| Information
for Our Patients
The following information
is provided for patients of the Vein Clinic:
Travel Related Deep Vein Thrombosis or the so-called 'Economy-Class Syndrome'
"Economy Class Syndrome" is a term used to describe the swollen, fatigued and aching leg symptoms that air travellers or air passengers encounter during long trips. It is also associated with a serious leg condition called deep vein thrombosis (DVT). Crowded, cramped conditions and limited physical activity during travel increase the risks for ECS and DVT Travel related DVT was first recognised back in 1946, at that time medical publications have described a possible link between deep vein thrombosis (DVT) and air travel. However, it was the publicity surrounding 2 unexpected deaths from pulmonary embolism - a blood clot travelling from the legs to the lungs - after long-haul air travel in 2000 that sparked renewed interest in the issue and much public debate.
Each year, DVT occurs in about one in every 1,000 people in the general population and in up to one-third of people who have had major surgery. Scientific study to quantify the risk of DVT posed by air travel - although it is suspected to be small in most people - is ongoing.
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. A DVT can occur some days or even weeks after a trip.
Is a deep vein thrombosis serious?
When a blood clot forms in a leg vein it usually remains stuck to the vein wall. The symptoms tend to settle gradually, but there are 2 main possible complications.
- Pulmonary embolus (a blood clot in the lung) occurs in a small number of people who have a DVT. An embolus is a part of a blood clot which breaks off and travels in the bloodstream. An embolus that comes from a clot in a leg vein will be carried up the larger leg veins to the heart, through the large heart chambers, but will get stuck in a blood vessel going to a lung (pulmonary embolus). This is serious, and can sometimes be fatal.
- Long-term discomfort and swelling of the calf occurs in some cases following a DVT (post-thrombotic syndrome).
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 the following factors increase the risk of travel related DVT:
- immobility for an extended period of time
- over 40 years of age
- who have had blood clots already
- suffering from or who have had treatment for cancer
- who have had recent surgery especially on the hips or knees
- existing clotting abnormality or inherited clotting tendency
- overweight and obesity
- Chronic illnesses
- Hormones or the oral contraceptive pill
- Varicose veins
- Pregnancy or 2 months post-partum
- being treated for heart failure and circulation problems
- Dehydration
How is DVT diagnosed?
DVT/PE is undiagnosed and misdiagnosed more often than not. Diagnosis usually involves a special type of ultrasound scan of the leg called a duplex ultrasound. If this test does not show a DVT but the doctor still suspects a DVT based on the symptoms, then further tests such as venography may be carried out. Venography uses an X-ray image to track the distribution of a special dye injected into the deep veins of the leg.
What are the symptoms of DVT ?
Leg symptoms (Deep Vein Thrombosis, DVT) may appear during flight or in the next few days.
. Sudden swelling in one lower leg. (A little swelling in both legs is normal in flight.)
. Cramp or tenderness in one lower leg.
. Bruise or swelling behind knee.
Chest symptoms (Pulmonary Embolism, PE) usually appear 2-4 days or more after the initial blood clot, which you may not have noticed:
. shortness of breath
. rapid breathing, panting
. cramp in your side, painful breathing
. chest pain accompanied by shoulder pain
. fever
. coughing up blood
. fainting (often the first sign, especially in older people)
Symptoms of a deep vein thrombosis include:
. redness, swelling and heat in the area over the path of a deep vein
. a deep vein feeling like a hard piece of rope or cord
. pain or discomfort over the path of a deep vein
. discoloration or ulceration of the skin over a deep vein
. no symptoms for some people, especially if the thrombus forms in a vein other than in the leg or arm .
NOTE: It can sometimes be difficult to tell if a person has a thrombophlebitis or a deep vein thrombosis. In these situations a Doppler - ultrasound or a venogram (x-rays done after ijection of dye into the vein) may be done to make the correct diagnosis.
If you have symptoms such as swelling, pain, redness or warmth over the path of a vein, contact your doctor immediately.
How many people are affected?
DVT is, more often than not, silent or asymptomatic, therefore it is hard to establish just how many people are affected by DVT after travel related activities, furthermore 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.
During the trip do:
• get comfortable in your seat and recline as much as possible
• bend and straighten your legs, feet and toes while seated every half-hour or so during the flight
• press the balls of your feet down hard against the floor or foot-rest to increase the blood flow in your legs and reduce clotting
• do upper body and breathing exercises to further improve circulation
• take occasional short walks around the cabin, whilst cruising at altitude
• take advantage of refuelling stopovers where it may be possible to get off the plane and walk about
• drink plenty of water
avoid:
• avoid alcohol, which in excess leads to dehydration and immobility
• avoid taking sleeping pills, which also cause inertia
• Don't wear anything that could impede the circulation (like a knee brace).
• Some experts recommend avoiding caffeine and alcohol. Others say this makes no difference. Drinking extra non-caffeine and non-alcoholic fluids is recommended.
Exercises
In-Flight Stockings and Socks
Research has shown that correctly fitting anti-thrombosis stockings 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.
Anticoagulant medication
Some people at particularly high risk of DVT may be advised to have a heparin injection before a long-haul flight. Heparin is an anticoagulant (it 'thins the blood' and makes it less likely to clot). Treatment with heparin is controversial as there is only limited evidence to confirm that it helps. However, see your doctor before the journey to discuss this option if you:
- Have had a previous DVT or pulmonary embolus.
- Have a family history of clotting conditions.
- Have cancer, or had treatment for cancer in the past.
- Had major surgery in the last three months. In particular if you had a hip or knee replacement within the last three months.
- Have had a stroke.
Note: There has been considerable attention focused recently on the risk of deep venous thrombosis (DVT) associated with air travel. Despite the lack of evidence among air travelers, a single dose of aspirin has been widely recommended as a means of preventing such thrombosis. Apirin alone should not be used as DVT prophylaxis. (Aspirin is widely used to help prevent blood clots in arteries which can cause strokes and heart attacks. However, aspirin has not been shown to be very effective at preventing clots in veins.)
Unfractionated and low molecular weight heparins protect against lower limb DVT. There is insufficient evidence to confirm either protection against pulmonary embolism or an overall benefit, or to distinguish between various applications of heparin.
Foot and calf pumping devices appear to prevent DVT, may protect against pulmonary embolism, and reduce mortality, but compliance remains a problem.
Note: This information is designed to complement and not replace the relationship that exists with your existing family doctor or travel health professional. Please discuss your travel health requirements with your regular family doctor or practice nurse. |
