Intraoperative Blood salvage : Quality Control and New Applications
Ernil Hansen MD, PhD
Dept. of Anaesthesiology, University of Regensburg
Intraoperative blood salvage with cell washing is capable of providing RBC of excellent quality. This blood is autologous, thus avoiding immunisation, transfusion reactions, and transfusion induced immunosuppression (1). This blood is fresh without any decrease in RBC function or viability, thus avoiding impairment of tissue oxygenation, overloading with mediators and cell debris, and immunosuppression caused by storage lesions in the blood (2). Therefore, this blood is superior in quality to most stored blood including predonations.
In Germany recently an expert group has proposed a quality control system for intraoperative blood salvage to guarantee that high level of blood quality. Specific education and a profound knowledge of the basis of blood composition, coagulation, and the cell separation is recommended. Limitation of vacuum and air mixture, and sufficient anticoagulation during blood collection is emphasised. For every application the measurement of volume and hematocrit in the RBC is suggested for control of product quality. Hematocrit is a quality parameter, since low filling of the centrifuge bowl is a major cause of insufficient cell washing. For control of process quality sample testing is recommended in a frequency of about 1%, for every autotransfusion device at least one per month. Recovery and elimination rate should be calculated from measurements of volumes and hematocrit, and total protein or plasma hemoglobin, respectively, in reservoir and final product. Microbiology testing is of no clinical relevance in unstored blood.
The recommended limits are: hematocrit >50%
RBC recovery >80%
elimination rate >90% (plasma Hb <2 g/l)
As requested for any new apparative development we have tested the new generation autotransfusion device ELECTA (Dideco, Italy) (with 125ml bowl), characterised by easy cassette set-up and by multiple sensor technique, and a 55ml-bowl (Dideco, Italy) for processing of low blood volumes like in pediatric surgery. With mean product hematocrits of 55.3%, or 53.2%, recovery rates exceeding 90%, and elimination rates of 98.3, respectively, both new equipment allow blood salvage at very high quality standards.
Blood irradiation has opened an important new field of application for intraoperative autotransfusion: cancer surgery, where about one third of all transfusions are used. The method is based on the analysis of tumor cells in the shed blood (3) and an the demonstration of their radiosensitivity (4). Blood irradiation proved efficious, practical and safe to eliminate the contaminating tumor cells, and effective in saving blood in cancer patients (5). Quality testing showed RBC unimpaired after blood salvage and irradiation (6). Thus, intraoperative autotransfusion is recommended in cancer surgery (7), while bacterial contamination remains a strict contraindication.
With the high quality of intraoperatively salvaged blood the evaluation of costs must be reconsidered, since with banked blood oxygen delivery might be impaired for many hours, and viability might be decreased to 75% one day after transfusion leaving the patient with hemolyzed blood and less oxygen transport capacity in the situation of a low transfusion trigger. The question is not any more, if we can or should use intraoperative blood salvage, but how we ever could possibly justify to our patients the routine disposal of their own blood that is collected under sterile conditions, and that can be processed to such a high quality blood product.
582-587
surgery. Anesthesiology 1997; 87(3a): 109
Transfus Sci 1999; 21:129-39