Blood Transfusion
/What’s in blood anyway?
Whole Blood - blood that basically contains all the following components
It contains everything! Most of the time, when we donate blood, we donate whole blood
Red blood cells (often called packed red blood cells)
Take whole blood and centrifuge it to separate out just the red blood cells. Usually, other additives will be placed in such as citrate, dextrose, and adenine to preserve the cells and keep them alive
Usually can be kept refrigerated for up to 42 days in the US, but can be frozen for up to 10 years
Usually 1 unit is from 1 donor, and the idea is that 1 unit should raise the HgB by 1 point
Volume is anywhere between 220-340cc, and the reason this can be different is because it depends on the original HCT of the donor. Most of the time, it is about 250cc.
Why do we use it?
Because one needs blood!
Should be considered in patients who have acute blood loss anemia, who are symptomatic
Usually can start to think about it if Hgb is <8 g/dL, when not at baseline for patient, and if they are symptomatic
Would recommend if <7 g/dL if they are postpartum or postoperative or wound healing
In other cases (ie. sickle cell disease), transfuse to a threshold to prevent sickle crisis
Things to know before transfusion
Before transfusion, someone should be typed and crossed so that they get blood that matches their own
If they don’t, their bodies can create antibodies against the donated blood, which can then lead to alloimmunization
This is a problem for future pregnancies possibly! See our episodes on alloimmunization
The only exception: massive transfusion or exsanguination protocol when there is no time to type and crossmatch someone
Some people will still have a fever or small allergic reaction to blood - which is why most people are predosed with Tylenol and Benadryl, but we’ll talk more about this in risks/benefits of blood transfusion
Different types of pRBC
Irradiated red cells - indicated for patients at risk of transfusion-associated graft-versus host disease. Components are irradiated by gamma or X-rays within 14 days of donation. Shelf life is about 14 days after irradiation
Washed red cells - for patients who have recurrent or severe allergic reactions to red cells. Also for patients with IgA deficiency with anti-IgA antibodies if red cells from IgA deficient donor is not available. Shelf life is 14 days from washing
CMV negative red cells - only from donors who are known CMV negative. Required for newborn babies because CMV can be fatal
Platelets
How do we get them?
Whole blood donation → centrifuged and the buffy coats (between the red cells and plasma layers are pooled from a few donations to the plasma of one of the donors
Usually, this will result in “pooled platelets” or “platelet packs” so when you transfusion a unit of platelets, it’s actually considered a “4 pack” or “6 pack” or even “10 pack” of platelets. Check with your institution.
Usually, volume is about 300cc, and can be stored at room temperature (20-24 degrees C) with constant agitation
Shelf life is about 5 days
Apharesis donation - platelets come from 1 donor and is apheresed (separated) immediately
Will results in only 1 donor per pack of platelets
Volume is around 200cc
Again, can be stored at room temperature with agitation and lasts 5 days
Why do we use it?
Usually when there are low platelets
Most places will have thresholds, ie. if platelets are <50K and patient needs urgent or emergent surgery or are actively bleeding
Some places may put threshold for transfusion of <100k if CNS bleed
If not bleeding, generally consider if Plt <10k to prevent spontaneous bleed
If coagulopathy but not bleeding, can consider higher threshold, around 20-30K
Other things to know
Platelets still need to be crossmatched to ABO and Rh antigens
Different types of platelets
Irradiated platelets - same reason to give these as irradiated red cells
Human leucocyte antigen (HLA)-selected platelets
Human platelet antigen (HPA) -selected patients
Population to keep in mind: pregnant patients with neonatal alloimmune thrombocytopenia - where their antibodies attack baby’s platelets
These types of platelets should be used to transfuse babies with NAIT
Plasma (sometimes referred to as fresh-frozen plasma)
How do we get it?
Plasma is from whole blood donation or component donation by apheresis
Usually frozen soon after collection to maintain activity of blood-clotting factors
Can be stored for up to 3 years
Thawed FFP can be stored for 24 hours
Why do we use it?
Contains ALL clotting factors, but the amount will depend on the amount from the donor
Volume of usually 250-300cc
Can be given to patients who have coagulopathy, or whom are bleeding and need massive blood transfusion
Should replace 1:1:1
Cryoprecipitate
How do we get it?
Thawing FFP to about 4 degrees C, which will produce a cryoglobulin rich in fibrinogen, Factor VIII, and von Willebrand Factor. It does NOT contain all clotting factors
Usually single-donor packs or pools
Why do we use it?
Originally developed for treatment of hemophilia
It is more concentrated and lower volume than FFP. 1 pack is about 50cc
Consider giving if patient is coagulopathic but also fluid overloaded
Other things about it
Should be stored frozen
Shelf life of about 3 years
Granulocytes
Not going to talk about this one as much, but essentially contains neutrophils
Controversial but sometimes used for patients with life-threatening conditions where they have low neutrophil counts
Human albumin solution
No clotting factors or blood group antibodies, so crossmatching not needed
Clotting factor concentrates
Can be single factor concentrates
Used for treatment of inherited coagulation issues (ie. for hemophilia A, can use recombinant Factor VIIIc)
PCC or prothrombin complex concentrate (PCC) contains factors II, VII, IX, and X.
Immunoglobulin solutions
Usually manufactured from large pools of donor plasma
Contains antibodies to viruses that are common in the population (ie. IVIG)
Specific immunoglobulins can be made from selected donors with high antibody levels (ie. Anti-D immunoglobulin or Rhogam!)
Benefits, Risks, and Safety
Benefits - and how to safely give blood
As discussed before, blood transfusion can be life saving in many people, but we need to do this safely
We already discussed: type and crossmatch blood
Right patient, right blood, right time → correct patient identification, good documentation and communication, and monitoring of the patient
Patient consent needs to be obtained
Also, do not give more blood than is indicated!
https://pubmed.ncbi.nlm.nih.gov/32652065/
Hamm et al reasoning for 1 u blood instead of 2 u in postpartum women with acute blood loss
Risks
Mostly morbidity and mortality from blood transfusion is preventable, but can still occur, especially when wrong blood is given
Non-infectious risks
Febrile non-hemolytic transfusion reactions (usually mild) - can sometimes be treated with benadryl/Tylenol pretreatment
Allergic reaction - can be mild (ie. urticaria) to severe (angioedema or anaphylaxis)
Acute hemolytic transfusion reaction - usually due to ABO incompatibility
Bacterial contamination of blood - can lead to sepsis
Transfusion-associated circulatory overload (TACO) - worsening pulmonary edema within 6 hours of transfusion
Transfusion-related acute lung injury (TRALI)
Caused by antibodies in donor blood reacting with patient’s neutrophils, monocytes, or pulmonary endothelium
Can lead to leaking of plasma into lung alveolar spaces → cough with frothy sputum, shortness of breath, hypotension, fevers
Usually presents within 2 hours of transfusion
CXR will show bilateral nodular shadowing in lungs
Can be confused with acute heart failure, but should not be treated with diuretics
May need to intubate. Supportive care for treatment
What to do about acute reactions?
Stop the transfusion and undergo rapid assessment of vitals, and make sure to check patient ID and blood ID (does it match?)
Usual evaluation of ABC (airway, breathing, circulation)
If mild reactions (ie. isolated temperature of >38 degrees, pruritis, or rash), can consider treatment, but could continue transfusion
However, if increasing temperature >39, life-threatening changes (ie. allergic reaction with anaphylaxis), stop immediately and proceed to resuscitate as needed
Infectious risks
Viral infections - risks are incredibly low because every blood donation is screened for HBV, HCV, HIV, HTLV, syphilis, west nile virus, Zika
Every first time donor is tested for Chagas disease
Creutzfeldt-Jakob Disease - prion disease that first appeared in the UK in 1996. People cannot donate if they have:
Been in UK >3 months from 1980-1996.
Diagnosed with vCJD, or
Had blood transfusion in UK, France, or Ireland from 1980 to present.
What if your patient declines blood transfusions?
Respect the values, beliefs, and cultural backgrounds of all patients
Frank discussion with patients about blood transfusion and components of blood
Jehovah’s Witness patients usually will refuse transfusion of whole blood and primary blood components (ie. red cells, platelets, white cells, and plasma)
However, some may accept derivatives of primary blood components (ie. albumin, cryo, clotting factors, immunoglobulins)
Discussion of how to save blood cells and discuss other methods of decreasing likelihood of transfusion
Intraoperative cell saver, apheres, dialysis, or cardiac bypass are usually ok
Iron transfusions if needed prior to procedures, if there is time
Discussion of autologous transfusion if possible
Signing advance decision documents (usually most hospital will have these) about which blood products are acceptable and which are not
Remember:
Emergency or critically ill patients with temporary incapacity must be given life-saving treatment (including blood transfusion) unless there is clear evidence of prior refusal