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Cold Weather Strategies

Cold Weather Strategies to Protect From A Classic Paddling Nemesis
- Jim Simmons

As we paddle into the cold weather season during this festive time of year (November 2010), we revisit here basic strategies about how to avoid being stricken with hypothermia, which is no fun. Our strategy is as simple as following the classic holiday refrain--eat, drink and be merry (that is, wary of hypothermia).

Medical experts refer to humans as 'naked radiators' because humans are designed to lose heat not conserve it. This means we're more suited for warm climates than for cold, a main reason that most of the earth's population lives near the warmth of the equator. Because naked radiators (us) need to stay covered when paddling we must be "dressed like an onion" in layers of fabrics that retain heat while dissipating moisture, but yet, are fast dry. Since our thermoregulatory system is water based we must strive to keep a balance between heat production and loss. That is why we must also keep our naked nadiators full even if not thirsty. DRINKING as an act of discipline at regular intervals is our first important strategy. We'll know our radiator is functioning properly by observing the color of our urine--it should remain clear if we're drinking enough.

Hypothermia may be defined as the 'lowering of the body's core temperature to a level that normal brain and muscle function become impaired'. The condition is commonly expressed in stages, or degrees, that identify how serious it is if a paddler becomes cold, or even worse, wet and cold. We have purposely not included a discussion of severe or profound hypothermia because that level is beyond the scope of this review. There is a lot of specific information on profound that can be found in the literature. A victim of severe hypothermia cannot be effectively cared for in a remote wilderness river environment and besides, it would be unforgivable if we allowed anyone in our paddling group to reach this life-threatening stage. In formally organized groups, hypothermia is essential a leadership issue.

It's quite common for backcountry rescues to involve individuals who've become hypothermic. Why is this? Because the brain centers that keep track of core temperature and control critical thinking and judgment are affected quickly by cold conditions. It is a cold brain that gives hypothermia its insidious reputation requiring paddling friends to watch out for one another and intervene if needed--the WARY part. Outdoor travelers may not take time to put on another layer, change a wet inner layer for dry, or even go back to the trailhead to get a parka from the car. The person affected usually has no forewarning and instincts for self-preservation are diminished. Critical judgment goes out the window. Observing someone becoming hypothermic might be compared to someone becoming intoxicated. Sometimes people in the company of a hypothermic person confuse it with fatigue, irritability, dehydration and mountain sickness.

Mild hypothermia affects a person's ability to walk, talk, shiver and eat, and fine motor skills don't work very well; fingers may not be capable of zipping up a PFD. The victim is usually lethargic, becomes withdrawn from the group and develops blue lips. If the body continues to cool, possibly after a second swim, a paddler will show signs of more serious heat loss. The next stage--more moderate hypothermia--is characterized by the classic "umbles" and an individual fumbles, stumbles, mumbles and gross motor skills become seriously impaired. Even walking becomes difficult and compulsive shivering becomes pronounced.

For anyone mildly hypothermic and alert have them perform light exercise to see if they can rewarm that way, along with EATING some quick sugars (jello made with sugar not chemicals, warm gatorade, chocolate bars, etc.)--it is the classic "feed'em and beat'em." Get this person out of the elements and create a stable enironment for recovery. Concentrate efforts on getting the patient dry and keeping them dry. Change wet fabrics for dry, build a fire and help them increase heat production. Harness the energy from their initial shivering by maintaining sufficient insulation throughout their recovery.

For the stage of more moderate hypothermia additional strategies can help. Once the patient is out of the elements and into dry clothes, use a piece of tyvek, or a thin mm 9 X 12 ft. dropcloth purchased at Home Depot or Wal-Mart, and create a hypothermia wrap to roll the patient just like a burrito. If available you can make use of deflated canoe air bags as ground insulation underneath.

Another idea is to use either the tyvek or the dropcloth to make a caving tent (heat dome) by having several people pull the outside edges down around their backsides, placing the patient in the middle. Light a small candle inside if you carry one and allow it and the mass of bodies to create a 'hot house'. Small chemical heat packs (again, if you carry them) can be used under the armpits and on the palms of the hands and soles of feet. Should you ever have to bivouac overnight unexpectedly, the tyvek or dropcloth would come in handy as a shelter.

The fragile nature of a cold body requires that first aiders be gentle when physically handling a person; and if you're assisting a hypothermic paddler out of the water, do your best to keep them level as you position them on land. As you help a paddler recover regularly monitor their level of responsiveness (LOR) which lets you know how alert they are. Also, checking their vital signs of heart and respiration rates verifies how well the paddler is improving and what needs to be done next.

Our paddling efforts (that's the 'beat'em' part of the equation) help us maintain heat production if we are dressed properly in suitable layers. Remember, for our apparel to work as it should we have to keep our covered radiators full with plenty of water, and prevent freezup by using quality anti-freeze--quick energy carbs that stoke the internal metabolic furnace. Snack and drink often.

Heat loss happens in various ways. By conduction (don't sit on a cold rock while having lunch), convection (keep on your PFD when taking a break to prevent wind currents from taking away already generated warmth), radiation, which is direct loss of heat from the body to the surrounding cold environment. Finally, heat loss by sweat or water evaporating on the skin. The evaporation of sweat accounts for about 90% of the cooling efficiency of the body, a process that works well when playing tennis in hot weather, but works against us in cold temps. Related but less recognized is the cooling effect of evaporation when we breathe. Covering the mouth with a bandana or something similar will help, as will covering the head with a skull cap to prevent radiational cooling.

As we tie all this together it should become apparent that our boating strategy hinges on the management of moisture we produce (the WARY part). Too much sweating can tip the scales because even small quantities of evaporation will rob the body of large amounts of heat being produced. Herein lies the value of dressing like an onion in high-tec, breathable fabrics such as gore-tex, wave tex, stretch fleece and others that allow moisture to escape while keeping us warm. If you have on too much take off a layer until you need it. Maintain an appropriate pace downriver that is fast enough for everyone to generate energy and warmth, but slow enough to prevent overheating and oversweating. This may mean not playing the river as hard as you usually do on warmer days.

Before departing the putin discuss decisions for rescue in the event of swims. Especially with open canoes, if a paddler doesn't roll it may be wiser to quickly swim out of the cold current and let paddling friends retrieve the boat. Strong physical effort is needed to exit cold river current and a swimmer may experience fast and graphic heat loss. For some, the shock of cold water immersion may cause the body to shift into 'survival' mode. In this case, energy (heat) is pulled away from the extremities and surface areas of the body toward the core causing the arms and legs to lose swimming strength and coordination.
Even a fit person may not be able to hold onto a thrown rope or make a long swim to the shoreline. Moving cold water is colder than cold, so to speak--it increases convective heat loss! When a paddler swims be prepared to treat for hypothermia right away and closely monitor that person. Hypothermia authorities have advised that if the water and air temperature total a combined 100 degrees F or less (50 degrees water temp plus 50 degrees air temp), paddlers should dress for maximum thermal protection. Have on a dry suit or wet suit and all suitable layers. Obviously, this all depends on how remote the trip as well as a paddler's tolerance for cold conditions. Some boaters even use a higher combo of 120 degrees total when dressing with maximum protection.

In a newsletter article, FROZEN MYTHBUSTERS (see reference #6), Hubbell, Giesbrecht, and Hamlet disspell thirteen long standing myths about the effects of cold conditions and hypothermia on the body. Two of the myths in their report relate specifically to treatment given to paddlers who have become hypothermic. With a more moderately hypothermic person, they advise checking the extremities for signs of frostbite. If the patient has a lower than normal core temperature the decreased peripheral circulation to the skin could produce frostbite. These writers indicate that most people don't usually associate frostbite with hypothermia.

Another myth they highlight when assisting cold, wet paddlers is this--don't hesitate to strip a cold person out of damp or wet clothing, right down to the bare skin. Contrary to what many believe, these researchers stress such exposure will not cause a large drop in the paddler's core temperature. In cold temperatures a wet paddler needs to be dry to be able to rewarm, along with sufficient insulation added to protect from the elements.
An important concept that Gordon Giesbrecht stresses is the concept of 1--10--60 (expressed in minutes). He shows that it may not be hypothermia that is the issue, but possible drowning. If a paddler takes a swim in cold water and temps, at the moment of hitting the water there will be an immediate acute cold response--the swimmer will be gasping, gagging and struggling to get a breath. In this first minute, the swimmer MUST get control of the breathing and relax enough that she can swim out of the river. There have been instances in which swimmers in very cold water have actually drowned because of not getting 'control of the breathing'.
Dr. Howard Donner, co-author of A FIELD GUIDE TO WILDERNESS MEDICINE and experienced river guide (reference #7), stresses the need to protect the airway when taking a cold swim. Being in the cold water, a swimmer can locally cool to the point she can't protect her airway because the face, mouth and jaw become so cold. Donner emphasizes that it is commonly thought that "you'll die from hypothermia" in these first minutes after swimming in cold water, when in fact, it be due to not protecting the airway and maintaining oxygenation.
Within 10 minutes of being in the water, a swimmer's large muscles may stop working--thus causing drowning. This could also mean the swimmer might not hold onto a thrown rope, or could not self rescue out of the river (again, possible drowning). After 60 minutes in the water the swimmer (depending on individual differences) may become unresponsive and possibly drown. Generally, Giesbrecht's studies show that a person can survive longer in cold water than is believed. Give some thought to this 1--10--60 concept and be mentally prepared for the acute cold response described--protect that airway in a cold water swim.

Get out and enjoy the wonder of winter's solitude and beauty. As you paddle along eat often on quick energy snacks, drink water even if not thirsty and be wary of hypothermia. Carry within your group all the necessary treatment items mentioned in this discussion and don't forget firestarting materials. Remind others in your paddling group to eat and drink at regular intervals and most of all be committed to taking prompt action on behalf of paddling friends who become cold. If you have to treat one person in the group check on everyone else as well. Ultimately, the best TREATMENT for this old paddling nemesis is prevention, prevention, prevention.

1. Wilderness Medicine Newsletter articles by Dr. Frank Hubbell and Buck Tilton.
2. Wilderness Medicine course formats by SOLO of New Hampsire and Wilderness Medicine Institute of NOLS.
3. Wilderness Medical Socety's Bible--Management of Wilderness and Environmental Emergencies, 2005.
4. Backcountry First Aid/Extended Care by Buck Tilton, 2005.
5. A Comprehensive Guide to Wilderness and Travel Medicine by Eric Weiss, M.D. Latest edition, 2005.
6. "Frozen Mythbusters", Wilderness Medicine Newsletter Article, November/December, 2004 by Gordon Giesbrecht, PhD; Murray Hamlet, DVM; and Frank Hubbell, DO.
7. A Field Guide to Wilderness Medicine, 2006 by Dr. Howard Donner.
Dr. Giesbrecht is a professor of thermophysiology and the Director of the Laboratory for Exercise and Environmental Medicine at the University of Manitoba, Canada. Dr. Hamlet is one of the foremost experts in hypothermia, frostbite, and nonfreezing cold injuries. Now retired, he spent 32 years at the Army Research Institute in Environmental Medicine. Dr. Frank Hubbell, along with his wife, developed the SOLO Wilderness Medicine training programs and workshops in the late 70's.
This is an excellent report that will benefit interested cold weather paddlers.

ACA Instructor, Vernon Seaman of Owasso, OK, contributed to the original article published about four years ago. This version has been edited and more current information has been included.

Jim Simmons--12/26/'07; updated 4/25/'10; revised Nov/2011
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