Ken Springer
Contributing Writer
Tis the Season
For cold injuries
“If the thermometer had been an inch longer, we’d all have frozen to death.”
~ Mark Twain
HYPOTHERMIA: The following are actual incidents:
Incident #1
The young secretary listened to radio reports throughout the day about the blizzard conditions and frigid temperatures outside. She knew that she would have to drive in the early evening gloom along a county road for 15 miles of reasonably isolated country to reach the comfort of her home and family. But, with a new SUV equipped with snow tires, there was little to worry about.
Her greatest discomfort, or so she thought, would be the bone-chilling walk from the office to her car in the parking lot. Dressed in a skirt, driving gloves, and lightweight coat, her body was found several hours later in a cornfield some 300 feet from her car that had slid off the road and into a ditch.
Apparently, she had seen the light from a farmhouse and was attempting to reach it. Tragically, her vehicle had a full tank of gas, which she could have started intermittently to warm up the car.
Her death was easily preventable with just a little education and having some cold-weather gear and supplies in her car. She left behind a husband and two children.
Incident #2
The hospital report read “dead on arrival” for the motorcyclist, citing the cause of death as massive injuries sustained when his motorcycle left the road for no apparent reason, striking a tree. This tragedy was so unusual because the rider was on a straight stretch of dry highway on a clear fall day with temperatures in the upper 50s.
Incident #3
An 82-year-old widower was found dead in his apartment by neighbors when they became concerned after noticing an accumulation of mail and newspapers on the porch and the absence of any activity for several days.
His reaction to a February cold front bringing frigid temperatures to the area was to lower his thermostat to 60 degrees to save money, as many aging people on a limited income do.
Incident #4
The couple’s canoe overturned on a rain-swollen creek, pinning one paddler’s legs to a large rock midstream. The unfortunate victim could sit against the rock and direct his partner on shore to seek help in a fairly remote area. He assured her that he was not in any immediate danger, considering that the canoe was only impinging on his lower legs.
In the hours that ensued on that 60-degree March day, he probably realized the terrible error of his statement. When rescuers arrived some three hours later, it was too late to save him.
What do these incidents all have in common? The common culprit in each case was a cold-induced condition called hypothermia.
Hypothermia means loss of body heat or low body heat, and it is often induced by doctors performing certain surgeries requiring decreased blood flow and reduced physiological demands. But when this state of reduced core temperature happens unintentionally, and the symptoms are ignored, hypothermia can be deadly.
Cold injuries such as hypothermia and frostbite are hazardous to everyone exposed to a cold environment. Outdoor workers and those participating in outdoor activities are not immune and may be at greater risk than the general population.
In addition to the risk of cold injuries, exposure to cold weather may cause a decline in work capacity and physical output. Cold exposure adversely affects physical and cognitive abilities, which often translate to increased accidents and injuries.
To prevent hypothermia, we must first be aware of the dangers that cold presents and be familiar with the symptoms. In addition, employers should instruct their employees in proper hypothermia and frostbite treatment and dress appropriately for cold exposure indoors and outdoors when subnormal temperatures are a factor.
The complex functions and processes within the body of a warm-blooded animal are optimally efficient at a relatively constant body temperature. In humans, the core temperature is approximately 98.6 degrees Fahrenheit. When our core temperature drops even a few degrees, our body’s thermo-regulatory system begins taking steps to maintain or increase our optimal temperature.
The body has at its disposal a series of mechanisms that function to maintain a near-constant temperature. When exposed to environmental conditions of heat or cold, which threaten the stability of the core temperature, these involuntary defenses come into play.
This fascinating physiological complexity is best understood if we consider the body as having two distinct parts: the shell and the core. The shell comprises the skin and the millions of ultrafine blood vessels, called capillaries, that permeate it. Also included in the shell are nerves, muscles and fat. The core comprises the vital organs, the heart, lungs, liver, kidneys, brain and other internal organs.
Receptors in the shell alert a portion of the brain called the hypothalamus, which acts as the body’s thermostat. If a drop in the body’s core temperature is detected, a neural signal is directed to constrict the capillaries, reducing heat loss from the skin’s surface. The shell now becomes an insulator rather than a radiator of body heat.
If this response is not enough to reduce further heat loss from the core, other mechanisms are called into play, such as involuntary shivering and inhibition of sweat glands. This reduction in sweating prevents heat loss through evaporation while shivering is a source of heat production analogous to the heat generated by physical activity. Through a series of involuntary reactions, the body’s shell protects the core from life-threatening heat loss.
So, what symptoms can we expect if the core temperature drops unabated? The initial symptoms of hypothermia are a sensation of being cold followed by shivering, sometimes intense enough to damage teeth. These symptoms continue until the core temperature drops to approximately 93 degrees F.
At this point, shivering ceases, and the muscles become rigid. There is a dramatic decrease in manual dexterity accompanied by slurred speech and a marked decrease in cognitive functioning. This stage of hypothermia could have dev- astating effects on those involved in operating machinery, such as vehicles, or activities requiring unwavering concentration, such as mountain climbing, for example.
The victim becomes unconscious at approximately 86 degrees F, and death may occur at 79 degrees.
Outdoor workers and people involved in cold manufacturing processes should be aware of hypothermia symptoms. In the initial stages of hypothermia, removing a victim to a warm location may be adequate to restore normal temperature, but as the victim progresses into deeper stages of hypothermia, more drastic first-aid measures are called for.
The main objective is to rewarm the victim correctly. This can be accomplished by immersing the body in warm water, no greater than 105 degrees. Alternatively, the rescuer can use heat packs or warm towels if available.
Do not rewarm the extremities and the core simultaneously, as this may precipitate something called “After Drop Shock.” This is dangerous because the cooler blood pooled in the extremities returns to the heart, causing vasodilation in the capillaries and an acute drop in core temperature. The effect can be fatal, so first responders should only use passive rewarming in the field to prevent further heat loss.
In the field, where warm water may not be available, the best rewarming method may be direct contact with another human body. This approach to rewarming can be accomplished by gently removing the victim’s clothes if wet and pressing your body against the victim’s in a blanket, sleeping bag or tarp. This measure could be the difference between life and death, so don’t hesitate. As soon as possible, all hypothermic victims should receive professional medical treatment.
The more fat on the body’s shell, the more insulation to protect the core from heat loss. Therefore, a thin person exposed to the same conditions will lose body heat faster than a victim sporting a liberal amount of adipose tissue.
What we eat for breakfast before we go out to work or play during cold weather—the temperature doesn’t have to be below freezing to cause hypothermia—will have a considerable effect on how warm we stay.
Some foods generate heat relatively quickly, carbohydrates being a great example. On the other hand, fats have longer-lasting effects; think of the Arctic Inuit people’s consumption of muktuk (whale blubber).
The very young and the aged are more susceptible to cold injuries. Both groups have less efficient defenses against rapid heat loss. Older people often have poor circulation, take medications that impair the thermo-regulatory system, and may have a diet deficient in calories, vitamins and minerals.
The level of physical activity in cold environments affects the stability of body temperature. Snowshoeing burns 400 to 600 calories per hour, which is an excellent reason to wear layered clothing, which will be discussed a bit later. One caution: try to avoid the post-activity chill, caused by the entrapment of perspiration, which results in a cooling effect.
One notable exception to the activity/heat rule is if the victim is immersed in cold water. In this situation, physical exertion, such as treading water, will cause body heat to be rapidly lost to the water by direct conduction.
Water is an excellent conductor of heat and is 25 times more efficient than air of the same temperature. A U.S. Coast Guard publication predicts survival time for an average person treading in 50-degree water to be two hours.
In the same situation and conditions where the victim is wearing a life-saving device and maintaining a “huddle” position, the predicted survival time extends to four hours.
When outdoors in colder weather, one should keep one’s clothing as dry as possible because wet clothing will cause body heat to flow away from the skin. This is particularly true of cotton garments; think of how long it takes a pair of jeans to dry compared to synthetics.
Wool and synthetic fleece are excellent choices because they provide some insulation even when wet.
As for drinking alcohol and those iconic brandy-toting St. Bernards, things are not always what they seem. Although a shot of brandy produces a warm glow, this feeling is mainly a result of irritation of the stomach lining.
Alcohol is a depressant and an efficient vasodilator, contributing to even more rapid heat loss, and is a predisposing cause in many hypothermia and frostbite cases. So, send that big cuddly St. Bernard back for hot chocolate.
In the next episode on cold injuries, we’ll discuss the causes and treatment of a dangerous condition called frostbite. The conclusion will include a suggestion for a unique Christmas gift that could save the life of a loved one.
Winter is upon us, so stay warm and stay safe.
Ken Springer
ken1949bongo@gmail.com
