Pulmonary embolism and DVT Flashcards
How do DVTs occur?
Starts with damage to the endothelium, which causes vasoconstriction and subsequent platelet activation (primary haemostasis) and of clotting factors (secondary haemostasis), which forms a fibrin plug
What are risk factors for the development of DVT?
- Trauma
- Hormones - COCP, pregnancy
- Road traffic accidents
- Operations
- Malignancy
- Blood disorder - polycythaemia etc.
- Old age, obesity
- Serious illness
- Immobilisation
- S plenectomy
Others include dehydration and previous DVT
What are signs of DVT?
- Calf warmth
- Swelling
- Tenderness
- Erythema
- Pitting oedema
What are symptoms of DVT?
Can be asymptomatic
If symptomatic
- Leg swelling
- Calf tenderness
- Persistent discomfort
What type of clot is a DVT?
Red clot - rich in fibrin and trapped erythrocytes (hence redness)
Important to remember for treatment - red clots are treated using heparins and warfarin, as they target fibrin production
If someone presented with suspected DVT, what is important to do when examining the leg?
Look at colour, feel warmth, feel for pulses, and MEASURE CALF CIRCUMFERENCE
How would you determine what investigations to do on someone presenting with DVT?
Wells Score for DVT to assess risk
If someone presented with features of a DVT, what else would be part of a differential diagnosis?
- Cellulitis
- Ruptured baker’s cyst
- Tumour
- Calf muscle haematoma
- Necrotising fasciitis - if really acute
How would distinguish a DVT from cellulitis?
Usually manifest redness, heat, and swelling in the dermis of the affected leg.
The affected area is likely to be smaller than in DVT (which may involve the entire foot, calf, or thigh), but the signs more pronounced.
What criteria are assessed in the DVT Wells score?
- Active cancer = +1
- Paralysis/plaster = +1
- Bed >3 days/surgery within 4 weeks = +1
- Tender veins = +1
- Entire leg swelling = +1
- Calf swelling >3 cm = +1
- Pitting oedema = +1
- Collateral veins = +1
- Alternative diagnosis likely = -2
What does a DVT Wells score of =0 mean?
DVT unlikely
What does a DVT wells score of 1-2 indicate?
DVT moderately likely
What does a DVT wells score of >2 indicate?
DVT highly likely
What investigations would you do if someone had a Wells score of <2?
- D-dimer
What investigations would you do in someone with DVT Wells score of >2?
D-dimer and Doppler ultrasound
What are important questions to ask in someone with swollen legs (9 questions…)?
- Is it both legs?
- Any trauma?
- Any pain
- Is she Pregnant?
- Any Pitting?
- Any skin changes?
- Are they Mobile?
- PMH/Medical History?
- Any oedema elsewhere?
If someone presented with swollen legs, what oedematous conditions would you consider?
- Nephrotic syndrome
- CCF
What does bilateral leg swelling indicate?
Implies systemic disease with increased venous pressure or decreased intravascular oncotic pressure
What are causes of bilateral leg swelling?
- Right heart failure
- Renal/liver failure
- Venous insufficiency
- Vasodilators - nifedipine, amlodipine
- Pelvic mass
- Pregnancy
How would you managet someone with a DVT?
Early mobilisation
Adequate hydration
Medications
- LMWH
- Introduce Warfarin - switch to just warfarin when INR 2-3
Procedures
- Inferior vena caval filter
How long would you treat someone with a DVT with warfarin which was caused by a surgical procedure?
3 months
How long would you treat someone with warfarin for a DVT if no cause of DVT was found?
6 months
How long would you treat someone with warfarin for DVT if they had recurrent DVT?
Lifelong
What measures could you take to prevent DVT from developing?
- Stop the pill 4 weeks pre-op
- Mobilisation
- Prophylactic LMWH
- Compression stockings
- Intermittent pneumatic compression devices - those that are immobile
What are complications of a DVT?
- Pulmonary embolism
- Stroke - if ASD present
- Post-phlebitic syndrome
- Bleeding complications from treatment
What is the mechanism behind dyspnoea in thromboembolism?
It is thought that pressure receptors or C-fibres in the pulmonary vasculature or right atrium are activated and interact with central systems, contributing to dyspnoea
If you found a DVT on investigation, what other investigation might you do?
Look for causes
- Thrombophilia testing
- Underlying malignancy - Urine dip, FBC, LFT, Ca2+, CXR +/- CT abdo/pelvis if >40
What is a pulmonary embolism?
https://www.youtube.com/watch?v=Lp65yGitCNo
A venous thrombi, usually from a DVT, passes into the pulmonary ciruclation and blocks flow to the lungs