Are you sitting comfortably? Don't

By STEVE HART travel editor

Only a few months ago, the words "deep vein thrombosis" were mentioned every time you opened a newspaper or watched the TV news.

There were reports of passengers, often those who had travelled long distances on aircraft, feeling unwell with pains in their legs (which is one of the symptoms of deep vein thrombosis and can be a sign of potentially fatal blood clots). Some people had died as a result of the condition (which is also known as DVT, or economy class syndrome), which led to fingers being pointed at the airlines.

But is deep vein thrombosis caused simply by long periods of immobility on aircraft or are other factors involved?

While the issue has apparently died down, beneath the surface questions about air travel and its possible health risks are still being asked, causing the airline industry great concern, says one aviation expert.

Airlines are now better at informing passengers of the risk of deep vein thrombosis, with articles in their inflight magazines and videos and warnings on some air tickets.

Doctors who have studied the condition say victims are as likely to suffer it while seated in roomier seats on any type of transport, not just in economy class on planes, and it may simply be linked to long periods of immobility.

However, some doctors say the risk during long-haul flights may be compounded by dehydration in the overly dry atmosphere and the change in air pressure inside the aircraft.

On May 20 Australian law firm Slater and Gordon will argue that deep vein thrombosis is an injury caused by air travel (under the Warsaw Convention) before a judge sitting at the Victorian Supreme Court.

Patrick Over, associate lawyer at the firm's Melbourne office, says his company is representing about 1000 clients in all - some from New Zealand - who are making individual claims against airlines such as Air New Zealand, KLM, British Airways and Singapore Airlines (along with others that fly out of Australia).

The airline industry has known about deep vein thrombosis since the 1970s, says Over. His firm wants to test the Warsaw Convention, which covers all commercial air travel, in a case against British Airways and Qantas. Neither airline was prepared to comment on the case.

"What we are saying," says Over, "is that airlines knew about the risk of deep vein thrombosis before they decided to warn passengers of it. The convention covers injury to commercial airline passengers, and we are claiming that deep vein thrombosis is an injury caused by the airlines."

Over says both Qantas and BA are fighting the action and have applied to have the "deep vein thrombosis is an injury" clause removed from the claim at the May 20 hearing.

"This is a test case to determine one crucial issue in relation to the liability of airlines to passengers who have suffered deep vein thrombosis," he says.

It's a novel point and Over, whose firm is well-known for accepting challenging cases from clients, admits the legal issue could go on for years. "Either side may challenge and appeal any decisions made by the courts."

In Frankfurt, airline Lufthansa won its case against a passenger who claimed he developed deep vein thrombosis as a result of remaining seated during a 10-hour flight.

The State Court, sitting in April 2000, dismissed the passenger's claim for the equivalent of $15,000 for pain and suffering, ruling that developing deep vein thrombosis was not an accident under the Warsaw Convention. It also said that developing the condition did not mean the airline had breached its duty of care and seating arrangements, but rather that the passenger had a pre-condition that could have caused deep vein thrombosis.

But what if the decision goes against the airlines this time - how would that affect air travel?

Peter Harbison, managing director of the Centre for Asia Pacific Aviation in Australia, has been watching the issue closely.

"There is extreme nervousness in the industry over any deep vein thrombosis legal action because of the unpredictability of the courts. The whole aviation industry will be watching the court action this month, but they also have other things on their mind - like staying afloat.

"This is an international industry that can be affected by a minor court, say in Rarotonga, which could theoretically make a judgment that's flashed around the world, with the possibility of setting legal precedents.

"Whatever happens on May 20, nothing will change [in the industry] overnight. Even if this case were successful, it would be contested all the way by the airlines."

One way to give passengers more space, if this does turn out to be the issue, is to remove some seats. Harbison says that if airlines are forced to do this, ticket prices will have to go up.

"And any attempt to do that would mean they would lose passengers. They are already flying fewer aircraft since September 11 to save money and pushing the load factor of their fleets to 80 per cent capacity.

"If an airline is forced to take out 10 per cent of its seats then they will have to fly at 90 per cent capacity. That would be practically impossible," Harbison says.

"One of the things that intrigues me is that passengers are being encouraged to get up and walk around and drink a lot more water. First, there isn't enough room and second, airlines will need to provide more toilets onboard.

"But, with the publicity surrounding deep vein thrombosis, anybody who doesn't get up and walk around is arguably contributing to the risk of suffering the condition."

Litigation and possible consequences aside, what does the medical profession say about it all? It's had almost two years to think about it since the publicity first erupted over the possible link.

Some point out that deep vein thrombosis can occur on a bus, in a car, on a train or just lying in bed (for example, while recovering in hospital).

Last year the World Health Organisation held a meeting of experts in Geneva, with medical researchers and members of the airline industry reviewing the whole question of deep vein thrombosis and air travel.

Paul Giangrande, a haematologist from Britain, said there was a link between deep vein thrombosis and travel but that the "overall risk is low" - about one in 10,000 air travellers may be affected.

But the consensus of the WHO meeting is that an association probably exists between air travel and deep vein thrombosis, but that the condition mainly affects passengers who already have risk factors such as: having a history of thrombosis, cancer or heart disease, being over 40, overweight, smokers or women taking the birth control pill or HRT.

The issue affects New Zealanders in particular, says Dr Marc Shaw of World Wise Travellers Health Centre in Auckland.

"One of the problems of living here is that we are forced to travel for long periods of time to get anywhere. Anyone travelling longer than four or five hours, and those older than 35, should seriously consider wearing compression stockings.

"People who wear these stockings have got a less than a 1 per cent chance of getting deep vein thrombosis. Of all the things available to help prevent deep vein thrombosis, it appears that the stockings are probably the best. Walking around the plane hasn't been proven to have any effect, drinking a litre of water hasn't been proven to have any effect.

"The stockings compress the leg, stop the fluid going into the tissue and therefore stop the potential of clotting in the veins."

Shaw says airlines are doing the best they can with the information available.

Britain's House of Lords' science and technology committee has studied the issue and sums up the problem quite well: "For healthy individuals, the risk of getting a clinically significant deep vein thrombosis solely because they are taking a flight seems to be exceedingly small.

"For those who are already at risk because they are subject to predisposition factors, there may be an additional risk from flying, but it is not currently quantifiable."

Tips for preventing deep vein thrombosis

* Stand up and walk around at least once an hour.

* Exercise your calf muscles by going up on your tiptoes several times while standing.

* Drink enough fluid - at least 1 litre every five hours while flying.

* Avoid alcohol as it makes your blood platelets more sticky (and therefore more likely to clot) and makes you lose fluid.

* Avoid crossing your legs, or prolonged awkward hip or knee positions whenever seated.

* Stop smoking.

* Wear loose-fitting clothing while you are travelling.

* Lose weight.

* Discuss with your doctor any family or personal history that might predispose you to deep vein thrombosis and increase your risk while travelling. Ask whether folic acid, therapeutic compression stockings and/or an anticoagulant would help you to avoid deep vein thrombosis.

* Raise your legs when possible.

* The effectiveness of using aspirin to prevent deep vein thrombosis is being hotly debated.

Slater and Gordon

Centre for Asia Pacific Aviation

Worldwise travel health

Feature: Economy class syndrome

nzherald.co.nz/health