Predictors of increased transfusion requirements and optimizing transfusional support in patients on Extracorporeal membrane oxygenation (ECMO)
Authors: Ang A. L. 
Published: June 2012

ECMO has an established role in neonatal, paediatric and adult patients with cardiac and/or respiratory failure who failed to respond to conventional therapies. It provides temporary cardiopulmonary support until the recovery of the patients or the institution of definitive treatment. Patients undergoing ECMO, especially adults, have high requirements for all blood components. High transfusional needs have been associated with increased mortality in the adults. Neonatal patients generally have lower overall transfusion requirements than the adults. The significant transfusion requirements among ECMO patients is contributed by increased bleeding from the need for systemic anticoagulation to reduce circuit thrombosis, activation and consumption of platelets and clotting factors, and anaemia from haemodilution and haemolysis. The need to prime the ECMO circuit with red cells may also account for part of the neonatal transfusion requirements

There can be wide inter‐individual variations in the transfusion requirements of ECMO patients. Differences in pre‐determined transfusion triggers may account for differences in blood utilization between centers. Central cannulation can be associated with higher cannulation bleeding rates and blood utilization than peripheral cannulation. In neonates, factors associated with increased daily platelet transfusions include the use of venoarterial ECMO and the presence of concomitant sepsis and meconium aspiration. Neonates with sepsis or congenital diaphragmatic hernia may have the highest overall platelet transfusions due to longer ECMO duration. Neonates with intracranial haemorrhage were observed to require more platelet transfusions.

In our retrospective analyses of adult ECMO patients in a cardiothoracic surgical unit in Singapore, there were positive correlations of total red cell, platelet and FFP transfusions with ECMO duration which in turn increased in non‐surgical or septic patients. On multivariate analyses, nadir haemoglobin of <7.5 g/dL associated with increased average daily red cell and FFP transfusions. Recent antiplatelet usage and maximum haemoblobin decline of >5.5 g/dl while on ECMO independently associated with increased average daily platelet transfusions. In addition, increased ECMO duration (which correlated negatively with nadir platelet count) was also independently associated with average daily transfusion of >3 platelet concentrate units. Bleeding was not an independent factor associated with any of the blood component utilization. Our findings suggest that the patients' haemoglobin levels and the perceived need to minimize coagulopathies among patients with significant anaemia and/or additional bleeding risks may have the greatest impact on clinicians' transfusion decisions in adult patients undergoing ECMO.

Measures including the use of activated recombinant factor VII to reduce haemorrhage, and reduction in allogeneic blood transfusion with the use of an autotransfusion device during elective changes of ECMO systems have been reported to reduce transfusion requirements. Close collaboration between the transfusion service and the ECMO team is necessary to optimize the transfusion support of patients undergoing ECMO.