Week 1 - E - Overview of Blood Transfusion - Red Cells, Plasma, Platelets, ABO/Rhesus/Irregular Antibodies, Transfusion Reactions

Question 1

What does a transfusion service supply? Blood components

• 1. Red cells
• 2. Platelets
• 3. Fresh frozen plasma
• 4. Cryoprecipitate

How are these blood components obtained?

Answer 1

These components are obtained via centrifuging anticoagulated blood

Question 2

Blood components are obtained by centrifuging anticoagulated blood to separate it What is the blood layers separated into?

Answer 2

Red blood cells - these are most dense and lie at the bottom - roughly 45% Buffy coat - white blood cells + platelets - these lie in the middle - roughly <1% Plasma - these are the least dense and therefore rise to the top - roughly 55%

Question 3

When obtaining donated blood from one patient, how many units of RBCs, Plasma and platelets do we obtain? When giving a patient one unit of red blood cells, how many patients are they exposed to? When giving a patient one dose of platelets, how many donors are they exposed to?

Answer 3

From one donation of blood, you obtain: * One unit of red blood cells * One unit of plasma * 1/4 the therapeutic dose of platelets Therefore if giving a patient: * One unit of RBCs - they are exposed to one donor * One dose of platelets - they are exposed to 4 donors

Question 4

How is fresh frozen plasma obtained from centrifuging a blood donation?

Answer 4

Once the blood is collected, if the plasma is frozen within 8 hours (from collection time including centrifuging), then this is fresh frozen plasma and contains almost all the same coagulation proteins as the donor in almost the same concentration as when given

Question 5

Blood products are obtained by subjecting human plasma to a manufacturing process to obtain various plasma fractions What are different types of blood products that can be obtained from the manufacturing process of plasma? How many donations might go into making up the separate batches?

Answer 5

Blood Products * 1. Human Albumin * 2. Intravenous immunoglobulin * 3. Human normal immunoglobulin * 4. Specific immunoglobulins (eg tetanus, hepatitis B, varicella-zoster, rabies immunoglobulins) * 5. Anti-D immunoglobulin * 6. Prothrombin complex concentrates Starting batches my include up to 20,000 donations

Question 6

How many donors is a patient receiving one unit of red blood cells exposed to? How many donors is a patient receiving one therapeutic dose of platelets exposed to? How many donors is a patient receiving a dose of blood products from plasma is potentially exposed to?

Answer 6

A patient receiving one unit of RBCs is exposed to one patient A patient receiving one therapeutic dose of platelets is exposed to 4 donors A patient receiving a dose of blood products from plasma is potentially exposed to 1000-20000 donors

Question 7

Blood products are different and made from plasma and contain anywhere from a starting pool of 1000 to 20000 donations – therefore giving a patient this potentially exposes them to thousands of donors So, when you infuse a bottle of albumin to a patient, you are exposing that patient to many thousands of donors. (one bad donor patient can make the whole batch bad) A unit of red cell concentrate has 3 labels attached. What are the three labels?

Answer 7

The top left corner is the donation in barcode and readable format The label below this is the component label telling the reader what the bag contains The tall thin label on the right hand side tells the patients ABO group, Rhesus status and the expiry date of the sample

Question 8

As a medical student, all you need to remember is: if you need to identify a blood component, you quote what is on the component label (eg red cells in additive solution) and the donation number (eg G101604 921 865Y). * Why is the donation number so long (and weird)? * Why is the expiry date on the bags referred to as 23.59? Donation number label, components of the bag label, ABO group label

Answer 8

The donation number ensures that no two bags in the world will have the same number and allows for tracking of the exact person who gave the donation The expiry date is referred to as 23.59 because this gives no confusion as to which day midnight is referring to

Question 9

This is a pool of platelets ie an adult therapeutic dose of platelets How many donors will this have came from? A complete adult dose of platelets can also be obtained from a single donor How is this possible and how would it be labelled?

Answer 9

A standard dose of platelets will have come from 4 donors A complete adult dose of platelets can be obtained from a single donor using a cell separator machine These platelets would have to be labelled “Platelets Apheresis”

Question 10

One bottle of blood products is given eg * human intravenous immunoglobulin * human albumin * varicella-zoster immunoglobulin * anti-D immunoglobulin What should you remember about the number of donors?

Answer 10

It is important to remember that giving one bottle of blood product to a patient can potentially expose them to 20,000 donors

Question 11

Since 1998, we have been unable to use plasma from UK blood donors for the manufacture of blood products. Why is this?

Answer 11

This is because of the threat of disseminating variant Creutzfeld Jacob disease (vCJD) - it appears to have occured through feeding cows to cows causing them to get an encephalopathy and then once humans ingested the cow, we got the vCJD

Question 12

The infectious agent causing mad cow disease, although most highly concentrated in nervous tissue, can be found in virtually all tissues throughout the body, including blood. When it has been transmitted to humans, it is known as new Variant Creutzfeldt–Jakob disease (vCJD or nvCJD) WHat is the infectious agent in this disease known as?

Answer 12

This is known as Bovine Spongiform Encephalopathy We import the plasma we require from countries that do not have vCJD in their populations, and fractionate it in the UK

Question 13

donor selection methods try to ensure that neither donors nor recipients are harmed by the process Donors must be healthy * We want donors to survive the episode of acute blood loss (eg, we would not take blood from individuals with cardiac or pulmonary disease), & we don’t want to transmit ill-health to recipients. What is the minimum weight and haemoglobin requirements of a blood donor?

Answer 13

Minimum weight is 50kg Minimum haemoglobin concentration Males -135g/L Females -115g/L

Question 14

Donated blood must be anticoagulated so that it can subsequently be separated into components using the centrifuge. What agent is given to anticoagulate the bloods?

Answer 14

Citrate based agents eg sodium citrate is given to anticoagulate the blood - this is because citrate binds to calcium and calcium is required for blood clotting

Question 15

We must exclude from donating any donor whose donation may be contaminated by bacteria (eg suffering from diarrhoea, unhealed cut to finger, skin disease at the venepuncture area, etc), viruses (eg drug addicts, health care workers who have suffered a recent inoculation injury, recent tattoos, travel to areas of the world where certain viral diseases are endemic, and protozoa (foreign travel with risk of malaria or trypanosomiasis). How long after having a malignancy can you donate?

Answer 15

Although there have been no cases whereby a malignant process has been transmitted by transfusion, we exclude anyone who has a history of potentially invasive malignancy, no matter how long ago this occurred.

Question 16

Donated blood is collected into anticoagulant at the blood donor session. Donations are then transported to central sites (currently Edinburgh and Glasgow for SNBTS, but will move to the new SNBTS National Centre at Riccarton during 2018) for processing. There, each donation is loaded into a centrifuge (primary bag in one bucket, accompanying bags in the other bucket). The units are spun. What is the anticoagulant?

Answer 16

The anticoagulant is citrate Citrate is an anticoagulant which binds calcium in the blood. Calcium is required for blood clotting. Since it is bound up the blood cannot clot resulting in a whole blood sample, red blood cells and PLASMA.

Question 17

Diagram of primary collection bag after it has been centrifuged – the components have different densities, so red cells (most dense) end up at the bottom, plasma (least dense at the top of the bag) with buffy coat (platelets and white cells) between. Once spun, what happens to the primary bag?

Answer 17

Once spun, each primary bag is carefully removed from the centrifuge and placed between the plates of a press. Seals within the tubing exiting the bag are snapped open, then the plates are drawn together to express plasma into the top bag, and red cells into the bottom bag, leaving buffy coat in the primary bag.

Question 18

WHat is the process of removing the centrifuge components from the primary bag into 3 separate bags known as?

Answer 18

Expressing the components is the process

Question 19

The red cells are run through a filter to deplete them of residual white cells, into a bag of nutrient solution (leucodepletion) The red cells are then stored in a bag containing nutrients, why is this? What are the nutrients (hint SAG-M)

Answer 19

They are stored in a bag containing nutrients to prevent damage during the 35 days of storage (RBCs have a 35 day shelf life) The nutrients are SAG-M or saline-adenine-glucose-mannitol

Question 20

The buffy coat from 4 donations can be pooled, then spun to separate platelets from white cells, and the platelets expressed into a final collection bag, suspended in the plasma from one of the four donations to make a Platelet Pool. What temperature are the red cells stored at?

Answer 20

The red cells are stored at 4 degrees +/- 2 degrees

Question 21

Red cell concentrate Must be stored at 4C +/- 2C (to limit bacterial growth) in a proper blood fridge. Proper blood fridges have chart recorders that give a paper record of the temperature within the fridge, and also are wired so that an alarm will sound (usually in the hospital switchboard) if the temperature goes outwith this range. Can red cells be stored in a domestic fridge? What is the shelf life of red cells?

Answer 21

Red cells cannot be stored in domestic fridge as the temperature in these fridges is not static enough The shelf life of red cells is 35 days

Question 22

If the red cell concentrate is removed from controlled storage for more than 30 minutes, must either be transfused or discarded How long after removing from the controlled storage do you have to transfuse the RBCs?

Answer 22

Have up to 4 hours to tranfuse the red blood cells after removing from the controlled storage

Question 23

What temperature are platelets stored at? What does continual agitation mean? This process is ongoing thoughtout the storage of the platelets What is their shelf life?

Answer 23

Platelets are stored at 22 degrees with continual agitation - this process ensures that the platelets are continuously oxygenated, that sufficient oxygen can enter the storage container and that excess carbon dioxide can be expelled. The shelf life of the platelets is 7 days

Question 24

Why must the platelets not be stored in the cold? How long do you have to transfuse the platelets once removed from storage?

Answer 24

This is because the cold activates the platelets and once activated the platelets cannot be reactivated again to prevent bleeding in the person Once the platelets are removed from storage there is one hour to transfuse

Question 25

What degrees is fresh frozen plasma stored at? What is its shelf life? What happens prior to transfusion once it is removed from controlled storage? Transfuse within how long of leaving controlled storage?

Answer 25

Fresh frozen plasma stored at -30 degrees Shelf life is 3 years Prior to transfusion it is thawed - takes around 40 minutes and the platelets must be transfused within 4 hours of leaving controlled storage

Question 26

Red cell concentrate vs Platelets vs Fresh frozen plasma Storage temp? Shelf life? How long for transfusion after removal from controlled storage? In any other info?

Answer 26

* Red cell concentrate - store at 4 +/- 2 degrees, shelf life =30 days, transfuse within 4 hours of removal, if removed from controlled storage for more than 30 minutes - transfuse or discard Platelets - stored at 22degrees with continual agitation (efflux CO2, influx O2), shelf life = 7days, transfuse within one hour of removal * FFP - stored at -30 degrees, shelf life = 3 years, thaw before tansusion (approx 40 minutes), transfuse within 4 hours of removal

Question 27

Which blood product transfusion has the highest risk of bacterial contamination?

Answer 27

It should be noted that platelet transfusions have the highest risk of bacterial contamination compared to other types of blood product.- this is because they are stored at room temperature

Question 28

Main blood groups are * ABO, RhD and others There are currently 33 recognised blood group systems. Within each system, there may be a number of different antigens. For example, within the ABO blood group system, there are two antigens, giving rise to 4 possible blood groups – A, B, AB, and O. What is the most important system with regards to transfusion and compatibility?

Answer 28

ABO blood group system is the most important Know about ABO, RhD and occasionally know about others

Question 29

You can be group A, group B, group AB, or group O. What do these groups mean?

Answer 29

Group A means that the red cells carry the A substance (A-antigen) Group B means that the red cells carry the B substance Group AB means that the red cells carry both substances Group O means that neither substance is carried by the red cells

Question 30

WHat is the commonest ABO groups in order

Answer 30

O group is the commonest - 47% Then A group - 42% B group - 8% and finally AB group - 3%

Question 31

Some environmental bacteria, especially some of those that colonise our gut, carry substances on their surface that, as far as the human immune system is concerned, look for all the world like A and B substance. As soon as we’re born, our gut becomes colonised with bacteria. By about six months of age, our immune systems are beginning to respond to these bacteria. A component of that immune response is the production of antibody. A group O person expose to A and B substances therefore forms antibodies against what?

Answer 31

A group O person who is exposed to bacterial A and B substances, recognises both as foreign and therefore develops antibodies to A substance (Anti-A antibodies) and to B substance (Anti-B antibodies)

Question 32

The group A person, exposed to bacterial A and B substance, recognises only the B substance as foreign, so develops only anti-B antibody. By the same argument, the group B person develops only anti-A antibody. Why would blood group AB not form any antibodies?

Answer 32

This is because neither A substance or B substance is foreign to blood group AB as it has both substances and therefore no antibodies are made.

Question 33

Once these antibodies are formed, they remain present (with very few exceptions) throughout life, because of continual exposure to bacterial substances. If we inadvertently transfuse ABO-mismatched red cells (eg group A red cells to a group O recipient), binding of antibody to antigen in the recipient’s circulation may lead to a fatal haemolytic transfusion reaction (more about this later). State the order and percentage of each ABO blood group?

Answer 33

O group - 47% A group - 42% B group - 8% AB group - 3%

Question 34

What type of immunoglobulins are most of the naturally occuring ABO group antibodies? What is the main type of immunoglobulin good at activating in the blood?

Answer 34

Naturally occurring ABO-antibodies are primarily IgM (pentameric structure), with a small proportion of IgG (monomeric). In the test tube, IgM antibodies are able to directly agglutinate target red cells. In the bloodstream, the binding of IgM antibody to its target antigen on the red cell will activate complement, resulting in rupture of the red cell IgM antibodies are actually very good at activating complement

Question 35

Which immunoglobulin is dimeric?

Answer 35

Immunoglobulin A is dimeric

Question 36

The genes that determine our ABO group are located on which chromosome? What do the AandB genes code for? What do the add to the precursor substance on red cell membranes?

Answer 36

The genes that determine our group are located on chromosome 9 The “A” and “B” genes code for specific transferase enzymes which add a sugar residue to a precursor “H” substance on the red cell membrane.

Question 37

Inheritance is Mendelian, the alleles A and B being codominant, and both dominant over O. What genotype is required to have the: * O phenotype? * A phenotype? * B phenotype? * AB phenotype?

Answer 37

O phenotype - requires OO genotype A phenotype - requires AA or AO genotypes B phenotype - requires BB or BO genotype AB phenotype - requires AB genotype

Question 38

The genes are carried on chromosome 9 and code for a transferase enzyme Basically if you are blood group O – you must have inherited both O alleles from the parents Only way to be AB is to inherit A gene from one parent and B from the other What do the A and B substances code for again? What blood group in ABO patients is said to be the universal donor? Which is said to be the universal recipient?

Answer 38

A and B substance code for specific transferase enzymes that add sugar residue to a precursor “H” substance present on the red cell membrane ABO groups O group - universal donor (can only receive blood from other O groups) AB group - universal recipient (can only donate to other AB groups)

Question 39

The presence or absence of the Rh(D) protein on the surface of one’s red cells determines whether one is Rh(D) positive or Rh(D) negative respectively. Rh(D) is independent of ABO group, so one can be A Rh(D) positive (often shortened to A pos), A Rh(D) negative (often shortened to A neg), O pos, O neg, etc etc. Are the majority of the UK population RhD (pos) or (neg)?

Answer 39

83% of the UK population are RhD positive

Question 40

Unlike the situation for ABO blood groups, no bacteria carry substance that resembles Rh(D). So most of us, whether Rh(D) positive or negative, do not have antibody against Rh(D) in our blood. WHat are the genotypes for the RhD protein?

Answer 40

• * DD - positive
• * Dd - positive (majority)
• * dd - negative

Again, inheritance is Mendelian. There are two alleles: “D” codes for the Rh(D) protein, and “d” does not (we don’t think “d” codes for anything). “D” is dominant, d is recessive

Question 41

What chromosome codes for ABO group alleles? (A, B or O) What chromosme codes for RhD group alleles? (D or d) How may one develop antibodies to RhD positive proteins?

Answer 41

ABO group alleles - chromosome 9 RhD alleles - chromsome 1 If a rhesus negative patient is exposed to a rhesus positive patient (someone who has the RhD protein), they will then formulate antiboides to this protein to attack the cells - the result may not be as bad this time but upon exposure next time, the antobodies will attack the ‘invading’ red blood cells

Question 42

It follows from the foregoing that when we are asked to provide red cells for transfusion, we are going to have to determine patients’ ABO group (Sure - we could simply stock group O red cells and not worry about patients’ ABO group, but that would mean trying to supply 100% of patients from 47% of the donor population – we would quickly run out of blood) and it also makes sense to determine their Rh(D) status. Blood group determining is based on what phenomenon?

Answer 42

Blood group determining is based on the agglutination phenomenon

Question 43

Blood group determination is based on the agglutination phenomenon. If one adds directly-agglutinating antibody to red cells in a test tube that carry the appropriate antigen, the antibody is able to cross-link the red cells so that they stick together, or agglutinate. So, the addition of anti-A antibody to group A red cells, or the addition of anti-B antibody to group B red cells will result in what?

Answer 43

The addition of anti-A antibodies to group A cells will result in agglutination The addition of anti-B antibodies to group B cells will result in agglutination Adding anti-A antibodies to group B or O cells will not result in agglutination

Question 44

What is the test where directly agglutinating antibodies is added to the cells known as?

Answer 44

This is known as a Direct-Coombs Test Direct antiglobulin test (DAGT/DAT)

Question 45

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Answer 45

If the patient’s cells dont clump in the Anti-B tube - then the patient is group A blood type If the cell’s do clump, the patient is group AB blood type

Question 46

We check our results by typing the patient’s plasma. For instance, we would expect a group A patient to have anti-B antibody in his plasma. What would we therefore do to confirm that the previous patient was group A? (explain how the results of the forward group are confirmed by the reverse group)

Answer 46

By confirming whether or not the patient’s cells agglutinate when adding the patient’s plasma to group A red cells and group B cells, we confirm the results for the forward group (the testing of the patient’s red cells) by performing this reverse group (the testing of the patient’s plasma). ie this patient with blood group A Add the patients plasma to group A and B blood groups, would expect agglutination in the group B blood due to anti-A antibodies

Question 47

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Answer 47

Patient’s red cells do not agglutinate when Anti-A,b or A,b antibodies are added -this implies there are no A or B substances on the cell so the patient is group O To confirm the forward result we add the patients plasma to group A and B red cells, and this shows agglutination here meaning the patients plasma must have antibodies against both of these - group O Agglutination occurs when anti-D meaning patient is RhD pos = So, this patient’s blood group is O Rh(D) positive.

Question 48

Remember that red cells carry many more markers on their surface, in addition to A, B and Rh(D). There are hundreds of them. “lesser” red cell antigens need only be taken into consideration when the patient has an antibody to one or more of them.

Answer 48

When anti-A is added - agglutination occurs When anti-B is added - no agglutination - Patient is Group A Typing the plasma - shows patient has formed antibodies to B cells = Patient is Group A RhD positive Having determined the patient’s blood group, we cannot simply issue units of the appropriate group. We must first determine whether or not the patient has any irregular antibodies. Remember this

Question 49

ABO antibodies remember are mainly IgM antibodies and are able to cross like cells In irregular antibodies, what are the immunoglobin for these antibodies mainly? Is cross-linking possible?

Answer 49

Irregular antibodies, unlike ABO antibodies, are IgG (monomeric instead of pentameric) antibodies and cannot cross-link red cells directly.

Question 50

Again, we rely on the agglutination phenomenon to detect and identify irregular antibodies. What blood group is used and why when screening for irregular antibodies? What Coomb’s test is used here?

Answer 50

Group O red cells are used from 3 donors when screening for irregular antibodies - excludes any influence from anti-A or anti-B antibodies The indirect antiglobulin test (IAT) or indirect Coomb’s test

Question 51

To ensure trnasfusion sample requests are never mixed up, where is the patients blood sample labelled? What type of pen should be used to label the patients blood sample?

Answer 51

The patients blood sample should be labelled at the bedside table - remember to check ID before taking the blood and afterwards Use a fine fibre tip pen The bedside check is critical for ensuring that the correct component goes to the correct patient

Question 52

2. Have some understanding of how we select red cells for patients 3. Be aware that compatibility testing includes screening for irregular antibodies. If present, we must identify their specificity before being sure that the red cells we issue are compatible. What procedures may you have wanted to identify compatability for so that the red cell are readily available?

Answer 52

For elective procedures

Question 53

For operations in which it is likely that red cell transfusion will be required, we routinely crossmatch and set aside red cells. For operations in which there is a less than 30% chance of requiring red cells, what is the compatibility testing that is carried out on the cells?

Answer 53

If there is a less than 30% chances of requiring red cells, we perform ABO group, RhD and iregular antibody testing

Question 54

If after performing the ABO group, RhD and irregular antibody testing in those with a less than 30% requirement of red cells, and the irregular antibody comes back negative, is blood set aside? WHat happens if it comes back positive?

Answer 54

If the antibody screen is negative, we go no further, but we keep the patient sample. If the patient does subsequently require red cells, we can issue group-specific red cells within 10 minutes of you asking. If the antibody screen is positive, we must proceed to identify the antibody(s), and then crossmatch and set aside compatible units

Question 55

The manoeuvre is standard transfusion practice designed to make the most efficient use of available blood stock without compromising patient safety. What is the manoeuvre known as? (where if likely red cell transfusion is needed or less than 30% chances of requirement but irregular antibody positive then compatible RBCs is set aside and if irregular antibody negative, patients plasma sample is held)

Answer 55

This is known as the Group and Save or Group and Screen manoeuvre

Question 56

Gone are the days when, if your haemoglobin was less than 100g/L, you get two units of red cells to make you feel better. The transfusion of blood components is a dangerous business, to be avoided if possible. What haemglobin level usually merits transfusion depending on the whether the patient is stable or not? For every unit of RBCs transfused, what is the epxected rise in Hb?

Answer 56

Usually a haemoglobin level of 70g/L merits transfusion if unstable, if stable then usually not given If in response to transfusion, rough rule of thumb is to expect a 10g/L rise in Hb with each unit of red cells transfused

Question 57

It is important to distinguish between acute blood loss that is limited and predictable, and blood loss that is unpredictable and potentially unlimited. For example, a patient who loses half a litre of blood during a hip replacement operation , are they likely to require blood transfusion? For example, a patient with alcoholic liver disease and oesophageal varices, who has during his first five minutes in the ward already vomited half a litre of blood?

Answer 57

Half a litre during hip operation - Not likely to require a blood transfusion as the blood loss is predictable and likely to be limited Half a litre due to vomiting from oesophageal varices and liver disease - likely to require a blood transfusion as the bleeding is unpredictable and potentially unlimited

Question 58

Acute Blood Loss - Approach 1. Arrest bleeding 2. Gain IV access 3. Samples for cross-matching, and other tests Is it next more important to give fluids to replace the blood or give red blood cells?

Answer 58

It is more important to give fluids as maintaining circulating blood volume is important Of course, if you replace blood losses with fluid other than blood, the haemoglobin concentration is quickly going to fall, so you need to be making immediate plans to obtain blood components while you resuscitate your patient.

Question 59

You need to establish IV access, and you need to obtain a sample of blood for crossmatching, making sure it gets to the lab quickly, and making sure the BMS (biomedical scientist) knows the urgency involved. Bear in mind: from receipt of sample to issuing of compatible blood usually takes around how long if the patient has no irregular antibodies?

Answer 59

Bear in mind: from receipt of sample to issuing of compatible blood usually takes about 60 minutes, and that’s if the patient has no irregular antibodies (if the antibody screen is positive, we then have to try to identify the antibody, then select appropriate blood, and crossmatch it, which could take all day, or indeed, in extreme difficulty, days). 60 minutes is a very long time if you’re watching a patient bleed to death.

Question 60

If you don’t think you can wait the 60 minutes or potential days, there are a number of shortcuts we can take, but shortcuts equate to risk. First, we can determine the patient’s ABO group and Rh(D) type (10 minutes), select appropriate units, and check for incompatibility between patient and donor units by mixing plasma and donor red cells, spinning and tipping - this method is known as the immediate spin crossmatch How long does it take and what are the risks?

Answer 60

The immediate spin crossmatch method takes around 10 minutes to determine blood group and 10 minutes for the spinning and tipping Risks - the immediate spin crossmatch is so crude that we could fail to detect ABO incompatibility, and this compatibility technique will completely miss the presence of any clinically significant irregular red cell antibody

Question 61

Even quicker, you could take a chance with completely uncrossmatched group O negative red cells. In certain locations (crossmatch lab, main theatre, A+E in Ninewells, crash box for trauma team) we set aside 2 units of what type of blood?

Answer 61

Group O (universal donor) RhD negative, Kell negative blood group O (can give it to any ABO group), Rh(D) negative (anti-D is one of the more commonly found irregular antibodies), Kell-negative (anti-Kell is probably the next most commonly found irregular antibody Clearly, the risk in using them is the possibility that the patient has an irregular antibody that will react with these red cells.

Question 62

If the Group O, RhD negative and Kell negative emergency red cell units are used, what must you do?

Answer 62

If you do decide to use these, you must tell the lab you are using them (so that the lab can replace them, and so that the lab can get on with providing you with fully crossmatched units as soon as possible).

Question 63

Platelets can be prepared from whole blood donations, as previously described (platelets from 4 donations pooled together and suspended in the plasma of one of the donations, making an adult therapeutic dose of platelets) How are they stored? What is their shelf-life? How can platelets be retrieved from one donor?

Answer 63

Platelets can be prepared from whole blood donations, as previously described (platelets from 4 donations pooled together and suspended in the plasma of one of the donations, making an adult therapeutic dose of platelets) Stored at 22 degrees with constant gentle agitation with a shelf life of 7 days Platelets can be retrieved from one donor via a cell separator machine

Question 64

What is the procedure in which the single donor gives enough platelets for a therapeutic dose known as?

Answer 64

Apheresis - a medical technology in which the blood of a person is passed through an apparatus that separates out one particular constituent and returns the remainder to the circulation.

Question 65

A low platelet count is not in itself an indication for platelet transfusion: the whole clinical circumstances must be considered Normal platelet count is between 150-400x10^9 What is now the threshold before platelets are given: * If no active bleed?

Answer 65

5-10x10^9 platelets before they are given nowadays if no active bleed

Question 66

What is the platelet threshold for platelets to be given if active bleed?

Answer 66

If the patient has a fever or active bleed, prophylactic platelet transfusion is given at a higher threshold (eg 20 –30 x 10^9/L) as platelet survival is shorter in the presence of infection. Platelet thresholds for transfusion are higher for patients with severe bleeding (World Health organisation bleeding grade 3or4)or bleeding at critical sites, such as the CNS - give if platelet level drops below 100x10 9

Question 67

If the patient has undergone ophthalamic or neurosurgery, when would you give platelets?

Answer 67

Give platelets prophylactically if less than 50^9 in ophthalmic or less than 100x10^9 platelets /L in neurosurgery

Question 68

What are contraindications to platelet transfusion even if the levels drop below 10x10^9?

Answer 68

If no active bleeding or planned invasive procedure a threshold of 10 x 10 9 except where platelet transfusion is contradindicated or there are alternative treatments for their condition: * For example, do not perform platelet transfusion for any of the following conditions: * Chronic bone marrow failure * Autoimmune thrombocytopenia * Heparin-induced thrombocytopenia, or * Thrombotic thrombocytopenic purpura.

Question 69

Fresh frozen plasma is plasma frozen to –30C within 8 hours of the blood being donated. The coagulation factors present in the original blood are thus preserved. FFP can be stored for 3 years. What is it stored at? What is the commonest indication for those requiring fresh frozen plasma?

Answer 69

Store at -30 degrees The commonest indication is to correct the coagulation deficiency in patients with liver disease who are bleeding.

Question 70

Does pre transfusion cross matching checks need to be carried out when transfusing Red blood cells? Platelets? Plasma?

Answer 70

No cross-match procedure required for platelets, but account needs to be taken of donor and recipient ABO and Rh(D) groups Compatibility labelling, and pre-transfusion checks for plasma are the same as for red cells.

Question 71

When IgM anti-AorB binds to a patients A or B antigens, what happens in the test tube and what happens in actual blood circulation? This is Immediate Haemolytic Transfusion Reaction

Answer 71

In the test tube, this would usually cause crosslinking (agglutination) of the cells. However, in a patient’s circulation, the binding of IgM anti-A or anti-B to its corresponding antigen on red cells immediately activates the complement cascade.

Question 72

What is acute (immediate) haemolytic transfusion reaction better known as?

Answer 72

This condition is better known as ABO incompatibility usually associated with the naturally-occurring IgM antibodies of the ABO system

Question 73

The acute haemolytic reaction activates three systems that are interlinked * The complement system * The coagulation system * The kinin system What is the purpose of the complement system?

Answer 73

The complement system is a part of the immune system that enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promotes inflammation, and attacks the pathogen’s cell membrane

Question 74

What are the main opsonins? WHat do both C3a and C5a in the complement system cause? What specific complements form the membrane attack complex and what does this do?

Answer 74

• Opsonins - C3b, C4b and IgM are opsonins - phagocytic activation
• C3a&C5a both are pwoerful anaphylotoxins - leads to vascular permability, bronchiole smooth muscle contraction, dilation of vessels, hypotension
• C5b - C9 (MAC) form the membrane attack complex - cytolysis occurs

Question 75

Coagulation thromboplastic material from haemolysed red cells leads to indiscriminate activation of the coagulation mechanism What does this cause? What does activation of the kinin pathway cause?

Answer 75

COagulation system leads to disseminated intravascular coagulation Activated factor XII activates the kinin (bradykinnin) system arteriolar dilatation and increased vascular permeability

Question 76

State the effects of the complement, coagulation and bradykinin system

Answer 76

Comlement * Phagocytosis * Cytolysis - red cell lyse due to MAC * Anaphylotoxins - C3a and C5b lead to increased vascular permeability, bronchospasm, hypotension Coagulation - disseminated intravascular coagulation Kinin - activated XII in the coagulation pathway activates bradykinin * Increases vascular permability * Arteriolar dilatation

Question 77

The net effects of acute haemolytic tansfusion reaction are: systemic hypotension; DIC; renal vasoconstriction; formation of renal intravascular thrombi; shock; renal failure; What are the symptoms of the condition?

Answer 77

Pyrexia Rigors Sweating Hypotension/tachycardia, tachypnoeic Local chest pain Cyanosis

Question 78

In the ward, with the conscious recipient, it will probably be a nurse who is first on the scene. The transfusion must be stopped immediately, and then you will be summoned. Never delay your response to this sort of telephone call. If you think this is an immediate haemolytic transfusion reaction, remove the giving set from the cannula: What should be done with the cannula?

Answer 78

DO NOT REMOVE THE CANNULA FROM THE PATIENTS VEIN Accessing a vein again when the patient is very hypotensive will be an extreme struggle and therefore keep cannula in to administer more (correct cross matched) fluids

Question 79

Delayed haemolytic transfusion reaction is a type of reaction where the features arise how long after the transfusion? Syptoms are very similar but not as acute as in IHTR (immediate haemolytic transfusion reaction) Does delayed haemolytic transfusion usually involve ABO incompatibility or no?

Answer 79

Usually the symtpoms appear 5-10 days after the transfusion Usually invovles irregular antibodies incompatibility (ie anti-Kell donor blood being given to the patient who is Kell positive) This type doesnt tend to involve ABO

Question 80

Why is it that there is no intravascular cell destruction in delayed haemolytic transfusion reactions?

Answer 80

This is because IgG does not activate the complement (IgG is the immunoglobulin in irregular antibodies incompatibility, IgM is the antibody in ABO incompatibilty - IgM activates the complement)

Question 81

When antibody-coated red cells go through the spleen, macrophages there mount an attack on these cells, and this results in piecemeal destruction of the antibody-coated red cells. Red cells damaged in this way lose some of their cell membrane. However, if they manage to escape back into the circulation, they have an opportunity to repair the damage. However, because some membrane has been lost, their shape changes from biconcave disc to sphere. What are these cells on microscope described as being?

Answer 81

These cells would be described as being spherocytes

Question 82

With such reticulendothelial red cell destruction, the haemoglobin released from the damaged cells is eventually metabolised to bilirubin, so the patient may develop jaundice. If a sample of blood is sent to us, we may be able to detect free antibody (as an irregular antibody by the indirect antiglobulin test method previously described) and we may also be able to detect antibody bound to circulating transfused cells How is the bound antibody tested for?

Answer 82

Simply add anti-human globulin to the mixture to test for the bound antibody - direct coombs test (doesnt require waiting for the cells to mix before addition of anti-human IgG Antibody) In indirect - we have to add the donors blood to recipients (possibly containing IgG) and then allow the IgG antibody to bind to any antigen present, then add anti-human immunoglobulin antibody to cause agglutination = +ve test

Question 83

In delayed haemolytic transfusion syndrome, what would be seen on FBC, blood film?

Answer 83

Elevated bilirubin and lactate dehydrogenase Low haemoglobin Spherocytes seen on blood film positive DAT also

Question 84

Different transfusion reactions 1. ABO incompatibility - IHTR 2. Delayed haemolytic transfusion reaction 3. Febril non-haemolytic transfusion reaction 4. Urticarial reactions 5. Circulatory overload 6. Bacterial reactions 7. Viral infections Which transfusion reaction can occur when there is contamination of WBCs causing antibody development?

Answer 84

This would be febrile non-haemolytic transfusion reaction

Question 85

Febrile non-haemolytic transfusion reaction are fairly common, not usually life-threatening, but cause problems in that one cannot be sure that the symptoms do not represent a more serious type of transfusion reaction. What type of transfusion reaction can they mimic and therefore the transfusion needs to be stopped to excluse this? Why is this less common now?

Answer 85

Can mimic immediate haemolytic transfusion reaction due to the rapid pyrexia and rigors This is less common now because we now leucodeplete all red cell and platelet components during their production

Question 86

What is given for the treatment of febrile non-haemolytic transfusion reaction?

Answer 86

Give anti-pyretic eg paracetamol and monitor closely

Question 87

4. Urticarial reactions Mast cell - IgE response to infused plasma proteins Rash / weals within few minutes of starting transfusion Slow the transfusion What drug may be considered?

Answer 87

Simple anti-histamines may do the job

Question 88

5. Circulatory overload Pulmonary oedema Elderly, and those with CCF, especially at risk What are the symptoms and what is the treatment?

Answer 88

Symtpoms - hypoxia, tachycardia, dyspnoea, crepitations, oedema Treat with oxygen and IV furosemide

Question 89

6. Bacterial infection * fever, immediate collapse,shock,DIC Potentially fatal. Transfusion of bacteria may produce a response that closely resembles an immediate-type haemolytic transfusion reaction. Initial response should be exactly the same as it was for an IHTR Once the laboratory has proved that your patient has NOT HAD an ABO-incompatible transfusion, you will want to start broad-spectrum IV antibiotics. Symptoms?

Answer 89

fever, chills, hypotension, tachycardia, collapse

Question 90

What bacteria are common in red cell transfusions? Which are common in platelet transfusion?

Answer 90

Red cell transfusions - pseudomonas Platelet transfusions - staph aureus, strep, salmonella Viral infection cases basically dont exist

Question 91

What are the 7 types of tranfusion reactions discussed in this lecture again?

Answer 91

1. Immediate haemolytic transfusion reactions - within 24 hours but usually immediate 2. Delayed haemolytic transfusion reactions >24 hours but usually 5-10 days post transfusion 3. Febrile non-haemolytic trnasfusion reaxtion 4. Urticaria reaction 5. Fluid overload 6. Bacterial reaction 7. Viral

Question 92

Revision questions - True or False * 1. Each bag of red cells manufactured by the Blood Transfusion Service contains red cells from up to 1000 different donors * 2. Red cell components are routinely stored frozen until required * 3. Platelets have a shelf life of 35 days * 4. If your ABO blood group is AB, your red cells can be given to any recipient because there aren’t any antibodies in your plasma

Answer 92

1. False - Each bag of red cells - one unit - comes from one donor 2. False - they are stored at 4 degrees (+/- 2 degrees) 3. False - platelets have a shelf life of 7 days 4. False - If your ABO group is AB, you can recieve cells from any recipient as there are no antiboies, all other groups have antiboides so cant give blood there

Question 93

* 5. Group A Rh(D) positive is the commonest blood group in the UK population * 6. Platelets must be stored in a fridge to guard against bacterial contamination * 7. Human albumin solution is made by genetic engineering so there is no human-derived material in it at all * 8. The component “Red cells in optimal additive solution” contains very little plasma from the original blood donation

Answer 93

5. False - Group O RhD positive is the commonest blood 6. False- Platelets must be stored at 22 degrees (storage in a fridge will activate the platelets) 7. False - Human albumin is a blood product from plasma 8. True - Typically all but 20 ml of plasma is removed from the collected whole blood and replaced with an additive solution designed to optimise red cell preservation, such as saline solution containing added adenine, glucose and mannitol (also called SAGM or optimal additive solution)

Question 94

* 9. To have the blood group A it is possible for one of your parents to be blood group O and the other to be group AB * 10. It is possible for your blood group to be O Rh(D) negative when one of your parents is A Rh(D) positive and the other is B Rh(D) positive * 11. Blood grouping tests rely on the coagulation phenomenon * 12. Blood group O individuals develop antibodies against A-substance and B-substance only after they have received a blood transfusion from a group A or B donor, respectively

Answer 94

* 9. True - A and B are co-dominant * 10. True - Parents alleles could be AO (Dd) & BO (Dd) * 11. False- Blood grouping tests rely on the agglutination phenomenon 12 - False - Environmental bacteria, especially some of those that colonise our gut, carry substances on their surface that, as far as the human immune system is concerned, look for all the world like A substance and B substance. As soon as we’re born, our gut becomes colonised with bacteria. By about six months of age, our immune systems are beginning to respond to these bacteria. A component of that immune response is the production of antibody.

Question 95

* 13. If you have never been transfused or pregnant, it is very unlikely that your plasma will contain irregular red cell antibodies eg anti-K, anti-Fya * 14. When requesting blood transfusion support the sample must be taken by a qualified doctor * 15. When obtaining a blood sample from a patient for crossmatching it is best to fill the sample label in from the patient’s casenotes to be sure of getting the details right

Answer 95

13. True - it is not naturally occurring, develops due to previous transfusion or pregnancy 14. False 15. False - have to accurately ID the patient

Question 96

16. When we screen patients for the presence of irregular red cell antibodies we test the patient’s plasma against group O red cells to see if there is any reaction in the indirect antiglobulin test. 17. If the irregular antibody screen is positive, we need to be more selective when choosing red cells for the patient 18. When the BMS (biomedical scientist) issues blood components for a patient he/she writes the patient’s name and date of birth on the bag with an indelible marker pen.

Answer 96

16. True - 3 different group O red cell samples used and tested in the IAT 17. True - need to do further compatibility tests 18. False - Uses Fine (thin not thick) Fibre Tip Pen

Question 97

19. When the nurse checks the component that she/he is about to transfuse, she/he shouldn’t be too concerned about bubbles inside the bag, or the fact that the component has passed its expiry time by a couple of minutes 20. If a patient receives weekly blood transfusions and is well-known to the staff, it’s OK for the patient not to bother wearing an identity wrist band when receiving blood transfusions

Answer 97

19 - wrong there should be no bubbles, can cause air emboli or bacteria can grow here 20 - FALSE - needs to wear an identity wrist band for every transfusion

Question 98

* 21. If a male patient has a haemoglobin level of 9.5 g/dL reference range 13.0 - 18.0 g/dL), he should be transfused with at least two units of red cells to bring his haemoglobin up to a safe level * 22. A patient who loses 500ml of blood during hip replacement surgery may not need to have a blood transfusion during or after surgery * 23. If a patient arrives in A+E bleeding to death it might be acceptable to transfuse Gp O red cells before the laboratory has completed all of its tests

Answer 98

21. False - Clinicians are now being encouraged to reassess patients’ response to red cell transfusion after the first unit has been administered, rather than routinely administering a minimum of two units for each transfusion episode. (also dont adminsiter routinely until Hb is 70) - can cause pulmonary oedema if over-adminstering 22. True 23. True - this is the emergency 2 units of Group O, RhD negative, Kell negative blood (hopefully no incompatibility)

Question 99

24. If a Gp O patient is transfused Gp A red cells by mistake the blood pressure is likely to fall because clumps of red cells get stuck in the lungs 25. Of the staff groups who take samples for crossmatching (doctors, nurses, phlebotomists), doctors are most likely to make mistakes

Answer 99

24. Confident it is false - BP will fall because the complement system has been activated as well as the coagulation and kinin system - there is vascular permability, arteriolar dilation and red cell lysis all leading to hypotension 25. UNsure who gets it wrong the most - probably doctors

Question 100

Describe the difference between Coomb’s?

Answer 100

Direct Coombs test - direct antiglobulin test The blood sample from the donor agglutinates when anti-human (anti-A,anti-B or anti-A,B) antibodies are added to the patients blood sample These antibodies (they are IgM) will cause the cells to agglutinate if any antigen (A, B or AB substance) is present on the red cell

Question 101

Describe how Indirect Coombs test is carried out? (Indirect anti-globulin test IAGT)

Answer 101

When the recipients blood sample is recieved, the donors blood sample is added to a part of the patients blood sampe If there is an irregular antibody in the patients blood sample and the donor has this antigen present, the antibody will bind. Agglutination does not occur as IgG cannot agglutinate. We must then add anti-human immunoglobulin which will bind to the IgG and cause agglutination (if addition of the human immunoglobulin doesnt cause agglutination - test is negative)- this is the indirect Coombs test