Seriously, it’s too hot outside. All of a sudden I’ve turned the heating off in my small apartment, started watering plants daily and begun the countdown for the first bath of 2013!
Inspired by such a summerish weather, I thought it could be interesting to read something about Hypothermia and its causes. Hope this post will help cooling down a bit – but not too much, it wouldn’t be nice to freeze down completely 🙂
The first notion to know is that of Body Temperature (BT), the temperature that a living being autonomously keeps more or less constant through biologic processes such as homeostasis or thermoregulation. BT is about 37 °C for a human being, 38.5 °C for a pig, 39 °C for cats and cows, between 34 °C and 40 °C for camels and dromedaries, 42 °C for birds (whoa!) and so on… There is a sort of threshold, different for each single species, for the minimum temperature required to allow normal metabolism and body functions. Now, cows hypothermia is for sure an awesome topic and could raise kind of interesting discussion, but we’ll focus on the human being. For a normal healthy man, the threshold value is 35.0 °C. If our core temperature (i.e. “the temperature of an organism at which it is meant to operate”) drops below such 35 °C, we start feeling bad since our body does not like working in suboptimal conditions.
Wiki says that “Hypothermia usually occurs from exposure to low temperatures, and is frequently complicated by alcohol. Any condition that decreases heat production, increases heat loss, or impairs thermoregulation, however, may contribute”.
That’s the point! We lose our body heat in many ways, as shown in this nice image. Or better, we continouosly exchange our body heat with every single thing that surrounds us in daily life. In a sense, we are nothing more that walking heaters. Our internal mechanisms, normally, are enough to keep a constant BT. But in the case of, for example, prolonged exposure to cold, our body might become unable to replenish the heat that is being lost. As a consequence, a drop in core temperature occurs. This change causes a host of characteristic symptoms (according to the hypothermia degree), such as:
- mental confusion (difficulty in speaking, sluggish thinking, and amnesia),
- muscle mis-coordination,
- cyanosis (exposed extremities become blue),
- decreased heart rate, respiratory rate and blood pressure.
If you ever plan to swim or dive in cold water, to explore snowy landscapes, to drink alcohol and smoke outside at night (alcohol and tobacco -> vasodilatation -> sensation of warmth while, instead, heating loss is rapidly increasing), to chase russians in their homeland in 1812 and so on… well, you’d better take your time and think about all the risks you’re going to take.
A subject found in hypothermic conditions needs to be rewarmed. Rewarming can be achieved in three main ways:
- passive external rewarming: the subject is moved to a warm environment and provided with properly insulated dry clothing. Then, their own heat generating ability will be enough to restore proper BT conditions.
- active external rewarming: external warming devices, such as warmed forced air or hot water bottles placed in both armpits and groin, are employed to help the subject warming up faster.
- active internal rewarming: it involves the use of intravenous warmed fluids, irrigation of body cavities with warmed fluids or inhalation of warm humidified air.
In case of severe hypothermia, extracorporeal rewarming such as via a heart lung machine may reveal to be the fastest (and only) solution.
Watch out also for really hot environments! Hyperthermia, the opposite of hypothermia, can lead to heat exhaustion and heat stroke.
sources: one, two and google images