Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

No link between low air-pressure on long-haul flights and DVT says new study

17.05.2006


Researchers simulating conditions of reduced cabin pressure and reduced oxygen levels, such as may be encountered during an 8-hour aeroplane flight, found no increase in the activation of the blood clotting system among healthy individuals, according to a study in the May 17 issue of JAMA. (Journal of the American Association).



Venous thromboembolism, a term used to describe deep vein thrombosis (DVT; blood clots forming in the veins) and pulmonary embolism (clots passing to the lungs where they may obstruct the blood flow), has been associated with long-haul air travel, but it has been unclear whether this is due to the effects of sitting for a long time, or whether there is a relationship with some other specific factor in the aeroplane environment, according to background information in the article. One hypothesis has been that hypoxia (reduced oxygen in the blood), associated with the decreased cabin pressure that occurs at altitude, produces changes in the blood that increase the risk for blood clots.

Dr William D. Toff, from the University of Leicester’s Department of Cardiovascular Sciences and colleagues –including in the UK Professor Mike Greaves, Head of the University of Aberdeen’s School of Medicine -conducted a study, from September 2003 to November 2005, to assess the effects of hypobaric (reduced air pressure) and hypoxia, similar to that which might be encountered during commercial air travel, on a variety of markers of activation of the haemostatic (blood clotting) system. The study included 73 healthy volunteers who spent 8 hours seated in a hypobaria chamber and were exposed to hypobaric hypoxia, similar to the conditions of reduced aeroplane cabin pressure that might occur during a long-haul flight (cabin pressure may be reduced to the equivalent of that at an altitude of about 8,000 feet). Blood was drawn before and after exposure to assess activation of factors associated with haemostasis (blood clotting). Similar measurements were taken of the same volunteers, on a separate occasion, before and after they spent 8 hours seated in a controlled environment, equivalent to atmospheric conditions at ground level (normobaric exposure).


The study was a collaboration between the Universities of Leicester and Aberdeen. The chamber studies were performed at the RAF Centre of Aviation Medicine at Henlow in Bedfordshire and Aberdeen. Analysis of blood samples was performed at Leicester and Aberdeen, and also by colleagues at the Academic Medical Center at the University of Amsterdam.

The researchers found that when comparing the results between the normobaric and the hypobaric exposures, there was no significant difference in the overall change for markers of coagulation activation (clot formation), fibrinolysis (the normal breakdown of small, naturally occurring blood clots), activation of platelets (small cells in the blood that clump together when stimulated to promote clot formation), and activation of endothelial cells (the cells that line the interior surface of blood vessels).

Dr Toff said: “Our study provides, for the first time, a carefully controlled assessment of the effects on blood clotting of the low air pressure and low oxygen level that might be found during a long-haul flight. We found no evidence that these conditions cause activation of the blood clotting mechanism.

“In our study we predominantly used healthy young people without known risk factors for thrombosis. We included some users of the combined oral contraceptive pill and some older subjects (aged over 50 years), both of which are factors that increase the risk of thrombosis. Although we found no difference in the results in these groups, the numbers of each were relatively small. We plan to extend the study to look at more people with these and other risk factors to see if they respond differently.

“Our volunteers abstained from alcohol during the study, to avoid any possible confounding of results. Air travellers are often advised to moderate their alcohol consumption in-flight, as excessive alcohol may induce somnolence and decrease mobility. Prolonged seated immobility is probably the most significant factor predisposing to thrombosis during long-haul travel. For the same reason, hypnotics (sleeping tablets) are sometimes also discouraged.”

“In conclusion, our findings do not support the hypothesis that hypobaric hypoxia of the degree that might be encountered during long-haul air travel is associated with prothrombotic alterations in the haemostatic system in healthy individuals at low risk of venous thromboembolism,” the authors write.

Alex Jelley | alfa
Further information:
http://www.le.ac.uk

More articles from Health and Medicine:

nachricht New malaria analysis method reveals disease severity in minutes
14.08.2017 | University of British Columbia

nachricht New type of blood cells work as indicators of autoimmunity
14.08.2017 | Instituto de Medicina Molecular

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>