Flashcards in Tranfusions and Complications Deck (30):
How do we determine someone’s blood group (i.e. blood type)?
Forward group: which antigen on RBC when AB added (anti your antigens)? Reverse group: which AB in your plasma when RBC added? Rh: add anti Rh AB. Look for clumping in the tubes
What is an antibody screen?
Any unexpected non-ABO red cell antibodies in the plasma? Come from past transfusion or pregnancy. React patient plasma and 3 sample red cell lines (which represent many but not all antigens). There is also a more extensive panel to do if initial screen is positive. No clumping = negative screen
What is a crossmatch?
After type and screen and AB screen negative, electronic match - scan blood bag barcode, compare computer results to test results, then to patient. No physical mixing. If AB screen is positive, physical mix w/ sample (serologic cross match)
What does a positive antibody screen mean?
Another AB is present, additional time for testing before giving units. If situation is critical, give un-crossmatched (group O). Future transfusions need to keep this in mind (might have low AB but still concern)
So essentially, what is the goal of doing a crossmatch, esp for one who got a positive AB screen?
The goal is to mix donor cells with patient’s plasma to find a bag which is antigen negative for the specific ABs which they possess.
More on un-crossmatched cells
Usually means O-, but if they can type your blood quickly they can give you group specific but still un-crossmatched (ie give A+ if they are A+, but still don’t know about the other ABs)
Why is proper patient identification essential?
You could kill someone! proper patient ID and labeling are critical during collection. Must be labeled with First & Last names, ULI (Alberta healthcare number), and BBIN. Info on requisition must exactly match all info on the tube label. Specimen labeling must occur at bedside. Date and time of collection, 2 signatures
Rejected! Take again
What immediate actions should be taken if a transfusion reaction is suspected?
Stop the transfusion!! keep IV running with normal saline. Always obtain full set of vital signs: Temp, HR, BP, Resp Rate and O2 sat. Clerical check: verify info on product tag against the patient’s ID band, name, ULI, BBIN. New sample
After transfusion reaction and it is stopped, what do you do?
New sample, centrifuge, look for sign of hemolysis (red in plasma). Do DAT (Direct AB test), look at microscope
What is the differential diagnosis of a fever that is temporally associated with transfusion?
Can be unrelated (ie pre-existing condition). If related, one of 4 things. Febrile non-hemolytic transfusion reaction, contamination/sepsis, acute hemolytic transfusion reaction, transfusion related acute lung injury
Some residual WBC in blood bag release cytokines which affect the patient
What’s your role in a transfusion reaction investigation?
Ask questions, document signs and symptoms, compare signs before and after, blood cultures and hemolytic workup if needed, never restart the original transfusion!
What is the differential diagnosis of jaundice in the setting of a recent transfusion?
Jaundice + post-transfusion DAT with clumping indicates some immune response. Future crossmatch must be serological
What do PT and PTT look at?
PT, PTT look at different sides of the coagulation cascade (intrinsic vs extrinsic I think)
In an emergency and you want to give plasma to a type O patient, what do you want?
Give them type AB plasma. Less antibodies.
If you don’t know Rh type, what do you give them?
Men: give Rh+ or Rh- (will cause hemolysis, but delayed and easier to treat). For women of child-bearing age: give Rh- so they don’t have reaction to fetal Rh+ blood. But if you know they have been previously exposed to Rh+ and are Rh-, you must give Rh-
What can you make from a whole blood donation?
Blood components: RBCs, platelets, plasma, cryoprecipitate (fibrinogen, VWF, factor 8 precipitate after slow thawing). Can also have plasma fractionation of single products from plasma of many blood donors
Give to (all) pregnant Rh- women at 28 weeks (passive anti-D); and give again after birth if baby is Rh+.
Can also have ABO hemolytic disease of the newborn. Just monitor, can do transfusion if serious. HDN only lasts as long as the mother’s antibodies.
Would you give RhIG to a Rh- man who received Rh+ blood?
Probs not. It would take a large dose of RhIG. Not guaranteed to form Anti-D.
Alternatives to transfusion
For RBC: Erythropoietin, look at Fe, folate, B12, but you need time and bone marrow capacity. For Plasma: sometimes just lacking one factors in blood, so give specific factor concentrates. For low platelets: thrombopoietin, or platelet transfusion.
Ethical consideration for consent to transfusion
Need to know risk, benefits, and alternatives, plus some time to decide. Document it.
Risks of blood component vs fractionation
Blood component is riskier since it could have some contamination, not purified. Fractionated parts are chemically derived etc so more pure.
Main point of AB screen and crossmatch
Looking for AB for other factors other than ABO antigens.
What to do if someone starts having a fever reaction to transfusion?
Stop! Then do a DAT for pre- and post-transfusion test. Maintain saline.
Differential diagnosis of fever after transfusion?
Acute hemolytic transfusion reaction: react to antigens in blood, urine darkens. Febrile non-hemolytic transfusion reaction: cytokines in blood. Microbial contamination. Transfusion related acute lung injury: shortness of breath; more with plasma, anti-neutrophil AB from blood attack patient’s neutrophils, short lived. Finally, fever could be pre-existing anyways
Non-ST elevation myocardial infarction
ECG reading indicating sub-endocardial ischemia. Just part of heart is infarcted.
Differential diagnosis of jaundice after transfusion?
Delayed hemolytic transfusion reaction (esp a few days/weeks later). Indicated by low Hb, high bilirubin, high LDH, low haptoglobin (carries free Hb, so it gets consumed with free Hb). Post-transfusion purpura: platelets drop, rare but can be fatal. Transfusion Associated Graph vs Host Disease: in immunosuppresed, leftover lymphocytes attack host. Alloimmunization: -ve before, then exposed to foreign Ag, so now they are +ve for AB. Transfusion Transmitted Infections: be careful. Iron overload: extra Fe from new RBC, can deposit in places and cause destruction. Other option is Liver dysfunction.