Pulmonary Embolism Flashcards
What is DVT?
DVT is an obstructive disease caused by obstruction to venous flow, involving the lower limb deep calf veins and propagating proximally. Acute thrombosis formation results in extensive remodelling process where neutrophils and macrophages infiltrate the fibrin clot over several weeks, leading to cytokine release and fibroblast and collagen replacement of fibrin
What age group most commonly experiences DVT?
Over 40 age group.
What is a sign of DVT?
Pain may occur with passive dorsiflexion, known as Homan’s sign.
List the common sites affected by DVT.
- Isolated calf vein
- Femoropopliteal vein
- Iliofemoral vein
The more proximal the vein, the more severe the thrombosis.
What is the relationship between the location of the vein and the severity of thrombosis in DVT?
The more proximal the vein, the more severe the thrombosis.
What are transient risk factors for DVT?
- HRT (hormone replacement therapy)
- Pregnancy
What are some risk factors for DVT?
- Increased venous pressure (CRP, malignancy, pregnancy, congenital conditions)
- Increased blood viscosity (polycythaemia, thrombocytosis, dehydration)
- Conditions like anticoagulation protein C and S, antithrombin III deficiency, and factor V mutation
What does Virchow’s triad include?
- Stasis
- Hypercoagulability
- Endothelial injury
What causes stasis of blood?
Post operative state, paralysis, long travel time
What causes hypercoagulability of blood?
Malignancy
Pregnancy
Nephrotic syndrome (due to reduction of clotting factors)
anti-phospholipid syndrome due to anti-cardio lipid antibodies
-> heparin-induced thrombocytopenia
-> burns
->sepsis
-> mypocardial infarction, heart failure, IBS
What causes endothelial injury?
Smoking, surgical procedures and venous catheters
What are common symptoms of DVT?
- Leg pain with redness and swelling
- Limb oedema
- Red/hot skin with dilated veins
- Tenderness
*Homan’s sign
Which leg tends to be affected in DVT?
Left leg due to compresssion of left iliac vein by the right common iliac artery.
What is Phlegmasia cerulea dolens?
Progression of phlegmasia alba dolens, Iliofemoral DVT causing near-total venous occlusion causing cyanosis with blue lower extremity, leading to venous gangrene and circulatory shock. There may be skin bullae.
It is managed with thromboectomy.
What characterizes Phlegmasia alba dolens?
Arterial compression from DVT causing limb ischemia with a ‘white limb.’ It presents with oedema, pain and blanching of leg
What is post-thrombotic syndrome?
Chronic venous insufficiency occurring after an acute DVT. The veins have undergone persistent thrombosis hat has led to fibrosis of vessel wall which leads to increased venous wall pressure, tissue swelling and tissue oxygen deprivation. In the long-term, there may be skin ulceration and chronic pain.
What are the features of post-thrombotic syndrome?
It is characterized by leg discomfort, heaviness, vein dilatation, oedema, skin discolouration, and venous ulcers.
What is the Villalta score used for?
To classify the severity of post-thrombotic syndrome based on cramps, heaviness, paraesthesia, pruiritus, oedema, redness, hyperpigmentation and venous ulcer.
What is used to determine the pre-clinical probability of DVT?
Well’s score
What are the features of Well’s score?
Previous DVT/PE
Active cancer
Recent immobilisation
Leg swelling
Asymmetric
Pitting oedema
Collateral superficial non-varicose veins
What should be done for patients with high pre-clinical probability of DVT?
D-dimer test and proximal leg vein ultrasound.
What should be suspected in unprovoked DVT?
Investigate for the possibility of undiagnosed cancer
Thrombophilia.
How is thrombophilia tested?
antiphospholipid syndrome
When diagnosis is uncertain, what should be offered?
Interim therapeutic anticoagulation with apixaban or LMWH.
What should be prescribed for confirmed DVT in haemodynamically unstable patients?
continuous unfractionated heparin infusion and thrombolytic therapy
What should be prescribed for haemodynamically stable patients with renal impairment?
apixaban/dabigatra should be offered to treat confirmed proximal DVT/PE in patients with renal impairment or failure.
What are the two types of pulmonary embolism (PE)?
- Haemodynamically stable PE
- Haemodynamically unstable PE
What causes pulmonary embolism?
FATAL:
Fat embolus
Amniotic embolus
Thrombosis
Atheroma
Less common such as septic embolism