COMMENT: DVT ” The Truth
Dr Ian Perry has been ABTN”s advisor on medical matters concerning the airline business for many years. Ian graduated from Guy's Hospital London gaining membership of the Faculty of Occupational Medicine. He has a Diploma in Aviation Medicine (UK Royal College of Physicians, London.), and was one of the first to gain such a qualification. He served in the UK Royal Army Medical Corps where he also qualified as a VIP pilot. He was Master of GAPAN (Guild of Air Pilots and Air Navigators) 1996/97 and has numerous citations and awards concerning his chosen profession.
"Deep Vein Thrombosis, the very words conjure up some dreadful medical condition, that has wrongly been associated with air travel alone, and when talked about by an uneducated few, strikes terror into the minds of the gullible public at large.
There has been another outbreak of hysteria in the "Press" following the very recent publication of a paper in the Lancet about this subject. One telegraphic newspaper, that should have known better, had headlines shouting that "Poor Cabin Air Quality Causes DVT". The Lancet paper did not say that, it was pure supposition by the newspaper correspondent, in fact the Lancet paper has a number of scientific holes in it, that really show it to be rather a waste of valuable scientific resources.
Before anyone can blame any one thing, everything else must be excluded.
The experiment with its small number of volunteers did not do that. It should have repeated the same travel profile, first excluding the cabin pressure, then the cabin air, then the cabin temperature parameters and so on, until a finger could be pointed at one cause and one cause alone. This makes the comparisons that were used in the published experiment between a real aircraft and a cinema, rather unscientific.
It leaves more questions unanswered than it thought it had answered.
Complete studies are however very expensive. DVT has been around since medicine became a serious study. It was first recognised that it could be caused by sitting for long periods in a deck chair, in the 1940s, by my old boss Professor Keith Simpson, the famous pathologist. This occurred in people sleeping in wooden deck chairs, in the underground stations, during bombing raids. The wooden cross piece caused a lower leg constriction, which over a period of time caused an inflammatory reaction, leading to the formation of a clot. The comparisons to cramped seating in aircraft bear no resemblance to wooden deck chairs. Some have tried to make such comparisons. The only common factor is that people sitting anywhere, on boats, trains, coaches, etc. even in cars, for long periods of time, may have, in some cases but not all, an increased risk of some of the clotting factors. I have been involved in almost all of the UK and American Court cases, where someone has sought to blame the plane for causing the DVT. So far no one has produced one jot of any useful evidence proving that the plane was to blame. It may have contributed to an on going problem, but the plane has never been proved to be an initiating cause.
When one considers the thousands of military personnel and their families, for whom we have the medical records, who have been moved around the world, originally in cramped old smelly noisy aircraft, taking forever to get anywhere, there were no recorded cases of DVT. This is true for not only UK, but also of US families and personnel.
The only recorded case of a DVT, in thousands of troop movements to and from Vietnam and the US, in all sorts of very uncomfortable aircraft, was in a senior officer who had it before he left, he was warned it might get worse in flight, which it did, but he was treated and survived. My study along with that of an American colleague, involved over 500,000 recorded movements. We know that we hardly touched the surface of all the movements. The UK flights started in 1962/3 to Cyprus, Aden, and on to Malaya and Hong Kong. I went to Aden and back quite a few times as officer in charge of troops. This was when trooping by ship ended. Each flight leg could take 10/12 hours, always with women and children as well as military personnel. The flights were uncomfortable, in seats more akin to Professor Simpson”s deck chairs. The cabin air was not good compared with today”s superb standards. The cabin pressures were about the same; the food was not as good as today. There was no alcohol on most flights. The toilets were adequate and getting up to move around was not encouraged. There was not plenty of water to drink and we made our own amusement. The pill had not been invented, and smoking was allowed. It was also often very noisy and there could be lots of vibration and turbulence.
Today”s trooping is much better. No cases of DVT have ever been recorded post flight, in all of the years since trooping by air started. Air travel under these circumstances, does not therefore cause DVT. I have offered to investigate all of the contentious DVT cases in the UK, which it is claimed were caused by air travel, but so far none of the families concerned have accepted my offer.
I rest my case”.
Ian Perry MFOM DAvMed FIOSH FCIM FRAeS MBAE MBAC
http://www.ianperry.com