Deep Vein Thrombosis

Clot formation in a deep vein which are at risk of embolism.

VTE is an umbrella term encompassing both DVT and PE, and is used as there is substantial overlap in both pathologies. This distinction is not made here; this section covers DVT whilst PE is covered in detail under Pulmonary Embolism. Thromboprophylaxis is explored under Thromboprophylaxis.

Epidemiology and Risk Factors

Almost all ICU patients fall into a “very high” risk category on any conventional scoring system.

Risk factors:

Age
Post-operative
Pathology
- Inflammatory disease
  - IBD
  - Sepsis
- Malignancy
- Thrombotic disorder
  - Factor V Leiden
  - Protein C/S deficiency
  - Antiphospholipid syndrome
  - Previous DVT/PE
- Nephrotic syndrome
- Liver failure
Obstetric
- Peripartum
- Pregnant
In-dwelling devices
- High association with upper limb DVT
Immobility
- Travel
- Hospital admission
Drugs
- OCP
- HITT

Pathophysiology

Aetiology

Assessment

General features:

Pain
- Exacerbated by pressure to the medial plantar region
Phlebitis
Limb swelling
- Oedema
- Venous stasis
Paraesthesia
Palpable venous thrombus
“Cord-like”.

Catheter-associated:

Unable to aspirate
Loss of transduced waveform
Inability to inject

Assessment

History:

Provoking factors
- Malignancy

50% of patients with an upper limb DVT have an associated malignancy; and 10% of patients with an “unprovoked” DVT have a malignancy diagnosis in the following year.

Exam:

Investigations

Bedside:

Laboratory:

Imaging:

Ultrasound
- Incompressibility
- Visible thrombosis
CT venogram
For mediastinal and pelvic vasculature.

Other:

Diagnostic Approach and DDx

Management

Risk assessment
Determine provoked vs. unprovoked DVT, which influences risk of recurrence.
Anticoagulation

Resuscitation:

Specific therapy:

Therapeutic anticoagulation is covered under Anticoagulation.

IVC filters are covered in detail under Thromboprophylaxis.

Pharmacological
- Therapeutic anticoagulation
  - Duration varies depending on location and degree of provocation
  - Warfarin and DOAC are equally effective
    - Oral Xa inhibitors are preferred
    - Dabigatran initiation requires bridging for initiation
- Thrombolysis
  Facilitates rapid restoration of venous patency with moderate ↑ in bleeding complications.
  - Indicated for:
    - Essential vascular access required with no available central veins
    - Very-high risk clot
      e.g. SVC thrombosis.
    - Long-term anticoagulation higher risk than short-term, supervised coagulopathy
  - Catheter-directed thrombolysis preferred
Procedural
- IVC filter
Physical

Duration of Anticoagulation
Location	Provocation	Duration
Distal	Transient	6 weeks
Proximal	Transient	3-6 months
Proximal	Recurrent	“Extended”
Proximal upper limb	Transient	3 months
Proximal	Malignancy	3-6 months
Proximal	CVC	3 months

In catheter-associated DVT:

There is no need to remove a working CVC with associated thrombosis whilst it is present and it remains indicated
Anticoagulation should be considered whilst the catheter remains in place
↓ Clot propagation.
There is no distinction between occlusive and non-occlusive thrombi

Supportive care:

Disposition:

Preventative:

Marginal and Ineffective Therapies

Anaesthetic Considerations

Complications

↑ Length of stay
B
- PE
H
- Recurrent DVT
I
- Falls

Risk of VTE Recurrence After Ceasing Anticoagulation
Type of VTE	1-year recurrence	5-year recurrence
Provoked: Major surgery or major trauma	1%	3%
Provoked: Transient risk factor	5%	15%
Provoked: Persistent risk factor	15%	45%
Unprovoked distal DVT	5%	15%
Unprovoked proximal VTE	10%	30%
Second unprovoked VTE	15%	45%

Prognosis

Key Studies

References

Tran HA, Gibbs H, Merriman E, et al. New guidelines from the Thrombosis and Haemostasis Society of Australia and New Zealand for the diagnosis and management of venous thromboembolism. Medical Journal of Australia. 2019;210(5):227-235. doi:10.5694/mja2.50004