for the dominant role of lipid particles. First of all, brain damage has been reported with very different significance. A number of studies could not show any deterioration in cognitive functions, whereas biochemical markers of brain damage, such as S100β and enolase, showed in some studies small and transient appearance. Clearly, the specificity of such tests is not sufficient or sensitive enough to demonstrate brain damage. Perhaps new markers, such as carnosinase, may appear relevant for monitoring brain damage. The second problem is that lipid particles are only one of the suspects of brain damage. Gaseous emboli, macromolecules, inflammatory agents, and leukocyte-platelet aggregates may be involved in occlusion of the small vasculature as well. In their discussion the authors indicated that, eg, macromolecules may also be removed by the current technique of particulate separation, but other potential sources of embolization possibly remain in retransfusion blood. The combination with other techniques to remove platelets, leukocytes, and products that affect hemostasis or inflammation may be a future option. Third, the reuse of shed blood is a matter of dispute. It depends on the operation time, preference of surgeons, and need for immediate volume during the procedure. To obtain the technique widely used, it must be simple, fast, and cost effective. Nevertheless, the PARSUS technique presented here offers new possibilities to improve the quality of retransfusion with high efficacy for removing potential dangerous lipid particles. Hopefully these qualifications will be supported by adequate monitoring instruments. It would be exciting to see the efficacy of a larger scale PARSUS device in clinical practice.