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Prevention of venous thromboembolism in patients undergoing surgery

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VOL: 103, ISSUE: 18, PAGE NO: 23

NICE has published new guidance to tackle the problem of venous thromboembolism (VTE: deep vein thrombosis and pulmonary embolism) in surgical patients. The guidance covers all patients aged 18 and over who are admitted to hospital for surgery requiring an overnight stay and focuses on procedures that carry a high risk of VTE (NICE, 2007). This follows a recent report from the Department of Health on the prevention of VTE in hospitalised patients, which covers all medical patients and those undergoing surgery with different levels of risk (DH, 2007).

NICE has published new guidance to tackle the problem of venous thromboembolism (VTE: deep vein thrombosis and pulmonary embolism) in surgical patients. The guidance covers all patients aged 18 and over who are admitted to hospital for surgery requiring an overnight stay and focuses on procedures that carry a high risk of VTE (NICE, 2007). This follows a recent report from the Department of Health on the prevention of VTE in hospitalised patients, which covers all medical patients and those undergoing surgery with different levels of risk (DH, 2007).

INCIDENCE OF VTE
Venous thromboembolism is the formation of a blood clot (thrombus) in a vein, which may dislodge from its site of origin to cause an embolism.

Most thrombi occur in the deep veins of the legs - deep vein thrombosis (DVT). Dislodged thrombi may travel to the lungs - this is called a pulmonary embolism (PE) and can be fatal.

Thrombi can also cause long-term morbidity due to venous insufficiency and post-thrombotic syndrome, potentially leading to venous ulceration.

According to NICE 25,000 people die each year from VTE in England. DVT occurs in over 20% of surgical patients and in over 40% of those who are undergoing major orthopaedic surgery.

Formation of thrombi is associated with inactivity and surgical procedures. The risk rises with the duration of the operation and period of immobility. NICE states that pulmonary embolism following lower-limb DVT is the cause of death in 10% of patients who die in hospital, many after surgery.

PREVENTING VTE
First, the guidance emphasises the importance of patient-centred care. It recommends that treatment and care should take into account patients' needs and preferences, and patients should have the opportunity to make informed decisions about their treatment, in partnership with healthcare professionals.

The guidance stresses the importance of good communication between staff and patients, supported by evidence-based written information tailored to patients' needs. Treatment and care, and the information patients are given, should be culturally appropriate.

The first section of recommendations in the guidance focuses on risk assessment and patient advice (see box, p24). Nurses have a key role in patient information and education.

NICE recommends that all patients are assessed on admission to hospital to identify their individual risk of developing a VTE and that appropriate steps are taken to reduce any risk.

The NICE guidance outlines the many patient-related risk factors for VTE, which include:

- Active cancer or cancer treatment;

- Active heart or respiratory failure;

- Acute medical illness;

- Age over 60;

- Central venous catheter in situ;

- Continuous travel of more than three hours around four weeks before or after surgery;

- Immobility;

- Inflammatory bowel disease;

- Obesity (BMI of 30 or more);

- Personal or family history of VTE;

- Pregnancy or puerperium;

- Recent myocardial infarction or stroke;

- Severe infection;

- Use of oral contraceptives or HRT;

- Varicose veins with associated phlebitis.

The NICE guidance then outlines a three-step strategy for deciding the appropriate form of prevention, comprising mechanical prophylaxis, anticoagulation and regional anaesthesia.

Mechanical prophylaxis
The guidance states that inpatients who are having surgery should be offered thigh-length graduated compression/anti-embolism stockings from the time of admission to hospital unless contraindicated (for example, in patients with established peripheral arterial disease or those who have diabetic neuropathy).

If thigh-length stockings are inappropriate for a particular patient for reasons of compliance or fit, knee-length stockings may be used as an alternative.

The stocking compression profile should be approximately:

- 18mmHg at the ankle;

- 14mmHg at mid calf;

- 8mmHg at the upper thigh.

Healthcare professionals should encourage patients to wear their graduated compression/anti-embolism stockings until they to return to their usual level of mobility. The guidance states that patients should be informed that this will reduce their risk of developing VTE.

Patients who are using these devices should be shown how to wear them correctly by practitioners trained in the use of that particular product. The use of stockings should be monitored and assistance provided if they are not being worn correctly.

Intermittent pneumatic compression or foot impulse devices may be used as alternatives or in addition to graduated compression/anti-embolism stockings while surgical patients are in hospital. When used on the ward, intermittent pneumatic compression or foot impulse devices should be used for as much of the time as is possible and practical while the patient is in bed or sitting in a chair.

Pharmacological prophylaxis
In addition to mechanical prophylaxis, patients at increased risk of VTE because of individual risk factors (see list, p23) and patients having orthopaedic surgery should be offered low molecular weight heparin (LMWH).

Fondaparinux, within its licensed indications, may be used as an alternative to LMWH. For hip-fracture patients, LMWH/fondaparinux therapy should be continued for four weeks after surgery; this also applies to patients having a hip replacement with one or more risk factors.

The risks and benefits of stopping pre-existing established anticoagulation or antiplatelet therapy before surgery should be considered. The timing of drug prophylaxis should be carefully planned if using regional anaesthesia to reduce the risk of haematoma.

Regional anaesthesia
Regional anaesthesia reduces the risk of VTE compared with general anaesthesia. The guidance recommends that suitability of regional anaesthesia for an individual patient and procedure should be considered, along with the patient's individual preferences, in addition to any other planned method of thromboprophylaxis.

Other measures
The guidance emphasises that healthcare professionals should not allow patients having surgery to become dehydrated during their stay in hospital.

Nurses should encourage patients to mobilise as soon as possible after surgery, and they should also arrange for immobilised patients to do leg exercises. Vena caval filters should be considered for surgical inpatients with recent (within one month) or existing VTE and in whom anticoagulation is contraindicated.

A further section of the guideline outlines appropriate preventative measures for specific types of surgery when there are no patient-related risk factors, as well as additional measures to take in each case if patients have one or more VTE risk factors. Types of surgery covered in this section are:

- Elective orthopaedic surgery (for example, total hip or knee replacement);

- Hip fracture surgery;

- General surgery;

- Gynaecological surgery (excluding Caesarean section);

- Cardiac surgery;

- Thoracic surgery;

- Urological surgery;

- Neurosurgery (including spinal surgery);

- Vascular surgery.

The guidance adds that there may be other surgical procedures requiring an inpatient stay and recommends exercising clinical judgement when making decisions on the appropriateness of VTE prophylaxis.

INFORMATION AND ASSESSMENT
- Patients should be assessed to identify their risk factors for developing VTE (see list in main text);

- Healthcare professionals should provide patients with both verbal and written information before surgery about the risks of VTE and the effectiveness of prophylaxis;

- Nurses should inform patients that immobility associated with continuous travel of more than three hours in the four weeks before or after surgery may increase the risk of VTE;

- Patients should be advised to consider stopping combined oral contraceptive use four weeks before elective surgery;

- Healthcare professionals should give patients verbal and written information on the following as part of their discharge plan: the signs and symptoms of DVT and pulmonary embolism; the correct use of prophylaxis at home; and the implications of not using the prophylaxis correctly.

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