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National Clinical Guideline Centre – Acute and Chronic Conditions (UK). Venous Thromboembolism: Reducing the Risk of Venous Thromboembolism (Deep Vein Thrombosis and Pulmonary Embolism) in Patients Admitted to Hospital. London: Royal College of Physicians (UK); 2010. (NICE Clinical Guidelines, No. 92.)

16Vascular surgery

16.1. Introduction

This section covers inpatients undergoing vascular surgery. Vascular surgery encompasses two distinct patient populations: surgery for peripheral arterial disease (PAD) including carotid, aorto-iliac and limb arterial surgery; and patients with venous disease (superficial or deep venous reflux and varicose veins). A significant proportion of surgery for uncomplicated primary varicose veins is undertaken as day-case procedures.

We did not have enough data, from the incidence in the RCTs (chapter 5), to enable us to estimate the risk of developing deep vein thrombosis in vascular surgery patients not receiving thromboprophylaxis, according to our HES data, its ranking in among amongst other surgery would suggest that the risk is relatively high.

Factors that may alter the risk of VTE

  • Arterial surgery patients are often elderly and immobile.
  • Many arterial surgery patients will already be receiving antiplatelet therapy and some will be on warfarin.
  • Systemic heparin is frequently administered during surgery for arterial disease.
  • Surgery for varicose veins is mostly in women, oral contraceptive use and hormone replacement therapy are therefore more commonly associated with varicose veins surgery.

Factors that increase the risk of bleeding or hazard associated with it

  • Patients using anticoagulation or antiplatelet therapy not related to surgery will have an increased risk of bleeding.

Other factors that may alter the choice of prophylaxis

16.2. Evidence of methods of prophylaxis

16.2.1. Summary of comparisons identified for any outcome

Three randomised controlled trials which reported at least one of the three main outcomes were identified181,383,615. One of the RCTs615 data were extracted from a systematic review125.

All included RCTs were either individually critically appraised to be of a high quality (level 1+ or level 1++) or came from systematic reviews of RCTs which had been critically appraised to be of a high quality (level 1+ or level 1++).

Figure 16-40. Number of studies which compared various types of prophylaxis methods.

Figure 16-40Number of studies which compared various types of prophylaxis methods

Numbers in boxes indicate the number of RCTs for each comparison. Boxes shaded grey indicates areas where no studies were identified.

GCS – anti-embolism / graduated compression stockings; IPCD/FID – intermittent pneumatic compression devices or foot impulse devices; LMWH – low molecular weight heparin; UFH – unfractionated heparin; Asp (HD) – high dose aspirin (>300mg), Asp (LD) - low dose aspirin (≤ 300mg); mech – mechanical prophylaxis (i.e. anti-embolism / graduated compression stockings, intermittent pneumatic compression devices or foot impulse devices); pharm – pharmacological prophylaxis

16.2.3. Additional information

There is no additional information for this population.

16.3. Network meta-analysis results

Network meta-analysis was not completed for this population

16.4. Cost-effectiveness evidence

No cost-effectiveness evidence was identified and no model produced for this population.

16.5. Patient views

No patient views papers were found specific to this population.

For patient views about specific prophylaxis agents, see section 6.6.

16.6. Summary of evidence

Intervention(s)Comparison(s)Intervention favoured
DVTPEMB
Prophylaxis vs no prophylaxis
UFHno prophylaxisnot signot signo events
Single prophylaxis vs single
LMWHUFHnot sig-no events
Double prophylaxis vs double
LMWH + introperative UFHUFH + introperative UFHnot signo events-
Cost Effectiveness
No cost effectiveness model was completed for this population

The prophylaxis strategy which is significantly more effective in reducing DVT or PE; or resulting in significantly less major bleeding is stated in bold.

Not sig - not statistically significant difference; ‘-’ = not reported; no events – nobody in the study had the outcome. MB = Major bleeding

Overall, there is little RCT evidence covering prophylaxis in patients undergoing vascular surgery.

16.7. Recommendations and link to evidence

RecommendationOffer VTE prophylaxis to patients undergoing vascular surgery who are not having other anticoagulant therapy and are assessed to be at increased risk of VTE (see section 2.2.1). If peripheral arterial disease is present, seek expert opinion before fitting anti-embolism stockings
Recommendation from section 5.9Regard surgical patients and patients with trauma as being at increased risk of VTE if they meet one of the following criteria:
  • surgical procedure with a total anaesthetic and surgical time of more than 90 minutes, or 60 minutes if the surgery involves the pelvis or lower limb
  • acute surgical admission with inflammatory or intra- abdominal condition
  • expected significant reduction in mobility
  • have one or more of the risk factors shown in Box 1.
Box 1VTE Risk factor box For women who are pregnant or have given birth within the previous 6 weeks see Chapter 30 (Pregnancy and up to 6 weeks post partum).
Relative values of different outcomesThe outcomes considered were thromboembolic events (asymptomatic and symptomatic DVT, symptomatic pulmonary embolism and fatal pulmonary embolism), bleeding events (major bleeding, fatal bleeding and stroke) and other long term events occurring as a result of VTE (chronic thromboembolic pulmonary hypertension and post thrombotic syndrome
Trade off between clinical benefit and harmsThe benefit of reducing the risk of venous thromboembolism and long term events occurring as a result of thromboembolism were considered against the risk of major bleeding.
Economic considerationsThere is no cost-effectiveness evidence for vascular surgery patients. An economic model was developed for general surgical patients. The model concluded that a combination of drug and mechanical prophylaxis was cost effective for general surgery patients where the risk of major bleeding is less than 1%.
There is little trial evidence for vascular surgery patients but we believe the relative effects of prophylaxis will be similar. We consider it likely that combination prophylaxis is cost-effective for vascular patients with moderate risk of major bleeding, given their high baseline risk of VTE.
Quality of evidenceAll included RCTs were either individually critically appraised to be of a high quality (level 1+ or level 1++) or came from systematic reviews of RCTs which had been critically appraised to be of a high quality (level 1+ or level 1++).
There is little RCT evidence covering vascular surgery. Evidence was extrapolated from general surgery patients.
Other considerationsArterial surgery patients are often elderly and immobile.
Many arterial surgery patients will already be receiving antiplatelet therapy and some will be on warfarin. In addition, systemic heparin is frequently administered during surgery for arterial disease.
Surgery for varicose veins is mostly in women, oral contraceptive use and hormone replacement therapy are therefore more commonly associated with varicose veins surgery.
Patients using anticoagulation or antiplatelet therapy not related to surgery will have an increased risk of bleeding.
The use of intermittent compression devices and anti-embolism / graduated compression stockings will usually be inappropriate on the operated leg for a patient undergoing lower limb arterial surgery.
Anti-embolism / graduated compression stockings and intermittent pneumatic compression devices will be contraindicated for patients with peripheral arterial disease.
The average duration of VTE prophylaxis for ‘general surgery’ patients in the trials was 7 days. This concurs with the licensing conditions for pharmacological agents for surgical patients within the BNF where the recommended duration is 5–10 days, depending on the agent used. It is known in many cases surgical patients are discharged within 5 days of their operation. The guideline development group felt that the risk of VTE may still persist beyond this time period and prophylaxis may be effective after discharge. No economic analysis was conducted for patients who were discharged before the full course of VTE prophylaxis had been given.
There are other considerations for each agent when choosing pharmacological prophylaxis. UFH is not as widely used nowadays and is mainly used for patients with renal impairment. There are also practical considerations in that it requires 3 injections per day as oppose to one injection per day for LMWH.

16.7.1. Other recommendations of relevance

The specific recommendations for patients undergoing vascular surgery in this chapter should be read in conjunction with other relevant recommendations presented elsewhere in the guideline. These are:

16.8. Summary of recommendations

Box Icon

Box 1

Risk factors for VTE. Active cancer or cancer treatment Age over 60 years

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Cover of Venous Thromboembolism
Venous Thromboembolism: Reducing the Risk of Venous Thromboembolism (Deep Vein Thrombosis and Pulmonary Embolism) in Patients Admitted to Hospital.
NICE Clinical Guidelines, No. 92.
National Clinical Guideline Centre – Acute and Chronic Conditions (UK).

NICE (National Institute for Health and Care Excellence)

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