Venous thromboembolism (VTE)

 

 

Deep venous thrombosis (DVT), pulmonary embolism (PE)

 

VTE – Epidemiology (BBC 2008).

Pulmonary embolism following DVT kills more than breast cancer, Aids and traffic accidents combined, and 25 times more people than MRSA.

 

Clots kill more than 25,000 patients in England each year.

 

Many patients who develop clots show signs that something is wrong only after they have been discharged from hospitals.

 

 

Virchow`s triad

Disorders of vascular endothelium

Sluggish or abnormal blood flow

Increased blood coagulability

 

 

Aetiology

75% of PEs are from leg deep venous thrombosis.

Rare causes include, amniotic fluid, placenta, air, fat, tumour, septic emboli (from endocarditis).

 

 

Risk factors

PE affects 20% of surgical patients, 40% of major orthopaedic patients.

DVT and subsequent PE accounts for 10% of in hospital deaths.

Major abdominal or pelvic surgery

Lower limb orthopaedic surgery

Common mode of death in cancer and stroke

Pelvic or abdominal tumours

Risk in late pregnancy and puerperium, caesarean section, pre-eclampsia

Leg fractures

Varicose veins

Dehydration

Stroke and SCI

Any disabling disease, e.g. COPD, CCF

PMH of VTE

Oral contraceptives

Heart failure

Obesity

Familial antithrombin deficiency

Other genetic predispositions

 

 

Pathophysiology

Severity varies massively

 

 

Clinical features in small / medium PE

Pleuritic chest pain

Tackypnoea

Dyspnoea

Haemoptysis

Tachycardia

Crackles

Low-grade fever

 

 

Clinical features in massive PE

Apprehension

Faintness or collapse

Central chest pain

Severe dyspnoea

Tachycardia

Hypotension

Increased JVP

Some T wave inversion, right BBB

Diagnosis

CXR to exclude other pathology, e.g. CCF, pneumonia, pneumothorax, tumour.

Possible raised hemidiaphragm or effusion

Other non-specific changes on CXR.

ABGs, usually reduced PaO2, normal or low PaCO2

D-dimer, tests for a fibrin degradation product

Low D-dimer (<500 ng/ml) has a high negative predictive value

Normal D-dimer does not exclude VTE

CT pulmonary angiogram

Ventilation-perfusion (V/Q) scanning

Echocardiography shows acute dilation in the right heart

 

Management

CPR in moribund patients may break up an embolism

Maintain O2 sats over 90%

Opiates to relieve pain and distress

IV fluids for hypotension

Anticoagulation, aim for INR of 2.0 – 3.0

SC low molecular weight heparin for at least 5 days and until INR is at least 2

Warfarin probably for 6 months

Thrombolysis when massive and causing shock

 

Prognosis

Post op cases have a good prognosis

Other groups may be up to 9% recurrence per year

Pulmonary hypertension after 6 week indicates risk of RVF                    

Possible treatment for life

Post-thrombotic syndrome, which affects many people after a DVT, due to damage to the valves along the length of the vein can lead to chronic venous hypertension.

 

NICE (2008)

 

Consider stopping combined oral contraceptives 4 weeks before elective surgery

 

Journeys of 3 or more hours in the 4 weeks before elective surgery increases risk

 

Assess risk in all patients

 

Inpatients having surgery should be offered thigh-length graduated compression / antiembolic stockings from the time of admission. If full length are not tolerated use knee length.

 

Ankle                18 mmHg

Mid calf                        14 mmHg

Thigh                8 mmHg

 

Intermittent pneumatic devices or foot impulse devices may be used instead of or as well as stockings.

 

Use Low Molecular Weight Heparin or Fondaparinux in orthopaedic patients or other patients with high risk. This is as well as mechanical prophylaxis.

 

Do not allow patients to become dehydrated.

 

Continue LMWH for 4 weeks after hip fracture surgery.

 

Regional anaesthesia has a lower risk than general anaesthesia.

 

Mobilise early after surgery.

 

Pre discharge teach about S and S of VTE, instruct on correct use of prophylaxis at home and the risks in failing to do so.

 

Also

Good intra-operative care to minimise effects of muscle relaxation

No leg crossing in bed or on trolleys

Active and passive limb movements

No flying for a while after surgery or VTE

Oily fish, garlic,?aspirin