2006年VOA标准英语-Study Finds Airline Cabin Pressure Does No

By David McAlary
Washington
16 May 2006

  
  
Long distance air travel can increase the risk of blood clots¹ in the legs, a potentially fatal condition that has been known for more than half a century. Now British researchers report that the culprit is not airplane cabin air pressure, as some have speculated. They suggest that the condition is caused by lack of movement.

On a flight from Britain to Australia not long ago, Simon Snedden did what he always used to do on an airplane trip.

"The plan was always get in, get sat down, have a snooze, watch the film," he said.

Snedden will now alter that plan to include a little more leg movement. That is because he took part in a recent study looking into the air travel conditions that can lead to blood clots, or deep vein² thrombosis.

The condition is dangerous for reasons explained by University of Leicester physician William Toff.

"Particularly looking at clots that form in the larger leg veins³ higher up, they may break away and travel through the heart to the lungs, where they block the blood flow and they in some cases prove fatal," said Toff.

Toff and colleagues conducted the study in which Simon Snedden and 72 other healthy volunteers took part. They wanted to know whether blood clots were the result of the low oxygen and air pressure levels in an airplane cabin.

So they put the volunteers in a cramped⁴ chamber⁵ for eight-hour shifts to copy the conditions of an actual flight. The researchers lowered the air pressure and oxygen levels in the chamber to match flight levels and even put a table in the middle to simulate the close quarters of the cabin. For comparison, they also had the volunteers spend eight hours in the chamber with normal oxygen and pressure levels.

There were some changes in the blood toward clotting⁶, but they occurred at the same rate in both air pressure and oxygen conditions.

Toff says blood tests made before and after the simulated airline cabin conditions tell the story.

"We looked at a very wide range of blood markers, looking at all aspects of the body's clotting mechanism⁷. We found no evidence that the low pressure, low oxygen were activating⁸ the body's blood clotting mechanism," he explained.

The researchers say the clotting changes were probably the result of sitting still for eight hours. So Toff advises travelers to stretch their legs, extend and flex⁹ the knees and ankles, and stand and walk whenever possible.

"Any form of long-haul travel, whether by air, rail, or road is associated with an increased risk of thrombosis. People should take sensible precautions according to their level of inherent risk," he added.

The study appears in the Journal of the American Medical Association.

In a commentary accompanying the research, University of Heidelberg sports physician Peter Bartsch notes that the study included small numbers of elderly people and women taking oral contraceptives. As a result, he says it is not possible to draw conclusions about these two groups.

1 clots   

n.凝块( clot的名词复数 )；血块；蠢人；傻瓜v.凝固( clot的第三人称单数 )

参考例句：

• When you cut yourself, blood clots and forms a scab. 你割破了，血会凝固、结痂。 来自《简明英汉词典》
• Milk clots when it turns sour. 奶变酸就凝块。 来自《现代英汉综合大词典》

2 vein   

n.血管，静脉；叶脉，纹理；情绪；vt.使成脉络

参考例句：

• The girl is not in the vein for singing today.那女孩今天没有心情唱歌。
• The doctor injects glucose into the patient's vein.医生把葡萄糖注射入病人的静脉。

3 veins   

n.纹理；矿脉( vein的名词复数 )；静脉；叶脉；纹理

参考例句：

• The blood flows from the capillaries back into the veins. 血从毛细血管流回静脉。 来自《简明英汉词典》
• I felt a pleasant glow in all my veins from the wine. 喝过酒后我浑身的血都热烘烘的，感到很舒服。 来自《简明英汉词典》

4 cramped   

a.狭窄的

参考例句：

• The house was terribly small and cramped, but the agent described it as a bijou residence. 房子十分狭小拥挤，但经纪人却把它说成是小巧别致的住宅。
• working in cramped conditions 在拥挤的环境里工作

5 chamber   

n.房间，寝室；会议厅；议院；会所

参考例句：

• For many,the dentist's surgery remains a torture chamber.对许多人来说，牙医的治疗室一直是间受刑室。
• The chamber was ablaze with light.会议厅里灯火辉煌。

6 clotting   

v.凝固( clot的现在分词 )；烧结

参考例句：

• The study was also based only on the one anti-clotting drug. 所用抗血栓药物也仅限于一种。 来自互联网
• A plasma protein that is converted into thrombin during blood clotting. 凝血原酶一种血浆蛋白质，在血液凝聚时转化成凝血''。'酵'。''''。'素'。''。 来自互联网

7 mechanism   

n.机械装置；机构，结构

参考例句：

• The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
• The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。

8 activating   

活动的，活性的

参考例句：

• "I didn't say we'd got to stop activating the masses! “我并没说就此不发动！ 来自子夜部分
• Presumably both the very small size and activating influence of fluorine atoms contribute to this exception. 这大概是由于氟原子半径小和活性高这两个原因的影响，氟原子对这种例外做出了贡献。

9 flex   

n.皮线，花线；vt.弯曲或伸展

参考例句：

• We wound off a couple of yards of wire for a new lamp flex.我们解开几码电线作为新的电灯花线。
• He gave his biceps a flex to impress the ladies.他收缩他的肱二头肌以吸引那些女士们的目光。