DVT Flashcards
Name 6 differentials for unilateral limb swelling
• Dvt
• cellulitis
• ruptured baker’s cyst
• ruptured popliteal aneurysm
• arterial occlusion
• lymphoedema
Name 4 differentials for bilateral limb swelling
• Congestive cardiac failure
• DVT
• liver failure
• nephrotic syndrome
• fluid overload
Name the 3 factors that contribute to thrombosis
Virchow’s triad
• stasis of blood flow
• endothetial injury
• hypercoagulability
Name 3 complications DVT
• Pulmonary emboli
• phlegmasia caerulae dolens (“painfull blue inflammation”) : complete thrombosis of the deep venous system, including the collateral circulation. This results in significant venous congestion, fluid sequestration, and worsening edema. Untreated, it will progress to venous gangrene and cause massive tissue death.
• post thrombotic syndrome: chronic venous insufficiency with leg pain, leg heaviness, vein dilation, edema, skin pigmentation, and venous ulcers
Name 5 modifiable risk factors DVT
Lifestyle
• Obesity
• immobilization
Drugs
• oral contraceptives
• hormone replacement therapy
• drugs: chemotherapy, tamoxifen
Name 10 non modifiable risk factors DVT
Medical and surgical
•Previous DVT
• cancer
• surgery
• fractures
• paralysis
• acute medical illness
• varicose veins
• pregnancy
• hyper coagulable states:antiphospholipid antibodies, antithrombin deficiency, protein c and S deficiency, factor v Leiden, hyperhomocysteinaemia, prothrombin 20210a, high factor viii IX or xi
Host
• advanced age
Iatrogenic
• central venous line
Name and describe wells criteria for clinical probability of DVT
ACCEPTS BS
• Active cancer, treatment ongoing or within previous 6 months or palliative (1)
• paralysis, paresis, recent plaster immobilization of lower extremities (1)
• recently bedridden >3 days or major surgery within 4 weeks (1)
• localized tenderness along distribution of deep venous system (1)
• entire leg swollen (1)
• calf swelling by > 3cm compared with asymptomatic leg (measured 10 cm below tibial tuberosity) (1)
. Pitting Edema (1)
• collateral superficial veins non varicose (1)
• alternative diagnosis as likely or more likely than that of DVT (-2)
0-low probability 5%
1-2= intermediate probability 33%
≥3 = high probability 85%
Which investigations should be done for a patient with a low probability of DVT according to the wells score?
Controversial.
Some clinicians say always do duplex because D dimer can be falsely elevated.
Others say do D dimer. If low, 100% excludes DVT. If high, do duplex.
Which investigations should be done for a patient with a intermediate probability of DVT according to the wells score?
Duplex ultrasound
If positive, treat.
If negative, repeat after 5-7 days (duplex has low sensitivity and specitivity for calf veins. Only 2% will extend proximally within 2 weeks for which it is very sensitive)
Which investigations should be done for a patient with a high probability of DVT according to the wells score?
Duplex Ultrasound
What is D dimer?
Product of fibrin degeneration
Name 5 scenarios in which D dimer may be elevated
• DVT
• infection
• trauma
• surgery
• malignancy
Name 3 imaging options for DVT
• Venography: most sensitive and accurate, gold standard. But invasive, need contrast, time consuming. Only used therapeutically for thrombolysis
• venous duplex ultrasound: first line.
• CT v and MRI
Mechanical therapy for DVT?
• elevate leg
• compressive stocking
• Physiotherapy
Medical treatment of DVT? (7)
• Low molecular weight heparin eg enoxaparin (clexane) subcutaneous 1 mg/kg bd
• warfarin oral initially 5 mg daily for 2 days then titrate according to INR. Maintenance dose usually 2,5-10 mg daily.
Start both at the same time due to initial pro-coagulant effect of warfarin for the first 3 days.
Stop heparin once INR reaches therapeutic range of 2-3 for 2 consecutive days
Continue warfarin for
-6 months If first episode of idiopathic DVT
-3 months if reversible cause
-12 months if thrombophilic disorders or antiphospholipid antibodies
- indefinitely for patients above and recurrent DVT
Mechanism of action heparin?
Potentate inhibition of thrombin and activated factor Xa through antithrombin 3
Name 4 complications and limitations unfractioned heparin
• Unpredictable coagulation response, must monitor with aptt (activated partial thromboplastin time) to maintain it at 1,5 times the mean of the control value
• bleeding
• heparin induced thrombocytopenia
• osteoporosis
Name 6 advantages of using low molecular weight instead of unfractioned heparin
• Predictable coagulation response based on body weight so no need to monitor, cost effective.
• long half life and predictable clearance; can be given once (prophylaxis) or twice (treat) daily
• great bioavailability soon after subcutaneous injection
• fewer bleeding complications
• fewer complicating with heparin induced thrombocytopenia
• fewer complicating osteoporosis
Mechanism of action warfarin? (2)
• Inhibit vitamin K dependent factors 2,7,9,10
• thrombogenic by inhibiting vitamin k dependant proteins c and s first 3 days
Which 2 newer, expensive oral anticoag can be used instead of warfarin?
• Dabigatran
• rivaroxaban
Which location DVT is most likely to develop post thrombotic syndrome?
Iliofemoral 80-90% who are developed with anticoagulacion alone will develop
Name 3 methods of early clot removal in high risk. patients eg iliofemoral DVT to prevent post thrombotic syndrome and ulcers
• Catheter directed thrombolysis (CDT) (accelerate lysis thrombus and preserve valve function. Thrombolysis with tissue plasminogen activator tPA or urokinase)
• pharmacomechanical therapy
• surgical thrombectomy (for patients with venous gangrene with contraindications CDT)
Name 5 contraindications thrombolysis
• Bleeding diathesis (tendency)
• high risk bleeding eg recent surgery, gi bleed, trauma
• renal or hepatic failure
• pregnancy
• malignancy
Name 7 criteria for catheter directed thrombolysis
• Extensive acute iliofemoral DVT!
• symptoms < 14 days
• good life expectancy >1 year
• low risk bleeding
• angioplasty and stenting for underlying venous lesion
• pharmacomechanical therapy if expertise available (tPA, urokinase )
• still give normal anticoagulation therapy
Name 4 indications inferior vena cava filter for DVT
To reduce incidence pe:
•DVT with contraindications to anticoagulation
• recurrent pe on full anticoagulation
• anticoagulation complications that require discontinuation
• debatable: polytrauma or cancer patients with increased risk VTE because of increased risk bleeding
Which patients are at moderate risk of DVT following surgery? (3)
• Any surgery in patient age 40-60
• major surgery in <40
• minor surgery with 1 or more risk factors
Which patients are at high risk of DVT following surgery? (2)
• Surgery in age > 60
• major surgery in age 40-60 with 1 or more risk factors
Which patients are at very high risk of DVT following surgery? (8)
Major surgery in age >40 with
• previous DVT
• cancer
• hyper coagulability
• major orthopaedic surgery
• elective neurosurgery
• multiple trauma
• acute spinal cord injury
Thromboprophylaxis for low risk patients (<40, uncomplicated surgery, no risk factors) (3)
•Early ambulating
• graduated compressive stockings
• intermittent pneumatic compression
Thromboprophylaxis for moderate to high risk patients post op?
Mechanical methods plus anticoagulation.
0,5 mg/kg per day subcutaneous lmwh (some sources say 1 ) for 5-7 days or until mobilised
Can also use UFH, warfarin etc but need regular monitoring
Name 5 factors associated with increased mortality from pe
• CCD
• CLD
• syncope
• hypotension
• right heart failure
Name 5 symptoms pulmonary embolism
• Difficulty breathing
• tachycardia
• chest pain
• some may have haemoptysis
• May mimic acute mi or exacerbation of CLD
Name 4 investigations and findings for pe
• ECG: may show right bundle branch block, t wave inversion in leads V1 to v4, S wave lead 1, q wave and inverted t wave lead 3.
• D dimer: good screening
Troponin (cardiac biomarker) for risk stratification : elevation = increased mortality
• cxr: exclude other lung pathology but may show cardiomegaly, pulmonary artery enlarge, oligaemia (watermark sign) or wedge shaped infarction
. VQ ventilation perfusion scan: not used any more
Best - spiral CT scan
Treatment pulmonary embolism? (2)
• Low risk: anticoagulation alone (same as DVT)
• high risk with massive pe: thrombolysis or thrombectomy with anticoagulation.
