Theme 2: Lecture 7 - Thrombotic disorders Flashcards
DVT
Deep vein thrombrosis
Describe how DVT happens
- Due to activation of the clotting cascade in the veins when blood flow slows down
- This will cause swelling of the leg
- An embolus could break off and and travel to the lungs - life threatening
3 risk factors of Virchow’s triad
- Circulatory stasis
- Endothelial injury
- Hypercoagulable state
Thrombotic risk factors
- Post-operative, especially orthopaedic
- Hospitalisation
- Cancer
- Pregnancy
- Oral contraceptive pill
- Long-haul flights
- Obesity
- i.v. drug abuse
Presentation of DVT
- Can be no symptoms at all – clinically silent
- Unilateral calf swelling/ heat/ pain/ redness/ hardness
Differential diagnosis of DVT
- cellulitis
- Baker’s cyst
- muscular pain
Cellulitis
a common, potentially serious bacterial skin infection
Baker’s cyst
- A Baker’s cyst can form when joint-lubricating fluid fills a cushioning pouch (bursa) at the back of your knee.
- A Baker’s cyst is a fluid-filled cyst that causes a bulge and a feeling of tightness behind your knee
How is DVT diagnosed
Doppler ultrasound
What is the likelihood of of having a DVT assessed by
- D-dimer test
- Wells risk score
What do D-dimers indicate
activation of the clotting cascade
Negative predictive value
- Represents the probability that a person does not have a disease or condition, given a negative test result.
- NPV represents the proportion of individuals with negative test results who are correctly identified or diagnosed
What does a low wells score and a negative D-dimer test mean
There is a high negative predictive value for DVT, more than 99%
Initial treatment for above the knee DVT
- Therapeutic anti-coagulation using sub-cut LMW heparin (such as tinzaparin or enoxaparin)
- Dose of LMW heparin according to patient’s weight
- LMW heparin used as a bridge before patient can be treated with warfarin
- No monitoring required (but can use anti-Xa assay)
- Ensure adequate EGFR > 30ml/min
- Otherwise use iv unfractionated heparin (APTR 2.0)
Name 3 LMW heparin drugs
- Tinzaparin
- Enoxaparin
- Dalteparin
EGFR
estimated glomerular filtration rate
What is an adequate EGFR
> 30mL/min
When is LMW heparin stopped for treating DVT
once the INR > 2.0 for 2 days
How long is the patient treated with anticoagulation after their first DVT
6 months
How long is the patient treated with anticoagulation after their 2nd DVT/PE
lifelong
How often is the INR monitored on treatment with anticoagulants
every 3 weeks
What should the INR be
between 2.0-3.0 (target of 2.5)
What drug is the patient switched to after the initial treatment with LMW heparin for DVT
oral warfarin
Clinical presentation of a micro emboli
asymptomatic