DVT Flashcards
What is DVT?
The formation of a thrombus (blood clot) in a deep vein
Where does DVT usually occur?
Leg
What is the most common complication of DVT?
Pulmonary embolism
What is the cause of DVT?
Slow blood flow
What are possible causes of the slow blood flow?
Atherosclerosis, trauma or infection
What is an embolus?
When part of a blood clot breaks away and is transported through the body by the blood stream
What are the three inter-related factors in the formation of DVTs? *
- Venous stasis (pooling of blood in vein)
- Injury to blood vessel wall
- Altered blood composition
Why is a thrombus less likely to form in an artery?
Higher pressure
What feature of the veins makes venous stasis more likely?
One-way valves
What are some symptoms of DVT?
- Pain (worst when standing/walking)
- Swelling
- Warmth & redness
- Tenderness over calf muscle
- Venous distension
- Low grade pyrexia
What does PTS stand for?
Post thrombotic syndrome
What causes PTS?
After DVT treatment, vein can be anatomically altered (such as valve incompetence)
In PTS, residual venous obstruction and valvular reflux result in:
Higher venous pressure
In PTS, higher venous pressure results in:
Reduced calf muscle perfusion and increased tissue permeability
What are symptoms of PTS?
- Pain
- Heaviness
- Swelling
- Cramps
- Itching, or tingling in the affected limb
In PTS, how are symptoms aggravated?
Standing or walking
Who is at risk of DVT?
- Older age
- Pregnancy
- Obesity
- Varicose veins
- Immobility
- Puerperium
- High-dose oestrogen therapy
- Thrombophilia
Disease/surgical risk factors of DVT:
- Trauma or surgery stress response
- Malignancy
- Heart failure
- Recent myocardial infarction
- Lower limb paralysis
- Infection
- Inflammatory bowel disease
- Nephrotic syndrome
High risk situations for DVT:
- Major surgery, trauma or illness in patients with previous DVT, PE or thromboembolism
- Major limb amputation
- Fracture or major orthopaedic surgery of pelvis, hip or lower limb
- Major pelvic or abdominal surgery for cancer
What is the aim of treatment for DVT?
To prevent:
- clot increasing
- clot breaking loose and travelling
- new clots
- post-thrombotic syndrome
What is the treatment for suspected DVT?
Low molecular weight heparin, then oral anticoagulant
What is the treatment for DVT if thrombolysis should be considered in immediate post-operative period?
IV unfractioned heparin
What are mechanical prophylaxis for DVT?
Flowtron (IPC) boots, thrombo-deterrent (TED) stockings
How does heparin work?
- Reduces the blood’s tendency to clot
- Stop new clots from forming
- Stop old clots from growing
What is the difference in UFH and LWMH?
The duration of action is longer in LWMH
What does warfarin do?
Inhibits the action of Vitamin K
What check needs done regularly for those on warfarin?
International normalised ratio (INR) checks
What does the international normalised ratio (INR) check do?
Show how long a person’s blood takes to clot
How does aspirin work?
Inhibits vasoconstriction & platelet aggregation.
What are thrombolytics?
Drugs to get rid of blood clots
What does Streptokinase prevent?
Pulmonary embolism
What is a normal INR?
1-1.5
What is the INR kept at for those taking warfarin?
2-3
What conditions cause a prolongation of clotting time?
- Liver disease
- Use of oral anticoagulants
What are contraindications for the use of TEDs?
- Oedema of lower limbs
- Severe peripheral vascular disease
Symptoms of pulmonary embolism
- Dyspnoea
- Tachypnoea
- Sinus tachycardia
- Haemoptysis
- Chest pain
- Faintness, collapse
- Sudden death
What investigations can be carried out for a pulmonary embolism?
- ECG
- CT scan
- Arterial blood gas
- Perfusion/ventilation lung scans
- Pulmonary angiography
How may a CT scan show PE?
May show pulmonary vascular obstruction
How may an arterial blood gas show PE?
May show hypoxaemia and hypocapnia
What is the initial treatment for PE?
High flow O2 therapy, analgesia, fluids and UFH
What is given for PE after UFH?
Warfarin
What improves the efficacy of the heart, maintains BP and stroke volume for PE treatment?
Inotropic support
(adrenaline and noradrenaline, dobutamine, dopamine)
What is the heparin reversal drug?
Protamine sulfate
How does fonaparinux prevent DVT?
Inhibits Factor X
