This article captures a unique aspect to the old question: What is the ‘right’ level to maintain a patient’s hemoglobin?
As clinicians, we can be our own worst enemy. This center quantified their blood testing at 75mL/kg, and after removing the factor of circuit blood priming, cardiac patients were transfused 529 mL/kg and non-cardiac patients were transfused 74 mL/kg.
Most importantly, the authors report the affect of the RBC transfusions on tissue oxygenation as measured by an SvO2 or cerebral near-infrared spectroscopy.
“Most transfusions resulted in no significant change in either SvO2 or cerebral near-infrared spectroscopy. Only 5% of transfusions administered (31/617) resulted in an increase in SvO2 of more than 5%, whereas an increase in cerebral near-infrared spectroscopy of more than 5 was only observed in 9% of transfusions (53/617). Most transfusions (73%) were administered at a time when the pretransfusion SvO2 was more than 70%.”
The authors conclude that:
1. “In the majority of events, RBC transfusion did not significantly alter global tissue oxygenation, as assessed by changes in SvO2 and cerebral near-infrared spectroscopy.”
2. “Most transfusions were administered at a time at which the patient did not appear to be oxygen delivery dependent according to global measures of tissue oxygenation.”
An unstated conclusion may be inferred as well. The amount of blood testing that is performed on ECMO is the major contributor to the need for RBC transfusion. Can we, as clinicians, decrease the amount of testing? Can we rely on non-invasive monitoring? Has your center reviewed its testing protocols lately?