DVT / PE Flashcards
Define venous thrombosis
the formation of a blood clot (thrombus) within a vein, which can lead to a blockage of blood flow
Types of venous thrombosis
- Deep vein thrombosis
- Superficial venous thrombosis
what triad is used to describe the poathophysiology of the formation of a thrombus?
Virchow’s triad
SHE
Virchow’s Triad
- Stasis of blood flow
- Hypercoagulability
- Endothelial damage
Stasis of blood flow factors for VT
- immobility - long haul flight, post-op bed rest, bed-bound in hospital (most common)
Endothelial damage factors for VT
- atheroma formation
- inflammatory response
- direct trauma
Hypercoagulability factors for VT
- smoking
- blood disorders (Factor V Leiden, Anti-phospholipid syndrome)
- malignancy
- sepsis
- pregnancy
Define superficial veins
Veins located just beneath the skin (subcutaneous), drain into deep veins
GPS
Superficial veins of the LL/Pelvis
- Great saphenous vein - medially up to femoral vein
- Small Saphenous vein - back of calf –> popliteal
- Perforator vein - connects all superficial veins to deep veins
Deep veins of the LL/Pelvis
- Iliac –> common iliac –> inferior vena cava
- Femoral
- Popliteal
- Tibial –> popliteal
Venous thrombosis risk factors
- Increasing age
- Previous VTE
- Smoking
- Pregnancy or recently post-partum
- Recent surgery (especially abdominal surgery, pelvic surgery, or hip or knee replacements) or prolonged immobility (approx. > 3 days)
- HRT / COCP
- Current active malignancy
- Obesity
- thrombophilia disorder (e.g. antiphospholipid syndrome or Factor V Leidin)
Define DVT
refers to the formation of a blood clot in the deep veins of a limb, most commonly affecting those of the legs or pelvis.
DVT clinical presentation
- unilateral leg pain / swelling
how to measure calf size in DVT
- 10cm below the tibial tuberosity
- measure the circumference
- compare both calves
- > 3cm = significant
What score is used to calculate risk of DVT
DVT Well’s score
what does DVT Well’s score < or = 1 mean
- DVT unlikely
- D-dimer within 4hrs OR interim therapeutic anticoag
- -ve (consider other Dx)
- +ve (Doppler USS within 4hrs)
what does DVT Well’s score > 1 mean
- DVT likely
- Doppler USS within 4hrs
- Doppler USS +ve (confirm + treat)
- Doppler USS -ve (stop interim antocoag and perform d-dimer, repeat USS in 6-8 days)
what other conditions cause a raise in d-dimer
- malignancy
- HF
- Pregnancy
- Infection
- Surgery
what is the 1st line Tx for antiphospholipid syndrome (APS) to prevent DVT
Warfarin
VKA
what is the 1st line Tx for a DVT
DOACs
what is the INR target range DVT / PE
2-3
what is the 1st line Tx for DVT in pregnancy
LMWH - Enoxaparin
what is the duration of the Tx in unprovoked DVT
6 months
what is the duration of the Tx in provoked DVT
3 months
what is an inferior vena cava filter
Devices inserted into the inferior vena cava to filter out any blood clots that are travelling from the venous system towards the heart / lungs
Acting as a sieve
what should be considered in a first, unprovoked VTE (no clear risk factors)
Cancer
Indications for an inferior vena cava filter
- Reccurent PEs
- Unsuitable for anticoag
what further Ix should be carried out in a first, unprovoked VTE (no clear risk factors)
1.Consider cancer
- thorough med Hx
- Examination
- Baseline bloods (FBC, UEs, LFTs, Clotting screen)
- Antiphosphlipid Abs (APS)
- Hereditary thrombophilia (FMHx, 1st degree relative)
Main complication of DVT
PE
what type of shock does PE cause
Obstructive shock - Pulmonary occlusion from an embolus prevents blood from returning to the heart
Define Pulmonary Embolism
to a blockage of the pulmonary artery by a substance that has travelled there in the bloodstream
PE Sx
- sudden onset dyspnoea (SOB)
- pleuritic CP
- cough
- haemoptysis (rare)
PE signs
- Tachycardic
- Tachypnoea
- Low O2 sat. (hypoxia)
- Pyrexia
- raised JVP (rare)
- pleural rub on auscultation
- hypotension
what does PE Well’s score < or = 4 mean
- PE unlikely
- D-dimer within 4hrs
- D-dimer -ve –> NAD
- D-dimer +ve CTPA OR interim anticoag
what does d-dimer blood test detects
fibrin degradation products, indicating recent clot formation.
what is the gold standard Ix for DVT
Contrast venography (contrast dye into a vein and using X-rays to visualize venous blood flow and clots)
invasive, contrast/radiation risks
what is the 1st line imaging for DVT
Doppler USS
How is doppler USS used in diagnosing / managing DVT
- Detects thrombus presence, size, and location in deep veins.
- Evaluates venous valve function and risk of post-thrombotic syndrome.
- Can be used for follow-up to monitor clot resolution
when is contrast venography indicated
- inconclusive doppler USS
- complex DVT - ilian vein or recurrent DVT
Most common ECG findings for PE
- Sinus Tachy
- unremarkable
PE Well’s score > 4
- PE likely
- CTPA OR interim anticoag
- CTPA +ve –> Tx
- CTPA -ve –> susp. DVT –> Doppler USS
when is VQ scan indicated over CTPA in PE
- CrCl < 30
- Allergy to contrast
what is the Mx for massive haemodynamically unstable PEs
Thrombolysis
PE CXR findings
Normal
PE ABG findings
Resp alkalosis: hypoxia –> hyperventilation –> loss of CO2 –> low CO2 –> more alkalotic
PE VQ scan findings
- High V/Q ratio
- ventilation-perfusion mismatch
HHR
What are the clinical consequences of a PE
Hypoxemia due to impaired gas exchange.
Hyperventilation as compensation, leading to respiratory alkalosis (low PaCO₂).
Right heart strain due to increased pulmonary vascular resistance.
