No such thing as Economy Class Syndrome

[Aeromed-Doc]

Hi Pprunes,

I've been reading a variety of comments on these fora concerning the putative 'economy class syndrome' and would like to suggest that there is no such thing.

I think the phrase entered our lexicon in the late 1980s, possibly after a paper in The Lancet (Cruickshank et al. Air travel & thrombotic episodes: the economy class syndrome. Lancet 1988, ii, 497-98). The phrase has certainly been bandied around a lot and from physiological first-priciples seems to make sense:
- Dehydration and relative inactivity are felt to be predisposing factors for the formation of thromboses;
- Dehydration and relative inactivity, often for prolonged periods, are common during passenger air travel.

One problem, however, is that there has been virtually no scientific research that has been well structured and provides credible results that stand-up to rigorous scrutiny. A recent study, again published in Lancet, may be the start of a trend towards credible scientific research on the issue.

The report (Kraaijenhagen et al, Travel and risk of venous thrombosis, Lancet, 356;9240 of 28OCT00) can be found on the Lancet website at http://www.thelancet.com/journal/vol356/iss9240/full/llan.356.9240.original_research.14016.1 (you may have to enroll, for free, to get to it). This study analyses, with controls, the travel history of 788 patients with venous thrombosis and finds that having traveled by air, or road / rail / sea for that matter, does not increase the chance of getting a Deep Venous Thrombosis (DVT).

There is also a body of research developing that suggests that the folk who do get DVTs during flights have one of a number of underlying enzyme deficiencies / abnormalities.

While 'Economy Class Syndrome' is a title with great marketing potential, and certainly beloved of the media, lawyers, and the uninformed, there really is no evidence that such a syndrome actually exists ... what little evidence is available suggests otherwise (recall also that the plural of annecdote is not data).

Certainly people do get DVTs during and subsequent to flight ... but this is no more likely to happen than to similar people who do not fly.

Just my tuppence worth.

Sincerely
Dougal http://www.ozemail.com.au/~dxw/avmed.html

[Mac the Knife]

Good post. Well said Aeromed-Doc. Proper studies eliminate garbage.

[Tartan Giant]

Thank you Dougal for the very sensible 'post'.

I hope the idiots who believe in 'economy class syndrome' keep taking the brain cell replacement medicine.

Best regards,
TG

[bigseat]

Re :dVT

I agree with the ideas expressed about lack of definitive studies into this problem. I disagree therefore that DVT due to flying does not occur.

What is interesting is that certain people are predisposed to DVT either due to medication, or another disease process. The reason for media and passenger interest in this is that at no stage do airlines inform passengers of the health risks associated with flying, and that is where the difficulty lies.

The real question is, are those flyers predisposed to DVT the only people who get DVT when flying? So far, that question has not been conclusively addressed in a suitable study. Indeed one of the difficulties with patients suffering from DVT is that the most severe effects may not become apparent until some time has elapsed and the passenger has gone home

If anything, the media attention has perhaps helped to push the aviation medical fraternity to consider this as more of a priority. That can only be a good thing.

Calling DVT from flying 'economy class syndrome' is just an easy way of talking about (deep breath!) Deep vein thrombosis occuring due to flying in cramped seating on a commercial aircraft. I really do not see a phrase like this as a problem (medical snobbery anyone?).

The misleading reports in newspapers ARE a problem.

If the studies have not been done then no one, not even the most senior physician can say that it does not occur.

To suggest that it does not occur is patently rubbish.

What is correct is that it seems to occur in certain types of patients for sure, but nobody has properly studied the problem.

i.e nobody really knows.



[This message has been edited by bigseat (edited 05 November 2000).]

[Aeromed-Doc]

bigseat's repose (above) raises some very interesting thoughts:

> I agree with the ideas expressed about lack of definitive studies into this problem. I disagree therefore that DVT due to flying does not occur.

As I wrote in my earlier posting the data that is available and is credible indicates that air travellers are NOT at increased risk of DVT. Reading the papers mentioned should allay your concerns in this matter.

As for 'definitive studies' ... we all live in hope but so little of our scientitic knowledge base is built on definitive studies. Our knowledge tends to develop bit-by-bit as myriad not-so-definitive studies are interlinked and cross referenced.

> What is interesting is that certain people are predisposed to DVT either due to medication, or another disease process.

No doubt that some people are at higher risk of DVT than others ... all other things being equal. The big group you didn't mention is those with a malignant condition ... cancer.

> The reason for media and passenger interest in this is that at no stage do airlines inform passengers of the health risks associated with flying, and that is where the difficulty lies.

Ouch. I'm not sure that there is a right or wrong here. I have never received a risk-analysis sheet when I've ridden in a taxi ... I am much more likely to die in a taxi involved in a road accident than if I were to catch a bus. Are you proposing that all actvities that involve an increase risk should involve complete and detailed disclosure of all the known and potential risks? I suspect few amongst the travelling public would be willing to accept the extra couple of hours at the airport being briefed on these issues.

I think what will happen is that some semi-reasonable half-way measure will develop.

As for the airlines informing their passengers of risk .... read my previous post. Airline passengers are NOT at increased risk of DVT ... what are you suggesting they be informed about?

> The real question is, are those flyers predisposed to DVT the only people who get DVT when flying?

I doubt it .... a predisposition is just that. It means you're more likely to suffer the condition than another person. It does not mean that you're the only person who's gonna get the problem.

Perfectly healthy people can get DVTs out of the blue .... it's rare but it does happen. People with cancers are lots more likely to get DVTs. People who travel in aircraft, it would appear, are no more likely to get DVTs.

> So far, that question has not been conclusively addressed in a suitable study.

Vide supra concerning scientific research and the conclusivity of the results of any one study.

> Indeed one of the difficulties with patients suffering from DVT is that the most severe effects may not become apparent until some time has elapsed and the passenger has gone home.

Hmmmm ..... are we talking about patients or passengers here? People who get DVTs, be they patients, sportsfolk, professionals, musicians, travellers etc etc etc, often do not come to the notice of the medical profession for some days. This is, as you allude, usually because the DVT itself causes only rather subtle symptoms. It is often a catastrophic complication of the DVT that comes to the attention of the person and medical folk.

> If anything, the media attention has perhaps helped to push the aviation medical fraternity to consider this as more of a priority. That can only be a good thing.

:-) It doesn't take long for background attitudes and biases to become evident does it?

Anything that reduces the risk of injury to people, whether they're travelling or not, is uaully a good thing. Whether the end is always worth the means is another matter altogether.

> Calling DVT from flying 'economy class syndrome' is just an easy way of talking about (deep breath!)

Accurate terminology is very important when you're dealing with medicine or science. To simply make-up a fanciful, media-genic, if wholly inaccurate name is, IMHO, thoroughly inappropriate.

There is no evidence at all that DVT incidence relates to travelling in economy class of aircraft. There is no evidence that travelling in aircraft predisposes to the occurence of DVT.

There is ... as far as I can ascertain ... no evidence that DVTs occur because of flying in cramped seating.

> ..... (medical snobbery anyone?).

I guess that's one way of approaching an important issue.

> If the studies have not been done then no one, not even the most senior physician can say that it does not occur.

The evidence that is available does not indicate that air travel leads to an increased risk of DVT .... it wasn't very difficult to say. I suggest you actually read the evidence that is available.

> To suggest that it does not occur is patently rubbish.

I am happy to disagree with this statement and ... again ... suggest that you read the evidence that is available. Start with the references mentioned in my original post and then follow-up with the reports that they refer to.

To paraphrase the movie .... "Show me the data".


Cheers
Aeromed-Doc

[bigseat]

Aeromed,
It gets tiresome having to explain the obvious. If the evidence does not exist, then no one (including aero-med doc) can say for sure that the condition does not exist.

Trust me on this one.

If for example you are told their is a box which you cannot see, which is either red or black, and a few studies suggest the box is in fact a red colour, but others suggest it may be black. Can you know the colour? Of course not. This is a fundamental of scientific (as opposed to merely medical investigation). you could say it probably is black, but you cannot say it DEFINITELY is black. It's easy really. Concentrate.

QED, to say economy class syndrome does not exist is patently rubbish.

What is correct is to say it may OR may not. Nobody knows. Not even Aeromed.

Incidentally, in my experience anyone who responds to a comment on medical snobbery is invariably guilty of same. In this case, carping pedantry to boot.

Grow up!



[This message has been edited by bigseat (edited 07 November 2000).]

[Mac the Knife]

Gee bigseat, 'fraid you have to run that one past me one more time.

"If the evidence does not exist, then no one....can say for sure that the condition does not exist."

So if there is no evidence that something exists, that doesn't mean to say that it doesn't? Well, if there is no evidence that something exists there seems little sense in assuming that perversely it does anyway.

"Trust me on this one." Why should I/we? Who are you?

You red/black box story is a variant of the Shrödinger's Cat paradox - actually the box is neither red NOR black... :)

"This is a fundamental of scientific (as opposed to merely medical investigation)..... "

????

All this concentration on b*ll*cks is giving me a headache.

Reminds me of the story about the chap who went around scattering little scraps of paper on the pavement - "To keep the tigers away!"

"But there are no tigers in Llangerrub!"

"See! It works!"

[Aeromed-Doc]

In response to bigseat's most recent response:

> It gets tiresome having to explain the obvious.

Yes, it is very difficult wehen you're having to be so patient and understanding with ignoramuses. I apologise for making your life so hard and having such difficulty in understanding your concepts. I will try very hard to understand ... please forgive me my failings.

> If the evidence does not exist, then no one (including aero-med doc) can say for sure that the condition does not exist.

I think it was Mac the Knife that used the 'b' word. Modern medicine is scientific and evidence based. The existence of conditions and syndromes is based on the existence of credible and widely supported evidence to that effect.

Could there be a link between air travel and DVT? Sure there COULD but the available evidence does not support that link.

> Trust me on this one.

Yeah sure and 'Trust me I'm a doctor' is also a valid debate closer.

> If for example you are told their is a box which you cannot see, which is either red or black, and a few studies suggest the box is in fact a red colour, but others suggest it may be black.

Ohhh, c'mon ... get serious. If you're going to quote paradoxes from quantum theory you might want to get them right. In Shrödinger's Cat paradox the cat, or in your case the box, is NEITHER black nor red. A corollary is that, in part, the process of observation changes the nature of the observed.

Some of the recent work with paired particles (I think that's the term) has, however, started to suggest that the Shrödinger's Cat paradox is also not that accurate at the quantum level ... and that it is possible to determine the colour of the cat without opening the box.

I am not a quantum physicist so am treading tenuous ground here:-)

In the example we're discussing there is evidence ... it simply fails to support the premise that air travel causes DVT. We're not dealing with paired photons in quantum space.

> This is a fundamental of scientific ...

That paradox is a paradox used to explain some of the vagaries of quantum theory. Quantum theory is just that a THEORY and although it does presently explain many of the observations made on subatomic activities it may well be superceded, or incoporated, as string theory or any number of grand unifying theories continue to evolve ... it is NOT a fundamental of modern science.

> It's easy really. Concentrate.

You're right, not too difficult at all.

> QED, to say economy class syndrome does not exist is patently rubbish.

I think, if you were to take the time to read my post, you'd find that what I wrote was "While 'Economy Class Syndrome' is a title with great marketing potential, and certainly beloved of the media, lawyers, and the uninformed, there really is no evidence that such a syndrome actually exists ... what little evidence is available suggests otherwise."

The catch-line is that there is no evidence that such a syndrome actaull exists.

> What is correct is to say it may OR may not. Nobody knows. Not even Aeromed.

The balance of the available evidence fails to support the existence of such a syndrome. Certainly such a syndrome COULD exist ... vide supra.

> Incidentally, in my experience anyone who responds to a comment on medical snobbery is invariably guilty of same. In this case, carping pedantry to boot.

Wow! I am impressed. Do you have a habit of making comments about 'medical snobbery' just to determine the sort of person you're delaing with from whether you'll get a response or not?

Oh dear. I'm sorry this diuscussion is causing you so much pain bigseat.

> Grow up!

Ah yes, personal attack and accusation is a very sensible and useful tool in an important debate. Will I be accused of acting like Hitler next ... that's the usual follow-on after personal attacks when someone has placed themselves out of their depth in an internet debate.

Cheers
Aeromed-Doc

[Jackonicko]

Aeromed Doc

You seem like an educated and well-informed sort of chap. Yet you dismiss an early study and use a more recent one (again, a single study) to support your contention that ECS doesn't exist.

But just to pull it back to the real world for a moment, surely you'll agree that a low pressure environment, lack of leg movement/exercise, poor quality air, dehydration are all contributory factors?

And yet you state definitively (on the slenderest of 'evidence') that airline passengers are not more likely to suffer a DVT.

I'm unhappy about challenging a professional on his own turf, but would gently ask whether you're not being over-selective in your interpretation of the evidence (formal and anecdotal). There are some studies which do suggest that the condition exists, and that it's more likely to occur in cramped (economy class) conditions. Furthermore, there seems to be a growing consensus (even among aeromed specialists, including to sources at IAM) that the problem is real.

And while we are perhaps some way from definitive proof, good sense would surely indicate that some sensible precautions (like giving pax more leg room) would be sensible, and not beyond either the wit or the pockets of major airlines on the longer-range routes?

In a post over on R & N, Latest states that "There is a research paper to be published in the Lancet medical journal tomorrow that will say that economy class syndrome does exist and should be recognised by the airlines.
This study was by Norwegian scientists who put 20 healthy men into a specially constructed aparment in which the air pressure was as low as in an aeroplane. Then they were exposed to a rapid decrease in air pressure, similar to that experienced in a flight. They were allowed to carry out everyday activities but not physical exercise. The scientists found that levels of compounds associated with blood clotting increased between 2 and 8-fold in the men."

I wonder what the effect would have been if they'd been confined (for hours at a time) in economy class seats and kept dehydrated, too? I'm afraid Latest doesn't provide us with a handy link citing stacks of learned paper, but the point is that this is a controversial study, and that surely caution and precaution is better than apparently authoritative reassurances given by people on the basis of incomplete and partial research?

Mac the Knife: Proper studies do indeed eliminate garbage. But you do need studies, plural, and you must take account of those which contradict your preconceived ideas, as well as those which support them.

TG: Perhaps some open-mind medicine might also be of use?

[Mac the Knife]

Jackonicko - Aeromed-Doc is not dismissing the early Lancet study, which was really more of a trial balloon to see what people though about the matter and establish "I thought-about-it-first" rights. The Lancet study is a far more serious piece of work.

I would agree that on the surface all the factors that you (and other people) have cited would appear to predispose pax to DVTs. The sensible thing then is to set up a study and see if there is any evidence to support such a hypothesis. This was done by Kraaijenhagen et al. and perhaps rather to their surprise and chagrin no evidence was found (it can be disappointing when nothing surfaces to support one's study!).

I would agree, that by published articles alone, the evidence "con" is slender, but on the other hand we do not actually have much evidence "pro" either, apart from a few anecdotes of people who have presented with DVTs after flying.

Nothing, after all, is harder than proving the negative case.

Can we try and get it in perspective? JN - you perhaps more than anyone else would know how many billion-zillion airmiles are flown by pax globally every year. Docs DO actually talk to each other and are in fact keen to pick up things. If GPs and specialists were seeing significant numbers of pts. with DVTs/PEs soon after a trip it is likely that it would have been noticed - the situation is 25 years old! Lets try some facts:

DVTs are not a good idea because:

a) A good going DVT can stuff up venous return from the lower limb fairly permanently - pts. may have lasting symptoms of swelling and pain.

b) A DVT thrombus (clot) can detach itself and lodge in the lung, a pulmonary embolus (PE). A good sized PE can kill you dead very fast.

Unfortunately (or fortunately):

a) Most DVTs are mild and virtually asymptomatic, resolving spontaneously with no sequelae.

b) There is little correlation between the clinical severity of the initial DVT and the chances of a life threatening PE. In fact, most fatal PEs seem to occur after mild and un-noticed DVTs rather than big obvious ones.

c) Most PEs are minor and asyptomatic and go undiagnosed and un-noticed.
Perhaps 1/100 is noticed and 1/1000 is fatal.

DVTs/PEs are a significant problem in hospitals, mainly because few of us will ever forget those patients of ours who (after surgery/trauma ranging from the trivial to the severe) unexpectedly dropped dead from a massive PE.
Much attention has been given to preventing DVTs/PE, ranging from aspirin to heparin to early mobilisation to compression stockings etc., etc.

We have a rough idea which patients are most at risk (obese, cancer, immobile, pelvic surgery) and take precautions. Unfortunately there is still considerable controversy as to how effective these precautions are, with some quoting studies one way and some another.

Unfortunately, these days the matter is more legal than science driven.
Patients tend to receive anti-thromboembolism prophylaxis more on the basis of heading off lawsuits than on firm scientific grounds. I for instance, will use appropriate prophylaxis for at risk patients, but (having had a couple die in spite of ALL measures) feel in my heart of hearts that if it's going to happen then it's going to happen.

So the issue of passenger leg-room will probably (like so many issues in our society) become driven by lawyers and the third estate rather than by proper science. Airlines will compute a cost/benefit equation which relates cost of possibly lost (or more likely, conceded uncontested) lawsuits to cost of increasing seat separation and come out with an appropriate number.

Increased airline costs will simply be passed back to the pax, with a microcopic individual medical benefit. OK by me, if that is what society wants.

As for the Norwegian study, I do not doubt it's findings for a minute. Whether an increase in levels of compounds associated with blood clotting translates into a real increased risk of DVT is something else.

I agree wholeheartedly that we need further studies (doesn't everything?), but current evidence really does not point towards airline passenger DVTs being a major epidemiological phenomenon.

I'm sorry that you interpret my thoughts based on current evidence as being a sign of preconceived ideas. I am just as interested and concerned about the truth as you are - there are, after all, my patients! I hope that we are not getting into a situation where professionals have to say "Yessir nossir!" to any crusades that the press takes up for fear of being labelled obstructive and reactionary and being publicly pilloried.

Cheers :) Mac

[Jackonicko]

Thanks for the friendly reply. We seem to be close to agreement, except on the perception of risk and the cost/benefeit of doing things about it. I must admit that as seat pitches become ever more cramped and as airlines tolerate lower and lower air quality and pressurisation levels (sometimes, I suspect, in a quite deliberate attempt to immobilise pax, who are easier to manage in their seats) I become more and more concerned.

[Mac the Knife]

JN - cramped seat pitches bring to mind concerns about emergency evacuations esp. after Singapore. This is really almost another thread, but what are the regs. about this?

Lower and lower air quality - I know there was a thread about saving fuel by turning packs off - more info. pls.

Pressurisation levels - ?

These sound like more germane concerns - suggest that you start new threads as appropriate.

Cheers - Mac

[Jackonicko]

Mac.

I think all of these (and good point about seat pitch versus 'evacuability') are symptoms of corporate greed over-coming the carriers' duty of care to their customers. The ironic thing is that all bite hardest on long range routes, often where competition is least fierce and where excessive profits are already being made.

[Tartan Giant]

As a pilot (and passenger at times) with 38 years flying experience, and a possible contender for DVT, as I have been airborne for many a 10-14 hour flight, I have to counter some of the accusations and illogical comments made by the likes of BigSeat and Jackonicko.

Bigseat
You state, “at no stage do airlines inform passengers of the health risks associated with flying, and that is where the difficulty lies.”
Good God man, are you wanting “this flight could kill you” stamped on your ticket ?
Or “BEWARE you have a 99.999999% chance of walking away from this aircraft without a scratch”.

Does the manufacturer of your car inform you of the health risks involved with driving his car, or the passenger miles/fatal accident/year using the model you bought ?
Does the maker of your kitchen inform you of the health risks of cooking a meal whilst surrounded by his wares/other utensils ?
What about a label on your chip pan ( I assume you have one) stating,
“There have been 530 people killed in the UK due to chip pan fires in 1998 – be careful please” ?

I got a letter from SAGA (yes I’m over 50 !) the other day which informed me, “8 MILLION people (UK) require hospital treatment as a result of an accident at home, in the garden, on the road or at work”. Maybe that statement puts into sharp perspective this fanatical and foundless focus of DVT whilst flying in an economy class seat.

Maybe where the true “difficulty” lies, is the public are not told of the health risks of getting out of bed, so we could avoid DVT almost completely. What are airlines playing at !!!

Perhaps you want airlines to monitor their passengers AFTER they leave the aircraft to make sure DVT does not hit them, until “some time has elapsed”.
Maybe the rail operators do this already, seeing as a packed train could trigger DVT ? “Certain types of patients” will more than likely fall prey to DVT at some point in their life’s; is it because airlines are an easy touch for compensation that DVT is now the targeted hot potato ?

I’m sorry if this post is coming across as a very cynical view and biased, but of the MILLIONS that fly every year very, very few suffer any ill effects what so ever. The worst common ailment perhaps is jet-lag.

If you pay more attention trying to highlight killer diseases to those stuck on the ground than trying to screw airlines into believing they are responsible for contributing to DVT your energies would be worthwhile, instead of all that bloody nonsense about red or black boxes. Another area you could do well to attend to is your grammar dear boy ! “Their is a box….” Incorrect use of “their”.

I cannot afford to meddle with mind bending theory rubbish too much, and like the good doctors on this thread, I will stick to REAL scientific and medical evidence. I can handle that.

Jackonicko
Whilst we were all jerked back into your real world of, “a low pressure environment, lack of leg movement/exercise, poor quality air, dehydration are all contributory factors” I would challenge each point you make there !
Are you talking about modern flying ?
The “low pressure” you are talking about keeps you alive and warm, and keeps you as well as you were before you walked on the aircraft.
If you were ill, or harbouring some ailment prior your flight, then don’t fly….nobody is forcing you.
The “lack of leg movement” is as much your fault for not getting your bum off the seat and having a wander about; you are not tied in or handcuffed you know - there is no extra charge for taking a walk up and down the aisle.
The lack of “exercise” is a bit thick; 99% of people do not take proper “exercise” anyway, never mind having facilities for such “exercise” on an aircraft. I’m sure there are some good books you can buy on seated exercise manoeuvres.

If it’s more leg room you are really after, then buy a seat in the class which gives you the leg-room you want. You pay for what you get.
How much leg movement/exercise area does your car give you ? Do you spend more time in your car than on an aircraft ?

“Dehydration” is self induced - if you do not drink, what do you expect ? Does the airline you are talking about not give you a cup of tea or coffee, or a glass of water every time you ask for one ? Be prepared is a good old motto.

Whilst airlines are in a business and not running a charity organisation, then the needs of the passenger and the business will be met appropriately, and in that regard, “some sensible precautions (like giving pax more leg room)” have indeed been made…there are BIG seats in BIG areas in First Class….in fact you can have a BED if you want !
Virgin don’t even call it First Class. Sure it costs money, but if you want all the comforts of home, then you have to pay for them if you travel by air. Likewise with your choice of hotel.
Should I mention your car ? Electric windows/air conditioning/twin air bags/side impact protection/CD player, and hooks in the back for your jacket……Perhaps not !

So airlines have been “sensible” and have proved before now it is, “not beyond either the wit or the pockets of major airlines on the longer-range routes” to supply goods and services which are appropriate.
Maybe this, “open-mind medicine might also be of use” to passengers who have yet to sample what others have experienced, and not suffered DVT during their extremely limited exposure to these facilities.

There is a “risk and the cost/benefeit (sic) of doing things” in all walks of life, and I think… in fact I know…. current major western carriers have proved adequately they have that balance right.

I cannot agree with you that, “seat pitches become ever more cramped”. What airlines are you talking about ? Have you the before and after figures ?
If you want to hire a jumbo for yourself with all the space you could ever want, then pay the price and stop moaning about seat-pitch.
If you want to get to New York and have LOTS of leg room, air and water, take a ship. If you are in a hurry, fly. Mind you, there are other things to moan about during a sea voyage no doubt…..Oh! that salty smell in the air.

I cannot believe you when you say, “as airlines tolerate lower and lower air quality and pressurisation levels”.
In case you had not noticed, more and more prohibit that repulsive habit of smoking. The quality of cabin air, when matched with that of a restaurant which allows smoking, fairs very favourably I would strongly suggest.
It is just not in an airlines interest to “lower and lower air quality” - when did you last see a foggy haze of noxious fumes in the cabin ? When did you last walk down the streets of London during rush hour – that’s low quality air my boy !

As for your strange “pressurisation levels” jibe, I can tell you air pressure within a cabin is kept as near as possible to MSLP as the airframe will allow. Even at high cruise levels, the cabin pressure is equivalent to being up a 7500/8000 foot mountain, and you have not strained your body climbing it either.

The silly and presumably humorous intent in your statement, “sometimes, I suspect, in a quite deliberate attempt to immobilise pax, who are easier to manage in their seats, I become more and more concerned” is taking things too far.
The management of 200/300/400 passengers in a confined space is an organisation task around their needs for sociability and feeding routine, not to mention the proximity of “conveniences”.
The only thing deliberate is attempting to keep them safe for the period of “duty of care” and has little to do with “corporate greed” - we leave that to the fat cats who run Utility companies and the like. Will I mention the “Dome” ? No… better not.

If your train is cancelled due to a technical failure, does the operator give you a hot meal then put you up in a hotel for the night – bussing you back and forward at no cost ? The lengths to which an airline is willing to go to under their “duty of care” surpasses all other transport mediums - unless you can prove to me otherwise ?

Getting back to facts about DVT and risk exposure whilst flying as an airline passenger (presumably paying the lowest airfare) is absolutely minuscule - such cases highlighted in the popular press by the search for a “good story” by airline ‘knockers’ are not worth the candle towards proving DVT is a positive danger whilst flying long-haul.

Pilots should be good candidates for a research study into DVT, seeing they fly longer (a lifetime) in a confined space in a pressurised tube for extended periods, yet I do not know one in my 38 years flying who has suffered such an ailment/attack, never mind it being attributed to flying.
As “Mac the Knife” pointed out so succinctly, Kraaijenhagen et al. and perhaps rather to their surprise and chagrin no evidence was found (it can be disappointing when nothing surfaces to support one's study!) perhaps says it all.

The Norwegian Study
I’m no doctor, but some of the methods/descriptions used do NOT simulate a typical airliner under normal operating conditions.
For instance, the “hypobaric chamber” was capable of reducing pressure equivalent to 18,040 feet (50.7kPa) – if you were in an aircraft’s cabin with THAT pressure…..then there’s something seriously wrong !
They were “exposed to 76 kPa within 10 minutes” - this rate of change of pressure is too fast, and does NOT occur regularly under normal operating conditions. A typical airliner would take 20 minutes to climb (that’s twice as long before being exposed) to its cruise level equivalent to that 76 kPa as ATC seldom give a continuous climb, and if it’s a long range flight, sea level to max cruise would be at best 2000’/min so it would take 18.5 minutes roughly.
So this sudden exposure only taking 10 minutes would certainly mask results.

Each “exposure” normally lasted 8 hours, but they did not say how long the “descent” took. If they took the same time to ‘come down’ as they took to go up, then again any results do not match a typical flight !!
They also say, after 8 hours eight males returned to “baseline level” whilst the other 8 “participated in another high altitude experiment”. This would suggest another RAPID climb (that 10 minutes again) which again does NOT replicate an airliner climb to altitude and a slow reduction in ambient pressure.

The researchers may have shot themselves in the foot by using the phrase, “volunteers who were suddenly exposed to a hypobaric environment”. Airline passengers are NOT suddenly exposed to anything.

From a cabin altitude of 76 kPa ( 7872’ ;) down to MSL an airliner takes about 20 minutes and sometimes longer.
The rate of change of ambient pressures to the body is just as important that what happens within as a result.
An explosive decompression is more traumatising than a slow decompression – needless to say !

The doctors conducting this very limited experiment which could be said barely related to normal airline ops admit, “Despite the lack of an adequate control group at normal atmospheric, our study suggests that RAPID exposure to an air pressure encountered in aeroplane cabins activates coagulation”.
On a similar footing, a diver RAPIDLY coming from depth to the surface faces the “bends” - so what does these rapid exposures to simulated airline passengers count for ?

Would all those haemostasis readings taken and catalogued be more valid and relevant if the volunteers were exposed to climb and descents that took twice as long ?

As I said before, I’m no doctor, but I would ask the same question as “Mac the Knife”…….
“ Whether an increase in levels of compounds associated with blood clotting translates into a real increased risk of DVT is something else”……..with the added twist, “is your ‘subject’ one who is at risk already because of his genetic make-up or a lingering, covert, disease that is conducive to DVT in a contrived environment.

[Jackonicko]

I'll ignore your deliberately provocative and sneering tone, as long as you don't start 'Dear Boying' again.

I'm not unusually tall, but have often found myself with inadequate leg-room in economy on long-haul flights (I'd expect it short-haul or charter), having to cant my legs into the aisle, or having to sit diagonally to avoid bashing my knees on the seat in front.

You're being either disingenuous or stupid if you seriously think it's possible or practical to walk about when you want, even if you've been lucky enough to get an aisle seat. This is discouraged by the cabin crew, who want you quiet, predictable and docile. Most of us are insufficiently arrogant or aggressive to go ahead and do what we want, and most of us don't like to 'make a fuss'.

And I'd be happy to pay a little more for human conditions, but don't necessarily want (and can't always afford) Business Class. We're talking about expecting a reasonable, tolerable degree of comfort and safety when we travel, not luxury. The last time I flew to the West Coast with BA, I had less space than I've ever had in a bus, train, or even the back seat of many cars, and that simply isn't good enough. On that particular route (Phoenix) there is no competition, and £520 return should have brought me something closer to a proper standard.

If they can afford to pay current salary levels, they can afford to give my knees an inch extra, I'm sure.

[Slasher]

Well I got it a day later after paxing JFK-NRT in cattle class. Its was quite a bloodey stabbing pain in my left thigh.

[This message has been edited by Slasher (edited 13 November 2000).]

[Mac the Knife]

Hmmm...I can see that this one is going to run and run...

TG - if I may correct you without weakening your case, bed is a bad place to be as far as DVTs are concerned - otherwise spot on (tho' clambering out of your economy seat for a stroll can be a major excursion and is not exactly encouraged by cabin crew).

My better 'alf rather sourly comments that you are so bl**dy uncomfortable most of the time that you can't help fidgeting and giving your legs some exercise...

And on that note....

[Jackonicko]

In a report entitled "Could these seats be the death of you?" the Daily Telegraph said that:

"One in 10 air passengers is at risk of suffering DVT - blood clotting that is potentially fatal. But the danger, as Carole Cadwalladr reports, is an avoidable one."

THERE'S not much left when the news moves on. A fortnight ago the story of how Emma Christoffersen, a 28-year-old "bride-to-be", collapsed and died minutes after she stepped off the plane home from "the holiday of a lifetime" briefly caught the nation's attention. Young and pretty, she was the perfect newspaper victim; her frozen smile from the family snapshot reproduced in grainy black and white - the familiar mark of one who has died in circumstances that are always tragic and usually avoidable.

You may think you've read this story before, but you haven't. Emma's death has more or less been consigned to the status of a freak accident. But it wasn't. The immediate cause of death was a pulmonary embolism, or blood clot, on the lungs, brought on by DVT - deep-vein thrombosis. And the cause of the DVT, said the consultant, was prolonged immobility on the long-haul flight.

For a couple of days, stories about DVT filled the newspapers and the airwaves. And then the news moved on. All that is left is her family's memories, a wilting floral tribute and a book of remembrance in a corner of Newport's Marks & Spencer, where she worked. But the key to this story lies in the newspaper portrait: she died in circumstances that were tragic and that were avoidable.

Flying-related DVT may have only just hit the headlines but this does not mean that it has recently been discovered - far from it. But the difficulty in tracking cases, the lack of research into it, the absence of any recorded figures has enabled the airlines to avoid the issue.

Emma's death was not a freak accident; four of the specialists we contacted claim that on average they see two cases of flying-related DVT a week we have evidence of three people, living within 50 miles of each other, who have developed DVT after long-haul flights in the past three months. Two of them died. One of them, David Billington, survived. None of them could be considered high-risk cases; their deaths have not been investigated. No one has any clearer idea why they developed it, whether the design of the seats or the cabin air is a contributory factor or not. The airlines have accused journalists of "scaremongering". This is not scaremongering; it is scary.

Two days after Emma's death was reported, another story appeared in the newspapers. Research published in The Lancet, it was claimed, showed that there was no link between flying and blood clots. The timing could not have been worse. The report has been systematically slated by every scientist working on DVT in Britain yet it provided the airlines with another excuse not to investigate further, to ignore what is clearly mounting evidence.

By contrast, preliminary results of the first "prospective" (ie, examining people before and after) clinical study into DVT among airline passengers, obtained by The Daily Telegraph, indicate that one in 10 developed clots after long-haul flights.

John Thomas, 30, lived 30 miles from Emma Christoffersen. As a policeman, he had just undergone a rigorous fitness examination and, says his mother Ada, had "not just passed with flying colours but had been complimented on his strength". With his new wife, Sarah, he had an uncomfortable 11-hour flight home from Hawaii with American Airlines. "He said that he felt very cramped on the plane, his legs ached and he felt very thirsty," says Mrs Thomas. Back at his home in Cowbridge, Vale of Glamorgan, he started feeling under the weather.

Two weeks after their return from Hawaii, his wife found him dead. The cause of death was a pulmonary embolism, which in the opinion of the pathologist at the Princess of Wales hospital, Bridgend, had been caused by DVT brought on by the long-haul flight and the sub-tropical climate, which had left him dehydrated.

Because John had been such a fit man, doctors suggested the whole family be tested for a predisposition to DVT. The tests were negative. The next day the family read about Emma Christoffersen. "We just felt so guilty," says Mrs Thomas. "We thought maybe if we had told the newspapers about what happened to John she might have known, she might still be alive."

Twenty miles from Emma's home in Bristol, David Billington, a fit and healthy 48-year-old, also found himself reading about her death in the newspaper on the morning of October 23. Like Emma, he had just returned from Australia and had cramps in his legs. "I was on almost exactly the same route, travelling back to Britain via Hong Kong. And on Sunday night I started getting excruciating pains in my legs. When I read the story about Emma I started wondering if that was what I had, but I thought, 'Don't be so stupid, it's just cramp.' "

He flew to Zurich the next day to attend a business meeting as planned, but when he returned the pain had worsened. He called the local health helpline and was advised to go to hospital. He had DVT. In the opinion of the haemotologist, it had been brought on by the long-haul flight. "I was incredibly lucky. The riskiest thing I could have done was to go on another flight. If the clot had broken away from my leg I would probably be dead."

It is not idle speculation that the deaths of Emma Christoffersen and John Thomas and the DVT suffered by David Billington might have been brought about by long-haul flights. That is the medical diagnosis. But because pulmonary emboli are regarded as "natural" causes of death, there have been no inquests. There are no statistics. The airlines have never been summoned to produce evidence. And there have been no inquiries.

In the front room of their terraced house outside Newport, Emma's parents and her fiancé have the letter they were sent by Qantas. John, Emma's father, shakes as he hands it over. He is not tearful, he is furious. "On the news we watched the Qantas spokesman saying that they wanted to get in touch with us . . . And the only thing we've heard from them is this . . ."

This is a letter that runs to three paragraphs and ends with the sentence: "Regrettably we know little of the details involved in Emma's death. If you wish to speak directly with our Aviation Medical Department, please let me know."

"You would think that they might want to know why Emma died," says Ruth Christoffersen, Emma's mother. But since Emma collapsed 50 yards from the door of its plane, Qantas is under no legal obligation to record, let alone investigate the matter. Heathrow keeps no records of such incidents. Neither does the Civil Aviation Authority.

Tim Stuart, Emma's fiancé, tells the next part of the story. "It was a completely normal flight. She had no pains, no symptoms. She and Rhian were rushing because they were late for the bus. They were laughing and joking At the end of the walkway from the plane, she said to Rhian, 'Oh I need to sit down. I'm not feeling so good.' And then she passed out."

Emma did not regain consciousness. She was taken to Ashford Hospital, where she was pronounced dead. "When we asked the ward sister why, she said that she couldn't be certain, but she was sure it was DVT from the flight. She said that she sees two to three cases from Heathrow a week. What was unusual was that it had happened to someone as young as Emma."

Camera crews from CNN and ABC arrived in Newport. Reporters from Holland, Australia and Germany were on the phone.

Most victims of DVT don't die at the airport. Death usually occurs several weeks later. Or even, as Professor Kevin Burnand, professor of surgery at Guy's, King's and St Thomas's hospitals, suggests, years later. "Many people don't realise they've had DVT until they end up in the hospital years later with an ulcer in their legs, or until they drop down dead from a pulmonary embolism."

Even so, Professor Burnand estimates that he sees two people a week who have developed DVT after a long-haul flight, as does Professor John Scurr, consultant surgeon at Middlesex Hospital.

John Belstead, Accident and Emergency specialist at Ashford Hospital, says that on average he sees one passenger from Heathrow a month who has a pulmonary embolism. And, on average, they are dead. "The point is that we only see the really serious cases and that means that they are usually dead when they get here. Unless you are seriously ill, you are just going to go home. The cases are dispersed all over the country, hence the problem in knowing what the numbers are." On further questioning, it becomes evident that his "one-a-month" figure only relates to fit, healthy, young people. Older passengers, or those in a higher-risk category (which includes, he says, being on the Pill) are not included in this figure. Of them, he sees one every 10 days.

Emma had not heard of DVT. Nor had John Thomas. He exhibited symptoms for two weeks but did not recognise them. "How are you supposed to know about it if the airline doesn't tell you?" demands Mrs Christoffersen. "We've been talking to medical people and they all know about DVT. Their families all know. The ward sister told us that she takes aspirin for a week before a flight. The airlines have a moral duty to tell people of the risks. How are you supposed to know that you can be killed by just sitting on an aeroplane? What can be the harm in that?"

The harm, according to preliminary research conducted by Professor Scurr, is that you have a one in 10 chance of developing a clot. He has enlisted the help of 200 volunteers, all over 50, have no previous history of clotting, and who would be flying for more than eight hours to their destination and the same back again. "It is a pure group. We have excluded anybody who might be considered high-risk. We scanned them before they went, and we are scanning them as they return. And some of them have come back with clots."

The results are still being analysed and will not be published in The Lancet for a month, but indications are that the problem could be greater than anyone envisaged.

"Most of these people are unaware that they have it. They don't necessarily have swollen legs. They don't have any symptoms. These are not necessarily big, life-threatening clots but we are getting some idea of how common it is. We don't want to scare people and we certainly don't want to discourage them from travelling. But we had no idea that it would be as high as 10 per cent. If it is as common as our research is suggesting, then we must think about giving advice. The bottom line is that there is a link between clotting and flying."

George Geroulakas, consultant vascular surgeon at Ealing Hospital (which, like Ashford, is in the Heathrow catchment area), is conducting another study on DVT risk factors and incidence. His preliminary results show that 10 per cent of all DVTs occur after long-haul flights.

The link between pulmonary emboli and prolonged periods of immobility was first noticed among people who sought refuge in air-raid shelters during the Blitz; the first suggestion that sitting immobile in an aeroplane could be a cause was published in 1992, in a paper that related anecdotal evidence from attending physicians.

More research has to be done. "The difficulty is one of funding," says Professor Scurr. "The airlines haven't been interested in drawing attention to a negative aspect of flying."

Professor Burnand, on the other hand, has the funding. Two years ago he was awarded a grant from the Occupational Health Institute to undertake the largest study of DVT among airline passengers ever attempted. He has the money, the nurses and the equipment. What he doesn't have is the passengers. "I have been down to British Airways countless times. I have sent them thousands of emails and they have faffed around. And Virgin has too, for that matter. The problem is that they don't believe it's in their interests. Our line has always been that we have to know what the numbers are."

Passengers who volunteered would be blood-tested immediately before they stepped on to the plane at Heathrow and immediately after stepping off it in Australia. "I have seen lots and lots of patients who have developed DVT after flying. Now, there may well be underlying factors but this is what we need to find out," says Professor Burnand.

The standard health advice is to drink water, walk around, move your legs. "The airlines have been saying that you should drink water," says Mrs Thomas, "and yet they serve up alcohol and tea and coffee - all the things you're not supposed to drink." The airlines, says Mrs Christoffersen, have a moral duty to warn people of the dangers of DVT. But the layout of their planes does not encourage passengers to follow their own good advice; their provision of beverages hardly promotes hydration; their efforts to investigate the causes of DVT have been underwhelming and their failure to co-operate with medical studies such as Professor Burnand's into the effects on actual passengers, is, under the circumstances, a shame.

Dr Richard Dawood, a travel medicine specialist, is even more critical of the airlines. This summer he gave evidence to an inquiry into air travel and health being conducted by a select committee of the House of Lords. Its findings will be published at the end of the month, and it is believed that they are likely to recommend action on the part of the airlines. "It is very clear that something needs to be done," says Dr Dawood. "And it is equally clear the airlines should not be left to police themselves. It is in their commercial interests to get away with what they can but it is not in the passengers' interests."

The airlines, says Dr Dawood, "have hidden behind semantics". DVT is not caused by flying but by sitting still, they say. "You can get it on a car journey or in the theatre," says a BA spokeswoman, "there's nothing to link it to flying." Few people tend to watch 10-hour plays, however, and the effects of cabin pressure, dehydration and types of seating have yet to be researched.

A Qantas spokesman says it has revamped its health information in its inflight magazine and audio programmes and next month is looking at producing video segments to play inflight. British Airways, again, says the information is in the inflight magazine and "on the website". It claims to have helped Dr Kesteven of the Freeman Hospital in Newcastle-upon-Tyne with his research, but as yet this has been limited to providing some information "on the lengths of flights etc"; no clinical study into actual passengers has been undertaken or scheduled.

Qantas says it is working with Griffiths University in Brisbane, and that it would like to investigate Emma's death further but is sensitive to the feelings of the relatives. Surprisingly perhaps, Britannia, a charter airline, is already doing more than both major airlines. It has started making cabin crew announcements during the flight, urging passengers to at least stand up occasionally and to move around when possible; and is sending all cabin crew on a DVT-awareness course.

Without knowing the precise causes of DVT and whether or not you are at risk, the only way to protect yourself is by being aware of its symptoms and its dangers. "John was an intelligent man," says Mrs Thomas. "And he didn't know about it. He had a degree in geology, a degree in law. If he got it wrong, then anybody can."

"We can't turn back the clock," says Mrs Christoffersen. "But had we known about DVT, had we known, I can guarantee you that it is 100 per cent certain Emma would be sitting here today."

* David Billington's name has been changed.

DVT and how to avoid it


What is DVT?
The blood in our legs is returned to the heart as a result of muscle contractions when we walk. Periods of immobility can cause a clot in the muscles of the lower leg - DVT.

And the symptoms?
Throbbing, or pain, in the leg; cramp or swelling or both. Having these does not necessarily mean you have DVT; but not having them doesn't necessarily mean you haven't got it.

What's the worst that can happen?
If the clot remains in the leg, it can be treated with blood-thinning drugs such as Warfarin. If it breaks free, it can travel to the lungs, the heart, the brain - with fatal consequences.

Why has it been called "economy-class syndrome"?
The term was coined by a scientist writing in The Lancet - who had also seen DVT in passengers from first and business class. There is no evidence that diminution in seat sizes has increased the number of cases. But no research has disproved the theory that cramped seating may make things worse.

Is the connection to long-haul flights proven?
The connection between DVT and immobility was first recognised in air-raid shelters during the Blitz. No one, not even the airlines, disputes that sitting in one position for a long time can cause DVT.

Is the risk any greater than going on a long car journey?
Few people drive for eight hours without stopping and car journeys are not necessarily dehydrating. The effects of cabin pressurisation are much debated, but dehydration has been shown to increase the likelihood of blood clotting.

Why don't airlines tell you this during safety announcements?
Because they don't have to. It is only in the past couple of years that they have admitted that passengers are contracting DVT after long-haul flights.

Are some people more at risk?
Yes. Those who smoke, take the Pill or HRT, who are pregnant, who have spent a few days lying in bed or who have a family history of blood clots. You may be prone to clots without realising it.

So, what should I do?
John Belstead, Dr Kesteven and Professor Scurr all take an aspirin (which thins the blood); Professor Burnand's wife wears elasticated stockings (which compress the veins). You must drink lots of water and move your legs regularly. Don't take a sleeping pill and stay in one position.

If your meal has been left on your tray for more than 45 minutes, making it impossible to leave your seat, complain.

[CD]

Jackonicko...

Just wondering which 'Daily Telegraph' you found the article in? (There's one in Australia too!) I tried the online edition of the Telegraph and they have two stories relating to DVT - the October 23rd and November 10th ones, but neither of these are the ones you posted.

Do you recall the date your article was published?

Thanks!

[Jackonicko]

Saturday 11 November, but in the Travel section, which has a separate search engine!

[Tartan Giant]

Jackonicko,
My dear chap......I am wondering which I should be for you, "disingenuous or stupid" ?

Whilst I think on it, can I tell you this; if I thought I was in danger of suffering from DVT on an aircraft, there would be nobody on board who would prevent me from walking about for some exercise !

Let me play the stupid option (just for the sake of argument)for I do think, "it's possible or practical to walk about when you want, even if you've been lucky enough to get an aisle seat."

Good God man....you paid for the seat, not for any glue pinning you to it.

If you have a need to walk about (not everybody does) then exercise the option please.....I'm sure the Commander would prefer you doing a walkabout than you throwing a wobbly/dying on his flight due to a proven case of DVT.

You must fly with some right mean and tough CC if they actively discourage you some movement.
Sure it makes their job easier if everybody was, "quiet, predictable and docile."
It would make it very easy for them if all the lights went out, and they did not feed you or give you a drink at regular intervals. But everybody is not QPD.

You have paid good money to stay alive in that plane, and if that involves your need to have a walk (Seat Belt Sign OFF) then be a man and not a mouse, trying to please some frosty bloody Cabin Crew.
If they object, too bad; tell them you need to move...ask their name/s so your doctor and lawyer will mention them in the letters to the CEO of the airline.
Your safety is their utlimate concern, and if your personal health/safety is put at risk just because they think you should stay in your seat for hours on end, then they need some brain cell replacement therapy.

Whilst I appreciate you are one a band who subscribe to the ethos of, "insufficiently arrogant or aggressive to go ahead and do what we want, and most of us don't like to 'make a fuss' " which in my book is splendid, BUT for for the benefit of your health....buggar all the nice stuff....get on the move.

If the choice I had was between DVT and perhaps, "make a fuss" I know what I would do.....but then I'm stupid (allegedly).

[Jackonicko]

Isn't it strange how "My dear chap" is so much nicer than "My dear boy"? So much nicer, in fact, that I'll apologise for suggesting stupidity.

BUT: Most people (not you, clearly, and not me, in truth) don't like to make a fuss, and do feel constrained not to get out of their seats. And serving drinks reinforces this, since most pax do stay in their seats when there are trolleys about, timing their essential 'loo-breaks' to avoid them. And how often have you heard some-one say:
"Oh no, I'll wait until we've landed."

But you seem to have made up your mind that a DVT is a) nothing to do with flying and b) the passengers' own fault anyway, so I'm not minded to apologise for using the word 'disingenuous'.

[Mac the Knife]

Well now Jackonicko, this is actually starting to get interesting. I happen to know Kevin Burnand slightly (worked around him at Tommies in '84-'85). If he smells a rat then it is just possible that some sort of rodent exists.

The anecdotes are tragic and the opinions are interesting but now it's data gathering time. To start off with. how many pax transit yearly thru LHR? Can you or anyone make a stab at kids, geriatrics, adults and sex ratios? From published national/international stats on DVT/PE we can then work out what the number of events that we would expect from a similar (assumed non-flying) population. An awful lot of pax transit LHR per year, so this expected figure might well be alarming (since DVTs are not exactly rare in the general population).

Answers on a postcard please.

After that one is faced with the task of getting data on:
1) Pax presenting with DVT/PE within an arbitrary cutoff period
2) Subtract predisposers and sundry other arithmetic.
3) Do we have a statistically significant excess over expected?
4) If yes, then more detailed questions.
5) If no, forget it.

I suspect that the S/N ratio is small and that this will be a difficult analysis. If a genuine excess exists then it may be possible to define a single addressable problem and fix it. Alternatively, no single factor will stand out and there is effectively no answer. Pax might then have to accept that another small risk has been added to the known list of prices that we pay for getting from A to B in hours rather than weeks.

Any epidemiologists or statisticians out there?

PS - ERRATA - Earlier I referred to you as being part of the third estate. Since as far as I know you are not a member of the house of Commons this was incorrect. I meant of course the Fourth Estate (the originator of the term was Burke, referring to the Reporters Gallery in the House, though it does not appear in his published works).

[Tartan Giant]

Jackonicko,
My Dear Chap (two brownie points ? ) I am delighted we are approaching agreement in that,
(a) I don't think DVT is caused by AIR TRAVEL
(b) Susceptible passengers can do lots to prevent self induced DVT – so they are at fault.

I know this view may be disappointing but I have MEDICAL reasons for arriving at it – not least some of the doctors in this thread already believe AIR travel is NOT the root cause of DVT.

With due acknowledgements to The National Library of Medicine and the authors of the ‘papers’ I reproduce here, I am still of the solid view DVT is NOT the fault of airlines.

Take this ‘paper’ from the French doctors who conclude, “travel” …..NOT… AIR travel is a risk factor, even on SHORT journeys. Note well the greater number who travelled by CAR.

“CONCLUSIONS: A history of recent travel is a risk factor for VTED. Posttravel venous thrombotic events can occur after short journeys in patients with no other risk factors or concomitant disease”.

QUOTE
Travel as a risk factor for venous thromboembolic disease: a case-control study.

Ferrari E, Chevallier T, Chapelier A, Baudouy M

Cardiology Department, Hopital Pasteur, Nice, France. [email protected]

BACKGROUND: The link between travel and the risk of venous thromboembolic disease (VTED) has been widely suspected. However, only cases or series of cases have been reported in the literature.
STUDY OBJECTIVES: By means of a case-control study, we sought to confirm this relationship and to determine the main features, if any, of these posttravel VTEDs.
DESIGN: The history, in particular the history of recent travel, of 160 patients presenting in our department with VTED was scrupulously investigated. All journeys undertaken during the preceding 4 weeks and lasting > 4 h by whatever means of transport were considered. The same questionnaire was submitted to a control group.
RESULTS: When the two groups of patients are compared, a history of recent travel is found almost four times more frequently in the VTED group (p < 0.0001). The odds ratio for having a VTED in patients who traveled was 3.98 (95% confidence interval, 1.9 to 8.4). Means of travel used included the train in 2 cases, airplane in 9, and car in 28. Mean duration of travel was 5.4+/-2.1 h. These posttravel VTEDs are not confined to a specific location, seem to involve no particular predisposition, and are more often "idiopathic." This fact supports the hypothesis that travel alone can produce vein clot formation.
CONCLUSIONS: A history of recent travel is a risk factor for VTED. Posttravel venous thrombotic events can occur after short journeys in patients with no other risk factors or concomitant disease

PMID: 10027445, UI: 99149691
UNQUOTE

The next ‘paper’ highlights the PREVENTION is better than cure idea………thus my argument to walk about if you feel the need is alive and well.
As the ‘paper’ was originated in Rome, then when in Rome do as the Romans do !

They conclude, “The combination of physical and pharmacologic methods seems to be able of enhancing the efficacy of prophylaxis.” Which I reckon that means, roll down your socks, walk about, then roll them back up again . :)


QUOTE
Risk factors and prevention of venous thromboembolism.

Storti S, Crucitti P, Cina G

Istituto di Semeiotica Medica, Universita Cattolica del S. Cuore, Policlinico A. Gemelli, Roma, Italy.

In the last 20 years within the clinical research on venous thromboembolism a major objective was to identify and develop increasingly effective and safe methods of prevention. This trend is justified by the high incidence of thromboembolism as well as by the relevant mortality for acute pulmonary embolism and postphlebitic sequels of difficult treatment. A significant contribution to the rational application of methods of prevention was given by the knowledge of risk factors. Together with acquired risks, as surgery, age, malignant tumors, in the last 30 years some conditions of thrombophilia were identified. They are caused by deficiencies in coagulation inhibitors (antithrombin III, protein C, protein S) or other alteration of the anticoagulation system as resistance to activated protein C or antiphospholipid antibodies. The primary prophylaxis of venous thromboembolism is aimed at the prevention of thrombosis by pharmacologic methods able to oppose the procoagulant alterations while avoiding hemorrhagic complications. The physical methods tend to reduce the stasis in the veins of the lower extremities. Subcutaneous calcium heparin at the dose of 5000 U twice or three times a day is the most common pharmacologic method used. It was shown to be safe and effective especially in postoperative prophylaxis of venous thromboembolism in general surgery. More recently, low molecular weight heparin fractions have been introduced. As compared to standard heparin they have the advantage of a single daily dose and a better efficacy in some groups of patients, as those undergoing hip replacement. Among the substances under clinical experimentation, dermatan sulfate seems promising. Most common physical prevention methods consist in the use of elastic graduated compression stockings and systems of intermittent pneumatic calf compression. The former can be used also in presence of a hemorrhagic risk as in neurosurgery. The latter have shown a good efficacy in increasing flow velocity and probably also in enhancing the fibrinolytic activity. The combination of physical and pharmacologic methods seems to be able of enhancing the efficacy of prophylaxis.

Publication Types:
 Review
 Review, tutorial

PMID: 9063062, UI: 97217026
UNQUOTE

I hope you are still awake out there……..and not getting DVT in front of the PC screen !!! 

The next ‘paper’ is getting away from the legs and looks at the head, but it shows you that OTHER factors can and do influence a passengers air travel health experience.

How does the airline know the passenger is not ill before they get on board ?
As you stated, “don’t make a fuss” - so sometimes an airline can innocently get passengers with quite severe pre-existing conditions (diarrhoea; been mountaineering at high altitude; deep diving scuba swimmers; had donated plasma; oral contraceptives – the list goes on and on) which could precipitate DVT and so it is not AIR travel that is the root cause of their ailment is it ?

QUOTE
Cerebral Venous Thrombosis - a new diagnosis in travel medicine.

Grotta JC

The University of Texas, Houston School of Medicine, Department of Neurology, Houston, Texas.

[Record supplied by publisher]

Dr. Pfausler and colleagues report in this issue of Journal of Travel Medicine a series of patients with an interesting and potentially fatal neurovascular disorder; they raise the question, is this condition more frequent in travelers? Over a period of 18 months, Dr. Pfausler and colleagues identified five of fifteen consecutive patients presenting with occlusion of the cerebral veins who had been traveling on long distance flights. Some of these patients also had a history of diarrhea, and exposure to heat or dehydration associated with their air travel. It is important to note that their air travel experience was also associated with other precipitating factors in several of the cases. One patient had been mountaineering at high altitude and also had donated plasma. Another had severe diarrhea. A third patient was taking oral contraceptives. Whereas more than a coincidental link appears to be related to air travel, some of the authors' statements implying causality should be qualified in the absence of a larger, more formal, epidemiologic analysis. How might air travel lead to cerebral venous thrombosis? In clinical practice, thrombosis of the cerebral veins most commonly occurs after trauma or infection of the head and neck. However, thrombosis is also seen in conditions of heightened coagulability or viscosity. One could conjecture that prolonged air travel in a cabin, pressurized to the equivalent of high altitude, might lead to compensatory hemoconcentration and heightened blood viscosity, which could be aggravated further by other conditions such as diarrhea or oral contraceptive use. A critical point made by the authors is that the clinical presentation of cerebral venous thrombosis differs from that of conventional stroke. Patients with venous occlusion often present with headache and behavioral abnormalities, which often lead to a mistaken diagnosis of psychogenic illness before seizures or signs of increased intracranial pressure become obvious. Neurologists are trained to have a high index of suspicion for this condition in patients with trauma, infection, or in the peri-partal period. If the observations of Pfausler et al are confirmed, we should add prolonged air travel to the list of predisposing conditions. Cerebral venous thrombosis is a very treatable type of stroke. Major morbidity is due to increased intracranial pressure, which can be relieved by steroids or dehydrating agents. Treatment of underlying infection or hypercoagulability is critical. In the past, most patients were given anticoagulants, despite the risk of hemorrhage into a venous infarct. If the major draining veins of the brain are affected - in particular, the sagittal sinus - a malignant form of increasing intracranial pressure with high morbidity ensues. Recently, direct infusion of thrombolytic agents in the venous sinuses through a retrograde placed catheter has been used in patients with this condition. Cerebral venous thrombosis can be diagnosed readily with magnetic resonance imaging and angiography, which have largely replaced conventional angiography in suspected cases. The development of thrombolytic therapy for acute occlusive stroke and the demonstration of its efficacy and relative safety in carefully selected patients1 have focused attention on the need for ultra-fast recognition and treatment of cerebrovascular disease. As stroke enters the era of emergency therapy, all health professionals, including those who care for air travelers, should be aware of the various presentations of stroke syndromes and the need for urgent therapy.

PMID: 9815440

UNQUOTE

I know this lecture is getting quite boring now, so let this German doctor close the case I put forward that AIR travel alone is not the root cause of DVT….he agrees with me as well !
“From these investigations no increased risk for thromboembolic diseases during long distance flights for healthy volunteers could be derived.”

Read on My Dear Chap (another two brownie points ? )

QUOTE

Economy class syndrome: fiction or fact?

Landgraf H

Wenckebach-Krankenhaus, Berlin.

Several reports about the occurrence of deep vein thrombosis and pulmonary embolism following long-distance flights have led to the term "economy class syndrome". The underlying hypothesis was that a long term immobilisation in narrow economy class chairs of modern jet aircraft plays an important role for the development of deep vein thrombosis. Studies in healthy volunteers during several simulated long distance flights and during an actual long-distance flight confirmed the swelling of the lower legs complained by many long distance passengers, however, failed to reveal relevant changes of hemorheological or hemostaseological parameters. From these investigations no increased risk for thromboembolic diseases during long distance flights for healthy volunteers could be derived. Since this may be completely different for patients with risk factors for thromboembolic diseases prophylactic measures (compression stockings, anticoagulation) might be necessary.

PMID: 10568252, UI: 20034247

UNQUOTE

Exit aircraft fit and well :)

[CD]

Tartan Giant...

Thanks for the information. Would you happen to know if these papers are available online or are they only available in hard copy?

[Tartan Giant]

CD,
No problem - hope it helps to clear the matter up. :)

The 'papers' are all available on-line at, www.ncbi.nlm.nih.gov/htbin-post/PubMed/wgetcit? (http://www.ncbi.nlm.nih.gov/htbin-post/PubMed/wgetcit?)

If that does not get you to the heart (pun intended) of the matter on DVT then you can access the 'papers' via The Lancet (might have to register though) at, http://www.thelancet.com/journal/vol356/iss9240/full/llan.356.9240.original_research.14016.1

and then go to the Reference Notes at the end of their 'paper' under any "PubMed" link.

If you have any snags let me know, and I will try and give you a better 'link'.

Cheers,
TG

[Jackonicko]

TG

It looks as though there are currently medical papers to support either conclusion, and we can both ignore those that don't agree with our pre-conceived conclusions. It strikes me as being like the early days of the cigarette/lung cancer link, when some impressively learned medicos dismissed it out of hand. I'm trying not to make a hard and fast conclusion, but believe that a sensible precaution, in view of the possibility of the 'alarmist reports' being right, is to treat the matter seriously, and put in place some simple precautionary measures.

[Mac the Knife]

Well chaps...

"The exact incidence of DVT is unknown because most studies are limited by the inherent inaccuracy of clinical diagnosis. More importantly, most DVT is occult and usually resolves spontaneously without complication. Existing data that underestimates the true incidence of DVT suggests that about 80 cases per 100,000 persons occur annually. Approximately 1 person in 20 will develop DVT over her/his lifetime, and 600,000 hospitalizations for DVT occur annually in the US."

"In hospitalized patients, the incidence of venous thrombosis is considerably higher and varies from 20-70%. Venous ulceration and venous insufficiency of the lower leg, which are long-term complications of DVT, affect 0.5% of the entire population. Extrapolation of this data reveals that as many as five million people suffer from venous stasis and varying degrees of venous insufficiency. Mortality/Morbidity: Death from DVT is attributed to massive pulmonary embolism, which cause 200,000 deaths annually in the US. Pulmonary embolism is the leading cause of preventable in-hospital mortality. "

Figures from Donald Schreiber, MD, CM, Research Director, Assistant Professor, Department of Emergency Medicine, Stanford University School of Medicine.

"A total of 61 million passengers used Heathrow Airport in 1999."

Source: Roger Cato, Managing Director of BAA Heathrow Airport

A little rough arithmetic gives us an expected figure (probably an underestimate) of 48,800 pax yearly with DVTs provided that flying is NOT an added risk. If we do a 50% correction for underestimation and assume a very modest increased risk we could quite reasonably project 100,000 LHR victims/year.

Comments anyone?

And: "Whisky is by far the most popular drink at Heathrow: on average, a bottle is bought every seven seconds".

[bigseat]

Re Economy class syndrome

Just returned to find a lot of hot air as a means of stroking BIG EGOS.


To the authors of the silly comments regarding my last posting, you should know that when you try on this forum to look clever, you end up looking quite pathetic, as many, if not most people reading this forum are scientists or medics- its just we dont need to SHOUT about it.

The sarcastic comments made in my second posting were used to respond to the sarcasm of Aeromed.

What's all this about a cat?

Aeromed, this was your first posting ,and you should realise that if you strongly express an opinion on this forum, someone may strongly disagree. You shouldn't use personal snide comments in retaliation, but argue the facts. Look at my first post, it was not a personal critique of you, but of the opinion expressed, yet you felt the need to reply with trite remarks regarding grammar etc.. Usually I dont worry too much about spelling etc on internet sites like this. Just remember, a strong opinion is not necessarily correct, so don't get angry if someone has a different point of view.


Really, some interesting posts, but the evidence is incomplete, regardles of which review/article is cited, and most within the medical profession are unsure too. Insufficient evidence to make a firm call either way.

So stop waffling.


Sorry, Aeromed, just realised its not your first post....so no excuse then..


[This message has been edited by bigseat (edited 17 November 2000).]

[Mac the Knife]

Bigseat again...Lordy me! Anyone care to discuss Erwin Schrödinger with BS? Thought not...

More figures. Working on the 80/100,000/year datum.

If no increased risk we would expect
48000 DVTs/year among the 61M/year LHR pax
4000/month
1000/week
143/day
6/hour

If 5% develop PEs expect 2400 PEs/year
If 10% of PEs die expect 240 deaths/year

If underdiagnosis and mod. increased risk we would expect, say
100000 DVTs/year among the 61M/year LHR pax
8333/month
2083/week
297/day
12/hr

If 5% develop PEs expect 5000 PEs/year
If 10% of PEs die expect 500 deaths/year

If my sums are right BAA must be burying them secretly.
Or else flying is actually DVT/PE protective :)

Off to London to visit my brother on Wednesday - CPT/LHR BA58 22/11
11+hrs in cattle. No special DVT precautions. Watch this space.

[Jackonicko]

The tendency of the scientist to ignore all anecdotal evidence as being invalid is just plain stupid. Young, healthy, fit people have died as a result of DVTs after long-haul economy flights. Not many of these sort of people die of them in the general population unless they belong to another risk group (pill-takers, etc.). Who's arrogant (or brave) enough to say that the stats don't prove it, half the research tends to undermine it, therefore there's no risk.

Make sure you exercise on board, walk about, drink lots of water, and wear one of those funny elasticated sock jobs, Mac, because you getting a DVT and proving the point wouldn't be the kind of victory any of us would want!

[Tartan Giant]

Bigseat
Welcome back….where have you been ? No….don’t tell me, “flying, flying, flying”.
We have missed your scientific/doctor input. I am assuming you are either one or the other (no clues in your profile).

I confess I write in as one of the defined “pathetic” contributors, as I am neither a scientist nor a doctor so you will have to put up with my “silly comments”. I do have that logic correct don’t I ? Using your statement,
“….you should know that when you try on this forum to look clever, you end up looking quite pathetic, as many, if not most people reading this forum are scientists or medics”.
Now who is stroking BIG EGOS ?

DVT and Flying
You say there is, “…..Insufficient evidence to make a firm call either way.” What utter rubbish !
I would say the logical data “Mac the Knife” has just supplied would allow even a mad scientist, or a lesser mortal (such as an airline pilot) to make a considered call, “flying is NOT the root cause of DVT”.

You say, “Young, healthy, fit people have died as a result of DVTs after long-haul economy flights”.
Forgive me, but I cannot recall any reported post-mortems nominating such passengers who have allegedly died of DVT post long-haul flights, as being, “Young, healthy, fit….”.
Can you give me the data (who, where, when, how, why) on half a dozen of whom you pledge died in such circumstances please ?

In that data, can you give me your scientific definitions of, “young” “healthy” and “fit” please.

Regards,
TG

PS Does an MSc in Air Transport Operations make one a scientist ?

Mac the Knife
Have a safe and happy flight.... :)

[Mac the Knife]

Apologies JN - my fishing gets a well-deserved slap with a wet one.

Your advice is sensible for ALL travellers & I'll take it.

I suspected that a lot of pax passed thru LHR/year but 61M is a helluva lot. I sort of thought that chance alone would throw up a lot of victims, but even I was surprised. The problem is that with such huge number of people even things like frinstance "one-in-a-million" ultra-rare tumours are going to appear more often than you would initially expect.

Fit young people ARE dying after travelling. So, presumably, are old folks and unfit berks like me. IS this happening more often than we would expect from chance in a non-flying population? In spite of all the toing and froing on this thread we still don't know. Nonetheless it's a very legitimate question for chaps like you (or anyone) to ask and be concerned about. Living where I do I'm very very glad that our press is still free to ask embarrassing questions.

My only plea is only that before we start exploring the role of cramped seating or stale air or booze-and-boredom or inflight movies that we try to establish whether a REAL (as distinct from perceived) problem specifically associated with flying exists. Maybe it doesn't. Maybe it does. Maybe carriers are aware of it and trying to minimise it. Who knows?

But first things first - let's make sure that the shadows that we are barking at are cast by something more substantial than vague suspicions.

Cheers Mac :)

[Jackonicko]

I know personally two victims of clots/thromboses, both young (in their early 30s at the time) and both ferociously fit (county and national-level athletes). One was also on the high-dose pill, and at the time (four years ago) I blamed that, and not her bucket-and-spade trip back from North Africa, when the symptoms manifested themselves. She spent time in the JRII on Warfarin, with a leg blown up the size of mine. The other (two years ago) had no such easy explanation at the time, though it occurred on the plane home from Florida. Insofar as I am aware, both girls got home and were then hospitalised locally (the same day), and my suspicion is that probably neither of them are in the statistics for flying-related DVTs.

[Aeromed-Doc]

Some interesting discussion folks ... thanks. I've been reading with great interest but keeping my opinions to a low profile ... ya got most of them up front.

One problem with your statistical approach MTK is, I believe, that DVT does not usually get noticed immediately. So even if that many were occuring they'd be being buried throughout the world not just in one of those vacant areas beside LHR.

Also, Jackonicko, I don't think scientists necessarily ignore annecdotal evidence ... they just treat it for what it is - annecdote :-) It's the annecdotes and individual suspicions that lead scientific research in one direction or another. On this topic we have some annecdotes and lots of suspicions and we're starting to see the results of some scientific work being done to investigate the concerns.

Young healthy people do get DVTs for no obvious reason although you can usually identify some potential causes upon careful questioning. It is rare but we've seen a couple over the last few years.

Whether my initial assertion in this thread is correct or not is immaterial ... my ego can cope with occasionally (OK, rarely :-) being wrong ... what matters is that our individual and community responses are based on valid information and not sensationalist media exposition. I will be watching and reading with great interest over the next couple of years as quality research on this topic filters out into the world, although the mass-media will have doubtlessly turned to another matter by then.

As for that [expletive deleted] cat .... it should probably be buried, both dead and alive, in MTK's mass-grave somewhere near LHR :-)

Safe Flying All
Aeromed-Doc
Out

[Paterbrat]

Whew, having read the preceding thread with utter fascination, it is now way past pubtime and bedtime. I am however interested from a purely practical point of view. Being temporarily away from the best seat in the house and being reduced to sharing the delights in the rear, no not even club, and with a number of rather long sectors all six hours plus, I will now drink plenty of water, forsake the booze, firmly face down the frostiest CA to wander purposfully around the cabin. Fidget like mad during the meal and hope that I survive my excursions to sim and hols, without any sudden pains and heaven forbid collect a windfall I won't be around to spend. Seriously though it's been interesting reading some firm frank and obviously informed opinion. I just hope I don't get it.

[Jackonicko]

Interesting that the UK House of Lords (with access to some pretty powerful and high-priced expert help) don't dismiss the link between DVT and flying. Anyone want to bet that within five years the link will have been proven, and within ten they'll do something about it.

Interesting that BA's latest marketing gimmick is a sub-club, more legroom, ticket-price-equivalent-to-undiscounted-economy class.

The way ahead?

[Paterbrat]

I for one would definitely be interested. I think it would definitely sell as the present pitch and space I heard compared as being marginaly greater than that afforded on some of the Blackbirding slave ships enroute to the Carolinas.