Transfusion Strategy: Impact of Haemodynamics and the Challenge of Haemodilution

Abstract

Blood transfusion is associated with increased morbidity and mortality and numerous reports have emphasised the need for reduction. Following this there is increased attention to the concept of patient blood management. However, bleeding is relatively common following cardiac surgery and is further enhanced by the continued antiplatelet therapy policy. Another important issue is that cardiopulmonary bypass leads to haemodilution and a potential blood loss. The basic role of blood is oxygen transport to the organs. The determining factors of oxygen delivery are cardiac output, haemoglobin, and saturation. If oxygen delivery/consumption is out of balance, the compensation mechanisms are simple, as a decrease in one factor results in an increase in one or two other factors. Patients with coexisting cardiac diseases may be of particular risk, but studies indicate that patients with coexisting cardiac diseases tolerate moderate anaemia and may even benefit from a restrictive transfusion regimen. Further it has been shown that patients with reduced left ventricular function are able to compensate with increased cardiac output in response to bleeding and haemodilution if normovolaemia is maintained. In conclusion the evidence supports that each institution establishes its own patient blood management strategy to both conserve blood products and maximise outcome.

A New Intraoperative Protocol for Reducing Perioperative Transfusions in Cardiac Surgery

“…It is well established that preoperative and intraoperative anemia is associated with greater morbidity in cardiac surgery patients [1,2,17]. Yet, it is also clear that transfusing blood products is not without its own peril.…”

Risks of Anemia in Cardiac Surgery Patients

“…19 CPB can further reduce the Hb level and exacerbate anemia through hemodilution or as a consequence of increased blood loss in the context of a coagulopathy. 20…”

Development of a diagnostic sensor for measuring blood cell concentrations during haemoconcentration

“… 12 Haemodilution strategies during cardiopulmonary bypass (CPB) procedures have adverse effects on fluid balance 13 and the significant decrease in patient packed cell volume (PCV) and haemoglobin is associated with perioperative morbidity and mortality 14 and increased blood loss. 15 …”

“…12 Haemodilution strategies during cardiopulmonary bypass (CPB) procedures have adverse effects on fluid balance 13 and the significant decrease in patient packed cell volume (PCV) and haemoglobin is associated with perioperative morbidity and mortality 14 and increased blood loss. 15 HemoSep  , a technology developed at the University of Strathclyde and manufactured and marketed by Brightwake Ltd (Nottingham, UK) is an ultrafiltration and haemoconcentration device for the concentration of residual bypass blood following surgery. This technology is capable of reducing blood loss in cardiac and other types of "clean site" procedures, including paediatric surgery.…”