The effect of red blood cell transfusion on the microcirculation after cardiac surgery.

Cardiac surgery is normally associated with traumatic blood loss a low cardiac
output and the requirement for multiple red blood cell (RBC) transfusions.
Although circulatory insufficiency and blood loss are clear reasons to
administer RBC units, the effects on tissue oxygenation are less clear.
Parameters, able to unmask dysfunction of the microcirculation after RBC
transfusion,are actively searched.

The aim of this clinical study is to determine, what the effect of RBC
transfusion is on the microcirculation after cardiac surgery in the ICU, as
compare to asanguineous colloid (Gelofusine®) infusion.

Twenty-four patients, who are administered to the Intensive Care Unit after
cardiac surgery and who receiving their first RBC transfusion or Gelofusine®
infusion, will be measured prior and after transfusion/infusion. With the use
of SDF, the flow of the RBC and the number of perfused capillaries will be
measured in the microcirculation. The data of the RBC transfusion and
Gelofusine® infusion, measured before and after the RBC transfusion or
Gelofusine® infusion, will be compared. The reflectance spectrophotmetry will
be used to measure the oxygenation of the microcirculation.
Bloodsamples will be used for global hemodynamics.

The capillary perfusion (flow and oxygenation) will be measured under the right
side of the tongue. The method is safe to be used on the Intensive Care Unit.
The method is non-invasive. Participating in the study contains no burden and
no risk for the subjects. The nature or duration of the treatment will not
change.