Blood groups and transfusions

Describe the 3 responses to blood loss

1. Haemostasis

2. increasing production of RBC

3. actions of SNS increase HR, force of contraction, CO, constriction of veinss, venous return, PVR, and production of adrenaline

Describe the process of erythropoiesis

kidney cells detect low levels of oxygen in blood flowing through them and produce an increase amount of EPO, which is released into blood and carried to red bone marrow. EPO stimulates RBC production, so once normal levels of oxygen are achieved kidney cells reduce level of EPO and RBC production rate returns to normal

Define antigen

a substance that is recognised as foreign by the immune system and generates an immune response

Name the 4 blood groups and what antigens each blood group has

Type A - RBC w A antigens

Type B - RBC w B antigens

Type AB - RBC w A & B antigens

Type O - RBC has no antigens

State what antibodies would be in the plasma of each blood type

Type A - Antibody B

Type B - Antibody A

Type AB - neither antibody A or B

Type O - A and B antibodies

State the blood type for universal recipients and why

AB positive are 'universal recipients' as they have A, B and D antigens and therefore no A, B and D antibodies in their plasma

State the blood type that are universal donors and why

O negative are universal donors since they don't have A, B or D antigens and do have A and B antibodies

Explain the difference between blood typing and cross matching

blood typing is identifying the blood group whereas cross-matching is mixing of donor and recipient blood for compatibility

List the 6 different transfusion reactions

acute haemolytic reaction, febrile reaction, mild allergic reaction, anaphylaxis and severe allergic reactions, circulatory overload, sepsis

What causes a febrile reaction

reaction to donor WBC, platelets or plasma proteins

Clinical signs and symptoms of circulatory overload reaction

cough, dyspnoea, pulmonary congestion, headache, hypertension, tachycardia, distended neck veins

2 major physiological events that occur during acute haemolytic reaction

agglutination - obstruction of blood capillaries

haemolysis - renal failure and heart arrythmias

Explain why acute haemolytic reaction is so severe

the recipient will produce antibodies in huge numbers to attack the donors RBC

What is meant by rhesus positive

people with D antigens on RBC surface are rhesus positive and people without are rhesus negative