The efficacy of blood transfusions to improve microcirculatory oxygen delivery in anemic patients.

The primary goal of giving blood transfusions for correcting anemia, is to
provide oxygen rich blood to the microcirculation where it can give oxygen to
the tissue cells. There is little evidence, however, that shows that this goal
is actually achieved in anemic patients. In fact in certain disease states
there is evidence that blood transfusion may even have deleterious effects.
Even though systemic variables of hematocrit and hemoglobin concentrations rise
following transfusion, the efficacy of transfused blood to actually reach the
microcirculation and oxygenate the tissues may not be achieved. Experimental
studies conducted by us and others have identified various factors associated
with deterioration of red blood cell (RBC) function during storage and
transfusion which impair its ability to provide oxygen to the microcirculation.
The main purpose of this project is to investigate the conditions under which
blood transfusions are successful in promoting microcirculatory circulation and
oxygenation in anemic patients. In this project we wish to apply our state of
the art optical spectroscopic techniques to patients undergoing blood
transfusion to asses the success of blood transfusion in supplying the
microcirculation with oxygen-rich blood. We will also measure parameters known
to affect RBC function related to the transfused blood as well as parameters
relating to the condition of the host. Since the pathogenic nature of the host
and cause of anemia can impact the ability of transfused blood to reach the
circulation we have chosen to investigate 2 patient categories where blood
transfusions are needed. These include anemic patients and patients who are
under chemotherapy treatment.

The hypotheses we wish to test in this project are as follows:
1. Transfusion of RBCs in anemic patients causes an improvement in
microcirculatory blood flow and oxygen delivery.
2. Storage of RBCs impairs the ability of transfused cells to supply the
microcirculation with oxygen rich blood.
3. Underlying disease can affect the microcirculation and/or the transfused
blood, impairing its ability to oxygenate the microcirculation.
4. Nitric oxide and its products altered during storage and disease are the
main cause of RBC and microcirculation dysfunction impairing proper transport
of transfused cells to the microcirculation.

The main purpose of this project is to investigate the conditions under which
blood transfusions are successful in promoting microcirculatory circulation and
oxygenation in anemic patients. In this project we wish to apply our state of
the art optical spectroscopic techniques to patients undergoing blood
transfusion to asses the success of blood transfusion in supplying the
microcirculation with oxygen-rich blood. We will also measure parameters known
to affect RBC function related to the transfused blood as well as parameters
relating to the condition of the host. Since the pathogenic nature of the host
and cause of anemia can impact the ability of transfused blood to reach the
circulation we have chosen to investigate 2 patient categories where blood
transfusions are needed. These include anemic patients and patients who are
under chemotherapy treatment.

This is observational research with invasive and non-invasive measurements.
The measurements we are going to carry out can be classified in two groups. The
first group of measurements is going to be performed by using in-vivo clinical
techniques to investigate the microcirculatory perfusion and oxygen
availability. For that purpose we are going to use SDF and O2C techniques. A
second group of measurements will be with samples collected from the patients
and blood bags in certain time points. This group of measurements includes full
blood count, blood gases (including lactate, systemic hemoglobin), blood
chemistry, RPC as an inflammatory marker, hematocrit viscosity, RBC morphologic
test (MCV, MCH, MCHC), strong ion difference, nitric oxide products (nitrite
and nitrate), 2,3-DPG, ATP, eNOS, and RBC deformability and aggregability. For
these measurements 3 tubes of blood (2 times 15 ml) will be taken. Collected
samples will be immediately sent to the laboratory or rapidly cooled to below 4
degree Celsius. Patient characteristics, systemic parameters and the storage
age of blood cells will be recorded at all time points.

Baseline measurements will be performed before the beginning of blood
transfusion. The administration of blood transfusion needs 90 minutes in all
groups. Second measurement will take place at 60 minutes after transfusion is
completed.

N.v.t.