DVT Flashcards

1
Q

What is DVT?

A

The formation of a thrombus (blood clot) in a deep vein

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2
Q

Where does DVT usually occur?

A

Leg

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3
Q

What is the most common complication of DVT?

A

Pulmonary embolism

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4
Q

What is the cause of DVT?

A

Slow blood flow

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5
Q

What are possible causes of the slow blood flow?

A

Atherosclerosis, trauma or infection

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6
Q

What is an embolus?

A

When part of a blood clot breaks away and is transported through the body by the blood stream

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7
Q

What are the three inter-related factors in the formation of DVTs? *

A
  • Venous stasis (pooling of blood in vein)
  • Injury to blood vessel wall
  • Altered blood composition
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8
Q

Why is a thrombus less likely to form in an artery?

A

Higher pressure

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9
Q

What feature of the veins makes venous stasis more likely?

A

One-way valves

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10
Q

What are some symptoms of DVT?

A
  • Pain (worst when standing/walking)
  • Swelling
  • Warmth & redness
  • Tenderness over calf muscle
  • Venous distension
  • Low grade pyrexia
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11
Q

What does PTS stand for?

A

Post thrombotic syndrome

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12
Q

What causes PTS?

A

After DVT treatment, vein can be anatomically altered (such as valve incompetence)

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13
Q

In PTS, residual venous obstruction and valvular reflux result in:

A

Higher venous pressure

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14
Q

In PTS, higher venous pressure results in:

A

Reduced calf muscle perfusion and increased tissue permeability

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15
Q

What are symptoms of PTS?

A
  • Pain
  • Heaviness
  • Swelling
  • Cramps
  • Itching, or tingling in the affected limb
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16
Q

In PTS, how are symptoms aggravated?

A

Standing or walking

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17
Q

Who is at risk of DVT?

A
  • Older age
  • Pregnancy
  • Obesity
  • Varicose veins
  • Immobility
  • Puerperium
  • High-dose oestrogen therapy
  • Thrombophilia
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18
Q

Disease/surgical risk factors of DVT:

A
  • Trauma or surgery stress response
  • Malignancy
  • Heart failure
  • Recent myocardial infarction
  • Lower limb paralysis
  • Infection
  • Inflammatory bowel disease
  • Nephrotic syndrome
19
Q

High risk situations for DVT:

A
  • 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
20
Q

What is the aim of treatment for DVT?

A

To prevent:
- clot increasing
- clot breaking loose and travelling
- new clots
- post-thrombotic syndrome

21
Q

What is the treatment for suspected DVT?

A

Low molecular weight heparin, then oral anticoagulant

22
Q

What is the treatment for DVT if thrombolysis should be considered in immediate post-operative period?

A

IV unfractioned heparin

23
Q

What are mechanical prophylaxis for DVT?

A

Flowtron (IPC) boots, thrombo-deterrent (TED) stockings

24
Q

How does heparin work?

A
  • Reduces the blood’s tendency to clot
  • Stop new clots from forming
  • Stop old clots from growing
25
Q

What is the difference in UFH and LWMH?

A

The duration of action is longer in LWMH

26
Q

What does warfarin do?

A

Inhibits the action of Vitamin K

27
Q

What check needs done regularly for those on warfarin?

A

International normalised ratio (INR) checks

28
Q

What does the international normalised ratio (INR) check do?

A

Show how long a person’s blood takes to clot

29
Q

How does aspirin work?

A

Inhibits vasoconstriction & platelet aggregation.

30
Q

What are thrombolytics?

A

Drugs to get rid of blood clots

31
Q

What does Streptokinase prevent?

A

Pulmonary embolism

32
Q

What is a normal INR?

A

1-1.5

33
Q

What is the INR kept at for those taking warfarin?

A

2-3

34
Q

What conditions cause a prolongation of clotting time?

A
  • Liver disease
  • Use of oral anticoagulants
35
Q

What are contraindications for the use of TEDs?

A
  • Oedema of lower limbs
  • Severe peripheral vascular disease
36
Q

Symptoms of pulmonary embolism

A
  • Dyspnoea
  • Tachypnoea
  • Sinus tachycardia
  • Haemoptysis
  • Chest pain
  • Faintness, collapse
  • Sudden death
37
Q

What investigations can be carried out for a pulmonary embolism?

A
  • ECG
  • CT scan
  • Arterial blood gas
  • Perfusion/ventilation lung scans
  • Pulmonary angiography
38
Q

How may a CT scan show PE?

A

May show pulmonary vascular obstruction

39
Q

How may an arterial blood gas show PE?

A

May show hypoxaemia and hypocapnia

40
Q

What is the initial treatment for PE?

A

High flow O2 therapy, analgesia, fluids and UFH

41
Q

What is given for PE after UFH?

A

Warfarin

42
Q

What improves the efficacy of the heart, maintains BP and stroke volume for PE treatment?

A

Inotropic support
(adrenaline and noradrenaline, dobutamine, dopamine)

43
Q

What is the heparin reversal drug?

A

Protamine sulfate

44
Q

How does fonaparinux prevent DVT?

A

Inhibits Factor X