Unit 9 - Transfusions Flashcards
what determines blood type
antigenic glycoproteins on cell membranes of erythrocytes
what is required for a successful transfusion to occur
requires no antigen-Ab reaction
(plasma contains opposite antibodies from erythrocytes)
universal donors
erythrocytes: O negative
plasma: AB positive
universal acceptors
erythrocytes: AB positive
plasma: O negative
RBC Antigens & Plasma antibodies - Type O
no RBC antigens
Anti-A and anti-B antibodies
RBC antigens and plasma antibodies - type A
A RBC antigens
anti-B plasma antibodies
RBC antigens and plasma antibodies - type B
B antigens
Anti-A plasma antiobdies
RBC antigens and plasma antibodies - AB
A, B antigens
no plasma antibodies
blood compatible with type A
A, O
blood compatible with type O blood
O
blood compatible with type B blood
B, O
blood compatible with AB blood
A, B, AB, O
RBC antigens and plasma antibodies for Rh-positive blood
D antigens
no plasma antibodies
how can an Rh-negative person be sensitized to Rh-positive blood
transfusion or pregnancy (delivery)
how can Rh-negative mother be sensitized to Rh antigen
Rh antigen can cross placenta during delivery and sensitize mother
why is the first baby not at risk for Rh sensitization
- It takes several days for the mother to develop antibodies to the Rh antigen
- If the mother becomes sensitized and develops antibodies, a subsequent pregnancy with an Rh-positive fetus may lead to erythroblastosis fetalis (hemolytic disease of the newborn)
when might a woman need Rhogam
a Rh-negative mother with 2nd pregnancy whose first baby was Rh-positive
starting at 28 weeks
who does a fetus receive Rh antigen from
father
universal PRBC donor
O blood
universal FFP donor
type AB
universal FFP acceptor
Type O
universal RBC acceptor
AB
lab test that tests for ABO and Rh-D antigens
type
determines the presence of ABO and Rh-D antigens in recepient’s blood
typing
determines the presence of the most clinically significant antibodies
screening
provides the most accurate determination of compatibility by mixing recipient’s plasma with blood in actual unit to be transfused
crossmatching
how long does blood typing take
5 minutes
how long does blood screening take
45 min
how long does blood crossmatching take
45 minutes
chance of transfusion reaction with blood typing
0.2%
chance of transfusion reaction with blood screening
0.6%
chance of transfusion reaction with blood crossmatching
0.05%
what does blood screening test for
most clinically significant antibodies
recommended order of admin. uncrossmatched blood
(most to least favorable)
- type-specific partially crossmatched blood
- type-specific uncrossmatched
- o negative uncrossmatched
what percent of the population is Rh-D positive
85%
when is it ok to use O positive blood for emergency transfusion
emergency transfusion if pt isn’t a woman of childbearing age and has not received a previous transfusion
1st choice for administering emergency uncrossmatched blood
type-specific partially crossmatched blood
hgb level that often requires transfusion
< 6 g/dL
hgb > ____ rarely requires transfusion
10 g/dL
components of PRBC transfusion
RBCs only
components of whole blood
RBCs
WBCs
plasma
platelet debris
fibrinogen
when is whole blood indicated
RBC replacement
blood volume replacement
components of FFP
- all coagulation factors
- fibrinogen
- plasma proteins
indications for FFP transfusion
- coagulopathy (PT or PTT > 1.5x control)
- warfarin reversal
- antithrombin deficiency
- massive transfusion
- DIC
- C1 esterase deficiency
dose of FFP for warfarin reversal
5-8 mL/kg
dose of FFP for coagulopathy
10-20 mL/kg
10-20 mL/kg of FFP increases factor concentration by:
20-30%
half life of factor 7
3-6 hours
time frame to give FFP
complete within 24 hours of thawing
plt count for NSGY that should get a platelet transfusion
< 100k
plt count that should get plt transfusion for most surgeries
< 50 k
components of cryopreceipitate
fibrinogen
factor 8
factor 13
vWF
cryo dose
5 bag pool to ↑ fibrinogen by 50 mg/dL
cryo infusion should be completed by:
within 6 hours of thawing
indications for cryo
- fibrinogen deficiency (< 80-100 mg/dL)
- von Willebrand disease
- hemophilia
what should blood loss be replaced with
crystalloid or colloid solutions until the risk of anemia outweighs the risk of transfusion
when should pts with CAD be transfused
when hematocrit falls below 28 - 30%
indicators of tissue perfusion that should be considered before transfusing
DO2, SvO2, acid-base status, lactate, hemodynamic instability, myocardial ischemia, and oliguria
if a 70 kg patient has a Hgb of 12 g/dL and acutely loses 1L of blood, what’s the new Hgb value?
12 g/dL
Even though the patient has lost 1/5th of his blood volume, the amount of hgb per deciliter of blood hasn’t changed.
what does the MABL calculation assume about the patient?
euvolemic
blood volume of premature neonate
90-100 mL/kg
blood volume of full term neonate
80-90 mL/kg
blood volume of infants
75-80 mL/kg
blood volume of school aged child
70 mL/kg
blood volume of adults
70 mL/kg
MABL calculation
volume and hct of 1 unit PRBCs
~300 mL
Hct ~ 70%
how does 1 unit PRBCs affect hgb & hct
increases Hgb by 1 g/dL and Hct by 2 - 3%