Why don't long haul pilots die from DVT?

[Captain Gidday]

I wonder if any experts out there can tell me why it is that young and fit women and men can and do die from Deep Vein Thrombosis due to sitting inactive in cramped conditions, yet there appears to be no recorded instance of an airline pilot suffering the same fate, despite many sitting relatively inactive for quite long time intervals for perhaps 20,000 hours all told in a typical working career. Why is this? Anyone?

[Skip Undo]

Next time spend a little more time on your homework Gidday before posting such an absurd assertion.

Of *course* there have been cases of pilots collapsing and dieing at the end of long flights - why would they not? - apart from having more generous legroom than the poor sods back in steerage.

Many in the past, but most recently reported in the case of an American at Narita - just one of the 25 people Dr Toshiro Makino reports have died at Tokyo airport over the
past eight years due to blood clots
caused by cramped airline seating.

Dr Makino said all the victims, including
the American pilot, had collapsed after
disembarking from long flights and
had died in the airport hospital.

As you're no doubt aware all the major airlines are most keen to keep a lid on this sort of thing for obvious reasons - not the least of which is desire to keep their most experienced crew well in the dark on both DVT and radiation hazards.

Seems they've succeeded with you Gidday.

[Mac the Knife]

Checkout http://www.pprune.org/ubb/NonCGI/Forum52/HTML/000249.html for a longish thread on the subject.

[Skip Undo]

Aye Dr. Mac, I did indeed follow that thread closely, flawed as it was, by vested interests and closed minds.

And duly filed it with the rest of the huge folder full of the travel related DVT, thrombosis, PE, tobacco, asbestos, harmless British Beef and cosmic radiation rubbish perpetrated by members of the medical profession who are in the pockets of large corporations - and especially airlines.

Flatly denying any, or all of these issues is like peeing into the breeze as public awareness and the evidence continues to accumulate.

http://www.thetimes.co.uk/article/0,,2-63436,00.html

[CrashDive]

Skip Undo – I don’t normally frequent this forum however, w.r.t. your reply above to Capt Gidday, I have to say that I don't much care for your tone.

Imho Gidday asked a reasonable question (i.e. question which I too am interested in – but on which neither of us might have done our ‘homework’ ) but which you then seemed to think as being beyond the pale; Worse still than that was that you then seem to think it ok to make rude / insulting suggestions w.r.t whether he has been hoodwinked by some huge conspiracy by (the) airlines.

Now, for many a moon, I have known pilots from both long and short haul and I have not been aware (until recently) about the subject of DVT and of how it might affect them. So, rather than try and rubbish peoples questions why not try and answer them with facts and figures as to the scale of the problem, and why is it that pilots are not reported as dropping dead from DVT on a regular basis, especially so when given their massive exposure to the problem ?!

Note: Below is copy/paste of a posting, made in Rumours and News, by a colleague on this subject:

<font face="Verdana, Arial, Helvetica" size="2"> This by ‘Old King Coal’: This whole DVT thing is quite worrying, particularly so as I often spend absolutely bloody hours sitting in my (not very comfy) flight deck seat.

By way of proof, if on a four sector day it transpires that I do the first and last sector (and the other chap does the middle two), then when I’ve completed the walk-around it’s quite likely that I won’t then have much of a chance to get out of my seat for what can be 7+ hours, i.e. until prior to the last sector and it’s associated walk-around check – end even then this walk only lasts for about 4 minutes. Nb. ( we do 25’ minute turn-arounds and if running behind schedule then we have to really go at it to be on our way asap – thus not much time for a constitutional )

Now I do this day in day out, week in week out, month in month out – perhaps I’d better book an advanced place in a cardiac unit. 

Also, and as if the potential for the above wasn’t bad enough, I‘m also starting to suffer some very intense lower back and neck pains – where my seats lumbar support is totally crap.

To be honest, and imho, the pax have a lot more opportunity to move about than the flight deck crew ever do.
</font>

<font face="Verdana, Arial, Helvetica" size="2"> This in reply by ‘Jurassic Jet Man’: I think you have to make yourself get up and stretch. I get out of my seat at least once an hour, depending on workload, and do some sretching exercises in the cockpit. I also take a quick walk through the cabin once during a long flight. My cousin has DVT from being couped up in a French hospital with a broken ankle. The British docs cannot shift it - she is seriously looking at total leg amputation - tough for a pretty 30 something with kids.

This condition is a total bugger, and is utterly avoidable.
</font>

<font face="Verdana, Arial, Helvetica" size="2"> This in response by ‘Old King Coal’: JJM, good advice and point taken - however there's not too much room for 'streching' in a B737 flight deck.

Also, and to this day, I have only once ever seen a fellow colleague activily indulge in some stretching exercises (he placed his toes on the 'stirrups' and his backside on the top of the seat - resulting in loads which are a testiment to the strength of Boeing engineering, i.e. that the seat back didn't break - and 'pulled' out on his leg muscles.

Yep, outside of that single example, all I've ever known is us sitting there for hour after hour as if glued to the seats, i.e it just doesn't seem to be the done thing to leave the flight deck for something so 'unwaranted' as moving ones legs and / or retaining vascular circulation.

So, does anybody out there in PPRuNe land have any details on whether flight crew are prone to DVT etc ? ... because it seems to me like we ought to be !
</font>

So, as a MD (observed from your profile. Nb. does this stand for Doctor of Medicine, or Managing Director ?), could you please answer it for him / them, and hopefully in a civil manner.

[This message has been edited by CrashDive (edited 06 January 2001).]

[Mac the Knife]

OK Skip Undo, tell us about the "vested interests" and "closed minds" you found.

What (I hope) all all us would like to do is to sort out the truth from the scare. Pilots get very irritated when a shock-horror newspaper story comes out to the effect that all type X aircraft are deathtraps, that flying with airline operator Z is tantamount to suicide, that aircrew are all drunks and so on and so on.

Nobody denies that pax (and even aircrew) have died during or after flights, long or otherwise. Some of then even of DVTs. Whether there is a causal link with flying, cramped or not, still has to be established. It is entirely possible that there is a link, though available statistics would seem to suggest that it isn't likely to be a strong one.

What impresses me is proper statistics, not anecdotes about Dr Makino.
Consider if you will - Approximately 22.94 million people traveled to and from Narita Airport on international flights in 1997. If only 25 people have died of DVTs there in eight years then it must be one of the safest places on earth.

The question is quite simple. Is there a statistically significant excess of people suffering/dying from DVTs after long (or short) airline flights over that that you would expect in a comparable non-flying population?

The jury is still out on that one, but current evidence is not strong.

Nobody, as far as I am aware, is flatly denying anything - certainly not me.
And please tell me the large corporation whose pocket I am in - I'll must ask them for a raise :)

Actually I've just realised that I must be a member of the International Medical Conspiracy - we've got the pax, now for the crew!

I think I detect a Conspiracy Theory theoretician

[Code Blue]

&gt;&gt;The question is quite simple. Is there a statistically significant excess of people suffering/dying from DVTs after long (or short) airline flights over that that you would expect in a comparable non-flying population?&lt;&lt;

A well designed epidemiological study could answer this, but at some considerable financial cost.

The number of people who drop dead within minutes or even hours of developing a DVT seems to be a minute proportion of all those who develop DVTs. Perhaps only very active individuals can exert enough muscle pumping in their legs to dislodge the fatal clots early. The participants would need to be followed for probably 14 days after their flight to ensure an accurate estimation of death rate.

The prevalence of DVTs varies in the literature depending on the screening test used. The easier the test the fewer clots it finds - ultrasound vs isotope scans for example.

Who would want to pay the costs of such a study? Especially if there exists a likelihood that the sponsor won't get the answer they wish. Back to the Conspiracy Theorists :)


My take on this is that the case is Not Proven, but there's enough smoke....
I'll carry on with my bottled water and aspirin and await the experts deliberations.

PS: The ER docs in S Manchester used to teach that long haul flight contributed to rupture of intracranial aneurysms and consequent sub arachnoid haemorrhage. Anyone want to comment on that can of worms?

edited for nocturnal dyslexia

------------------
-.-- --.- -..-

[This message has been edited by Code Blue (edited 06 January 2001).]

[I Kid]

I can't answer the initial question, but I can confirm that Aircrew have in the past, and still do, suffer from DVT. I suffered a Pulmonary Embolism at the age of 37. At the time I was flying relatively short ad-hoc charters, (ten hours once, Belfast- Tel aviv but it was a DC6 :) ) Luckily after three months off work thee CAA re issued my class one.

No one, including the Specialists could Identify what the cause was, but suggested I packed the Cigarettes in and kept fit. Recently a Colleague of mine suffered the same fate and luckily he survived as I did.

I sincerely hope no one suffers the same fate but unfortunately is does happen, Aircrew or Pax.

Regards.

[Mac the Knife]

As Code Blue says: "A well designed epidemiological study could answer this, but at some considerable financial cost."

Not necessarily that expensive. Give out FreePost postcards with tickets or boarding passes. Offer a little incentive - airmiles would be easiest. Ask for flightnumber, date, seatnumber and when/where DVT diagnosed. Ask for return of card between within 2/52 and 1/12 of traveldate. Obviously the dead won't be able to answer, but we have good data on treated/untreated death rates so could reasonably extrapolate.

As Code Blue notes: "The number of people who drop dead within minutes or even hours of developing a DVT seems to be a minute proportion of all those who develop DVTs.. & ..participants would need to be followed for probably 14 days after their flight to ensure an accurate estimation of death rate."

Another simple matter would be to mail all registered doctors in the UK asking for anonymous patient data and including a very simple FreePost postcard with a few similar tick-the-box questions. Again offer a few airmiles as incentive.

The response rates from pax/doctors might not be all that good, but it would start to give us some idea of what is (or is not) going on. A lot better than blundering around in the current maze of speculation and anecdote.

I would venture that the cost to (say) BA would be relatively small (and tax-deductible).
As for the answer "they want" - what about the kudos of being the first carrier to "take it seriously" and do a proper study? And if the answer is not "what they want" then what? Will people suddenly stop flying in significant numbers? I doubt it. Even if you double the risks for a standard population a DVT death remains a relatively much smaller risk than driving. Incidentally, on my recent CPT/LHR/CPT flight (horribly cramped - thanks BA), there was a rather muted announcement about stretching your legs and drinking plenty of fluids.

I Kid - glad you and your mate made it, but we KNOW that pax/crew get DVTs/PEs. What we need to know is whether a statistically significant excess of people are suffering DVTs after long (or short) airline flights over that that you would expect in a comparable non-flying population.

Until one of the major carriers gets off it's @rse and gets a proper study off the ground we will never find out. A little bit of gumption is all that is needed.

[I Kid]

Mac the Knife, "but we KNOW pax/crew get DVT/PA's",

Well sorry, but the initial post " Why don't long haul pilots die from DVT ?" which also included " yet there appears to be no recorded instance of an airline pilot suffering the same fate ", and previous posts on this subject would indicate to me that a fair percentage of my colleagues are unaware that this problem is quite common amongst aircrew worldwide.

My post was not only to signify this, but also to reassure my fellow Aviators that, in the UK at least, if you are unlucky enough to suffer a DVT/PE that the Civil Aviation Authority do not adopt a draconian attitude towards the problem ie: withdraw your medical for life, on the contrary they are very helpfull and understanding and that within a period of time you could be flying commercially again. This is of course that when you did suffer the DVT/PE you did'nt end up Brown Bread.

May I say I'm glad that your glad that " me & my mate survived ". :)

Regards.

[Code Blue]

The problem here is a lack of credible data surrounded by a distinct feeling that all may not be as the current scanty data suggest.

Unless a well designed survey is implemented that situation will continue.

Postal surveys have response rates of 20% under IDEAL circumstances - it's usually around 10-12%. Death rates for untreated vs treated DVTs relate to in hospital or condition specific DVTs and cannot be extrapolated to the population under discussion here.

The choice of diagnostic test for DVT is paramount: a postal survey of Family Docs, with all due respect to you and them, simply is a non-starter. What types of DVT do you want to hunt for? Iodinated fibrinogen scans cost - even a Doppler U/s is expensive and are thought to be less sensitive for popliteal or distal DVTs - they are best suited for the potentially lethal proximal clots. Are you interested in all DVTS or just the potentially lethal? Some would argue that ascending venography is the gold standard assessment for DVT - who would finance that?

What is the role, if any, of a sudden return to activity -eg. the Baggage wrestle - in the presence of DVT, particularly in the young and more active population?

What other coexistent risk factors might confound the issue - the Pill, smoking, dehydration &c? These could each be addressed if only the design of the study is well thought out.

Whichever perspective you come from, a bullet-proof study is needed. The money is as always the key - you get what you pay for. Over the years I have also realised that the piper calls the tune and I have grave reservations that a major carrier would design deliberately, a study which would have even a slight chance of showing it's service needs a health warning. :)

It is going to cost and I cannot see anyone who both can and wants to afford it. http://www.pprune.org/ubb/NonCGI/frown.gif


------------------
-.-- --.- -..-

[This message has been edited by Code Blue (edited 07 January 2001).]
edited for Sunday Morning dyslexia

[This message has been edited by Code Blue (edited 07 January 2001).]

[Grandad Flyer]

A start would perhaps be to do an aircrew survey, to find out how many pilots and cabin crew had had DVT.
From this it would surely be possible to gauge the numbers we are talking about?
Also, the CAA I guess would have info on the number of pilots who had suffered as their medicals would have been suspended.
This would be relatively straightforward, I am sure most airlines would (certainly should) be willing to participate.

[Mac the Knife]

I Kid - your point is well taken. As I read it your post implies a question - if DVT/PE is such a dreadful danger how come I(you) have not noticed my mates dropping dead like flies after long trips?

Crashdive has "known pilots from both long and short haul for many a moon" and not noticed anything alarming.

If the syndrome IS real, then either you and Crashdive are remarkably unobservant or there is something different about pilots (yes :) I know there is but we won't go into that here).

Code Blue - through much of these DVT threads runs a suspicion that DVT/PE is a megamega problem the extent of which is being wilfully withheld from the public by Skip Undo's "..members of the medical profession who are in the pockets of large corporations - and especially airlines".
All that I can say is that long-haul flights have been going on for many many years and while you can conceal an elephant for a while it tends to make it's presence felt fairly soon, whether you like it or not. A mouse, on the other hand, may go un-noticed for years.

Postal surveys do indeed have a low response rate - that is why I suggested the airmiles bribe - but even 12% of 100 million pax/year would be a sizeable sample.

We don't have to be perfect methodologically first time round. Just get the big picture - 10,0000 pax and 10,0000 nonpax - any excess events. If none, then forget it. If yes then by all means start looking more closely at smokers/pill/etc.

As for the DVTs, we are not talking about picking up silent events - just the clinically obvious to start with. You were not suggesting subjecting all disembarking pax/crew to ascending venography were you? No, most people with symptomatic DVTs will end up (in the first world) in hospital, on heparin and probably have some kind of confirmatory investigation. The investigations will have already been done and the data is there.

Grandad Flyer's suggestion is excellent and 20,000 PPRuNers would be an immediate though imperfect sample to checkout (have mercy on us cry Danny's servers....) At least we could get some idea what size animal is in the room with us!

[Code Blue]

MTK:

If some form of ballpark screening exercise is what you want then any of the suggestions made here would provide some data. How you interpret those data would depend on perspective and to perhaps a lesser extent on the results themselves.

There seem to be 2 groups here: those who think there is a problem and those who don't. Everyone has agreed http://www.pprune.org/ubb/NonCGI/eek.gif that the info just isn't there. A screening survey might not clarify matters - it might just provoke a whole series of methodological arguments.

Try it by all means .."a journey of a thousand miles begins &c...." but don't be surprised if the results start an identical version of this thread, with identical comments at some time in the future.

I don't see the 'definitive' study ever getting off the ground (groan) because I do believe there are groups who would be happy to perpetuate the current state of ignorance on this.

------------------
-.-- --.- -..-

[This message has been edited by Code Blue (edited 07 January 2001).]

[This message has been edited by Code Blue (edited 07 January 2001).]
[This message has been edited by Code Blue (edited 07 January 2001).]
:) still can't type ;) :)

[This message has been edited by Code Blue (edited 07 January 2001).]

[I Kid]

Mac the Knife, check thou's E-Mail.

Eamonn Williams.

[faheel]

I have read that DVT is caused by blood pooling in the lower legs during long periods of inactivity. The blood may have clotted. So when you get up and move around after the flight if a clot breaks off and travels to the brain you are pretty well done for.
Now for a few years now I have taken half an asprin a day to thin the blood (my hypochondria about heart attack being the reason) so I would assume that if your blood is thinned you would be less likely to have your blood "sludge" in your lower legs after sitting for hours and hours on your bum :)
Maybe those worried about DVT should see their doc and ask if an asprin is the answer, at least in the short term.

[Code Blue]

faheel:

In general DVTs are associated with blood pooling in the legs and usually this is from immobility. Clots which dislodge actually arrive in the lungs first because of the way the plumbing is arranged - it can be fatal when the clot is big enough to stop the circulation of blood there completely.

An aspirin will reduce the chances of blood clotting - indeed it works as well as the so-called clotbusters for heart attacks. Stomach problems sometimes limit its usefulness.

PS: It has only been shown convincingly to reduce the risk of Heart attack in patients over 40 who have already had one such attack.

------------------
-.-- --.- -..-

[Pandora]

Faheel,
please don't take the aspirin daily. As Code Blue has already said, it has only been proven to work to prevent certain conditions in certain patient groups, and as one who has been involved in aspirin studies in UK hospitals in a previous career, I can tell you there is no evidence to suggest that aspirin will prevent a DVT or PE at all, let alone during flight.
There is, however, conclusive evidence that statistically significant numbers of regular aspirin takers will develope gastrointestinal problems including stomach bleeding, and therefore you should only take it daily under the supervision of a doctor (which I am not). I often used to be told that if aspirin was invented today, it would be considered not safe for use in any patients.

[faheel]

hmmm,
Just don't know what to believe these days.
Have not heard about those studies, will have to do some serious research now.
The asprin I now take is a 100mg coated pill which is surposed to be absorbed thru the gut instead of the stomach If I understand it correctly.

[I Kid]

Pandora,

What are your views on the 75mg Apirin taken daily ?, with a view to preventative measures like thinning blood etc.
Regards.

[Skip Undo]

CrashDive - that "tone" towards Capt Gidday (to which you took exception) is the one normally reserved for trolls who mischievously post disinformation. And when the topic title is so demonstrably wrong one can only assume that Capt Gidday is intent on perpetuating the "No such thing as Economy Class Syndrome". Also CrashDive please note that my post was addressed to his "absurd assertion" - and not (as you suggest) rubbishing his question, which being based on a false premise I totally ignored, regarding it merely as a sarcastic footnote.
I note that Gidday has not returned - reinforcing my perception it was pure mischief. Nevertheless valuable discussion has ensued.

Mac the Knife - thank you for your good humoured replies and confirmation that crew HAVE indeed died from DVT - even if you are personally unconvinced of a causal link.

&gt;"Nobody…..is flatly denying anything"&lt;

Errr - maybe re-check the topic Mon Ami.

Closed minds? - well I think the titles alone of this thread and that given to the prior thread by Aeromed-Doc speaks volumes. Clearly miffed at the great unwashed bandying about of a pop term, rather than than something unpronounceable with Latin roots he loftily posted "To simply make-up a fanciful, media-genic, if wholly inaccurate name is, IMHO, thoroughly inappropriate." and proceeded to lobby to have it expunged from the language, denying it's very existence with about as much effect as King Canute against the tide.

Wonder how he feels about German Measles? J

Strange though how eagerly Aeromed and others seized on the freshly published Kraaijenhagen Lancet lamp post because here at last, there was a study which supported their entrenched position yet (with the notable exception of Jackonicko) were dismissive of the opposing Norwegian study from the same supposedly reputable journal.

Even stranger that nobody (least of all AeroMed-Doc) sought to comment on the subsequent discreditation of the Amsterdam study by other learned colleagues let alone the historical doubts which have clouded the credibility of certain corporate sponsored Dutch research in the past.

Code Blue and Mac - you said
&gt;&gt;The question is quite simple. Is there a statistically significant excess of people suffering/dying from DVTs after long (or short) airline flights over that that you would expect in a comparable non-flying population?&lt;&lt;

Indeed it is my friends and the data is staring you right in the face - in the example I gave you from Narita - dismissed by Mac as anecdotal - you seem unprepared to correctly analyse it for fear of the unpalatable result.

Let's see then - in the "No Such Thing as Economy Class Syndrome" thread Mac you provided a reference for DVT/PE morbidity in the US of 200,000 pa - I'm happy to accept that - it agrees roughly with my own references and gives a mortality rate of around 1.35 persons/1000 pa.

Next Mac, you reckoned on 22.94 million international pax p.a. to/from Narita. Not sure whether that excludes domestic short hauls who would not be at risk but anyway over 8 years I'll allow we'd have some 183.52 million pax thru Narita.

And as previously discussed some 25 of these (183.52 million) incl a pilot died of DVT/PE related complications. You contended this made Narita "one of the safest places on earth" for DVT's.

However I'm sure you'd agree that departing passengers were not at elevated risk? So we're left with just the half who arrived - 91.76 million pax.

And this is where you made the same GROSS statistical error as in the previous thread (re LHR) - you assumed that our notional population of 91.76 million "lived" at Narita for an entire year in comparing it with our normal population which did indeed live for an entire year in the US.

In reality the arriving pax only were exposed to the risk at NRT for the ONE hour it took for them to collect their bags and be on their way - 25 died in this short window! The Americans lived and died in the US over 8,760 hours!!

Do the arithmetic - you'll find the DVT/PE mortality rate for Narita airline pax is more than TRIPLE that for your normal population. If you don't find that statistically significant - then I give up!

Oh, and BTW - re "vested interests" absolutely no aspersions intended towards yourself MtK but intended as my disgust towards those other medical and scientific perverts who for personal and financial reasons perpetuate the human misery caused by various companies products. Tobacco and particularly asbestos spring to mind for disgraceful examples, see
http://seattlep-i.nwsource.com/asbestos/

IMHO the airline industry and some of its hired medicos will, in in the not too distant future, be brought to account and proven no different.

Perhaps some enterprising journalist could begin by popping across to the University of Amsterdam for a discussion on the level of funding support provided by their good corporate neighbours out at Schiphol who just happen to run a long haul airline.

Or maybe an interview with a certain Pprune poster on exactly why he is so intent to see the "Economy Class Syndrome" term expunged. Nothing at all I'm sure to do with his professional links to a certain long haul carrier???.

Speaking of which which reminds me of a certain carriers refusal to participate in a study-
http://news.ninemsn.com.au/national/story_5780.asp
BTW I'm personally aware of another similar request from a vascular specialist to this carrier which was refused point blank.

Or this - which clearly demonstrates they were aware of the problem over ten years ago
http://news.ninemsn.com.au/national/story_5578.asp

Then try to convince me there's no conspiracy? You haven't got a hope!!

Of course with todays reports of 40 more deaths (see R&N) we'll see if the truth will out.




[This message has been edited by Skip Undo (edited 09 January 2001).]

[Mac the Knife]

OK guys - perhaps I can introduce a new twist to the thread. This isn't a windup or a deliberate "reductio ad absurdum" so read on. Try to forgive the occasional humour - I can't be serious ALL the time.

Let us SUPPOSE HYPOTHETICALLY that the case is proven. That a moderate increase in DVTs/PEs is shown for flights over 6 hrs (if the increase is really large then you are all going to be out of a job soon because everyone will be going by boat and train again). Stick with the hypothetical moderate increase.

Now what? It is obviously impractical for people to stop travelling by air, so one must do what one can to reduce risks. What could be done?

1) Passenger screening to eliminate high-risk pax? Wouldn't be popular and many of the events reported have been in pax/aircrew with no obvious increased risk factors. Cost, administrative hassles and bureaucracy horrific. Appeals, mis-classifications - omigod! Maybe "self-vetting" with a signed Consent Form ("I certify that I have read and understood the published warning in in its entirety and certify that I do no suffer from xxx, zzz or yyy")? A lawyers dream (or nightmare).

2) Compulsory stopovers on long flights. Mrs Mac remembers the days when flights to SA had to stopover at Isla del Sol to refuel and everyone had to get off. A brisk walk around the perimeter would do everyone a lot of good. Of course it would take longer to get anywhere, an extra landing and TO would impact the service life of aircraft components and you'd use a lot more fuel. Imperial airways nostalgia.

3) Aspirin. Probably does reduce risk (not all studies agree). There are indeed risks of gastric bleeding though these are fairly small with occasional use. Enteric coated aspirin MAY reduce this risk (uncertain). Probably OK for occasional flyers, but what about crew/frequent flyers? And who pays for the asprin - the carrier or the passenger? We're talking hundreds of tons of aspirin/year here. Could patients who developed gastric bleeding sue? And who?

4) Low dose subcutaneous heparin injections. Probably prevent a significant number of DVTs. Effective for 8-12 hours (need repeating after that). Not really that expensive as an individual "one-off" item (ampoule[needs to be stored in fridge], disposable hypo and alcohol swab). Few complications apart from occasional bruising at injection site - true allergy rare. OK for occasional pax, difficult and uncomfortable for crew/frequent flyers. Who will give injections? GP? Airport docs/nurses (you'd have to recruit a lot more of them)? Who will pay and how? Who is responsible for problems like bruising/pain at injection site?

Treatment of crew/frequent flyers with oral anticoagulants (Warfarin) is theoretically possible (as for patients with artificial heart valves which mustn't be allowed to clog). Required dosages vary widely among people and blood tests at least monthly are be needed to keep the dosage safe. Oral anticoagulation has a variety of inconveniences and dangers - it would really be serious overkill.

5) Elastic stockings. Evidence suggests that these reduce the incidence of leg DVTs IF correctly fitted and worn. Who will fit the stockings? GP should and could if patient has access to cooperative GP (need to be prescribed or individually purchased by patient). Should the airline pay? What about patients who arrive at the airport without stockings? Back to the airport docs/nurses. Should someone who arrives stockingless as the AC is boarding be refused embarcation? Should the flight be delayed? Should they sign a waiver? Or could they be fitted on board from an emergency supply on the AC?

6) Alcohol and fluids. Alcohol certainly causes dehydration and there is a certain amount of rather circumstantial evidence that dehydration predisposes to DVT. Among pax alcohol seems to cause more trouble than anything else so a ban would not be unreasonable (and some would argue long overdue). I didn't die without a smoke on my recent 12 hrs to LHR and I have no reason to suppose that pax would die without their booze. A mandatory fluid intake would be unenforceable, though I noticed that BA cabin staff pressed mineral water on us regularly.

7) Exercise. As I mentioned in an earlier post, I (not a big chap) was horribly cramped. I got up and walked around when times were quiet because my legs were uncomfortable, not really to avoid a DVT. I note that a recent victim was travelling Business (with more leg room) so perhaps cramped seats are an incentive to get out and stretch! Mrs Mac suggested exercise breaks for pax, as in Japanese factories, which seems logical. I don't know what the cabin crew would feel about adding aerobics to their training but some kind of organised activity might be possible. Pax refusing to participate would be noted so as to prejudice any legal action that they might undertake if they DO get a DVT.

8) Exercise2. A real reduction in seat numbers would allow everyone more room to get up and walk about a bit more. There would have to be timely turbulence warnings. What it would do to profitability and the airline business generally I can only guess. With current aircraft you'd need a more aircraft and more pilots, which would be good news for some. Perhaps the next generation of really big aircraft will be the answer.

So there you have it. These are the only ways that I can sensibly think of that might significantly impact upon the incidence of DVTs in longhaul pax/crew. None of them are cheap and some are downright impractical but them's the answers. Whether pax will accept a large increase in airfares and inconvenience in exchange for an unquantified reduction in an uncertain risk is entirely up to them. If the perceived phenomenon is indeed real (and I STILL don't know whether it is) then just printing a warning on tickets is illogical.

May I say Skip Undo that although I have serious reservations about your interpretation of such statistics that we DO have and many of your remarks, that I am completely baffled by Quantas refusal to take part in a DVT study. Incomprehensible.

Flak jacket and hard hat ON...

[Code Blue]

MTK:

Being of a slightly cynical disposition, I suspect the carriers would do as little as possible if they ever accepted - for whatever reason - an increase in DVTs from flying. It will be cost driven.

You would probably get a personal bottle of water -free of course - no booze and some extra very small print on the back of your ticket. A warm and fuzzy employer might go all out and get elastic stockings for the flight deck crew - the cabin crew probably get enough exercise wrestling mental patients and the like :).

faheel:
There is some evidence (isn't there always ;))that the risk of stomach problems from aspirin is NOT related to the route it is given. Coated and non coated, rectal and IV aspirin have each at some time, been reported in the literature as causing gastric/duodenal problems.

[CD]

Since there's been some talk of statistics, here are some that I stumbled across that address the general population in the US...

"Frequency:
In the US:
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.

Sex: Males &gt; Females (1.2:1)
Age: Usually over 40"

http://www.emedicine.com/emerg/topic122_pr.htm

[Pandora]

I Kid

Usual dose of aspirin recommended by doctors for anti-clotting purposes varies between 50-325mg, with no evidence that the higher the dose, the better the effect.

PLEASE NOTE - THINNING YOUR BLOOD UNNECESSARILY IS NOT A GOOD THING. IT CAN CAUSE DANGEROUS SIDE EFFECTS AS LIFE THREATENING AS A DVT.
Faheel, if you want a study to read, start with the CAPRIE study (1996). It was originally presented at the American Heart Association meeting 1996. Not sure where to find it, my old company just used to give me boxes of copies of it. It is a good starting point for medical references regarding anti-clotting effects of aspirin and gastrointestinal bleeding.

Regarding your enterically coated pill, it is not where the aspirin is absorbed so much as a function of its blood thinning properties that cause the GI bleeding. Also the gut is a term used to encompass the entire gastrointestinal tract, and bleeding has been diagnosed in all parts of the gut as a result of taking aspirin, not just the stomach. If you do get hold of the CAPRIE study you will find that there are lots of other unpleasant side effects of taking aspirin daily over a long period.

Once again, I recommend that you see your doctor before considering taking aspirin as a prophylaxis.

And finally, Mac the Knife,

do you really think heparin or warfarin is a good idea as a pre-flight treatment? Are you aware they are used only as a last resort by cardiovascular and neuro surgeons, simply because they are so difficult to dose correctly and interact with so many other drugs? Elastic stockings are a good idea, but still the best idea is the one passengers have been told for years by medical experts - drink lots of water and stretch your legs regularly

[Captain Gidday]

Well Skip, first I am a victim of a conspiracy, next a conspirator! Which is it? In fact the actuality is more mundane. Your replies so far have not been particularly helpful and frankly I just could not be bothered engaging with them. Thanks CrashDive for putting it succinctly.
Hope we can stick to the point, which is NOT whether DVT exists, but the apparent discrepancy or, if you wish, my allegation of a discrepancy, between passenger deaths and pilot deaths from DVT/PE.
Can we start with a statistic which I hope is beyond dispute? The mean passenger load of long haul aircraft, averaging across the capacity of 747s, tri-jets and twins and allowing for average load factors, would be about 300, would it not? Each of these aircraft in flight, allowing for in-flight relief pilots, flight engineers etc. would be crewed by about 3 pilots So, the flight deck crew population airborne at any one time would be about 1% of the passenger population. Agreed?
If we can believe the now widely reported study from Ashford Hospital that "2,000 people DIE from flight-related DVT each year in Britain" then it would be reasonable to assume, circumstances being equal, that there would be 20 DEATHS per year of longhaul pilots in Britain alone from flight related DVT. In ten years, therefore, we would expect 200 pilot deaths from flight related DVT in Britain.
My question, to put it crudely, remains; "where are all the bodies?"
I am very glad you and your co-worker survived, 'I Kid', and therefore do not qualify as a pilot DEATH statistic; same goes for Slasher and others on parallel threads who have reported surviving these events [interestingly, nearly all after being passengers, if you read closely].
Naturally the worldwide count of pilot deaths should be proportianally greater, yet so far on this whole forum, as far as I know, we have one pilot in Tokyo reported by Skip Undo, above, [could just be part of the "background rate"] and a whole lot of experienced pilots wondering out loud why their work mates are not dropping dead all around them. And believe me Skip, you can't die in this industry without everybody noticing that they have just moved up one place on the seniority list, so conspiracies are unlikely.
Perhaps there is something critical, or a group of things more likely, which pilots do in flight and passengers don't which are more important than any of us have previously realised. There are a lot of possibilities we could explore here, if we can first agree that there are reasonable grounds for believing that there are significantly less than expected pilot deaths occurring.


[This message has been edited by Captain Gidday (edited 12 January 2001).]

[Mac the Knife]

Pandora - of course I'm not seriously suggesting that pax/crew heparinise or Warfarinise themselves preflight. I was, 'ow you say? - fishing to see just how crazy people could get.

Thanks Captain Gidday for injecting some long overdue commonsense. Where, as you say, are the bodies? For pax, working on a figure of 61M pax/year thru LHR, normal risks should give us 48,000 DVts/year, 2400 PEs/year and 240 deaths. Allowing for underdiagnosis and a moderate risk increase we get to 100,000 DVTs/year, 5000 PEs and 500 deaths. Where do they bury 'em?

What I would do if I were a professional pilot?

Given that we really don't know where we are in the flying/DVT/PE story I'd do things that weren't too inconvenient or uncomfortable or have added dangers of their own.

If I didn't have any history of ulcers or indigestion I would take (after discussing it with my GP) 1/2 an aspirin a day.

If I flew long routes I'd wear properly fitted support stockings.

I'd try to get into the habit of doing leg exercises while seated and I'd take a little walk every two hours.

I'd make an effort to drink rather more fluid than my normal thirst says.

I'd take a reasonable amount of exercise when not flying, eat reasonably healthy food, keep an eye on my weight and enjoy life as much as possible.

Would these stop me getting a DVT/PE? No, but on current evidence my chances of getting a DVT/PE would be less. (And I'd stop worrying about unproven dangers that I can't do a great deal about)

[This message has been edited by Mac the Knife (edited 12 January 2001).]

[Goldie]

In answer to the original question, remember that?

Most of them are dead, they just won't lay down

[I Kid]

Hmmm ! http://www.pprune.org/ubb/NonCGI/confused.gif

[cirrus driver]

Unfortunately many people normally perceived as low risk, carry a gene mutation which produces a protein(Factor V Leiden) which greatly(maybe 3 to 4 fold) increases the risk of DVT and its relatively rare complication of pulmonary embolism and sometimes death.
In the absence of wide base population screening for this abnormality one cannot be sure how many of the inactive-but-healthy passengers have this problem.
I support my colleagues in advocating strenuous prevention and education of all passengers(air,rail or bus) of the potential risk.
However if passengers could be persuaded not to smoke,exercise their calf muscles and not dehydrate and sedate themselves with copious quantities of alcohol ,risk could be markedly reduced.
I hope the emphasis is on prevention and education rather than punishment and blame!
The information has been available for years but like the exhortation to fasten seat belts at all times whilst seated , is often ignored.