Blood, Anemia Flashcards
What are the components of the CPDA1 Preservative?
1) Citrate: Chelates Calcium, disrupting clotting mechanism
2) Phosphate: Buffer
3) Dextrose: energy source for cellular metabolism
4) Adenine: Substrate source for cells to produce ATP
-Extends shelf life to 35 days
-Preserves blood and prevents coagulation
What is the difference in shelf life between CPD (without adenine) vs CPDA1?
CPD (without adenine): 2 weeks
CPDA1: 35 days
What are the benefits of Component Therapy?
Maximizes the number of recipients and preserves function of essential blood elements.
What are the basic purposes of transfusing each component?
-Packed RBCs: oxygen carrying capacity
-Platelet concentrates: thrombocytopenia
-Fresh frozen plasma: coagulation proteins
-Cryoprecipitate: Fibrinogen, Factors VIII vWF, XIII
-Leukocyte poor RBCs: filtration to remove WBCs
Describe the process of separating blood components:
1) First centrifuge at room temperature produces platelet concentrates
-By separating plasma (containing platelets) from RBCs
2) Then the other products are separated by centrifuging at cold temperatures (1-6˚ C)
Describe PRBCs with CPDA-1
Hct 70-75%
50-70 mL of residual plasma
Volume 250-275 mL
Shelf life 35 days
-Similar pH and K+ content to additive solution
Describe PRBCs with Additive Solution:
Hct 60%
Less plasma (10-15 mL)
Volume 250-350 mL
Less citrate
Longer shelf life–42 days
Regenerates 2,3-DPG more quickly
Less TRALI
-Similar pH and K+ content to CPDA-1
1 unit of PRBCs should increase Hgb by ___ g/dL or the Hematocrit by approx. ____%
1 unit of PRBCs should increase Hbg by 1g/dL or the hematocrit by approximately 3%
Describe biochemical changes that occur in stored PRBCs.
1) pH decreases to 6.7 by 21 days
2) K+ = 4 mEq day of donation → 76 mEq at 35 days (slow leak of K+ from banked blood)
3) Dextrose:
-Day of donation raises blood sugar to 400 mg/dL
-At 35 days glucose level drops to 100 mg/dL
4) Decreased 2,3 DPG:
-Levels at 10% of baseline at 35 days, left shift in Oxy-Hgb curve
What is 2,3 DPG?
A compound that binds deoxyhemoglobin and increases oxygen delivery to cells).
-Decreased levels shift oxyhemoglobin dissociation curve to the left (increased O2 affinity for Hgb)
- 2,3 diphosphoglycerate and it comes from glycolysis
What are saline-washed RBCs?
For patients who experience reactions to foreign proteins that attach themselves to RBCs
-↓allergic reactions due to IgE or IgA antibodies
-Washed with isotonic saline solution
-Resulting units must be transfused within 24 hours
What are Leukocyte-reduced RBCs?
-Filtration or irradiation
-Done to eliminate or reduce white blood cell passengers
-Prevent non-hemolytic febrile transfusion reactions
What is the Hgb level that triggers transfusion?
There is NO transfusion trigger or Hgb level at which to transfuse.
What is Chronic Anemia?
-S/Sx begin to develop at a Hgb of <7/8 g/dL
Compensatory mechanisms:
-Increased cardiac output
-Increased 2,3 DPG so that oxygen unloads at lower oxygen saturation of hemoglobin
-Healthy bone marrow can increase production up to 6-fold
Decision to transfuse depends on pt’s underlying health status, the s/sx of decompensation due to anemia, cardiorespiratory reserve, and activity level
Chronic anemia patients rarely require transfusion until Hgb levels drop to 5g/dL overwhelming compensatory mechanisms.
Tolerance of acute anemia depends on what?
-Maintenance of intravascular volume
-Ability of the patient to increase cardiac output
-Health of the patient
What is the major function of RBCs (erythrocytes)?
To transport Hemoglobin.
-The bound hemoglobin carries oxygen from the lungs to the tissues of the body.
Describe the structure of hemoglobin.
-Hemoglobin has four protein subunits
-The binding affinity of hemoglobin for O2 is increased by the oxygen saturation of the molecule
-When the first oxygen binds, it influences the shape of the binding sites for the next O2 molecule, making it easier to bind
-Alterations or abnormalities in these subunits or hemoglobin chains can alter the physical characteristics of the hemoglobin molecule. Ex: Sickle Cell
What is the Oxygen-Hemoglobin Dissociation Curve?
Describes the relationship between available oxygen and amount of oxygen carried by hemoglobin.
-The horizontal axis is Pa02, or the pressure of oxygen in the blood (mmHg).
-The vertical axis is SaO2, or the amount of hemoglobin saturated with oxygen, shown as a percent.
-Once the PaO2 reaches 60 mmHg the curve is almost flat, indicating there is little change in saturation above this point. So, PaO2 of 60 or more is usually considered adequate.
-But, at less than 60 mmHg the curve is very steep, and small decreases in the PaO2 greatly reduce the percent saturation of hemoglobin.
What is “p50”?
The partial pressure of O2
at which hemoglobin is 50% saturated.
-The P50 is 26-27 mmHg.
What does an increased p50 mean?
Indicates a rightward shift of the curve, which means that a larger partial pressure is necessary to maintain a 50% oxygen saturation.
-This indicates a decreased affinity of the oxygen to hemoglobin.
What does a decreased p50 mean?
Indicates a leftward shift and a higher affinity of the oxygen to hemoglobin.
What factors cause a Left Shift in the O-H Dissociation Curve?
P50< 26-27 mmHg
-Decreased Temperature
-Increased pH (decreased H+ concentration)
-Decreased PCO2
-Decreased 2,3 DPG
Fetal Hemoglobin
Carboxyhemoglobin
Methemoglobin
What factors cause a Right Shift in the O-H Dissociation Curve?
P50 > 26-27 mmHg
-Increased Temperature
-Decreased pH (increased H+ concentration)
-Increased PCO2 (Bohr effect)
-Increased 2,3 DPG
Sickle Cell
Maternal Hgb
Renal failure
What is the Bohr effect?
As the blood passes through the tissues, CO2 diffuses from the tissue cells into the blood. This diffusion increases the blood PCO2, which in turn raises the blood H2CO3 (carbonic acid) and the hydrogen ion concentration. These effects shift the oxyhemoglobin dissociation curve to the right and downward, forcing O2 away from the hemoglobin and therefore delivering increased amounts of O2 to the tissues. Exactly the opposite is seen in the lungs – CO2 diffuses from the blood to the alveoli, reducing the blood PCO2 and decreasing the hydrogen ion concentration – causing a leftward and upward shift of the curve to facilitate increased binding of O2 to hemoglobin – allowing greater O2 transport to the tissues.
