Venous Thromboembolism Flashcards
Where does a DVT usually form?
in the lower extremities
DVT
deep vein thrombosis
PE
Pulmonary embolism
What are the 3 factors (known as Virchow's Triad) that play a role in clot formation? These factors are abnormalities in. . . 1. 2. 3.
- blood flow
- clotting components
- surfaces in contact with blood
Signs & symptoms of DVT:
leg pain & swelling
temperature difference b/w the 2 extremities
palpable cord along the vein in the affected extremity
Homan’s sign
What is Homan’s sign?
dorsiflexion of the foot leads to pain behind the knee of the affected extremity (if the patient is laying down, and you pull back on their toes, it is extremely painful for them)
What is a clot that forms in the venous circulation and presents as either a DVT or PE
venous thromboembolism
Signs & symptoms of PE:
cough chest pain/tightness shortness of breath hemoptysis dizziness/light-headedness tachypnea tachycardia diaphoresis distended neck veins cyanosis
What is the most commonly used pretest probability scoring system?
Wells score
FYI
A _________ ________ is used most commonly to diagnose a DVT?
Doppler ultrasound
- -non-invasive
- -can measure the rate & direction of blood flow to identify clots in proximal veins (cannot detect small clots in distal veins)
What is a byproduct of thrombin generation and may be elevated in patients with a DVT and PE?
D-Dimer (a blood test to determine if a pt has a clot)
What is the gold standard for detecting a DVT?
Venography
- -not used as often because it is more invasive and some patients experience anaphylaxis
- -requires use of a radiopaque dye
____________ _________ scan images of the lungs to help detect an embolus.
Computerized tomography (CT)
The risk of DVT or PE doubles with each decade after _____ years of age.
50
What are the risk factors for DVT?
age (doubles for each decade past 50 yo) prior VTE inherited or acquired thrombophilia major medical illness or surgery paralysis/immobility obesity varicose veins trauma (especially to pelvis, hips, or legs) indwelling venous catheters (rougher surface) pregnancy/postpartum cancer/cancer therapy estrogen-containing products (birth control, hormone-replacement)
__________ increases the risk of VTE and is compounded in patients who _______ and are taking an estrogen-containing drug.
Smoking, smoke
What are some coagulaopathies that can cause abnormalities in coagulation?
Factor V Leiden (most common) protein C or S deficiency antithrombin deficiency antiphospholipid antibodies hyperhomocysteinemia
Factor V Leiden is also called. . .
activated protein C resistance
What do we do if no risk factor can be identified for a pt developing a VTE?
coagulation studies
Since a pt isn’t likely to use medical terminology, what words would a patient use to describe symptoms of a DVT?
my leg is swelling (when did this start?)
one leg feels hotter or colder than the other (have you noticed any kind of temperature differences?)
(any other conditions?)
(questions to ask the patient)
A patient presents to the ER with sudden onset CP (chest pain) and SOB (shortness of breath). What tests would be used to rule in or out a PE?
CT
look for coagulopathies
explain the pathophysiology of a VTE to a pt without using medical terminology. this pt has Factor V Leiden and is about to start warfarin.
You’re blood is too thick and this medicine will thin it and decrease your risk of clotting
Which parenteral anticoagulant is the easiest to reverse (has an antidote)?
heparin
Once we know a patient has a VTE, what do we do?
start drug therapy immediately
to prevent further growth of a blood clot
What is the purpose of starting drug therapy immediately after diagnosing a VTE?
to prevent future growth of the blood clot
[SATA] What is the bolus dose (LD) of UFH? A. 18 units/kg/hr B. 80 units/kg C. 5000 units/hour D. 1000 units/hour
B or C (if we don’t know pt’s wt)
SATA] What is the continuous infusion dose (MD) of UFH? A. 18 units/kg/hr B. 80 units/kg C. 5000 units/hour D. 1000 units/hour
A or D (if we don’t know pts wt)
aPTT
activated partial thromboplastin time
What is the lab test that is typically used to identify the appropriate level of anticoagulation?
aPTT
aka: PTT
What is the most common adverse effect of heparin?
BLEEDING
____________ is suspected when platelet count decreases by 50%, even if the platelet count remains above 150 x 1000000000/L (10,9) (10 to the 9th)
Heparin-induced thrombocytopenia (HIT)
Pros of UFH compared to LMWH?
UFH:
short half-life (good to stop anti-coagulation quickly)
antidote available
drug is inexpensive
Cons of UFH?
unpredictable dose-response
requires frequent monitoring
increased incidence of thrombocytopenia compared with LMWHs
What tests do you obtain before starting heparin bolus?
PTT
CBC
What do you do daily while a patient is on heparin?
obtain a CBC EVERY DAY
How do you monitor for bleeding in patients on heparin?
CBCs
In patients on LMWHs, who need to be monitored for efficacy?
pregnancy
newborns & pediatrics
renal impairment (CrCl < 30 ml/min)
obesity
*don’t have to monitor most patients
What are the pros of LMWHs compared to UFH?
LMWHs have:
more predictable dose response
better BA from SC route
longer half-life
lower incidence of HIT and of major bleeding
routine monitoring for efficacy is not necessary
What are the cons of LMWHs compared to UFH?
protamine is not as effective for reversal (antidote)
What are the pros of Fondaparinux?
platelet monitoring is NOT necessary
What are the cons of Fondaparinux?
Cannot use in some patients with renal dysfunction
What test for PE scans to detect a mismatch between air movement (ventilation) and blood flow (perfusion)
Ventilation-perfusion (V/Q)
What is the gold standard for detecting a PE?
Pulmonary angiography
Problems: invasive, expensive & contrast die can cause anaphylactic runs and nephrotoxicity
For otherwise “healthy patients” what dose should you initiate warfarin on?
5-10 mg po daily for the first 2 days and then adjust based on INR values
What is “bridge therapy” with warfarin?
giving parenteral anticoagulation on day 1 with warfarin until pt reaches 2 consecutive therapeutic INRs to provide anticoagulation during the delayed onset of action of warfarin
For patients with: HF, liver disease, elderly, malnourished, debilitated, recently had surgery, or are taking meds that interact with warfarin. . . what dose should you start them on for warfarin?
start at 5mg or less for the first 2 days and then adjust to INR
J.K. comes to the ER with sudden-onset CP (chest pain) and SOb (shortness of breath). What tests should be used to rule in or out a PE? What tests would the patient receive once the diagnosis is made?
CT (computerized tomography)
coagulopathies
What is the recommendation for warfarin management when INR is above the therapeutic range but <4.5 with no significant bleeding?
- lower dose or omit dose
- monitor more frequently
- resume at lower dose when INR is therapeutic
- (if only minimally above desired range, no dose reduction may be required)
What is the recommendation for warfarin management when INR is ≥4.5 but less than 10, with no significant bleeding?
- omit next one or two doses
- monitor more frequently
- resume at lower dose when INR is in desired range
What is the recommendation for warfarin management when INR ≥10 with no significant bleeding?
- hold warfarin and give 2.5-5 mg orally of vitamin K
- INR will be substantially reduced w/in 24-48 hours
- monitor more frequently
- restart warfarin at lower dose when INR is therapeutic
What are factors that affect INR stability for long-term patients?
- age (pts > 70 had better stability)
- absence of chronic disease predicts better stability
- HF and DM (more instability)
- goal INR ≥ 3 (more instability)
- an increase in physical activity may increase warfarin requirements
- changes in vitamin K intake in diet
- nonadherance
When should you monitor a warfarin pt after a dosage change?
Follow-up in 1-2 weeks since it takes 5-7 days to see full effects of dosage change
Patients who have a consistently stable INR should be monitored once every ______ weeks.
12
True or false? A patient who is motivated and demonstrates competency may self-manage with home testing equipment instead of being required to get outpatient INR monitoring.
True
Foods HIGH in vit K may \_\_\_\_\_\_\_\_\_ efficacy of warfarin and \_\_\_\_\_\_\_\_ INR. A. decrease, increase B. decrease, decrease C. increase, decrease D. increase, increase
B.
Foods high in vitamin K include:
green, leafy vegetables chickpeas certain oils green tea* chewing tobacco
_______ is high in vit K, has antiplatelet and fibrinolytic actions and can decrease the INR or potentiate bleeding
Green Tea
just tell patients, DON’T drink it
True or false. It is not important that warfarin pts avoid foods high in vitamin K, but that they are consistent in how much or how often they eat them.
true
Can warfarin pts take Vit K supplements?
Chest Guidelines say NO (not routinely)
[SATA] Which of the following should warfarin pts avoid? A. NSAIDs B. Tylenol C. COX-2 inhibitors D. certain antibiotics
A. NSAIDs
C. COX-2 inhibitors
D. certain antibiotics
True/False. If your warfarin pt wants to take a multivitamin, try to find one without vitamin K in it.
true
How does binge drinking effect warfarin and the INR?
binge drinking can compete with warfarin metabolism and increase the INR
How does chronic alcohol ingestion affect warfarin and INR?
can induce hepatic enzymes that metabolize warfarin and DECREASE the INR
What is the recommendation for warfarin patients who have serious bleeding at any elevated INR?
- hold warfarin & give 5-10 mg vitamin K by slow IV infusion. may be repeated every 12 h
- urgent? Give prothrombin complex concentrate or recombinant factor VIIa
What is the recommendation for warfarin pts that have life-threatening bleeding and elevated INR?
- hold warfarin & give recombinant factor VIIa or prothrombin complex concentrate along with 10 mg vitamin K1 by slow IV infusion
- repeat as necessary depending on INR
What is the dosing for Apixaban?
10 mg po BID x7 days, then 5 mg po BID x 6 months (atleast)
no routine lab monitoring required for efficacy
What is the maintenance dosing for Dabigatran?
150 mg po BID
What are some instructions to tell pts on Dabigatran?
keep medication in manufacturer’s bottle
do not empty contents from capsule
How do we choose a drug for maintenance therapy?
- inpatient vs. outpatient (UFH likely not used fro bridge therapy)
- risk of bleeding? (choose drugs with short half-life and reversibility)
- drug-drug interactions (with warfarin especially)
- renal or hepatic disease?
- prescriber preference
What is the dosing for Rivaroxaban?
15 mg po BID for the first 21 days, then give 20 mg po QD for a total of 6 months
Does rivaroxaban require monitoring?
NO
True/False? Rivaroxaban 10 mg BA is not affected by food, but the 15 and 20 mg dose should not be taken with food.
False
take 15 and 20 mg WITH FOOD
How often and at what dose do you give UFH for patients at risk of developing a VTE?
give UFH 5000 units q 8-12 h
*give q 8 hours for HIGH risk patients
Hemoptysis
Coughing up blood
Disphoresis
Sweating a lot
