Weber Recorded Lecture Flashcards
Where do venous thrombi (blood clots) form?
Areas of slow/disturbed blood flow
*promoted by stasis blood
What affect does stasis blood have on clotting factors?
Stasis blood decreases clotting factor clearance
What is the connection between PE’s and DVT’s?
All PE’s come from DVT’s
BUT
Not all DVT’s come from PE’s
What is Virchow’s triad and what are its 3 components?
Virchow’s triad consists of the 3 main things that contribute to the development of a blood clot
(nearly all patients who develop a blood clot will have one or more of these, but not all patients with these will develop a blood clot)
- Hypercoagulable state
(abnormal clotting components, seen in pregnancy and cancer) - Circulatory Stasis
(abnormalities in blood flow, seen in long periods of immobility and afib) - Endothelial injury
(abnormal surfaces in contact with blood flow, seen when blood vessels are injured such as during surgery or after traumatic injury)
What is the pathway for blood clot formation and degradation?
Vessel Wall Injury (Endothelium becomes exposed)
Platelet Adhesion and Aggregation
Coagulation Cascade Activation
Thrombin
Fibrin Formation
Stabilized Fibrin Clot
Fibrinolysis and Clot Degradation
Recanalization and Healing
What is the role of Von Willebrand Factor?
ACTIVATES platelet adhesion and aggregation to the endothelium after injury occurs
What is the role of:
Tissue Factor
Factor VIIa (7)
Factor Xa (10)
Factor XIIa (12)
Thrombin (Factor II)?
ACTIVATE the formation of thrombin through the coagulation cascade
What is the role of Factor XIIIa (13)?
ACTIVATES formation and stabilization of the fibrin clot
What is the role of Tissue Plasminogen Activator?
**This is the exception to the activators
Activates clot degradation
What is the role of Heparin and Thrombomodulin?
INHIBIT platelet adhesion and aggregation to the endothelium
(Opposite of Von Willebrand factor)
What is the role of:
Antithrombin
Protein C
Protein S
Tissue Factor Pathway inhibitor?
INHIBIT the formation of thrombin through the coagulation cascade
What is the role of Plasminogen activator Inhibitor-1?
*This is the exception of the inhibitors and the opposite of Tissue Plasminogen Activator
Inhibits clot degradation
What happens during the “Initiation” phase of the coagulation cascade?
Trace amounts of thrombin develop
What happens during the “Amplification” phase of the coagulation cascade?
Trace amounts of thrombin from the Initiation phase leads to more thrombin being produced
-This leads to the activation of clotting factors
What happens during the “Propagation” phase of the coagulation cascade?
A large amount of thrombin is produced
-This leads to fibrinogen being converted to fibrin
-The fibrin clot forms
What Factor # is thrombin?
IIa
What Factor # is prothrombin?
II
*not the active form
What is postthrombotic syndrome?
A long-term complication of DVT
*caused by damage to venous valves
What must we do before diagnosing postthrombotic syndrome?
Rule out recurrent thrombosis
What are 4 non-pharmacological treatment options for DVT?
-Bed Rest
-Elevation of Feet
-Pain Management
-Compression Stockings
What are 3 non-pharmacological treatment options for PE?
-Oxygen
-Mechanical Ventilation
-Compression Stockings
What is a PE?
A blood clot that blocks and stops blood flow to an artery in the lung
Is unfractionated heparin (UFH) long-acting or rapid?
Rapid
How is UFH administered?
Given as a continuous infusion
True or False: UFH has a variable dose response
True
What is aPTT monitoring?
The monitoring system put into place for UFH
-Stands for: activated Partial Thromboplastic Time
**Monitors how long blood takes to clot
What is the goal for aPTT monitoring?
1.5-2.5 x Control
(will be given what control is)
How is UFH dosed?
*Based on weight and has two parts:
80 units/kg IV bolus
and
18 units/kg/hr infusion
What are the adverse effects associated with UFH?
-Bleeding
-Thrombocytopenia
How often should aPTT monitoring occur?
-At baseline
-6 hours after dose or with each dosage change (for first 24 hours)
-Check daily after first day (and if in goal)
What are some key differences between Heparin Associated Thrombocytopenia (HAT) and Heparin Induced Thrombocytopenia (HIT)?
HAT:
-AKA: HIT-Type 1
-Non-immune mediated
-Mild decrease in platelets (remain > 100,000)
-Occurs 48-72 hours after heparin administration (early onset)
-Transient (lasts short time)
-DO NOT NEED TO DISCONTINUE HEPARIN
HIT:
-Immune mediated
-Thrombotic complications
-Occurs 7-14 days after heparin administration (late-onset)
-Can occur up to 9 days after stopping therapy
-Platelets drop >50% from baseline (<100,000)
For which heparin-associated complication do we need to stop ALL heparin products? (HIT or HAT)
HIT
(heparin induced thrombocytopenia)
What platelet levels are indicative of HIT?
Platelet levels that drop > 50% from baseline or are < 100,000/mm^3
Which of the heparin-associated complications has a quick onset (HIT or HAT)?
HAT
(occurs around 48-72 hours after administration)
When a patient develops HIT how should it be managed?
-Stop all heparin products
-Give alternative anti-coagulant (lepirudin, argatroban, bivaliruden, or fondaparinux)
-Evaluate for thrombosis
Should platelet infusions be given when a patient develops HIT?
NO (even though platelet count is low)
At what platelet count are we able to give a patient warfarin after they develop HIT?
We can give a patient warfarin once their platelet count reaches > 150,000
What are the advantages of LMWH over UFH?
-Reduced protein binding (good bioavailability, predictable dose response, no resistance)
-Predictable dose response (fixed or weight-based dosing, no monitoring required)
-Longer plasma half-life (once or twice daily dosing)
-Smaller molecule (improved subq absoprtion)
-Less effect of platelets and endothelium (reduced HIT and possibly bleeding)
What is the dosing of enoxaparin (Lovenox) for prophylaxis?
Surgery: 30mg subQ every 12 hours
Medical: 40mg subQ daily
What is the dosing of enoxaparin (Lovenox) for treatment?
Every 12 hours: 1 mg/kg subQ
Daily: 1.5 mg/kg subQ
What is the dosing of enoxaparin (Lovenox) for renal dysfunction (CrCl <30)?
Prophylaxis: 30 mg subQ daily
Treatment: 1 mg/kg subQ daily
What is the monitoring parameter for LMWH?
*Routine monitoring is not generally recommended (Unlike with UFH)
*Monitoring of Anti Xa Levels only done in special populations
What populations should have their Anti Xa Levels monitored when receiving LMWH treatment?
Children
Severe Kidney Failure
Obesity
Long Courses of treatment
Pregnancy
How are Anti Xa levels monitored in special populations?
Twice Daily Dosing:
—Goal: 0.6-1 units/mL
(obtained 4 hours post-dose) [This is the peak]
Once Daily Dosing:
—Goal: 0.1-0.3 units/mL
(obtained immediately before dose is given) [This is the trough]
What is the one INJECTABLE (IV) Factor Xa Inhibitor?
Fondaparinux
When would we use Fondaparinux?
-Prophylaxis following: THA, TKA, Hip replacement (hip and knee surgeries), abdominal surgery
-Treatment of DVT and PE
HIT
What is the dosing used for Fondaparinux?
Prophylaxis: 2.5mg subQ once daily (for knee, hip, or abdominal surgery)
Treatment (HIT):
<50 kg: 5mg subQ once daily
50-100kg: 7.5mg subQ once daily
> 100kg: 10mg subQ once daily
When should Fondaparinux not be used?
Renal dysfunction (CrCl <30 mL/min)
Prophylaxis with low body weight (<50 kg)
What is the monitoring procedure for Fondaparinux?
No routine monitoring for efficacy
(but can monitor anti-Xa levels similar to LMWH)
Is Fondaparinux safe in pregnancy?
YES
What are the IV direct thrombin inhibitors?
Lepirudin
Bivalirudin (Angiomax)
Argatroban