Should the airlines be held responsible for the suffering and death of passengers due to DVT?
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Echo Issue Outline 2001 / 05
The potentially fatal condition, deep vein thrombosis (DVT), also known as "economy class syndrome", has attracted considerable media attention since the death in October of a 28-year-old British woman after a 20-hour flight from Australia.
The Civil Aviation Authority of Australia (CASA) responded to the situation by immeditaely publishing warnings about the risk of DVT on its website. Qantas and Ansett were initially reluctant to place such warnings, but by January 2001 had agreed to do so.
In November 2000 the British House of Lords released a report on health and air travel which included the conclusion that more should be done to inform passengers of the risk of developing DVT. The report also suggested passengers be allowed more leg room and encouraged to drink more water.
Shortly afterwards a report from the University of Amsterdam was published in the Lancet. This disputed that long haul flight was a major contributing factor to the development of DVT.
The debate continues, intensified by the prospect of legal action on behalf of many passengers who believe they have developed DVT as a result of the airlines' negligence.
What they said ...
'I would say that without question ... [the airlines] have failed in their duty of care to the travelling public and to their staff'
Federal Labor MP Neil O'Keefe, who suffered a deep vein thrombosis after a long-distance flight.
'... there is still absolutely no evidence to suggest that the airline environment is any more likely to cause DVT than other environments where one is immobile for a long period of time'
British Airways statement on the DVT risk for passengers taking long distance flights
Copyright © Echo Education Services
First published in The Echo on-line newspaper information site.
Issue outline by J M McInerney
DVT (deep vein thrombosis) is a condition in which a small blood clot, or thrombus, forms, usually in the deep veins of the legs.
Such clots may cause swelling of the affected leg, sometimes accompanied by pain.
DVT is not dangerous in itself but complications arising from it can be life-threatening.
Complications occur when a thrombus breaks away from the wall of the vein to which it is attached and is carried along with the flow of the blood as what is termed an embolus.
If the embolus reaches a blood vessel through which it cannot pass, it blocks the vessel. Such a blockage is called an embolism. The most serious of these occurs in the lungs (a pulmonary embolism) causing chest pain, breathing difficulties and, in the worst cases, death from respiratory failure. Blockage to other vital organs, such as the heart can also be fatal.
The most commonly recognised risk factors for DVT are:
* Increasing age above 40 years
* Former or current malignant disease
* Blood disorders leading to increased clotting tendency
* Inherited or acquired impairment of blood clotting mechanisms
* Some types of cardiovascular disease or insufficiency
* Personal or family history of DVT
* Recent major surgery or injury, especially to lower limbs or abdomen
* Oestrogen hormone therapy, including oral contraception
* Immobilisation for a day or more
* Depletion of body fluids causing increased blood viscosity
It can be seen that these last two risk factors, prolonged immobility and dehydration or depletion of body fluids, can be a feature of long-haul or long distance air travel.
The British House of Lords Science and Technology Select Committee recently released a report making recommendations about air travel and health.
It suggested that a number of features of air travel might further increase a passenger's risk of developing DVT. These are:
* Seating constraints, particularly leg-room
* Seated posture, including when asleep
* Reduced cabin pressure leading to abdominal distension acting against venous return from the legs
* Reduced oxygen and/or pressure leading to increased blood clotting tendency
* Low humidity affecting body fluid content
* Excessive consumption of alcohol and coffee leading to dehydration
* Safety procedures compounding immobility
* Cabin crew activities discouraging mobility
* Increasing duration of non-stop flight sectors
In November, 2000, the British House of Lords released a report produced by its Science and Technology Select Committee. The Committee was charged with investigating and making recommendations about air travel and health.
A summary of the Select Committee report and a list of its recommendations can be found at
These include recommendations to reduce the risk of deep vein thrombosis.
The full contents page for the Select Committee report can be found at http://www.publications.parliament.uk/pa/ld199900/ldselect/ldsctech/121/12101.htm
Chapter 6 of the report, titled 'Deep vein thrombosis, seating and stress' can be found at http://www.publications.parliament.uk/pa/ld199900/ldselect/ldsctech/121/12109.htm
On November 22, 2000, the BBC broadcast a report on the findings of the British House of Lords Science and Technology Select Committee recommendations about air travel and health.
The BBC report was titled 'Airlines "neglect" passenger health'. It gives a clear summary of the British House of Lords Science and Technology Select Committee report referred to above. It can be found at
On November 22, 2000, the United States' news service CNN also produced a report on the findings of the British House of Lords Science and Technology Select Committee recommendations about air travel and health.
Titled 'Airlines urged to issue health warnings', the CNN report is interesting because it also details British and Australian airlines initial response to both the highly publicised death of a 28-year-old woman from DVT, apparently developed during a flight from Sydney to London, and the recommendations of the House of Lords report.
The CNN also gives information on what is apparently the only recent study to suggest long haul flights are not a contributory factor to the development of DVT. This study was conducted by the University of Amsterdam .
The CNN report can be found at http://www.cnn.com/2000/HEALTH/11/22/airtravel.thrombosis/index.html
On October 27, 2000, CNN produced a report on the findings of the University of Amsterdam study. The CNN report is titled 'Long flights don't increase blood clot risk, study says'
It can be found at http://www.cnn.com/2000/TRAVEL/NEWS/10/27/economyclass.syndrome.reut/index.html
UniSci has a more detailed report on the findings of the University of Amsterdam's research team studying the relationship between DVT and long haul flight.
The article, which gives a detailed summary of the Dutch findings, is titled 'Study Shows Long Trips Don't Hike Risk Of Thrombosis'
It was posted on October 27, 2000. It can be found at http://unisci.com/stories/20004/1027001.htm
UniSci was the first science daily news site on the Web. It selects stories based on their scientific importance. Its home page can be found at http://unisci.com/
The site is searchable.
The Aviation Health Institute has a detailed fact file on DVT. One of the Institute's key concerns is to reduce the risk of DVT among long haul air travellers.
This fact file can be found at http://www.aviation-health.org/dvtfacts.html
The Aviation Health Institute is a British-based registered charity. It provides information and comment on aviation health issues. It also encourages airlines and passengers to take action to address aviation health problems.
The Institute's home page can be found at http://www.aviation-health.org/
Qantas has a section of its Internet site given over to advising passengers about their inflight health. This includes advice on how to promote circulation in the legs and avoid dehydration during flights. This advice is specifically offered to reduce the risk of passengers developing DVT.
The same section of the site also gives information about predisposing factors for the development of DVT.
These DVT warnings were apparently put up after the widely publicised death of a 28-year-old British woman after a 20-hour flight from Australia.
They can be found at http://www.qantas.com.au/flights/essentials/healthinflight.html
Ansett's Internet site also offers passengers warnings on the risk of developing DVT, though this does not include detailed advice on how to reduce the risk. Again, this information has apparently been only recently added to the site.
It can be found at http://www.ansett.com.au/info/wellbeing_f.htm
CASA, the Civil Aviation Safety Authority of Australia, also has a section of its Internet site given over to warnings about passenger health during flight. This includes advice regarding avoiding DVT.
These DVT warnings were also apparently put up after the widely publicised death of a 28-year-old British woman after a 20-hour flight from Australia. CASA appears to have been the first Australian aviation organisation to issue these warnings.
They can be found at http://www.casa.gov.au/prod/airsafe/trip/health.htm
The Age regularly compiles selections of its articles on issues of interest. It has prepared such a compilation on Deep Vein Thrombosis Syndrome. A full list of the articles that are available on The Age's Internet site can be found at http://www.theage.com.au/issues/economyclasssyndrome/index.html
Arguments suggesting the airlines should be held responsible for not seeking to prevent DVT
The connection between sitting still for long periods and DVT has been known for more than 30 years
In 1940 a study linked sitting for long hours in air raid shelters with sudden deaths from blood clots. The first air travel related case of DVT was reported in 1954. In 1967 a British doctor warned British Airways of the potential link between air travel and DVT. The warning appears to have been ignored. Between 1977 and 2001 studies have been regularly published in prominent aviation medical journals claiming links between air travel and DVT.
Between 1995 and 1996 at least three prominent vascular surgeons approached Qantas. They requested that Qantas issue health warnings alerting passengers to the possibility of developing blood clots. They also asked that they be able to conduct urgent studies of the problem. The airline did not respond. Such warnings re the risk of DVT on flights to and from Australia have been made over many years. In 1993, an Australian doctor told a symposium in Hawaii that Australians appear to be at greater risk of developing clots because of the long distances they travelled.
A significant number of passengers have died either during flights of shortly afterwards from DVT
A recent study of coroners' reports in Australia has indicated that eighteen Australians have died from flight-related blood clots in the last eight years. Fourteen of the confirmed deep vein thrombosis victims died either during their flight, or at the airport or within two hours of landing. One was a 29-year-old Melbourne man who collapsed and died soon after a trip to Asia. Another was a 65-year-old woman who died on her way back to Melbourne after visiting the United States. Three-quarters of the victims were women and most were aged over 50.
It has further been suggested that the coroners' figures dramatically underestimate the number of deaths. These figures represent only those cases that have been investigated by the coroners' offices in each state. As DVT is generally regarded as a natural cause of death, many deaths possibly connected with long flights will not have been investigated. Some officials have suggested that the actual number of flight-related DVT deaths may be in the hundreds.
The airlines have made private settlements with a number of DVT sufferers
Since 1993 at least two Australians who have developed clots have received confidential out-of-court payments from the airlines. One of these settlements was made in 1996 and involved a 68-year-old man who had nearly died as a result of a clot apparently developed during a long flight. Critics claim that the airlines' readiness to make such settlements is an acknowledgment of responsibility. They also argue that the fact that these have been confidential settlements suggests that the airlines are trying to prevent the public becoming aware of the risk.
This point has been made by federal Labor MP Neil O'Keefe who has claimed that such payments proved that the airline concerned had long known about the syndrome and had failed to act.
Mr O'Keefe stated that he had been told of out-of-court settlements going back at least ten years.
The airlines have not issued health warnings to passengers or promoted research into DVT.
It has been claimed that the airlines have adopted a deliberate policy of not warning passengers, perhaps because they were concerned about the effect such a warning would have on the number of people willing to fly. It has been claimed that as early as 1989 a Victorian solicitor developed DVT after a London flight and complained to the airline. In reply he received a letter from a Qantas solicitor which apparently stated that warnings 'would not appear to be warranted at this time'.
It has further been claimed that since 1999 there have been several of meetings key air industry figures to discuss the problem. None of these meetings has resulted in warnings being issued.
The sister of an Australian citizen who died when a blood clot lodged in his lung shortly after getting off a plane in Lebanon has stated, 'if they [the airlines] know there is some danger, they should tell everyone about it.'
A similar criticism was made by a 51-year-old Sydney woman who developed deep vein thrombosis after a flight from Los Angeles. She has since complained about the lack of any warning from the airline and has stated, 'I had never even heard of DVT.'
It has been claimed that other nations, including Britain and Brazil, have handled the situation better. It has been suggested that Australian airlines recent promises to issues warnings of possible DVT risks are too little too late.
It has further been claimed that Australian airlines have refused requests by vascular surgeons over a number of years to investigate the link between long-distance fights and the development of deep vein thrombosis. Some of these requests date back to 1995.
Aeroplanes' seating arrangements, especially for economy passengers, are too cramped.
It has been claimed that arguments that long-distance flight is not more hazardous than other forms of long-distance travel are dishonest. According to this line of argument, it is easier to stretch one's legs and get some exercise when travelling by car, train or bus.
It is further noted that the cramped seating conditions supplied passengers in economy class flights not only make it difficult for people to exercise, they also increase the risk of clot formation.
This claim has been made by Frank Devine, writing in The Australian. Mr Devine has stated, citing the aerospace medicine program at Wright State University as an authority, '... the minimum safe space between seat backs, for health reasons, is about 100cm. Qantas ... gives its steerage passengers 79cm to 81cm ... Ansett Australia provides 86cm to 89cm.'
Mr Devine has further noted that most economy class seats are built to accommodate someone weighing 73kg and measuring 1.7m in height. Mr Devine points out that a majority of people are therefore too large to be comfortably seated in economy class.
Arguments suggesting the airlines should not be held responsible for not seeking to prevent DVT
There is not as yet any conclusive evidence that DVTs are caused by long flights.
This point has been made by Professor Eric Donaldson, of Griffith's University's aviation medicine research centre and former Qantas medical chief. Professor Donaldson has stated, '... we don't know what the true situation is.'
Professor Donaldson has further stated, 'This is a difficult problem and it's going to take the whole industry to work out where we go from here.'
According to this line of argument there are lots of factors which can contribute to someone developing deep vein thrombosis and it is premature to suggest at this point that long flights are a major causal factor.
British Airways has issued a statement claiming, '... there is still absolutely no evidence to suggest that the airline environment is any more likely to cause DVT than other environments where one is immobile for a long period of time.'
It has also been noted that a recent study conducted by a research team at the University of Amsterdam has failed to find any significant correlation between long distance flying and the development of DVT.
Professor Roderik Kraaijenhagen, who headed the Dutch research team, has stated, "These results do not lend support to the widely accepted dogma that long travelling time is a risk factor for venous thrombosis. Even for air travel and journeys lasting more than five hours, no association was apparent".
The airlines are concerned to avoid unnecessary panic.
Those who defend the airlines' reluctance to alarm passengers have noted the extent of popular apprehension since the media drew world-wide attention to the death of a 28-year-old British woman, who died on arriving in London after a 20 hour flight from Sydney.
Dr Andrew Keller, Sydney Airport's medical Centre director, has claimed he has been 'swamped with worried passengers'.
At least one person a day is reported to be coming into the Medical Centre convinced they were suffering from a blood clot. Most, it has been claimed were not.
In the air, it has been noted, many passengers are getting out of their seats on a regular basis to exercise.
Professor Eric Donaldson, a spokesperson for Griffith University's aviation medical research centre and a former Quantas medical chief has expressed concern as to what could happen if a plane hit turbulence while passengers were out of their seats.
Donaldson has noted, 'They could all end up with a serious neck injury - and we know for sure that's a risk'
The airlines are conducting research into the possible link between DVT and long distance flight.
Qantas is working with Griffith University's aviation medical research centre to undertake new research.
Professor Eric Donaldson, a spokesperson for Griffith University's aviation medical research centre and a former Quantas medical chief has noted that several research projects, backed by Qantas, are under consideration.
Professor Donaldson has further noted that the projects are at the protocol stage.
Australian airlines also met in February, 2001, for a summit on DVT and long distance air travel. Qantas, Ansett and the more minor airlines attended, in addition to the defence force surgeon general and several pilots associations.
This summit has been said to indicate the willingness of the Australian aviation industry to address any problem which might exist.
The airlines are fulfilling their duty of care as they are now issuing warnings to passengers of the possibility of developing DVT
In January, 2000, Qantas and Ansett both began issuing warnings to passengers about the dangers of possible blood clot formation during long distance flights.
Qantas began issuing a brochure giving health warnings to passengers. These brochures are being distributed when passengers buy their tickets.
In January a spokesperson for Qantas announced, 'We are now finalising details so that in future all front-line staff will have information on DVT for passengers when they book their tickets.
There will be an inflight video and we will also be including a brief message on tickets.'
Ansett is also providing information re DVT risks in their inflight magazine and is producing a video, to be used on international flights, giving similar warnings.
Both airlines have warnings about the dangers of DVT on their Internet sites. Qantas site includes exercise directions as a way of reducing the risk of developing a clot.
It has further been claimed that by world standards, leg room for passengers on Australian long distance aircraft is quite generous. This point has been made by Mr Peter Gibson, a spokesperson for CASA.
Many of the accusations being made against the airlines have dubious legal validity and have been prompted by lawyers seeking financial gain.
This point was made by Age commentator Peter Davis who has written an article dealing with what he claims is the current obsession with discovering syndromes and filing suits.
Mr Davis is particularly critical of lawyers. He claims, '... they are working in overdrive to prepare a series of class actions. Rumours are that one Melbourne company has retained a team of top silks in a state of heightened readiness. At the drop of a brief they will fly into action and attempt to secure compensation.'
It has further been noted that the airlines may have no legal case to answer.
This point was made in an editorial published in The Australian on January 15, 2001. The editorial states, '... as the lawyers rush in to capitalise on the DVT scare, a timely reminder: proving that greater warnings about DVT would have stopped any deaths is difficult. Warnings on cigarette packets are regularly ignored: airline travellers still drink alcohol and insufficient water; and those susceptible to blood clots are, or should be warned by their doctors anyway.'
There are many factors which will help to determine the future course of this issue. One will clearly be how successful the Australian law firm Slater and Gordon prove to be in suing the airlines for neglect. Over 800 people have cases which they law firm is likely to take to court and several thousand people have come to the firm seeking to have their cases taken up.
One delimiting factor is that it seems likely that, under the provisions of the relevant legislation, no case will be eligible for compensation if it involves injury incurred more than two years ago. It may also not be possible for the relatives of people who have died as a result of DVT to pursue legal action.
Even given these limiting factors, Slater and Gordon have so many potential clients that should they prove successful the airlines will be faced with huge compensation payouts. A number of media outlets have noted that other legal firms both in Australia and overseas are waiting on the result of the Slater and Gordon case before pursuing cases on behalf of their clients.
It also seems likely that, in addition to issuing the sort of warnings to passengers that Qantas and Ansett are now making, airlines may have to alter their seating specifications so that passengers in all classes are allowed more leg room. Australian airlines have noted that if they are required to make such changes than the cost of air travel will certainly increase. They are also concerned that if they are required to make these changes and other international airlines servicing the Australian market are not, then they will be at a competitive disadvantage.
In the final analysis, both the court cases and the changes that may be required of the airlines are likwely to hinge on the results of detailed research into the extent to which long haul air travel contributes to DVT. An answer to this question may not be readily available already a recent Dutch study is producing findings at odds with those of others studies. Further work appears to be necessary to clarify the issue.
One thing appears certain, now that it has been tagged as an issue by the media, it is very unlikely to go away. Popular awareness of the potential threat is likely to be enduring if it is fostered by regular reports of DVT death and injury possibly related to long haul flight.
Newspaper items used in the preparation of this outline
Available as a press cuttings package (with an issue outline reprint): price: $27.00 (NO LONGER AVAILABLE)
6/1/01 page 6 news item by Lyall Johnson, '800 sue over air travel clot injuries'
11/1/01 page 3 news item by Robert Wainwright et al, 'Airlines to warn about blood clots'
12/1/01 page 4 news item by Sharon Verghis, 'Doctor tells of flight clots scare'
14/1/01 page 5 news item by Steve Dow, 'Legal hitch in flight claims'
16/1/01 page 8 news item by Sharon Verghis, 'Consumer push for leg room'
8/2/01 page 15 comment by Peter Davies, 'Blaming others is a common symptom'
9/2/01 page 6 news item by Mary-Anne Toy, 'Doctors debate risk of clots after flying'
11/1/01 page 3 news item by Alison Crosweller, 'Blood clot warnings on tickets'
12/1/01 page 3 news item by Sophie Tedmanson and Alison Crosweller, 'Clots quite frequent but risk unknown'
15/1/01 page 12 editorial, 'All feet on deck to fight aircraft clots'
15/1/01 page 13 comment by Frank Devine, 'Mining a deep vein for profit'
The Herald Sun
10/1/01 'Clot victims list growing'
12/1/01 news item by Jen Kelly, 'Airline paid off clot victim: MP'
12/1/01 page 17 cartoon
13/1/01 news item by Jen Kelly, 'Airlines' deadly secret'
5/2/01 page 1 news item by Fiona Hudson, '18 deaths in secret'
5/2/01 page 4 news item by Fiona Hudson and Will Temple, 'Doctors call for air travel probe'
5/2/01 page 5 news item, 'Bride's dad dies after flight'
5/2/01 page 6 news item by Fiona Hudson, 'Passengers in a panic'
5/2/01 page 6 analysis, 'Diary of a syndrome'
6/2/01 page 18 editorial, 'Air dangers cover-up'
7/2/01 page 18 comment by Paul gray, 'Airlines need to level with us on the risks of long flights'