楼层:#1 由 边走边钓 » 12 12月 2017 00:00
又到了大雪纷飞的时刻,相信很多人都心里热血沸腾,摩拳擦掌准备上冰了。不经意间读到了这篇文章,分享给准备上冰的弟兄们。
Did you know that being submerged in cold water for just 20 minutes can lead to hypothermia, unconsciousness, and even death?
How long a person can survive in cold water primarily depends on the water’s temperature, exposure time, and the thermal insulation of the victim’s protective clothing. The insulation within clothing is measured with the unit “Clo.” By determining the rate at which heat is lost from the body, as well as the difference in temperature between the skin and the water, predictions can be made of the rate a person’s body temperature will drop when submerged in water.
For example, one “Clo” represents the thermal comfort of an average person in business clothing in a room temperature indoor environment. Fractions of this thermal comfort are what are perceived when worn in the water, because water transfers heat out of the body 25 times faster than air.
This graph indicates random samples of “Clo” values, and the corresponding estimation of survival times in calm water.
Clo Graph
Wearing an approved immersion suit can help to protect yourself from hypothermia and keep you afloat in cold water. The immersion suit keeps your body heat trapped inside the suit, while keeping the water out, and can significantly increase the time you can survive in water.
Remember that hypothermia can happen to anyone – even on warm, sunny days!
THE THREE CRITICAL PHASES OF COLD-WATER IMMERSION:
First 5 minutes – immediate shock You will experience the ‘gasp reflex,’ which is the sudden gasp of air as a result of the shock. You will be unable to hold your breath, and hypertension and increased cardiac output will result. Most casualties in this phase are due to drowning or a heart attack, even before hypothermia can begin to set in.
Next 15 minutes – inhalation of water You won’t be able to keep afloat or swim, and your ability to grasp or climb into/onto things will diminish. Typically, most casualties in this phase are due to drowning from excessive inhalation of water.
30 minutes – onset of hypothermia 37° C is considered normal body core temperature. When your core temperature drops to 36.1° C, muscle tone starts to become affected. Most people have experienced this feeling of tension in their back and neck when they’ve become chilled.
At a core temperature of 35° C, you would be considered mildly hypothermic. At a core temperature of 33.9° C, subjects experience amnesia - but of course, they don’t remember it! Another 1.1° C drop down to 32.8° C, and a lack of sensation or feeling can be experienced.
At 32.2° C you would be considered profoundly hypothermic and would start to lose the ability to shiver. At 31.1° C, shivering ceases. Since shivering is a human’s only method of increasing their internal heat generation, once it stops, core temperature starts falling rapidly. At 30° C, heart arrhythmias occur. Death follows at 25° C; however the majority of people would have drowned before ever getting to this point.
TIPS TO PREVENTING HYPOTHERMIA
If you’re in cold water, don’t swim unless you can reach a nearby boat, or floating object. Swimming lowers your body temperature, and even excellent swimmers will drown when swimming in cold water.
The more of your body that is out of the water, the warmer you’ll be. If you are near a floating object that is large enough, pull yourself up onto it.
Keep your head out of the water to lessen heat loss and increase survival time.
For more information on hypothermia and survival in cold weather, please visit the Transport Canada website
你知不知道在20分钟内被冷水浸泡会导致体温过低,意识不清,甚至死亡?
一个人在冷水中生存多久主要取决于水的温度,暴露时间和受害者的防护服的隔热性。用“Clo”单位测量衣服内部的绝缘。通过确定身体热量损失的速率以及皮肤和水之间的温差,可以预测人体的速率浸入水中时温度会下降。
例如,一个“Clo”表示在室温室内环境下的商务服装中的普通人的热舒适性。这种热舒适性的部分是在水中穿着时感觉到的部分,因为水从身体传出的热量比空气快25倍。
该图表示“Clo”值的随机样本,以及平静水中相应的生存时间估计值。
Clo图
穿着经过认可的救生服可以帮助保护自己免受体温过低,并让你在冷水中漂浮。浸入式衣服可以将身体内的热量限制在衣服内部,同时保持水分,并且可以显着增加在水中生存的时间。
请记住,低温症可能发生在任何人身上 - 即使在温暖,阳光明媚的日子里!
冷水浸泡的三个关键阶段:
第一个5分钟 - 立即休克你将体验到“喘息反射”,这是由于震动而突然喘气。你将无法屏住呼吸,并导致高血压和心脏输出量增加。即使在体温降低之前,这个阶段的大部分伤亡都是由于溺水或心脏病发作引起的。
接下来的15分钟 - 吸入水分你将无法保持漂浮或游泳,并且抓住或攀爬物体的能力将会减弱。通常情况下,这个阶段的大部分伤亡都是由于过度吸入水中的溺水造成的。
30分钟 - 低温37°C开始被认为是正常人体核心温度。当你的核心温度下降到36.1°C,肌肉开始受到影响。大多数人在变冷的时候,经历了背部和颈部紧张的感觉。
在35°C的核心温度下,您会被认为是轻度低温。在33.9°C的核心温度下,受试者经历失忆症 - 但当然,他们不记得!另外1.1°C下降到32.8°C,并且缺乏感觉或感觉能经历。
在32.2°C,你会被认为是深低温,并会开始失去颤抖的能力。在31.1°C,发抖停止。由于颤抖是人类增加内部热量的唯一方法,一旦停止,核心温度开始快速下降。在30°C时,会发生心律失常。死亡在25°C之后;然而,大多数人在此之前就已经淹死了。
提示预防低热
如果你在冷水中,不要游泳,除非你可以到达附近的船只,或漂浮的物体。游泳会降低体温,甚至优秀的游泳者在冷水中游泳也会淹死。
你的身体越出水面,你会变得越暖和。如果你靠近一个足够大的浮动物体,就把自己拉上来。
把头伸出水面,减少热量流失,延长生存时间。
有关寒冷天气中低体温和生存的更多信息,请访问加拿大运输部网站