DVT Flashcards
define DVT?
formation of thrombus within the deep veins ( commonly in calf or thigh)
summarise the epidemiology of DVT?
VERY COMMON
Especially in hospitalised patients
Explain the aetiology/ risk factors of DVT?
deep veins in the legs are more prone to blood stasis-> hence clots are more likely to form
VIRCHOW’S TRIAD
What are the risk factors for DVT?
COCP
Post-surgery
Prolonged immobility
Obesity
Pregnancy
Dehydration
Smoking
Polycythaemia
Anti-phospholipid syndrome
Heparin-induced thrombocytopenia
Malignancy
Factor V Leiden
Protein C/Protein S deficiencies
Prothrombin mutation
Antithrombin III deficiency
What are the presenting symptoms of DVT?
swollen limb
may be painless
what are the signs of DVT on examination?
- local erythema, warmth and swelling
- measure the leg circumerence
- varicosities ( swollen/toturous vessels)
- skin colour changes
- mild fever
- pitting oedema
HOMANS SIGN- forced passive dorsiflexion of the ankle causes deep calf pain
Remember to examine for PE- check for resp rate, pulse oximetry and pulse rate
how is the risk for DVT stratified?
Wells criteria
score 2 or more= high risk
what are the appropriate investigations for DVT?
Wells score
bloods-D-dimer and thrombiphilia screen if indicated
doppler ultrasound- GOLD STANDARD
venometer- a machine that uses automated strain gauge plethysmography to detect DVT. It is quick and non-invasive.
INR and aPTT
Urea and Cr/ LFTs/ FBC
If PE suspected-> ECG, CXR, ABG
Outline the general management plan for DVT?
__oxabans/ dabigatran/ ___aparin (LMWH+ warfarin)
DVTs that do NOT extend above the knee may be observed and anticoagulated for 3 months
DVTs extending beyond the knee require anticoagulation for 6 months
The dose of low molecular weight heparin depends on the patient’s weight in kilograms ->Low molecular weight heparin should be used with caution in severe renal failure due to increased risk of bleeding
Heparin is monitored using APTT and is stopped once INR is 2.5 but continue warfarin
if the patient is at a high risk of bleeding or renal fail they should be treated with unfractionated heparin and you should avoid fondaparinux.
Evidence that LMWH are better than warfarin for malignant conditions and are preferred in pregs as LMWH don’t cross the placenta
Recurrent DVTs require long-term warfarin
- Use INR to monitor
- -Aim for INR of 2 – 3 in uncomplicated DVT (norm is 1 – 2)
IVC- may be used if anticoagulation is conrtadicated and there is a risk of PE or patient
When can an IVC be used in the management of DVT?
Can be used in active bleeding or when anticoagulants fail to minimise the risk of PE
outline prevention of DVT?
Stop the contraceptive pill 4weeks pre- op
mobilize early
Graduated compression stockings
prophylactic heparin ( if high risk eg hospitalised patients)
what are the complications of DVT?
PE
Venous infarction (phlegmasia cerulea dolens) - rare
Thrombophlebitis (results from recurrent DVT)
Chronic venous insufficiency of lower limb
Damage to the vein valves
Of treatment:
Heparin induced thrombocytopenia
Bleeding
Outline the prophylaxis DVT management ( eg a patient taking a long term)
describe measuring D -dimer as an investigation for DVT?
D dimer is a protien present after fribrinolysis- they are sensitive but not very specific and only useful as a negative predictor in low-risk patients ( No use in preg ladies as would be raised anyway
What are the possible point ffor the Wells score?
- Active cancer (treatment ongoing, within the last 6 months, or palliative).
- Paralysis, paresis, or recent plaster immobilization of the legs.
- Recently bedridden for 3 days or more, or major surgery within the last 12 weeks requiring general or regional anaesthesia.
- Localized tenderness along the distribution of the deep venous system (such as the back of the calf).
- Entire leg is swollen.
- Calf swelling by more than 3 cm compared with the asymptomatic leg.
- Pitting oedema confined to the symptomatic leg.
- Collateral superficial veins (non-varicose).
- Previously documented DVT.
