Coag review Flashcards
PTT or aPTT evaluates for which pathway? Used to monitor what therapy
- intrinsic and common pathways
- used to monitor unfractionated heparin therapy
PT evaluates for which pathway? Used to monitor what therapy
- extrinsic and common
- used to monitor Warfarin (coumadin) therapy
- vitamin K dependent clotting factors
which factors are part of the intrinsic pathway
- 8, 9, 11, 12
which factors are part of the extrinsic pathway
- tissue factor
- VII
what is present in common pathway
- prothrombin (II)
- Thrombin (IIa)
- fibrinogen (I)
- V
- X
target INR therapy for DVT (prophylaxis)
1.8-2.5
target INR therapy for venous thromboembolism and AFIB
2-3
target INR therapy for mechanical heart valves
2.5-3.5
hemophilia A
factor VIII deficiency
how does liver cirrhosis cause thrombocytopenia
- liver cirrhosis -> portal HTN -> splenomegaly -> splenic sequestration -> thrombocytopenia
What is platelet dysfunction and what causes it? Treatment?
- impaired adherence or aggregation of platelets
- acquired: more common
- liver disease, von willebrand disease, myeloproliferative disease, drugs
- treatment:
- treat underlying cause
- platelet transfusion
Name conditions that cause increased destruction of platelets
- ITP
- DIC
- heparin-induced thrombocytopenia (HIT)
- thrombotic microangiopathies
- TTP
- HUS
what is heparin-induced thrombocytopenia (HIT)
- new onset thrombocytopenia/thrombus while on heparin therapy
- will occur 5-10 days after putting someone on heparin; patient develops antibodies that bind to platelets
thrombotic thrombocytopenic purpura (TTP) is more common in males or females
females
etiology of thrombotic thrombocytopenic purpura (TTP)
- inherited or idiopathic
- deficiency or antibodies ADAMST-13
- drugs, pregnancy, HIV infection
explain what happens in thrombotic thrombocytopenic purpura (TTP)
- ADAMTS-13 is responsible for cleaving vWF into a smaller molecule, so without it, platelets aggregate around huge vWF and leads to clots and low platelet levels in blood
- microthrombi are formed throughout the body
Name the Pentad of symptoms associated with thrombotic thrombocytopenic purpura (TTP)
- microangiopathic hemolytic anemia
- thrombocytopenia
- acute kidney injury
- neurologic defects
- fever
treatment of thrombotic thrombocytopenic purpura (TTP)
plasma exchange
hemolytic uremic syndrome typically seen in what patient population
children
etiology of hemolytic uremic syndrome
Ecoli O157:H7
name Triad of symptoms seen in hemolytic uremic syndrome
- microangiopathic hemolytic anemia
- thrombocytopenia
- acute kidney injury
- **most cases preceeded by bloody diarrhea
treatment of hemolytic uremic syndrome in adults
plasma exchange
treatment of hemolytic uremic syndrome in children
- IV fluid and electrolyte repletion
- dialysis if indicated
typical of what conditions
- microangiopathic hemolytic anemia
- fragmented RBC: schistocytes: helmet cells
TTP and HUS
clinical findings are associated with this condition
- increased indirect biliruben
- decreased serum haptoglobin (binds to iron to preserve it)
- negative coombs test
- thrombocytopenia
- PT and aPTT are normal
- acute kidney injury
- microangiopathic hemolytic anemia
- TTP
- HUS
name nutritional causes of impaired production of platelets
- Vitamin B12, folate deficiency
- alcohol
- direct toxicity to bone marrow
- hypersplenism secondary to liver disease
List the anticoagulants that are available for use
- IV unfractionated heparin (UFH)
- LMWH
- oral warfarin
- factor Xa inhibitors
- oral direct thrombin inhibitors
Contraindications to anticoagulation
- pregnancy
- risk of hemorrhage > than the potential clinical benefits of therapy
function of warfarin
- inhibits conversion of vitamin K to active form
- depletion of vit K dependent clotting factors (2, 7, 9, 10)
- inhibits Protein C and Protein S
- inhibits propagation - does not remove thrombus
indications for use of warfarin
- prophylaxis/treatment
- VTE
- AFIB
- prosthetic heart valve
- stroke
- post MI
when should warfarin treatment by initiated? Initial dose?
- initiated on day 1 or day 2 of heparin
- initial dose: < or = 5 mg/day
lower initiation doses of warfarin are recommended for
- elderly
- liver disease
- malnourished
warfarin requires on average how many days before full anticoagulation effect in achieved? peak effect of warfarin occurs when?
- requires 2-3 days before full effect
- peak effect of drug: after 48 hours
Treatment for patients with acute DVT of leg requires warfarin bridge therapy. describe this
- parental therapy (heparin) should overlap with warfarin for a minimum of 5 days AND until the INR is 2.0 or above for at least 24 hours
what is a normal INR for a patient who is NOT anticoagulated
1.0
patients on warfarin should be monitored how often?
- daily and then weekly
- once stabilized, every 2-4 weeks
hemorrhagic risk becomes dominant at an INR greater than
4
no warfarin efficacy below INR of ? Efficacy diminished when INR is ?
- no efficacy: < 1.5
- diminished efficacy: < 2.0
what common drug can cause decreased warfarin effect
oral contraceptive
food sources of vit K
- cauliflower
- green leafy vegetables
- spinach
what is given for supratherapeutic INR (non urgent)
vitamin K (oral, SC, or IV)
- will take 6-24 hours to correct INR
what is given for supratherapeutic INR ( urgent)
- 10 mg vitamin K (IV)
- fresh frozen plasma
- prothrombin complex concentrate (PCC)
- recombinant factor VII
time to anticoagulation reversal following discontinuation of warfarin
5-14 days
