This two part series of articles is meant to address a basic physiological need that may be severely threatened both in a TEOTWAWKI [1] situation and any time a lesser emergency takes us out of our bubble of comfort and preparedness. That issue is warmth: specifically how you stay warm and avoid hypothermia when your car slides off the road in a snow storm or you don’t get out of dodge fast enough and find yourself hoofing it overland with only what you can carry, through rain and wind. Part two deals with the possibility you or a loved one or team mate is succumbing to the cold, how you can best treat your patient to stabilize and revive them most effectively. Throughout this article I will not only lay out some basic concepts, examples, and treatments, but just as importantly I will debunk some of the myths about cold weather survival. My qualifications come from numerous years leading wilderness trips in the mountains, alpine search and rescue operations, and teaching wilderness medicine at the university level to doctors, nurses, EMT [2]s and paramedics, and laymen alike.
To begin with, it is easier to stay warm than to get warm. The classic newbie mistake when traveling outdoors in cold weather is invariably some variation of the following: you get up in the morning, and it is cold. You layer up, putting on your puffy down jacket and hat and gloves, eat a bite, strike camp, and make ready to move. You are cold and not real excited about taking off your many warm layers to start hiking, so you hoist your pack and set out. 15 minutes later you are warm, 30 minutes later you are hot, and 60 minutes later you stop to take off your warm layers, drink some water, adjust your boots and consult the map. Now soaked in sweat you cool rapidly, and before you finish your snack break you are chilly, so you toss your coat on. When it is time to get moving again, you do so with your coat still on. Every subsequent break follows the same pattern, so start moving warm, get hot, stop, get cold, put jacket on again and get hot again. This is the exact opposite of what you should be doing. Instead follow the habits of every mountaineer: start cool, almost cold in the morning. When you stop to rest, even before you get cold, throw on a warm layer. When you are ready to move again, drop the layer. You will avoid sweating and avoid wasting valuable calories to thermo-regulate. Stay warm, don’t get warm.
Notice in that piece I kept referring to layers. This is how you need to dress outdoors. A t-shirt and parka doesn’t cut it. You want a base layer (think polypropylene or wool or silk long underwear) amid layer (fleece pull over, wool sweater) and a shell layer (windproof/waterproof) at a minimum, with an option for a puffy layer like a down jacket or vest. How heavy and warm these layers are depends largely on the environment you anticipate, colder equals heavier. But the concept of layering stays the same. Notice what I did not include here: cotton. The oft repeated adage of wilderness medicine is: cotton kills. The cell structure of the cotton fabric collapses when wet, destroying its ability to insulate (keep you warm). Wet cotton in a cold environment is worse than nothing. Excellent in a desert for its breathability and also the same habit of retaining moisture and evaporating to keep you cool, in a cold environment is an invitation to disaster. Fabrics should be wool, silk, or synthetic. Wool and synthetic do not collapse when wet and will keep you warm even soaking wet (albeit not quite as warm, but better than nothing and much better than cotton). So the white cotton long johns you find at Wal-Mart are out. Invest in polypro or wool for you layers (don’t forget socks).
Why do I keep hammering away at sweat and cotton? Because moisture is the enemy when it comes to keeping you warm. Water conducts heat away from the body 15 times faster than air. You can survive a lot longer in 32 degree air than 32 degree water, whether you are immersed in it or because your clothes are wet.
So how to stay warm in the field? First, fuel the machine. We are talking food, calories, fats and carbs. No time for a diet, eating foods with a high fat content will keep you warm longer. I have been on winter expeditions where before going to bed each night my hot drink consists of hot cocoa powder, milk powder, peanut butter, a handful of chocolate chips, and a spoonful of butter or margarine, with brown sugar and topped off with hot water. Sounds terrible in August in the flat lands, but on a winter’s night the body craves it when the temperatures drop. While we are on the topic, let’s talk about sleeping warm. Aside from fueling the machine, you need to think of your sleeping bag as a thermos: keeps hot things hot and cold things cold. So don’t go to bed cold. Do jumping jacks, walk around, get in and do push-ups and rub your feet to get the blood flowing and get them warm. Start out warm in your bag and you will stay warm. A mat or pad is essential to getting you off the cold hard ground, not because it is hard, but because it is cold! Conduction will draw heat out of you all night long. I like a closed cell foam pad from my shoulders to knees because it is cheap, light, and nearly indestructible. Thermarest air pads are great and comfy but have the potential to leak air with extreme use. Pine boughs, pine needles, coiled rope, empty backpacks, clothes you aren’t wearing; all help keep you off the ground and warm. Speaking of clothes, there is the old saw about sleeping naked in your bag. This is really only applicable if the clothes you would be wearing are either: 1) cotton 2) wet or 3) constricting blood flow. And I usually overlook #2 if they are only damp. Otherwise wear you layers to bed and you’ll be warmer than if you had slept naked. Other tips: empty your bladder. Yes, I know it is cold out there and warm in your bag, but do you know how many kCal it takes to keep that ½-1 liter of urine in your bladder at 98.6 degrees? Lots! And that is energy that could be keeping you warm, so empty your bladder, feel better, be warmer. If it is a snow camping situation, do as most mountaineers do and use a pee bottle (be sure it has a different tactile feel in the dark than your regular water bottle). Yes, there are female adapters out there. Speaking of bottles, taking a hot water bottle to bed with you insulted in a wool sock and stashed in your sleeping bag at the foot to keep your toes warm or on your chest to keep your core warm. Done properly it will still be warm in the morning. If I’m not in bear country I keep a high energy snack close at hand for a midnight warmer; peanut butter, cheese, or chocolate all work well. Wearing a wool or synthetic hat to bed, which covers the ears, and scarf around the neck if your upper layers don’t zip up that high are also big time heat retainers. Avoiding the temptation to roll over and cover your face with your sleeping bag will keep your breath from condensing into water, possibly freezing, and then melting and wetting your sleeping bag when you pack up in the morning. A final consideration for sleeping warm addresses this issue of a potentially wet sleeping bag: down is warmer on a per/weight basis than any other insulation but clumps and fails entirely when wet. Synthetic is almost as light and warm as down, but will still insulate when wet. Cotton or square shaped Coleman brand type bags should be used as dog house liners or for indoor kid’s sleep-overs.
Take home points for staying warm and preventing hypothermia:
1) Fuel the machine
2) Stay dry
3) Sleep warm
4) These concepts are not for winter snow expeditions alone; most hypothermia happens in the fall and spring in what are normally considered “moderate” temps because people aren’t prepared or don’t consider the possibility of rain, wind, or nighttime.
Next time I will address signs and symptoms of hypothermia and how to treat it effectively in the field. – Lumberjack