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44 Cards in this Set

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The PT/PTT tests in vitro assess the patient's ____ hemostasis.
secondary (in other words, it does not involve the platelets, only the clotting factors)
Platelets are part of the ____ hemostasis.
primary
T/F: A PT value of 12 seconds means that a clot will form in 12 seconds in vivo.
False, this would be a long time to clot in vivo. The normal ranges for PT (12.4-14.4) are just laboratory reference ranges.
When should you order PT/PTT tests?
When are PT tests especially important?
When you suspect a problem w/ the secondary hemostasis.

When monitoring a patient on warfarin or w/ liver disease.
PT measures the ____ pathway.
initiation or extrinsic

VII + TF activate Factor X which combines w/ Factor Va which convernts prothrombin to thrombin which converts fibrinogen to fibrin... (yeesh)
Why do we need the INR equation instead of just PT times?
b/c of small variations from lab to lab including the amount of calcium, phospholipid, and temperature... gives a STANDARDIZED record of patient's coag status
The INR should be used for ___ NOT to predict ____.
monitoring a patient on warfarin

bleeding b/f a procedure
What is the problem with giving FFP as a means of reversal or anticoagulation over a period of time?
volume overload
What two things should be done b/f a patient on warfarin undergoes major surgery?
1) replace warfarin w/ heparin which is easier to counteract
2) give Vit K or FFP to replace clotting factors
PPT measures the ____ pathway.
propagation or intrinsic

everything but factor VII

abnormal in hemophiliacs

used to monitor heparin therapy
You graciously donate a pint of blood at the local blood drive, what is this blood most likely to be used for?
trauma patients
What percentage of blood if lost can make a patient hemodynamically unstable and can lead to death?
15%
What should you do in an acute hemorrhagic situation (e.g. GSW)?
1) replace volume w/ saline
2) transfuse PRBCs

Transfusing whole blood or plasma and ordering PT/PTT tests are not critical.
What is the problem w/ using whole blood instead of PRBCs?
whole blood was stored at 4 deg C (optimal for RBCs) but this was too warm for coag factors and platelets
What are three indications for PRBCs?
1) Blood loss greater than 15% (remember this leads to hemodynamic instability) w/ or w/o Pulse >100 or drop in SBP > 20%
2) chronic symptomatic anemia (e.g. kidney failure -> no EPO)
3) Anemic patient prior to surgery/anesthesia w/ Hct < 24%
2)
How do you calculate a patient's total blood volume?
70 ml/kg of body weight

so for 70 kg person TBV = 70 X 70 = 4900 ml or 4.9 L
What is the problem of giving a sickle cell patient w/o symptoms PRBCs b/c of a low Hct (22%)?
This low Hct is their normal value. They can live off of this, but if you give PRBCs you can cause polycythemia and make the blood more viscous.
One unit of PRBCs raises Hct by ?
3%
How long are PRBCs viable in storage?
6 weeks (42 days) in cold temperatures
Type A: ___ antigens on RBCs and ___ antibodies in serum.
A, B
Type B: ___ antigens on RBCs and ___ antibodies in serum.
B, A
Type AB: ___ antigens on RBCs and ___ antibodies in serum.
A&B, no
Type O: ___ antigens on RBCs and ___ antibodies in serum.
No, A&B
If you don't know the patient's blood type and you need to transfuse plasma, give ____ type? Why?
AB, because this plasma contains no antibodies to react w/ RBCs
If you don't know the patient's blood type and you need to transfuse RBCs, give ____ type? Why?
O, b/c these RBCs have no A or B antigen on them so they will not react w/ any A or B antibodies in patient's serum.
If you give an A blood type patient type B blood what will happen?
acute hemolytic transfusion reaction leading to DIC and acute tubular necrosis
A Rh (D) + donor can only donate blood to ____ recipients.
Rh (D) +, b/c if recipient is Rh - they will have antibodies to the D antigen
Three modifications of PRBCs:
1) leukoreduction
2) washing
3) gamma irradiation
Filtration of contaminating WBCs.
leukoreduction
Transfused WBCs do not work ex vivo and put patient at risk for (5)?
1) febrile transfusion rxn
2) alloimmunization to HLA (antigens on WBCs)
3) formation of antibodies to WBCs making future transfusion more difficult
4) Viral transmission - CMV and HTLV-1 are carried in WBCs
5) Host immune system becomes preoccupied and becomes more susceptible to infections and metastases
What is the purpose of washing PRBCs? Who is it used for most of the time?
removes residual plasma

patients w/ history of anaphylaxis or IgA defieciency (remember if you've never seen a IgA b/f if you are transfused w/ serum containing IgA, this can cause a rxn)
Washed RBCs must be used w/in ___?
24 hours
Gamma irradiation is done to prevent ?
graft versus host disease in immunecompromised and patients receiving blood from family members
How does gamma irradiation work?
crosslinks DNA so WBCs are unable to proliferate, but does NOT kill viruses
How does GVHD work?
Immunosuppressed patient can not remove donated WBCs from circulation... donated WBCs recognizes the host as foreign and proliferate and attack the patient
What percentage of GVHD is fatal?
100% b/c the bone marrow is attacked
What is a complication from gamma irradiation?
damages Na/K pump causing K leak leading to increased extracellular K (bad for heart patients)

therefore irradiation is done right before transfusion
How long are frozen RBCs viable?
What are they frozen in?
10 years

glycerol
FFP is mostly ___ but also contains ___, ____, and ____.
water

factor V, factor VIII, and protein
What is a massive transfusion defined as?
receiving 10 units of RBCs (one total blood volume) in 24 hours (6 units for a smaller person)

Recall that one unit of blood is about 400 ml, so 10 units is 4000 ml, which would equal the TBV in a 60 kg person
When is FFP indicated (5)?
1.) Dilution coagulopathy post-massive transfusion --- you've only been giving PRBCs, they also need factors
2.) Liver disease - can't make factors
3.) Warfarin overdose - can't make factors
4) DIC - factors being used up
5) rare isolated deficiencies or certain factors (not for f VIII, IX, or vWF)
What is cryoprecipitate?

When is it indicated?
concentrate of large insoluble proteins in FFP (F VIII, vWF, fibrinogen, XIII, fibronectin)

HYPOfibrinogenemia- cirrhosis, acute liver failure
Platelets are indicated (3)?

contraindicated in?
1) bone marrow failure - underproduction
2) DIC - excess consumption
3) aspirin/clopridogel - platelet dysfxn

contraindicated in idiopathic thromobocytopenia purpura (ITP) - transfusion futile b/c antibodies will clear ALL platelets out of circulation, need to remove antibodies (plasmaphoresis)
Why are apheresis platelets better than random donor platelets?
RDPs are centrifuged from donated whole blood, however and unit of whole blood does not provide enough platelets for a thromobocytopenic patient, therefore 6 platelet units (from different patients) have to be

In aphereis, the platelets are all coming from same person, so you are exposed to less disease!