5a The concept of autologous transfusion (CAT)

Because of the potential risks of transmission of viral diseases by homologous blood, the so-far unsolved relevance of immunomodulation-suppression by homologous blood and the seasonal shortage of homologous blood, autologous transfusion techniques have gained importance over the last decade. As each single autologous transfusion measure has limitations of its own, these techniques should most effectively be combined into what has been called the ‘concept of autologous transfusion’ (CAT). This concept consists of the technical measures of autologous transfusion, for example acute normovolaemic haemodilution with intra- and post-operatively salvaged blood being either mechanically processed or unprocessed and directly retransfused, the autologous pre-deposit being separated into autologous blood donation with or without haemoseparation and into autologous pre-operative plasmapheresis. Establishing and routinely applying CAT resulted in a decrease of homologous blood by approximately 90% in major bone and joint surgery; on differentiating between aseptic and infectious orthopaedic surgery, more than 90% of the former were supplied with autologous blood while the latter was supplied by approximately 20% of autologous blood. The incidence of adverse events occurring in an autologous pre-deposit programme in more than 28 000 patients with more than 130 000 autologous units was 2.08% with respect to the number of patients taking part in this programme or 0.44% with respect to the number of autologous units harvested. Among this total number of 588 adverse events there were three severe ones (two male patients with myocardial infarction and one female patient with an apoplexy) and two fatal adverse events (one patient dying of massive pulmonary embolism and one female patient dying of an acute severe asthmatic attack). While CAT has been proven to reduce effectively the need for homologous blood it has also been shown that the appropriate selection of the patients as well as close and experienced monitoring and management of adverse events are necessary to make CAT not only an effective but also a safe alternative to homologous blood transfusion.