Sebastián Transfusion of post - operative shed blood : laboratory characteristics and clinical utility

It is well known that the defence mechanisms provided by the immune system can be altered by traumatic injury, surgery and transfusions, and there is a growing interest for acquiring greater knowledge on the causes and mechanisms involved in the immunodepression induced by the anaesthetic-surgical procedure, since this increases the susceptibility to post-operative infection and tumour relapse after potentially curative surgery [15, 19, 62]. This interest further increases when it is seen that, in spite of current surgical techniques, of advances in anaesthetics and in the huge variety of anti-microbial agents, general and local infection continues to be one of the main causes of morbidity-mortality associated with traumatic injuries and surgery, increasing its incidence in those patients who have received allogeneic blood transfusions (ABT) [29, 61]. Abstract Increased awareness of the potential hazards of allogenic blood transfusion, such as incompatibility reactions, metabolic and immunologic disorders, or transmission of viral diseases, has led to an emphasis on allogeneic blood alternatives. For orthopaedic surgery, several autologous transfusion modalities have emerged as alternatives to allogeneic blood transfusion, avoiding its immunomodulatory effects. Among them, transfusion or return of post-operative salvaged shed blood has become popular in major orthopaedic procedures. However, although the effectiveness of this blood-saving method is well documented, several authors have questioned its safety and recommended the use of washed blood. Therefore, this review analyses the haematologic characteristics of unwashed filtered shed blood, including metabolic status and survival of red blood cells, the components of the haemostatic system, the content of fat particles, bacterial and tumour cells and the possibility of their removal, the content of inflammatory mediators, and the effects on the patient’s immune system. From data reviewed in this paper, it can be concluded that post-operative salvage of blood seems to be an excellent source of functional and viable red cells without many of the transfusion-related risks and with some immuno-stimulatory effects. In addition, from our experience, postoperative re-infusion of unwashed shed blood after major spine procedures has proved to reduce post-operative homologous transfusion requirements and to complement preoperative autologous blood donation, without any clinically relevant complication.