Cerebral oxygen saturation measurements in red cell transfusion

Anaemia is associated with decreased tissue oxygenation. It has been hypothesised that a fall in the oxygen extraction ratio (OER) following red cell transfusion demonstrates the appropriateness of the transfusion. If the red cell transfusion was necessary, then the OER would decrease post-transfusion, and this would be associated with an increase in cerebral oxygen saturation. If, however, transfusion was not needed then there would be no fall in OER post-transfusion. In this study, our objective was to compare non-invasive measurement of saturation with the invasive method of oxygen extraction determination. Thus, this is a test of the accuracy of the decision to transfuse. Cerebral (CsO2) and peripheral (PsO2) oxygen saturation were monitored with an INVOS 5100 in two groups of patients undergoing autologous red cell transfusion during elective abdominal aortic aneurysm (AAA) repair: patients showing a decrease in OER post-transfusion (group 1, n = 15) and patients showing an increase/no change in OER post-transfusion (group 2, n = 10). Systolic, diastolic and mean arterial pressure, arterial oxygen saturation, lactate concentration and end-tidal carbon dioxide did not significantly change during transfusion. Hb increased by 19.1 ± 10.4 g/L in group 1 and this was significantly higher compared to the increase of 8.7 ± 11.1 g/L in group 2 (p = 0.025), despite there being no significant difference in the volume of red cells transfused. The change in CsO2 in group 1 was also significantly greater: 11.7 ± 8.6% compared to an increase of 0.2 ± 7.3% in group 2 (p = 0.002). This was accompanied by an increase in pO2 in group 1 by 1.5 ± 2.0 kPa compared to a decrease by 0.5 ± 1.9 kPa in group 2 (p = 0.015), and a significant increase in mixed venous oxygen saturation (MvSO2) by 8.9 ± 10.5% (p <0.001) in group 1 compared to a non-significant change of 1.2 ± 2.7% in group 2. In the group of patients where OER decreased post-transfusion, cerebral oxygenation improved with an associated increase in Hb concentration. CsO2 measurements maybe useful in determining the efficacy of red cell transfusion, thereby possibly reducing unnecessary transfusions. © 2012 Springer Science+Business Media, LLC.