Extracellular haemoglobin, oxidative stress and quality of red blood cells relative to perioperative blood salvage.

BACKGROUND: The quality of blood-pack units in perioperative blood salvage was studied with respect to the presence of extracellular haemoglobin (Hb) and in terms of oxidative stress and the mechanical properties of red blood cells (RBC). METHODS: The study was performed on blood-pack units and patients' blood after retransfusion. Results were compared to those obtained in patients prior to autotransfusion. Free Hb, non-protein thiols (as antioxidant marker) and markers of oxidative stress (conjugated dienes, thiobarbituric reactive substances and protein carbonyl content) were measured. The mechanical properties of RBC were evaluated by their osmotic fragility, membrane fluidity by measuring the fluorescence anisotropy of an extrinsic probe and permeability by measurement of extracellular K(+) and lactate dehydrogenase. RESULTS: Despite washing, extracellular Hb concentrations remained high (up to 0.7 g/L in blood-pack units) and was associated with a decrease of haptoglobin in patients, despite a concomitant inflammatory syndrome. In blood-pack units, we observed a decrease in antioxidant markers along with an increase in oxidative stress markers in association with an alteration of RBC membrane properties. CONCLUSIONS: Haemolysis must be limited during perioperative blood salvage in order to prevent exposure to oxidative stress and improve the efficiency of autotransfusion.