DVT - Deep Vein Thrombosis

First recognised back in 1946, travel related DVT is an added potential problem for 'at risk' travellers who are immobile for extended periods of time. While the problem is often associated with air travel, the risk is equally reported among those travelling by car, coach and train.

What is Travel Related DVT?

A Deep Vein Thrombosis (DVT) is a clotting of the blood in any of the deep veins - usually in the calf. If a clot develops, it usually makes its presence known by an intense pain in the affected calf. Medical attention should be sought immediately if this occurs, especially after a long journey. In some cases this can be fatal, if the clot breaks off and makes its way to the lungs where it can then affect the lung's ability to take in oxygen.

What are the symptoms – How will I know it is a DVT?

A DVT can occur some days or even weeks after a trip. In most situations the person will have no symptoms and through normal movement the clot will break up.

If the clot is larger it can cause an obstruction and prevent the blood flowing through the veins. When this happens a person might experience pain, redness and swelling in the calf – this pain is made worse when walking or standing. If these symptoms are experienced you should seek medical help immediately.

Complications can occur if the cot breaks off and travels to the lungs, blocking the flow of blood. Breathlessness and chest pain can occur hours or days after the clot formation in the calf. This is a potentially fatal condition and urgent medical attention is required.

Who is at risk?

Most cases have at least 3 predisposing risk factors - the risk increases as risk factors increase.

Very little established research exists in relation to travel. However we do have a wealth of information from hospital research specific to DVT. We already know that immobility for an extended period of time can increase the risk of DVT with the following factors being added risk factors:

• Travel for more than 3 hours in the four weeks before and after surgery
  
• A personal or family history of DVT
  
• Active cancer or cancer treatment
  
• Recent surgery or leg surgery
  
• Existing clotting abnormality
  
• Obesity (BMI of above 30)
  
• Chronic or acute medical illnesses
  
• Hormones or the oral contraceptive pill
  
• Inflammatory bowel disease
  
• Varicose veins
  
• Pregnancy or 2 months post-partum
  
• Existing Cardiac problems or a history of cardiac problems or stroke
  
• Dehydration
  
• Severe infection
  
• Aged over 60
  

How many people are affected?

It is hard to establish just how many people are affected by DVT after travel related activities, as no official records are kept. However it is important to be aware that it is a potential problem for those with risk factors, due to the evidence we already have.

How can I reduce my risk?

Those in a high-risk category should see their travel health advisor before they travel and discuss prevention.

Those at risk should try to exercise at least every hour on long journeys. Exercise the calf muscles by rotating your ankles, or making use of the commercially available exercise equipment. The risk applies to any form of travel where you are routed to one place for hours at the time.

Good hosiery will encourage circulation. However it is important that you do not wear clothing that will cause a restriction of circulation. Any hosiery should be measured properly to ensure a suitable fit.

For long flights wear loose clothing. Due to the change in atmospheric pressure in a plane, parts of your body can expand due to increased gas! In the dry environment of a plane, it is a well-documented fact that too much alcohol, tea and coffee on flights can add to the problem of dehydration. It is therefore very important to remain hydrated during a long flight by drinking plenty of water and fruit juices.

In-Flight Stockings and DVT Socks

With much attention given over the potential risks associated with Travel Related Deep Vein Thrombosis, it is not surprising that many people are looking for products, which will offer protection. Research has shown that correctly fitting anti-thrombosis stockings or DVT socks increase blood flow, thus lowering the risk of DVT in those at risk. Advice related to stocking/socks should apply to all forms of travel when a passenger is sitting still for a long period of time.

• Before buying any products it is essential that you assess your personal risk factors and obtain advice from your own doctor regarding fitness to fly, if you are in any doubt. If you are in a very high-risk category you should seek advice from your doctor and consider postponing your travel plans.
  
  
• There are many different brands on the market at the moment, each expressing their own unique qualities. It is important that any DVT stocking/sock purchased be fitted properly by a professional. A stocking that is too tight and worn by a traveller with existing circulation problems can do more harm than good -- cutting into the skin on a long flight and potentially causing ulceration and increased risk of DVT.
  
• Never guess the size stocking or sock you require - ask to be measured properly. A good flight sock will come in a variety of sizes allowing for measurement from the knee to the ankle as well as the foot size. If a stocking is too tight around the knee it will prevent essential venous return causing the blood to pool around the knee.
  
• When buying your DVT socks make sure they are comfortable with your chosen footwear for travelling. Some flight stockings can be slightly thicker than normal leg covering and can be potentially restrictive with tight foot wear.
  
• Do not think that if you wear tight knee-highs during a flight you will save some money. Any clothing or tight shoes cutting into the skin around will prevent normal blood flow and increase the risk of travel related DVT.
  
• Wear your stockings around the house prior to travel to ensure you have a good, comfortable fitting. On the morning of your travel put them on when you get dressed, especially if you are travelling a distance to the airport. Hurriedly put on stockings in the airport lounge can cause no end of travel related anxiety!
  
• Flight socks and stockings are just one-way to help prevent travel related DVT - take advice from your doctor as well as preventative advice related to travel.

What can your Health professional do to help?

Your Health professionals will be able to help you determine your risk factors and provide you with both advice and written information. They will also be able to guide you as to the best time to travel after an illness or operation.

References

NICE Venous Thromboembolism