hemostasis pharmacology and transfusion therpay Flashcards
major blood group systems
ABO
Rh
3 pre-transfusion testing
- typing - ensures ABO/Rh compatibility
- antibody screen - tests for unexpected antibodies
- crossmatch - tests patient’s serum against prospective unit
Type testing determines the ABO and Rh phenotype of ____ blood
recipients
how to perform a type and screen test?
- mix recipient’s blood with type O that contains major antigens of other blood group systems
- observe for agglutination
when do you only order a cross-match test?
when there is a high likelihood that patient will receive PRBCs
what do you use during an emergency setting with not enough time to type or match blood?
use O-
3 reasons why we use transfusion therapy
- replace acute blood loss
- oxygen delivery
- morbidity and mortality
who do we recommend transfusion for?
hgb <6 g/dL - transfusion recommended except in exceptional circumstances
assessment post-transfusion hgb lvl can be performed as early as ?
15 mins
1 unit of PRBCs should increase hgb ___ in avg sized adults
1 g/dL
prior to non-emergency transfusions, what must you obtain?
signed informed consent
transfusion reactions occur when?
- during transfusion
- within 24 hrs
what is the most common sign of a transfusion reaction?
febrile non-hemolytic reactions
what is the top 2 causes of death from transfusion reaction
- circulatory overload
- CHF, renal failure more at risk - transfusion related acute lung injury
- smokers, asthma more at risk
5 types of transfusion products
- whole blood
- packed RBC (PRBC)
- fresh frozen plasma (FFP)
- cryoprecipitate
- platelets
what type of transfusion product provides O2-carrying capacity and volume expansion and commonly used during settings of massive hemorrhage
whole blood
what type of transfusion product increases the oxygen-carrying capacity in anemic pts
PRBC
3 modifications of RBCs to prevent reactions
- leukocyte reduced - reduces risk of immunologically-mediated effects
- irradiated - reduces graft-vs-host disease (GVHD)
- washed - reduces complications associated with infusion of proteins in residual plasma in red cell concentrates
what contains platelets and proteins (procoagulant and anticoagulant factors)
plasma
what 6 components are contained in fresh frozen plasma (FFP)
- coagulation factors
- fibrinogen
- antithrombin
- albumin
- protein C
- protein S
why is FFP the most commonly used plasma product?
can correct deficiencies of any of the circulating coagulation factors
main advantage of cryoprecipitate
allows vWF, factor VIII, factor XIII, and fibrinogen to be replaced using a much smaller volume
main advantage of factor concentrates
replaces specific factor deficiencies with minimal volume ONLY (no extra proteins)
4 indications for transfusion of PLT in critically ill pt that may be therapeutic or prophylactic
- PLT <10k - prevents hemorrhage
- PLT <50k
- actively bleeding
- scheduled for invasive procedure
- qualitative intrinsic PLT disorder - PLT <100k
- CNS injury
- multisystem trauma
- neurosurgery - normal PLT
- active bleeding
- PLT dysfunctions - congenital PLT disorder, chronic aspirin use, uremia
each unit of transfused PLT should increase the PLT count by ?
5-10k
4 hemostasis promoting agents
- protamine sulfate
- vit K
- desmopressin
- thrombin
neutralizes heparin and could result in severe hypotensive or anaphylactoid-like reactions (BBW)
protamine sulfate
reverses anticoagulant effect of heparin
dosage of protamine sulfate
depends on dosage of heparin
what is the reversal agent for warfarin (coumadin)
vitamin K (phytonadione)
dosage and route of vit K depends on:
- severity of bleeding
- INR
- procedure planned
MOA of desmopressin (DDAVP)
increases plasma level of vWF, factor VIII, and tPA = shortened activated partial thromboplastin time (aPTT) and bleeding time
indication for desmopressin and what must you monitor
hemostasis
- restrict fluid intake
- monitor sodium levels
MOA of topical thrombin
converts fibrinogen to fibrin directly at site
indication for topical thrombin
hemostasis whenever oozing blood and minor bleeding
contraindications for topical thrombin
- sensitivity to components of bovine origin
- massive bleeding
- large vessels
3 classes of antithrombotic drugs
- antiplatelet
- anticoagulant
- fibrinolytic agents
general indication for anticoagulants
prevent or treat clots!
contraindications for anticoagulants (3)
- bleeding
- impaired renal function
- allergic
4 parenteral anticoagulants
- heparin (unfractionated)
- low-molecular-weight heparin (LMWH)
- bivalirudin (angiomax)
- argatroban (acova)
MOA of unfractionated heparin
binds to antithrombin (III) = no activation of factor Xa and thrombin
no dosage adjustment is necessary for who when taking unfractionated heparin
renal patients
when on unfractionated heparin, you must monitor:
activated partial thromboplastin time (aPTT)
order daily CBC, monitor signs of bleeding
4 SE of unfractionated heparin
- bleeding
- thrombocytopenia
- osteoporosis
- elevate levels of transaminases
7 contraindications for unfractionated heparin
- HIT
- hypersensitivity
- active bleeding
- hemophilia (inherited bleeding disorder in which the blood does not clot properly)
- significant thrombocytopenia
- purpura
- severe HTN
what is HIT?
heparin-induced thrombocytopenia
induces immune antibody response resulting in PLT clearance and may also induce hypercoagulable state
when can HIT occur?
any dose, schedule, and route
more common in females
what is the most common manifestation of HIT
thrombocytopenia
a platelet count drop of >50% of baseline is typical
typical onset of HIT occurs ? after the initiation of heparin
5-10 d
takes 5-7 d to return to baseline following withdrawal
what is the most common thrombi in HIT and where is it most common
venous
sites: leg veins, cardiac vessels, small venules of skin
5 signs of suspected HIT
- new onset of thrombocytopenia <150k
- drop in PLT of +50% from prior value
- venous/arterial thrombosis
- necrotic skin lesions at injection site
- acute systemic reactions
what is the 4Ts scoring system for assessing HIT
1-3 = low
4 or 5 = intermediate
6-8 = high