Re-transfusion of salvaged washed red cells improves clot formation in pigs as measured by rotational thrombelastometry (ROTEM®)

Background and objective: Patients exhibiting considerable blood loss are prone to develop dilutional coagulopathy following volume supply. In such patients, in addition to transfusing stored blood components, cell saver systems are used to minimize allogeneic transfusion. Since red cell transfusion might influence the haemostatic system by further dilution, we investigated the effects of re-transfusion of salvaged washed red blood cells on the haemostatic process in an animal model of controlled haemorrhage using rotational thrombelastometry (ROTEM (R); Pentapharm Co., Munich, Germany). Methods: Anaesthetized pigs (n = 20) developed coagulopathy following haemorrhagic shock (withdrawal of 6696 of estimated blood volume) and volume resuscitation with 6176 hydroxyethyl starch 130/0.4. The shed blood was processed in a Cellsaver device (CATS (R); Fresenius AG, Bad Homburg, Germany), and the resulting salvaged red blood cells were re-transfused. ROTEM assays were performed at baseline, after blood loss, after volume resuscitation and following re-transfusion of salvaged red blood cells. Results: As compared with baseline, blood loss and subsequent volume resuscitation resulted In significantly increased median values of clotting time (CT: 47.0, 53.3 and 103.5 s), and clot formation time (CFT: 36.0, 40.0 and 186.0 s), while maximum clot firmness decreased (MCF: 72.0, 68.5 and 39.5 mm). After re-transfusion of salvaged red blood cells (805 +/- 175 mL all these parameters improved (CT: 80.5 s; P = 0.05, CFT: 144.0 s; P = 0.0008, MCF: 42.0 mm; P = 0.0019) although baseline values were not reached. Conclusion: In the case of extreme isovolaemic haemodilution, increasing the circulating red cell mass by re-transfusing salvaged red blood cells did not worsen the findings of dilutional coagulopathy but interestingly, at least partially, improves the clot formation process.