Understanding VTE

VTE is a major cause of death in the United Kingdom.

'Venous thromboembolism' (VTE) is a collective term for both 'deep vein thrombosis' (DVT) and 'pulmonary embolism' (PE). A DVT is a blood clot in the deep veins of the leg. A PE is when all or part of the DVT breaks off, travels through the body and blocks the pulmonary arteries. Every year, an estimated 25,000 people in the UK could die from VTE associated with hospitalisation. Any adult can get a DVT, but they are thankfully rare in children because they have much thinner blood.

VTE can be difficult to diagnose, and can very easily be confused with less serious conditions. For example, a DVT does not always cause any swelling or changes in the leg, sometimes just pain, and so can be mistaken can be mistaken for a torn leg muscle or a sprain.

Most hospital-acquired VTE occur AFTER discharge – the average DVT after surgery is on day seven, the average pulmonary embolism is on day 21- all long after the patient has gone home. So the health professionals looking after the patient in hospital often don’t recognise the condition exists!

View this animation to help you visualise normal circulation, clot formation and localisation as a PE by selecting the relevant tabs.

Deep vein thrombosis (DVT)

'Deep vein thrombosis' or 'DVT' is the term used to describe a blood clot that forms in any of the deep veins in the body. Although most people think of the legs in relation to a DVT forming they can form in other deep veins, including the arms. The deep veins cannot be seen beneath the skin as they are located within muscle. A DVT can occur in the calf, behind the knee, in the thigh or very high in the leg veins within the pelvis. Most DVTs occur in the calf veins, except during pregnancy, when they tend to lie within the thigh and pelvis. Symptoms of a DVT may include:

• swelling, usually in one leg
• leg pain - for 80% of DVTs, pain is the only symptom
• tenderness of the leg muscles, often the calf muscles
• reddish or bluish skin discoloration
• a leg that is warm to touch. 

A DVT may break off and travel to the lungs as a pulmonary embolism (PE).

Pulmonary embolism (PE)

'Pulmonary Embolism' or 'PE' is the term used to describe a blood clot in the lungs. A pulmonary embolism is caused by all or part of a DVT breaking free and travelling around the circulation to block some or all of the blood supply to the lungs. If the blood supply to the lungs is blocked then that individual can’t oxygenate blood properly.  If all the blood supply is blocked then oxygen supply is totally stopped and it is clearly fatal. If a clot blocks a smaller artery then that area of lung supplied by the artery dies off. This causes pain.

Signs and symptoms of a pulmonary embolism usually start suddenly, and can vary widely depending on the size and the site of a PE.Symptoms may include:

• sudden shortness of breath - this can vary in degree from very mild, to very obvious shortness of breath
• chest pain that is sharp or stabbing and that may get worse when breathing in
• rapid heart rate
• unexplained cough, sometimes with bloody mucus
• a mild fever
• feeling faint, unwell, or completely collapsing
• there may also be symptoms of a DVT, such as pain at the back of the calf, tenderness of the calf muscles and swelling of a leg or foot.

Sometimes there may be no symptoms at all, which is why VTE is sometimes referred to as 'the silent killer'.

Post-thrombotic syndrome

Post-thrombotic syndrome is a condition where anything from pain and swelling, to varicose veins or brown and white pigmentation can occur in the leg after a clot. This is due to the permanent damage of the legs veins after a DVT, so that that the veins can no longer drain blood from the leg properly. If the situation is very bad, then ulcers may develop on the inner side of the leg above the ankle due to this area being susceptible to poor drainage.

The cost of VTE and prevention

The additional cost of implementing the NICE recommendations for effective prevention of VTE is anticipated to be about £21.9 million nationally however, this is more than offset by an anticipated reduction in deep vein thrombosis and pulmonary embolisms that is estimated to save £26.3 million nationally. This estimate is based on costing work undertaken at the time the guideline was published (March 2010) and provides a useful sense of the scale of the achievable savings associated with the implementation of NICE guidelines.

Sadly, the average member of the public has little or no understanding about the causes and effects of thrombosis, or how it can be prevented. Surveys commissioned by Lifeblood: The Thrombosis Charity suggest that about 50% recognise that a DVT is a clot in the leg and can cause pain and swelling, but the vast majority think long-haul flights are the main cause. In fact long- haul flights cause only a tiny number of VTEs whereas two thirds are caused by hospital admission. The figures are chilling:

• Estimates suggest that there are more than 25,000 hospital deaths in the UK each year from VTE (House of Commons Health Committee Report, 2005).
• VTE is the single, most common, preventable cause of death in hospital patients (Lifeblood - The Thrombosis Charity; NICE).
• One in three surgical patients can develop a DVT if no preventative measures are given (Lifeblood - The Thrombosis Charity; NICE).
• VTE kills more people each year than breast cancer, road traffic accidents and AIDS combined (Fitzmaurice DA, Murray E. Thromboprophylaxis for adults in hospital. BMJ. 2007;334(7602):1017-1018, and Eurostat EU15; United Nations AIDS update).
• Roughly half of patients with DVT involving the thigh will go on to develop a pulmonary embolism (Lifeblood – The Thrombosis Charity. The epidemiology of venous thromboembolism, White RH. Circulation 2003;107(23 Suppl 1):I4-I8). 
• One person in three patients who suffer a pulmonary embolism will die (Lifeblood – The Thrombosis Charity: Heit JA. Venous thromboembolism epidemiology: implications for prevention and management, Seminars in Thrombosis and Hemostasis, 2002;28(suppl 2):3-13).
• One in every 1,000 women will develop deep vein thrombosis during pregnancy, these tend to be bigger than those outside of pregnancy and can lead to long-term health problems (Patient UK; Lifeblood – The Thrombosis Charity).
• Partly as a result of our ageing population and partly due to increased risk factors, the number of cases of DVT and PE is expected to rise (Heit JA., Venous thromboembolism epidemiology: implications for prevention and management, Seminars  in Thrombosis and Hemostasis 2002;28(suppl 2):3-13., and Ageing population, NCVO Third Sector Foresight). 

The NHS has made VTE a clinical priority for 2010/11. From 1 June 2010, nursing and health care staff have a direct and important part to play in reducing the numbers of preventable deaths from VTE in UK hospitals every year.

Who is at risk?

Most adults admitted to hospital are at risk of developing a DVT without preventative treatment. Potentially every patient may be at risk of VTE so to make the task of assessing who is at risk, the Department of Health has developed a tool that includes a thrombosis risk section which has patient related and admission related risk factors. The tool and the issue of risk assessments is covered in the section 'VTE risk assessments'.

A DVT doesn't always have obvious symptoms, but given the high percentage of potentially preventable deaths from VTE cases in UK hospitals, it's important to view every patient as a potential VTE candidate. In order to reduce deaths by VTE, it's vital to carry out an initial risk assessment immediately on admission to hospital, as well as regular risk assessments thereafter.