Deep vein thrombosis and pulmonary thromboembolism Flashcards
In what % of autopsies are PE found?
20%
What is Virchows triad?
Describes three broad categories of factors which contribute to thrombosis:
- Stasis
- Hypercoagulability
- Vessel damage
What conditions can cause hypercoagulability?
Pregnancy
Trauma
Heritable thrombophilia
Give some examples of conditions caused by thromboembolism
Limb deep vein thrombosis (DVT) Pulmonary embolism Visceral venous thrombosis (distended vessels on stomach) Intracranial venous thrombosis Superficial thrombophlebitis
What are the differences between an arterial and venous clot?
Arterial - white clot (platelets and fibrin), found at site of endothelial damage or turbulence, resulting in ischaemia and infarction, primarily secondary to atherosclerosis
Venous - red clot (fibrin and red cells), found at site of stasis, resulting in back pressure, and primarily due to stasis and hyper coagulability
What are the signs and symptoms of DVT?
Unilateral limb swelling Persisting discomfort Calf tenderness Warmth and redness Can be clinically silent
What are the signs and symptoms of PE?
Pleuritic chest pain (felt when breathing) Dyspnoea Haemoptysis Tachycardia Pleural rub on auscultation
If a big clot: Collapse Cyanosis of lips and tongue Low BP Raised JVP Altered heart sounds Can cause sudden death
What is long term consequence of DVT?
Post-phlebitic syndrome - swelling discomfort, pigmentation, ulceration
What is a potential long term consequence of PE?
Pulmonary hypertension
Most recover fully
What are some risk factors for blood stasis and therefore venous thrombosis?
Age Trauma Immobility Obesity Smoking Cancer Pregnancy Exogenous oestrogen
What is heritable thrombophilia?
Inherited predisposition to venous thrombi
What is the most prevalent heritage thrombophilia?
Factor V Leiden (human variant form of factor V). In this, the protein that stops facto V from inappropriately clotting is inhibited, leading to an increased tendency to form dangerous clots
Who have an increased risk of developing VTE when travelling?
Tall Short Overweight Women on COCP Those in window seats
How do you diagnosis DVT?
Clinical assessment with Wells criteria
Blood test for D-dimer
Imaging with compression ultrasound
How do clinicians assess the likelihood of DVT?
Wells criteria, 1 for each: - active cancer - paralysis/plaster - bed > 3 days/ surgery within 4 weeks - tender veins - entire leg swelling - calf swelling >3cm - pitting oedema - collateral veins ( - alternative diagnosis likely = -2 points) Low = 0 Moderate = 1/2 Severe = 3+
How do you diagnose PE?
Clinical assessment
D-dimer
Isotope ventilation/perfusion scan
CT pulmonary angiography
How can we prevent VTE in hospital?
Early mobilisation
Anti-embolism stockings
Other physical methods
Daily heparin injections
Describe the design in anti-embolism stockings
They provide:
- 18mmHg at ankle
- 14mmHg at mid calf
- 8 mmHg at upper thigh
What are the indications of graduated compression stockings?
prevention of DVT chronic venous insufficiency varicose veins oedema lymphoedema prevention of post-phlebitic syndrome
How do you treat VTE?
Low mol weight heparin for 5 days at least Oral anticoagulant (e.g. warfarin) 3 months
How do you treat PE?
Immediate thrombolysis if big
How can you prevent PE?
Vena caval filter
