VTE Part 2 Flashcards

Question

HIT Type II: | Consequences, Monitoring & Diagnosis

Answer 1

Potential Consequences: • Thrombotic complications occur in 20 –50% of patients • Thrombosis may be arterial or venous • Results in limb amputation in 10% of patients • Fatal in 8 –20% of patients Monitoring for: • Platelet count typically falls below 150 X 109 /L, however decrease from baseline platelets of 40-50% is hallmark • With heparin administration, clinical signs/symptoms of: • clot (venous or arterial) • skin necrosis/lesions at injection site • systemic reactions (fever/chills) after IV heparin bolus Diagnosis: • Based upon clinical sequlea (above) plus presence of HIT antibodies • Result of antibody testing is delayed

Answer 2

True ndirect again because they require that co factor don't act directly on the clotting factors they require that antithrombin to bind to to undergo that conformation change and then exert effects on clotting factors and they do act quickly because they act on the clotting factors that are fleet free floating in the circulation okay.

Answer 3

Warfarin has a delayed effect – must “cross cover” using a rapid acting anticoagulant, namely a parenteral one (LMWH, fondaparinux or UFH) – Overlap at least 5 days and until the INR is at least 2.0 for 24 hours (=2 consecutive days) – Initiate warfarin on day 1 or 2 that parenteral is used Those at high risk of clot (or embolism) for the 1st month of therapy, if INR falls sub-therapeutic (<2.0), “cross coverage” should be implemented with a rapid acting anticoagulant (e.g., LMWH) – Consideration for cross coverage for sub-therapeutic INRs should be done within the 1st 3 months of therapy minimum 5 days

Answer 4

interferes with interal recylcing of vit K prevent Vit K being reduced carboxyl groups necessary for activation impacts half life of clotting factors factor II is the last step, needed to make a clot don't use loading doses with warfarin

Answer 5

``` Prothrombin time (PT) measures an individual patient’s response to warfarin therapy • International Normalized Ratio (INR) standardizes the PT to allow universal interpretation INR = pt PT/mean normal PT ``` ``` INR measures (crudely speaking) the time it takes for a blood clot to form – INR without warfarin =1.0 (0.8-1.2) – INR while taking warfarin either 2.0-3.0 (or 2 – 3 times as long) or 2.5 -3.5 (2.5-3.5 times as long) to form a clot ```

Answer 6

``` • Bleeding (details later) – Major & minor bleeding • Teratogenic – Hypoplastic nose, stippled epiphyses, skeletal and ocular abnormalities – 6-12 weeks gestation • Much less common (rare) – Skin necrosis – Purple Toe Syndrome ``` ``` • Antidote for Warfarin – Vitamin K • Intravenous or oral (urgencydependent) – Prothrombin Complex Concentrate (PCC) • Factors II, VII, IX & X = blood product • Intravenous ```

Answer 7

``` 1. Initiation Phase – Establishing INR target – Hospitalized vs Ambulatory – Stability of Warfarin Dosing Achieved 2. Maintenance Phase – Ongoing achievement of target INR ``` • 2 questions to ask yourself: – Clot vs Bleed risk, with next INR would you prefer it above or below the target range? – Knowing what you know now, can you justify your actions to your peers?

Answer 8

• Initiation Phase typically lasts 2-4 weeks – Dose changes in response to INRs – Clotting factors are not at “steady state” – “map out the patient” and appreciate the delayed impact of warfarin * Warfarin Initiation – Important practice elements * INRs should be assessed regularly (2-3 times/week) * Must consider the delay of warfarin’s impact and that large variation in dosing is difficult to interpret * Take average doses in context

Answer 9

once dai;y dosing suggested over twice dialy tx for DVT/PE | often use twice daily dosing for extensive VTEs

Answer 10

1. Changes to Health - assess first – Acute changes (fever, flu, diarrhea, etc.) – Chronic Medical Condition Changes: • Exacerbation of heart failure • Alterations in thyroid function 2. Changes to Medications* – Prescription, non-prescription, herbals Drug Interactions: 1. Induction / Inhibition of Cytochrome P450 • Major 2C9 --> know that inhibitors of 2C9 should not be used • Minor 3A4, 1A2 2. Displacement of binding plasma proteins 3. Alterations in Vitamin K Status 4. Contributing to bleeding / clotting risk 3. Changes to Lifestyle – Vitamin K intake - impact INR, normal diet and if there is issue, then monitor diet – Alcohol Consumption - drunk, INR get high, drink in moderation (1-2 drinks a day) – Level of Activity - the more active, the more warfarin needed, significant changes