Blood and Fluids Flashcards
What does PT primarily test? What are some causes of prolongation?
Factor VII in the extrinsic pathway
Prolonged by vitamin K deficiency and Coumadin therapy
What does aPTT primarily test for? What are some causes of prolongation?
Factors VIII and IX of the intrinsic pathway
Prolonged by Hemophilia A, Hemophilia B, and von Willebrand’s disease
List the vitamin K dependent clotting factors
Factors II, VII, IX, and X
Formation of these factors are blocked by Coumadin
What type of matching is required for platelets before transfusing?
Rh matching only, although ABO-compatible platelets are preferred
Describe Von Willebrand Disease? What are the types? What is its treatment?
vWD is the most common inherited coagulation disorder
Type I - partial quantitative deficiency
Type II - qualitative deficiency
Type III - total deficiency
Treatment:
Type I - trial of DDAVP (stimulates release of von Willebrand factor)
Type II - trial of DDAVP
Type III - vWF concentrate
If needed, FFP and cryo can be given as well
What factor is deficient in hemophilia A? What is the treatment?
Factor VIII
Treatment is with Factor VIII concentrate
- half-life of Factor VIII is 12 hours so repeat doses must be given q12H
1 unit of platelets should increase platelet count by how much?
5,000 to 10,000
What factor is deficient in hemophilia B? What is the treatment?
Factor IX
Treatment with purified and recombinant Factor IX (FFP is a second choice)
For how long can blood be frozen?
Up to 10 years
Which clotting factor has the shortest half-life?
Factor VII (4 to 6 hours)
It is the first factor to become deficient in pts with severe hepatic failure, Coumadin therapy, and vitamin K deficiency
What disease is blood routinely screened for?
HIV Hepatitis B Hepatitis C HTLV West Nile
Which blood product is most likely to cause sepsis?
Platelets
Because platelets are kept at room temperature and not cooled, bacteria can survive and multiply.
What is a general estimation of blood volume?
About 70 mL/kg
What is the most common transfusion related infection?
Cytomegalovirus (CMV)
Describe citrate toxicity
Stored blood contains citrate, which is an anticoagulant that binds calcium and magnesium
With large transfusion, citrate can dramatically reduce levels of ionized calcium
Results in hypocalcemia, hypomagnesemia, myocardial depression
- seen as hypotension, narrow pulse pressure, increased LVEDP
What is the equation for maximum allowable blood loss?
EBV x (HCTs - HCTt)/HCTs
How do you calculate the sodium dose needed for serum correction?
Kg x 0.6 x (desired change in Na+)
How does Hetastarch interfere with clotting?
Dilution of clotting factors secondary to increased plasma volume
Decreased Factor VIII and von Willebrand factor
Decreased expression of glycoprotein IIb/IIIa on platelets
Fibrinogen deficiency
What are the effects on blood after storage with CDPA-1 as a preservative?
CDPA-1 stands for citrate, dextrose, phosphate, and adenine
At 35 days of storage:
- Glucose levels drop below 100 mg/dL
- pH falls below 7.0
- Potassium increases to over 70 mEq/L
- Concentration of 2,3-DPG fall below 1, causing a leftward shift of the oxyhemoglobin dissociation curve
How can you monitor anticoagulation with LMWH?
Anti-Xa assay
List the shelf life of blood with various preservatives
With CDP - 21 days
With CDPA-1 - 35 days
With modern additives - 42 days
What is the mechanism of action of Heparin? How is it reversed?
Heparin binds to the anticoagulant antithrombin III (AT3) and greatly enhances its effects
- AT3 inactivates multiple coagulation factors including IIa (thrombin), VII, IX, X, XI, and XII
Will result in elevated aPTT
Antagonized by Protamine via acid-base neutralization
- Protamine can cause hypotension, anaphylactoid reaction, and pulmonary HTN
What can be done to blood products to prevent GVHD?
Irradiation
Describe von Willebrand’s disease
Lack of a protein important for the function of Factor VIII as well as platelet function
Leads to prolonged bleeding time and PTT
Treatment is with Factor VIII concentrate or DDAVP
What is the mechanism of action of Coumadin? How is it reversed?
Interferes with the synthesis of vitamin K dependent factors (II, VII, IX, and X)
Prolongs PT
Reversed via vitamin K (takes time) or FFP (more immediately)
List some drugs affecting the fibrinolytic system
Urokinase - converts plasminogen to plasmin, leading to clot breakdown
Tranexamic acid / Aminocaproic acid - competitive inhibitors of plasminogen activation, stabilizing clot
Aprotinin - trypsin inhibitor, protecting clots
What is the normal lifetime of a RBC?
120 days
How is survival measured in blood banking?
Must have at least 70% RBC survival 24 hours after transfusion
Anaphylactic reaction to transfusion, in a pt who has previously been transfused, is most likely due to what?
IgA deficiency
What factors does FFP contain? How much does it increase factors? Are there any concerns with giving it? How long is it good for once thawed?
FFP contains all factors necessary for clotting except platelets
- only increases coagulation factors by 3 to 6% with each unit
Associated with TRALI and citrate toxicity (contains 5x the citrate levels found in PRBCs)
Must be used within 5 days after being thawed
What factors does Cryoprecipitate contain?
von Willebrand Factor Fibrinogen Fibronectin Factor VIII Factor XIII
Describe the treatment of hyperkalemia
Asymptomatic:
- Diuretics and IVFs
- Kayexalate
Symptomatic:
- Glucose (50cc of D50) and insulin
- cause intracellular movement of K+ - Bicarbonate
- helps reverse acidosis that may contribute to hyperkalemia - Calcium
- antagonizes the effect of K+ on the cardiac conduction system - Hyperventilation
- causes alkalosis which drives K+ intracellularly
What are some direct thrombin inhibitors? How do they work?
Bind directly to and inhibit thrombin
Argatroban Bivalirudin Dabigatran Hirudin Lepirudin
What are the advantages and disadvantage of cell saver? How does it affect platelets and clotting factors?
Advantages:
- reduced transmission of blood-borne disease
- reduced administration of incompatible blood
- administration of blood with normal concentration of 2,3-DPG
- removal of activated clotting factors
- removal of inflammatory cytokines
Disadvantages:
- cost
- delay in availability due to processing and need to recover specific amount I blood
- increased bacterial contamination
- lysis of RBCs due to collection procedure
- risk of embolism
Cell saver does not preserve either platelets or clotting factors (ultimately end up with thrombocytopenia and prolonged PT and PTT)
Which virus has the highest risk of transmission after a needle stick injury?
Hepatitis B
How does anemia effect coagulation?
Anemia leads to:
- delay in initiation of coagulation cascade
- stronger clot
- improved clot viscoelastic properties
