VTE Weber Exam 4 Flashcards
(149 cards)
1
Q
When and where are venous thrombi formed?
A
In areas of slow or disturbed blood flow in veins, leading to obstructed flow, vascular tissue inflammation, or embolus travels to other portion of body.
2
Q
What is an embolus?
A
A piece of a clot that has broken off and travels somewhere else to become lodged (pulmonary embolism in lungs)
3
Q
What are the three components of Virchow’s Triad of VTE causes?
A
Hypercoagulable state (malignancy, factor V leiden, pregnancy), endothelial injury (atherosclerosis, orthopedic injury), and circulatory stasis (immobility, paralysis, varicose veins)
4
Q
Why are the legs the most common site of DVT?
A
Blood flow in the legs is opposed by gravity. The popliteal vein is especially common.
5
Q
Name the physiologic anticoagulants.
A
Antithrombin III, protein C, protein S, tissue factor pathway inhibitor, and tissue plasminogen activator
6
Q
Which clotting pathway is the “spark” that gets the clotting cascade started? Which clotting pathway helps to amplify the initial clotting stimulus?
A
Spark: Extrinsic pathway
Amplification: Intrinsic pathway
7
Q
What is the long-term complication of DVT? What does this cause?
A
Post-thrombotic syndrome; damage to venous valves causes venous obstruction, venous hypertension, chronic pain and swelling, stasis ulcers, and development of infection
8
Q
What conditions put a patient at risk for a DVT?
A
Heart failure, immobilization, malignancy, MI, obesity, paralysis, postoperative state (3 mos), pregnancy, varicose, veins, and orthopedic injury.
9
Q
What patient history or demographics put a patient at risk for DVT?
A
Age >40 years, family history of DVT, OC/estrogen use, postoperative state (3 mos), history of prior DVT.
10
Q
What are appropriate nonpharmacologic treatment options for DVT?
A
Bed rest (if on appropriate anticoagulation), elevation of feet, pain management, compression stockings
11
Q
What are appropriate nonpharmacologic treatment options for PE?
A
Oxygen, mechanical ventilation, and compression stockings
12
Q
What are the goals of DVT treatment?
A
To stabilize the clot, prevent worsening/growing, prevent risk of embolism, and prevent another clot.
13
Q
What is the mechanism of action of unfractionated heparin (UFH)? What factors does it inhibit?
A
Binds to ATIII, improving its ability to inhibit thrombin, factor VII, IX, X, XI, XII, and plasmin
14
Q
What is the pharmacokinetic reason for aPTT monitoring?
A
Non-linear kinetics and variable dose response
15
Q
What is a therapeutic range for aPTT on heparin?
A
1.5 - 2.5 x normal range
16
Q
By what route can heparin be dosed?
A
IV or SQ (NOT IM)
17
Q
How often is aPTT monitored on heparin?
A
At baseline, 6 hours after dose and after each dosage change, daily after one day stable on dose.
18
Q
What are potential adverse effects of heparin?
A
Bleeding, osteoporosis, hypersensitivity, HAT, HIT
19
Q
How often are platelet counts monitored on heparin?
A
Every other day until day 14
20
Q
What is the half life of UFH when given IV?
A
30-90 minutes (caution about discontinuing)
21
Q
What route of administration of heparin puts a patient at higher bleeding risk?
A
IV
22
Q
What factors put a patient at high bleeding risk?
A
Age >65, h/o GI bleed or PUD, renal failure, EtOH use, malignancy, cerebrovascular disease, surgery, major trauma, concurrent medications like inhibitors and other anticoagulants
23
Q
What parameters are monitored for bleeding on heparin?
A
CBC – HGB, HCT – and BP
24
Q
How long does protamine persist when given to neutralize heparin? What is the half life? When should you check aPTT after protamine administration?
A
Persists 2 hours but half life 7 minutes. Check aPTT in 30 minutes.
25
If a patient has received a dose of heparin in the last 30 minutes, how should protamine be dosed to neutralize it?
1 - 1.5 mg protamine per 100 units of UFH given
26
If a patient has received a dose of heparin within 30 - 120 minutes, how should protamine be dosed?
0.5 - 0.75 mg protamine per 100 units of UFH given
27
If a patient has received a dose of heparin more than 2 hours ago, how should protamine be dosed?
0.25 - 0.375 mg protamine per 100 units of UFH given
28
What are potential adverse effects of protamine that must be weighed? How can these be controlled?
Risk for hypotension, bradycardia, and anaphylaxis
Check if pt history vasectomy, fish sensitivity, received protamine-containing insulin
Infuse protamine over 1-3 minutes, MAX 50mg over 10 mins
29
What differentiates HIT from HAT?
HIT is immune mediated, occurs later (7-14 days after heparin start), and is associated with a larger drop in platelets (>50% from baseline or
30
True or false: Due to the drop in platelets, patients experiencing HIT need to discontinue all anticoagulants immediately.
False -- although heparin products DO need to be stopped immediately, they must be put on an alternative due to the higher risk for thrombosis
31
What lab tests can confirm a diagnosis of HIT?
HIPA, serotonin release assay, or heparin-PF4 Ab ELISA
32
When can warfarin be used for HIT?
After platelet count is >150 and when patient stable on direct antithrombin already.
33
In pregnant patients with HIT, what agent is preferred?
Danaparoid (fondaparinux only if danaparoid not availble)
34
What factor do the LMWHs preferentially inhibit?
Factor Xa
35
LMWHs are smaller than heparin and have reduced protein binding, longer half life, less effect on platelets, and predictable dose response. Based on these, what are the advantages to using LMWH?
Predictable dose response allows for fixed or weight-based dosing and removes monitoring requirement. Better SQ bioavalability, reduced HIT incidence, and longer dosing intervals possible.
36
What is the mechanism for LMWH elimination?
Renally -- adjust for decrease in renal function CrCl
37
What are the upper weight limits that the LMWHs have been studied at?
Enoxaparin 144kg
Dalteparin 190kg
Tinzaparin 165kg
38
What parameters should be monitored for LMWHs?
CBC with plt, SCr, and fecal occult blood
39
What patients may need anti-Xa level monitoring when on LMWH?
Children, severe kidney failure, obesity, long courses, and pregnancy
40
What black box warning do all LMWH products carry?
Use with neural anesthesia or spinal puncture can lead to increased risk of spinal hematoma leading to paralysis
41
What adverse effects are associated with LMWHs?
Bleeding, thrombocytopenia, delayed hypersensitivity skin reactions
42
If protamine must be administered for LMWH-induced bleeding, how is it dosed within 8 hours of receiving LMWH?
1mg protamine/ 1mg enoxaparin
43
If protamine must be administered for LMWH-induced bleeding, how is it dosed after 8 hours of receiving LMWH?
0.5mg protamine / 1mg enoxaparin
44
What conditions is fondaparinux approved for?
Prophylaxis following THA, TKA, and abdominal surgery (NOT acutely ill pts) and treatment of DVT/PE
45
If a patient is
They can receive it for DVT/PE treatment, but not for prophylaxis
46
True or false: Fondaparinux must be renally adjusted for CrCl
False -- do NOT use if CrCl
47
What factor does fondaparinux inhibit?
Factor Xa
48
What should be monitored for fondaparinux?
Bleeding, SCr, potentially monitor Xa (not ideal)
49
What four conditions is rivaroxaban approved for?
DVT prophylaxis, DVT/PE treatment, NV afib, secondary prevention of recurrent DVT/PE
50
When is rivaroxaban initiated when used for DVT prophylaxis?
6-10 hours post surgery (confirmed hemostasis)
51
How long should rivaroxaban be continued in prophylaxis?
THA: 35 days
TKA: 12 days
52
What reversal agent may be helpful for rivaroxaban?
PCC
53
What is the brand name for rivaroxaban?
Xarelto
54
What conditions should rivaroxaban be avoided in?
CrCl
55
How is warfarin transitioned to rivaroxaban?
Stop warfarin and start rivaroxaban when INR
56
For rivaroxaban, apixaban, and edoxaban, how do you convert to warfarin?
Start warfarin and stop the NOAC 3 days later. (Can also stop NOAC and start warfarin with LMWH concurrently like normal initiation)
57
What are the two black box warnings for all NOACs?
Neural anesthesia or spinal puncture with NOAC can lead to epidural or spinal hematoma.
Premature discontinuation increases the risk of thrombotic event.
58
What is the brand name for edoxaban?
Savaysa
59
What is edoxaban approved for?
DVT/PE treament and NVAF (if CrCl 15-95 mL/min)
60
True or false: Edoxaban should be started immediately to treat DVT or PE.
False -- only started after 5-10 days of parenteral anticoagulant
61
What are the major sources of drug interactions with the NOACs?
CYP3A4 and Pgp
62
When should edoxaban, apixaban, and dabigatran be started when transitioning from warfarin?
When INR
63
What is the brand name for apixaban?
Eliquis
64
What is apixaban approved for?
DVT prophylaxis, DVT/PE treatment, and NVAF
65
True or false: Apixaban should be started immediately when treating DVT or PE.
True -- apixaban does not require parenteral coagulant first
66
What is the only pregnancy class B NOAC?
Apixaban (Eliquis)
67
What is the only NOAC that is a direct thrombin inhibitor?
Dabigatran (Pradaxa)
68
What direct thrombin inhibitor is often used as a UFH alternative during PCI?
Bivalrudin (Angiomax)
69
What is the brand name of dabigatran?
Pradaxa
70
What is dabigatran approved for?
DVT/PE treatment and NVAF
71
True or false: When treating PE or DVT, dabigatran should be started right away.
False -- started after 5-10 days of parenteral anticoagulation
72
With what patient population is dabigatran not recommended?
Extreme caution with patients 80 years and older
73
What are two unique counseling points with dabigatran among the other NOACs?
Keep in manufacturer bottle, may cause dyspepsia.
74
True or false: The dabigatran dose is adjusted for renal function in DVT/PE treatment.
False -- do not use if CrCl
75
In a patient with CrCl >50mL/min, dabigatran should be stopped ___ days later when transitioning to warfarin.
3 days after warfarin start
2 days if CrCl 31-50
1 day if CrCl 15-30
76
True or false: NOACs are dosed differently when used for prophylaxis in mechanical heart valve.
False -- use of NOACs is contraindicated with mechanical heart valve.
77
What is the only NOAC to have a reversal agent?
Pradaxa -- Praxbind antibody
78
What is the thrombolytic that can potentially be used for acute pulmonary embolism?
Alteplase
79
What are the available strengths of warfarin?
1, 2, 2.5, 3, 4, 5, 6, 7.5, and 10mg tablets (all scored)
80
What is warfarin indicated for?
Prophylaxis and treatment of thromboembolic disorders and embolic complications from atrial fibrillation or valve replacement, adjunct to reduce risk of embolism after MI
81
True or false: All warfarin products (generic, Coumadin, Jantoven) are roughly equivalent and can be exchanged easily.
False! Pt needs to get same one each time.
82
What clotting factors are inhibited by warfarin?
Factor II, VII, IX, and X in addition to protein C and S
83
When can effect from warfarin first be seen? When does the effect peak?
Effect within 24 hours but peak in 3-4 days
84
What isomer of warfarin is more potent? What enzyme degrades this isomer?
S isomer 5 times more potent; degraded by CYP 2C9, 2C19, 2C18 (genetic variability!)
85
What pregnancy category is warfarin? Is it safe for breastfeeding?
Pregnancy X but safe for breastfeeding
86
What genetic variant of CYP2C9 leads to an 80% lower dose requirement?
*3/*3 (lowest possible warfarin clearance)
87
What genetic variation of CYP2C9 is more common in Asians and African Americans?
*8: lower dose requirement
88
What variations of vitamin K oxide reductase gene (VKORC1) may lead to warfarin resistance and higher dose requirement? Which population has this more commonly?
VKORC1 GG: African Americans
89
What variation of VKORC1 leads to higher warfarin sensitivity and lower dose requirement? Which population has this more commonly?
VKORC1 AA: Asians
90
What three criteria must a patient meet in order to receive warfarin genetic testing?
Must be warfarin naive, at high risk of bleeding if elevated INR, and able to get test results before sixth dose.
91
What patients have an INR goal of 2.5 - 3.5?
Those with a mitral, caged ball, or high risk mechanical heart valve.
92
True or false: Once a patient reaches a stable dose, they are generally stable on that dose for the rest of their life.
False -- warfarin dosing is variable over time.
93
How long should LMWH/UFH/Xa therapy be overlapped when starting warfarin?
For at least 5 days and until INR therapeutic
94
What patients may need a starting warfarin dose lower than 5mg daily?
Patients >60yo, debilitated, malnourished, CHF, liver disease, concomitant medications, high bleeding risk, genetic factors (AA or *3/*3)
95
In the flexible initiation ("loading") warfarin initiation method, how often should INR be checked?
Daily through day 4, then within 3-5 days
96
In the average daily dosing method, how often should INR be checked?
Within 3-5 days, then within 1 week
97
How soon should INR be checked after hospital discharge if stable? If unstable?
Stable: 3-5 days
Unstable: 1-3 days
98
How often should warfarin be checked during the first month of therapy?
At least weekly
99
If a warfarin dose must be held, when should you next check the patient's warfarin?
Within 1-2 days
100
If a warfarin dose was changed, when should you next check the patient's warfarin?
Within 1-2 weeks
101
If a patient's warfarin dose was changed up to 2 weeks ago, when should the INR next be checked?
In 2-4 weeks
102
For an unstable patient on warfarin, how often should routine INR follow up occur?
Every 1-2 weeks
103
For a stable patient on warfarin, how often should INR follow up occur?
Every 4-6 weeks
104
For a patient consistently stable on warfarin, what is the longest you can wait before checking INR?
12 weeks (3 months)
105
What patients may be eligible to self adjust their warfarin doses?
Patients anticoagulated >3 months with good cognitive skills, dexterity, and communication and ability to use a POC INR test.
106
What are the 5 D's + B&B of a warfarin patient interview?
```
Drugs (change in meds/OTCs/herbals)
Diseases (change in condition/treatment)
Doses (missed doses)
Diet (changes in diet, esp green leafy veggies)
Drink (EtOH consumption)
Bruising & bleeding
```
107
What is the duration of therapy if a patient had an identifiable risk factor for their DVT?
3 months
108
What is an appropriate duration of therapy if a patient had an idiopathic DVT?
At least 3 months, then re-evaluate. Extended therapy up to 1 year.
109
How long should a cancer patient who experienced DVT be on therapy?
LMWH for 3-6 months, then warfarin or LMWH indefinitely or cancer resolves.
110
How long should a patient with a history of multiple DVTs be on therapy?
Lifelong
111
What medications require an empiric (25-50%) decrease in warfarin dose due to interaction?
Metronidazole, amiodarone, ciprofloxacin, fluconazole, and bactrim
112
What medication requires an empiric increase in warfarin dose due to interaction?
Rifampin
113
Do cholestyramine, carbamazepine, vitamin K foods, and chronic alcohol use increase or decrease INR? (when on warfarin)
Decrease INR
114
Do erythromycin, cimetidine, anabolic steroids, acute alcohol use, isoniazid, and propafenone increase or decrease INR? (when on warfarin)
Increase INR
115
True or false: Use of aspirin and other NSAIDS with warfarin may increase INR.
False -- increases bleeding risk but no change in INR.
116
Which condition may require a decrease in warfarin dose: chronic alcohol abuse with liver damage or without liver damage?
Chronic alcohol abuse with liver damage -- increased anticoagulant effect. Chronic alcohol abuse with normal liver actually induces hepatic enzymes that clear warfarin.
117
At what time of day is warfarin usually dosed?
In evening -- allows for good INR measurement in morning.
118
What should a patient be instructed to do in case of a missed dose?
When you remember, you can take it if it is within 12 hours of when you normally take it. If you are closer to the next dose than the one you missed, just skip it. Do not double up.
119
What should be a patient be counseled on regarding bleeding?
If you experience unexplained bruising or bruising that gets worse over time or bleeds that make you uncomfortable, seek medical help. Wear a medical ID bracelet just in case!
120
What dietary counseling points should you cover with a warfarin patient?
Keep vitamin K intake consistent (Boost shakes, green leafy vegetables) and no more than 1 drink of alcohol per day for women, 2 for men.
121
How and when is oral vitamin K given?
Given as a 5mg tablet if INR >10 and no evidence of bleeding. Acts in 24 hours.
122
If a patient has an INR of 6 and no evidence of bleeding, what should you do?
Hold warfarin doses and let INR come back slowly. Avoid vitamin K.
123
How is parenteral vitamin K dosed? How fast does it work?
Max rate of 1mg/min; works in 4-6 hours.
124
How is fresh frozen plasma dosed?
10-15 mL/kg
125
How is prothrombin complex concentrate dosed?
30 IU/kg
126
How can you achieve rapid (10-15 minute) reversal of warfarin?
PCC + IV vitamin K (FFP may also be used in addition)
127
What is the recommended VTE prophylaxis in patients who are ambulatory and undergoing minor surgery?
Just early, aggressive walking! No pharmacologic therapy recommended
128
What VTE risk are non-orthopedic surgery or acutely ill medical patients at?
Moderate -- VTE risk 10-40%
129
What are pharmacologic options for VTE prophylaxis for general surgery patients? How long should they be continued?
UFH, LMWH, and fondaparinux all options -- continue at prophylactic doses up to 28 days after discharge.
130
What are pharmacologic options for VTE prophylaxis for acutely ill medical patients (moderate risk)?
UFH, LMWH, and fondaparinux. Increased VTE risk d/t early discharge and immobility, but no specific recommendation for duration. Can stop anticoag on discharge.
131
What patients are at highest VTE risk?
Patients undergoing orthopedic surgery or who have experienced major trauma or spinal cord injury.
132
What six agents are approved for VTE prophylaxis in orthopedic surgery patients?
LMWH, fondaparinux, rivaroxaban, apixaban, UFH, or warfarin
133
In patients with high bleeding risk, what are VTE prophylaxis options?
Intermittent pneumatic compression devices, venous foot pumps, graduated compression stockings
134
What PE patients are most likely to benefit from a thrombolytic?
If PE associated with hypotension and a low bleeding risk
135
When using parenteral anticoagulation and warfarin to treat a VTE, when should warfarin be initiated?
Initiate warfarin on day 1-2 of treatment with LMWH/UFH/fondaparinux. Overlap at least 5 days and until INR >2.0 for 24 hours.
136
What CHAD2DS2-VASc score in a patient with NV atrial fibrillation warrants oral anticoagulants?
Score of 2 or greater
137
At what CHAD2DS2-VASc score in a NVAF patient can aspirin or anticoagulant be considered?
Score of 1
138
What are the criteria for the CHA2DS2-VASc scoring system?
```
1 - Congestive HF
1 - Hypertension
2 - Age 75 or greater
1 - Diabetes mellitus
2 - Stroke/TIA/TE
1 - Vascular disease (MI, PAD, aortic plaque)
1 - Age 65-74yo
1 - Female gender
```
139
Generally, what doses of anticoagulants do we use in NVAF?
Although anticoagulant is being used for prophylaxis, need to use treatment-like doses.
140
For the oral direct Xa inhibitors (rivaroxaban, apixaban, edoxaban), how long should they be stopped before a high bleeding risk procedure? For a low risk procedure?
Low bleeding risk: stop at least 24 hours before (36 hours if CrCl under 30)
High bleeding risk: stop at least 48 hours before
*same for dabigatran if CrCl 80 or greater*
141
If a patient is on dabigatran and needs to stop it for a high risk surgery and their CrCl is 35, how long before the surgery should they stop?
96 hours (4 days) before
142
When bridging any patient on warfarin therapy over a surgical procedure, when should warfarin be stopped?
5 days before surgery
143
When bridging a patient, when should LMWH be stopped before the procedure? UFH?
Stop LMWH 24 hours before procedure
| Stop IV UFH 4-6 hours before
144
When should warfarin be resumed after surgery?
12-24 hours after (if adequate hemostasis)
145
True or false: LMWH should be used when bridging the NOACs.
False -- don't need to bridge NOACs
146
What dose of enoxaparin should be used for bridging -- prophylaxis or treatment doses?
Treatment doses -- only exception is optional prophylaxis doses in 2 days after surgery.
147
When LMWH is dosed daily in bridging, what must the last dose before surgery be?
Last dose must be 24 hours before surgery and 50% of normal daily dose.
148
What anticoagulant should a patient receive in the day after their last warfarin dose in bridging?
None -- start LMWH in day after that.
149
When on dabigatran, rivaroaban, or apixaban, SCr, CBC, and PT/INR (direct Xa) or aPTT (dabigatran) should be monitored at least every ___ months.
3 months
