FN: DVT

Question 1

epi

Answer 1

DVTs occurs in 25% of surgical patients

Question 2

Risk factors: pathophysiology

Answer 2

Virchows triad

Question 3

Virchows triad

Answer 3

Blood contents
Blood flow
Vessel wall

Question 4

Blood contents

Answer 4

1. Surgery - raised platelets and raised fibrinogen
2. Dehydration
3. Malignancy
4. Increasing age

Question 5

Blood flow

Answer 5

• surgery
• Immobility
• Obesity

Question 6

Vessel wall

Answer 6

Damage to veins: esp. pelvic veins

Previous VTE

Question 7

Signs

Answer 7

• Peak incidence @ 5-10d post-op
• 65% of belo knee DVTs are asymptomatic
• Calf warmth, tenderness, erythema, swelling
• Mild pyrexia
• Pitting oedema

Question 8

Differential

Answer 8

Cellulitits

Ruptured baker cyst

Question 9

Investigations

Answer 9

• D-dimers: sensitive but not specific
• Compression US (clot will be incompressible)
• Thromobophilia screen

Question 10

Do a thrombophilia screen if:

Answer 10

• no precipitating factors
• Recurrent DVT
• Family Hx

Question 11

Diagnosis

Answer 11

1. Assess probability using Wells score
2. Low-probability - perform D-dimers
3. Med/high probaility - compression US

Question 12

Low probability results of D-dimer

Answer 12

Negative - excludes DVT

Positive - compression US

Question 13

Rx

Answer 13

Anticoagulate

• therapeutic LMWH: enoxaparin 1.5mg/kg/24h SC
• Start warfarin using Tait model: 5mg OD for first 4 d
• Stop LMWH when INR 2.5

Question 14

Duration of anticoagulation

Answer 14

below knee: 6-12 wks
Above knee: 3-6 months
On-going cause: indefinitie

Question 15

Graduated compression stockings

Answer 15

Consider for prevention of post-phlebitic syndrome

Question 16

Preventing DVT pre-op

Answer 16

• pre-op VTE risk assessment
• TED stockings
• Aggressive optimization: esp. hydration
• Stop OCP 4wks pre-op

Question 17

Intra-op prevention

Answer 17

1. Minimize length of surgery
2. Use minimal access surgery where possible
3. Intermittent pneumatic compression boots

Question 18

Post-op prevention

Answer 18

1. LMWH
2. Early mobilization
3. Good analgesia
4. Physio
5. Adequate hydration