It's officially winter but we probably should have had this discussion a couple of months ago because it doesn't have to be winter for the temperatures to drop to hypothermic levels. Temperature, not the official season, is what drives the train on this condition and it can happen in May or June depending on where you live. If the ambient temperature is 55 degrees Fahrenheit, and you're wearing skimpy enough clothing, and you're exposed long enough, you can become hypothermic to the point where your body's ability to maintain sufficient body temperature is overwhelmed.
The body's first response to hypothermia is to clamp down blood vessels supplying the extremities and shunt blood to your central circulation (basically the trunk including heart, pulmonary, and gastrointestinal system). Believe it or not the last extremity to be diverted from blood supply is the head, and as you would expect, when the blood supply to your head is reduced, your brain doesn't function so well. Your mental status decreases and you become less and less alert to the point where you just want to go to sleep---a sleep from which you quite possibly will never awake.
What to do? First let's talk prevention of hypothermia: dress for the coldest anticipated temperature and wind conditions (wind adds to the problem by “wicking away” any warmth your body might be giving off). If your clothing gets wet you might as well take ‘em off for all the insulation they WON'T be giving you. One of the best exceptions to this is wool clothing which retains its ability to provide insulation even when wet. Three layers of clothing are always better than two (the first layer being a pair of underwear and an undershirt). Gloves and a hat are a definite plus---you can lose up to 90% of your body heat off the top of your head. Remember, if you're warm you can almost always take layers (clothing) off, especially a hat, but it's hard to add layers (clothing) if it's not available. Another important thing to do to prevent hypothermic effects is to stay well hydrated. You'll know you're hydrated when you've drunk enough fluids so that you're urinating 4-6 times a day and the urine is coming out clear or light yellow, but not bright yellow or dark yellow. Again, when circulating blood volume is low, the body tends to shunt blood from the peripheral circulation (yes including the head) to the central circulation (chest and abdomen). By drinking warm fluids (soups, coffees, or teas), you not only preserve your circulating volume but you also actually warm your central circulation preferentially. Sometimes when a patient is brought to the Emergency Room with severe hypothermia, a nastrogastric or orogastric tube is placed into the stomach so that warmed fluids can be place directly into a central body cavity near the heart to help warm the central circulation.
Now let's talk treatment of hypothermia. Obviously, first get out of the environment that caused the problem. Sometimes just finding shelter from the wind can make the difference. Now you need warmth. If you can't get to a warm environment then make your own: start and build a warming fire. Add layers of clothing (I'd wait until I've warmed up by the fire first). Restore your circulating volume with warm fluids as indicated above. Almost always this is enough. A change in mental status is a clarion call for help: if you or your partner's mental status is deteriorating then that means the last defense of your final extremity has been breached and rapid deterioration will ensue. Call for help---now. Call a friend, or EMS if you must, but do it as soon as possible before your mental status deteriorates to the point where you're no longer capable of carrying on a lucid conversation.
Much as it would be nice to end on a light note, a final word of caution: these conditions can happen ANYWHERE. We usually associate these conditions with being outdoors, but it can happen just as easily in the home of an elderly person who didn't pay their gas bill. Old folks are especially unable to compensate metabolically to hazardous environmental conditions. Check on those you know whether they be family, friends or neighbors.
Take care and we'll look for you in the Spring.
