42/43: Blood Components - Kruse Flashcards
tests for antigens on the patients cells
forward typing
tests for antibodies in the patients serum
backward typing
Describe direct Coombs testing
reagent: anti-human immunoglobulin antibodies that binds to human IgG and IgM antibodies
whats does direct coombs testing test for?
autoimmune hemolytic reactions
aka direct antiglobulin test DAT - tests for antibody mediated hemolysis
What is an indirect coombs test?
aka indirect antiglobulin test
detects antibodies present in patient serum
what is used for ABO testing, RH-D testing, and crossmatching of blood products?
indirect coombs test
blood type refers to..
the antigen expressed by the red cells
A
B
AB - universal donor of plasma because no antibody to attack antigen
O (no antigen) - universal donor of RBC because no antigen for antibody to attack
what is the bombay phenotype?
bombay phenotype: lacks H antigen
type O blood without H antigen will have anti-H antibodies in serum –> bombay phenotype pts need to receive blood from other bombay pts
If mom is RhD antigen negative and she is exposed to Rhd antigen positive blood, she may form
anti-RhD antibodies (which can cross the placental barrier because IgG)
absence of which minor RBC antigen is protective against malaria
duffy antigen
special processing of RBCs
- leukocyte reduction ( reduces risk of CMV transmission in bone marrow transplant patients, does nothing for GvH)
- Washing (decreases risk of anaphylactoid reaction, particularly in IgA deficient patients)
levels of Hgb that indicate anemia
less than 12.5 in females
less than 13.5 in males
go to 7 before need blood
RBC transfusion triggers
- Hgb less than 7
- with active bleeding or active CVD less than 8
- general goal is to keep hemoglobin 7-9
hematocrit is roughly
3x hemoglobin
special cases - hemoglobin levels
- bleeding esophageal varices: keep pt as close to Hbg 8 as possible
type and screen vs. type and cross **
type and screen = screens pts blood, does not prepare donor blood
type and cross = screens pts blood and cross matches donor blood for pt use
contraindications to platelet transfusion
- heparin induced thrombocytopenia (increases rate of thrombosis, stop heparin)
- thrombotic thrombocytopenic purpura/ hemolytic uremic syndrome (accelerates disease process)
Transfusion related infections
HIV HCV HBV West Nile CMV Parasitic disease *Bacterial infection (most common*** 1/2000 - 1/3000 mostly platelets)
which transfusion has the highest rate of infection?
platelets **
allergic transfusion reactions
preformed antibodies to donor plasma prtns
urticaria, pruritus, flushing, mild wheezing
give antihistamines
not typically dangerous, wait for symptoms resolve and complete transfusion
anaphylactic transfusion reactions**
antibody to donor plasma prtns
hypotension, urticarial, bronchospasm, angioedema
rule out hemolysis, give epi IM**, anithistamines and corticosteroids
check pt for IgA deficiency*
use washed products in future
febrile non-hemolytic transfusion reaction
due to preformed anti-WBC antibodies in pt
temperature rise greater than 1 degree celsius in first 1-2 hr of transfusion
give acetaminophen and minimize recurrence by giving pre-transfusion acetaminophen and using leukocyte reduced blood products
delayed hemolytic transfusion reaction
occurs 1-2 wks after transfusion
fever, jaundice, falling hgb
repeat type and screen to look for new antibody formation, redo transfusion
acute hemolytic transfusion reaction
preformed antibodies incompatible attack donor product antigen
chills, fever, hypotension, back pain, DIC
aggressively treat with IV fluids
use pressors if needed
keep good urine otuput
TACO transfusion associated circulatory overload
hydrostatic fluid overload
essentially a decompensated CHF caused by transfusion
dyspnea, tachypnea, JVD, peripheral edema
prevent with slow transfusion rates and treat with diuretics
TRALI transfusion related acute lung injury
massive capillary leak in the pulmonary vasculature
hypoxemia, transient leucopenia, bilateral pulmonary edema
occurs w/i 6 hr transfusion
5-20% mortality, most common with whole blood transfusions
