blood groups and transfusion reactions Flashcards
Describe the three responses to blood loss
- Vasoconstriction(vascular spasm)
- Platelet plug formation
- Coagulation (blood clotting).
Describe the process of erythropoiesis
Formation of RBC’s
- pluripotent stem cell becomes an erythrocyte colony-forming unit (ecfu)
- the hormone erythropoietin (EPO) stimulates the ecfu to develop into an erythroblast
- erythroblast (aka erythrocyte precursors) develop a nucleus, ribosomes, golgi, as well as hemoglobin
- when hemoglobin production is complete, the nucleus shrives and is discharged from the cell
- protein making machinery begins to disintegrate
- cell is now considered a reticulocyte
- reticulocytes leave the bone marrow and enter the circulating blood
- when the last of the ribosomes disintegrate and disappear, the cell is considered to be a mature erythrocyte
Describe the response of the SNS (sympathetic nervous system) to significant blood loss
Actions of the sympathetic NS increase:
- Heart rate & strength of contraction & cardiac output
- Constriction of veins, venous return & cardiac output
- Peripheral resistance
- The production of adrenaline
what is the cardiovascular systems homeostatic response to blood loss?
1) 1.Reducing blood loss through haemostasis
- Vasoconstriction, platelet plug formation, coagulation
2) Increasing production of RBC.
3) Actions of the sympathetic NS which increases :
- Heart rate & strength of contraction & cardiac output
- Constriction of veins, venous return & cardiac output
- Peripheral resistance
- The production of adrenaline
Define the term antigen
- a substance that is recognised as foreign by the immune system & generates an immune response.
- Some red blood cells (RBC) have antigens called A, others have antigens called B.
Using the ABO classification name the four main blood groups and state what antigens each blood group has
- If a person has RBC with A antigens we categorise their blood as group A.
- If a person has RBC with B antigens we categorise their blood as group B.
- If a person has RBC with both A & B antigens we categorise their blood as group AB.
- If a person has RBC with no antigens we categorise their blood as group O.
For each of the four blood groups state what antibodies would be present in the plasma
- Plasma contains antibodies
- These develop in plasma early in childhood to attach to foreign antigens
- We don’t produce antibodies against our own antigens
- Type A blood= B antibodies
- Type B blood= A antibodies
- Type AB blood= neither antibodies
- Type O blood= both A and B antibodies
State the blood type for universal recipients & explain why this type can receive blood from all blood groups
People with type AB+ve blood are called “universal recipients” since they do have A, B and D antigens, and thus do not have any A, B or D antibodies in their plasma.
State the blood type that is called the universal donor and explain why this blood type can donate to all blood groups
People with type O-ve blood are called “universal donors” since they do not have A, B or D antigens, and so do have A, B antibodies (but usually not D antibodies)
Explain the difference between blood typing & cross-matching
- Typing is identifying the blood group.
- Cross-matching is the mixing of donor and recipient blood for compatibility
- Transfusion recipients should receive red cell components that are compatible with their own ABO group.
- Incompatible transfusions can result in serious harm/death.
List the six different types of blood transfusion reactions
- Acute haemolytic: Transfusion of incompatible blood transfusion.
- Febrile: reaction to donor WBC, platelets or plasma proteins.
- Mild allergic: sensitivity to foreign plasma proteins
- Anaphylactic & severe allergic: sensitivity to foreign plasma proteins
- Circulatory overload: Fluid administered faster than circulation can accommodate
- Sepsis: Transfusion of bacterially contaminated blood components.
Describe what causes a febrile reaction
- These are the most common type of reactions.
- Also called non-haemolytic reactions
- Cause: sensitization to donors leucocytes, platelets or plasma proteins.
- Symptoms: chills & temperature rise of >1⁰ , low BP, tachycardia, nausea & vomiting, headache, flushing, muscle pain
- in the absence of renal shutdown these reactions are rarely fatal
What happens in an acute haemolytic reaction?
- occurs when someone is given a transfusion of blood that isn’t compatible with theirs.
- the recipient’s antibodies attack the antigens on the donor’s red blood cells
- this is severe because the recipient will produce antibodies in huge numbers to attack the donor’s RBCs
Describe the clinical signs & symptoms you would observe if a person had a circulatory overload reaction
- occurs when Fluid administered faster than circulation can accommodate
- results in cough, dyspnoea, pulmonary congestion, headache, hypertension, tachycardia, distended neck veins
Describe the two major physiological events that occur during an acute haemolytic reaction
- Agglutination or clumping of RBC obstructs blood flow to tissues
- occurs when antibodies attach to a number of RBCs (carrying the corresponding antigen)
- causes them to clump together
- prevents them from flowing freely
- Obstruction of blood capillaries hindering blood flow to tissues - Haemolysis.- rupture of RBCs Haemoglobin is released into plasma & is trapped in kidney tubules blocking them & causing acute renal failure & may cause death.
- K+ released into plasma leading to heart arrhythmias
