Flashcards in Deep Vein Thrombosis and Pulmonary Thromboembolism Deck (23)
What is the incidence of DVT?
1 in 1000 per annum
What is the case fatality rate of venous thromboembolism?
What is the incidence of PE?
3000-5000 per annum
What percentage of autopsies reveal a PE?
20% of autopsies
What are the components of Virchow's Triad?
What are examples of presentations of venous thromboembolism?
Visceral venous thrombosis
Intracranial venous thrombosis
What are the features of venous thrombus?
Red thrombus - fibrin and red cells
Results in back pressure
Principally due to stasis and hypercoagulability
What are the features of arterial thrombus?
White clot - platelets and fibrin
Results in ischaemia and infarction
Principally secondary to atherosclerosis
What is the presentation of DVT?
Unilateral limb swelling
May also be clinically silent
What are the potential long-term consequences of DVT?
e.g. swelling, discomfort, pigmentation, ulceration
What is the presentation of PE?
Pleuritic chest pain
Pleural rub on auscultation
What is the presentation of massive PE?
Severe dyspnoea of sudden onset
Altered heart sounds
May cause sudden death
What are the potential long-term consequences of PE?
Most recover fully
May result in pulmonary hypertension
What are the risk factors for venous thromboembolism?
Systemic disease e.g. cancer
Genetics e.g. heritable thrombophilia
Exogenous oestrogen e.g. OCP, HRT
What is the most prevalent heritable thrombophilia?
Factor V Leiden
What is the link between VTE and travel?
Relative risk increased by 2-3
Increased risk in short, tall or overweight people, and in women on the OCP
How is DVT diagnosed?
How is a d-dimer test useful?
Negative result is more useful as it will rule out DVT
Positive result will not confirm DVT but will indicate need for more investigation
How is PE diagnosed?
D-dimer in unlikely patients
Isotope ventilation/perfusion scan
CT pulmonary angiogram
How can VTE be prevented in hospital?
Daily injections of low molecular weight heparin
What pressures are provided by anti-embolism stockings?
18mmHg at the ankle
14mmHg at the mid-calf
8mmHg at the upper thigh
Result in maximal femoral blood flow velocity of 139% of the baseline
When are graduated compression stockings useful?
Prevention of DVT
Chronic venous insufficiency
Prevention of post-phlebitic syndrome