Thromboembolism Strategies

Carol Makin, Wirral Hospital

Why? "Prevention is better than cure"

Eight to fifteen percent of patients develop venous thrombosis after undergoing major general surgical procedures

Significant morbidity from chronic venous insufficiency occurs in 60% of those with proximal venous thrombosis and 30% with calf vein thrombosis

Fatal pulmonary emboli secondary to proximal vein thrombosis occurs in 2 per 1000 post-operative patients.

Death from pulmonary emboli usually occurs within 30 minutes of the acute event.

Who? "All patients should be considered for venous thromboembolism prophylaxis"

Balance risks against benefits in relation to individual patient taking into consideration intended procedure, past medical history, current drug history, possible consequences of bleeding and cost. Stratify into one of three groups - low, moderate or high risk.

What?

Low risk: Early mobilisation

Graduated compression stockings

Moderate risk: As above plus low molecular weight heparin

Pneumatic compression boots

High risk: As above with high dose low molecular weight heparin

Think!

Position on operating table: pressure on calf

Laparoscopy: increased intra-abdominal pressure, reduced venous return

Drugs: HRT/OCP

Aspirin, clopidogrel, non steroidals, warfarin

Past medical history: DVT/PE, prosthetic valves, TIAs, renal impairment, peripheral vascular disease

Anaesthetic technique: adequate pain relief - epidural, PCA

Patient expectations: contract with patient for early mobilisation and discharge

Summary

Evidence based guidelines aimed at preventing venous thromboembolism are now well established in everyday clinical practice. As with all guidelines they are intended as a guide to managing thromboprophylaxis. Variations from expected practice should be clearly documented in the patient's case notes.

References

Thromboembolic Risk Factors (THRIFT) Consensus Group. Risk of and prophylaxis for venous thromboembolism in hospital patients. BMJ 1992;305:567-74

Venous thromboembolism prophylaxis used by consultant general surgeons in Scotland PJ Burns, RG Wilson, C Cunningham J R Coll Surg Edinb 2001; 46:329-333

Thromboprophylaxis Guidelines for Surgical Patients

Risk Group Includes

Low risk

No DVT prophylaxis required Minor surgery (<30 mins); no risk factors other than age.

Major surgery (>30 mins); age <40; no other risk factors.

Minor trauma or medical illness

Moderate risk

Enoxaparin 20mg s/c once daily Major general, urological, gynaecological, cardiothoracic, vascular or neurological surgery if age >40 or other risk factor.

Major medical illness e.g. heart or lung disease, cancer, inflammatory bowel disease.

Major trauma or burns.

Minor surgery, trauma or illness in patients with previous DVT, PE or thrombophilia.

High Risk

Enoxaparin

40mg s/c once

daily Fracture or major orthopaedic surgery of pelvis, hip or lower limb.

Major pelvic or abdominal surgery for cancer.

Major surgery, trauma or illness in patients with previous DVT, PE or thrombophilia.

Lower limb paralysis (e.g.hemiplegic stroke, paraplegia).

Major lower limb amputation.

CVA due to embolus.

Additional Risk factors

Patient Disease or surgical procedure

Age, Obesity Laparoscopic Surgery

Immobility - bed rest > 4 days Malignancy, especially pelvic, abdominal or metastatic

Pregnancy, Puerperium Heart failure, recent MI

Combined Oral contraceptive Severe infection

Hormone replacement therapy Inflammatory bowel disease

Previous DVT or PE Renal Impairment - see guidelines overleaf

Thrombophilia Polycythaemia

Homocystinaemia Paraprotinaemia

Varicose veins Behcets Disease

NB: Patients admitted on the day prior to surgery can commence their regular dose (according to risk) that evening.

For other patients the timing of enoxaparin administration will depend on the time of surgery and whether they are having an epidural.

Enoxaparin 40mg needs to be given 12hrs pre-op

Enoxaparin 20mg can be given 2hrs pre-op.

If the patient is having an epidural ALL doses of enoxaparin must be given 12hrs pre-op

Prophylactic TED stockings should be used for:-

Length of stay longer than 24hrs

Moderate and high risk patients

Laparoscopic procedures

Immobility

Renal impairment:

If Creatinine Clearance (CrCl) <30ml/min prescribe 20mg enoxaparin.

The following are intended as a guide to management of thromboprophylaxis. Any variation from routine practice must be documented.

Kath Phillips, Principal Pharmacist, Surgery and Anaesthetics