by David Page
Heat Prostration (Heat Exhaustion)
In contrast to heat stroke, heat exhaustion occurs despite appropriate and often severe sweating. Fluid loss may make the victim feel light-headed and weak, but the overall clinical picture with this heat problem looks exactly like shock. The problem is severe fluid loss. These victims are cold and clammy and have a weak, thready pulse; they eventually develop low blood pressure in severe cases—the classic picture of any shock patient. With heat prostration, the body core temperature is normal or sometimes reduced, but never elevated as with heat stroke.
Thus, the appearance of the person suffering from heat prostration includes the following features:
• The victim complains of weakness and light-headedness and describes a history of excessive sweating with little fluid replacement.
• The victim presents with severe sweating, body fluid loss that results in cold, clammy skin, a thready pulse and low blood pressure; symptoms could be confused with those of shock due to blood loss.
• If the condition is allowed to progress, the victim may lose consciousness.
• The body temperature is normal or subnormal.
Treatment for heat prostration involves replacing the large body fluid losses with large volumes of liquid by mouth. In severe forms, it may be necessary to hospitalize the victim and give IV fluids. This condition usually responds well to replacing body fluid without a lot of other complicated interventions.
Frostbite
Like burns, frostbite often results from impaired judgment and isn't solely a matter of random exposure to the injuring agent. Just as people who smoke in bed represent a large number of burn victims, so it is that the adventurous soul who doesn't prepare properly for a winter excursion often discovers herself in trouble. Most often, frostbite occurs on exposed areas, such as the nose, cheeks, ears, and poorly insulated fingers and toes.
Before actually suffering from the effects of full-blown frostbite, a
lot of outdoors folks experience what is called frostnip, a milder cold injury. Characterized by pain and numbness, this condition involves exposed parts, such as the ears, nose, fingers and toes, which become blanched (white). Recovery is complete with adequate rewarming. Frostnip may take your character out of action for hours with pain while frostbite could sideline someone for days or weeks. Severe cases of frostbite require hospitalization.
The treatment of frostbite is quite different in some respects from the management of burns and similar in others. After attention to general body rewarming, the partial thickness frostbite wound should be protected and left to heal itself. Sometimes bandages are used; often the part is left exposed. It's a waiting game. The body will replenish spent tissue with new tissue built up from the mother cells deep in the skin, just as with first- and second-degree burns. If full-thickness skin death occurs, skin grafting becomes necessary.
Then there's the matter of fourth-degree frostbite, and that, folks, means the entire body part is lost. Fingers, toes, ears or nose, the part turns black. Black tissue is dead tissue. In time, if it's a toe or finger tip, it will fall off spontaneously. But often the frostbitten part must be surgically removed.
Amputation.
If your character is isolated in the wilderness away from medical care, and if mummification occurs (the part is shriveled up, black, dry), then he may have to have to amputate his own dead thing—no matter what it may be. Lubricate that notion and push it through your plot plan.
Hypothermia
Ever wonder why a wolf's paw doesn't freeze while the animal is standing on the windswept northern tundra? Ever wonder why a sled dog
How to Diagnose Frostbite
Obtain a history of cold exposure with the following features:
■ High altitude
■ Windy conditions (windchill factor)
■ Wet environment
■ Prolonged exposure
■ Cigarette smoking
■ Chronic illnesses (diabetes, poor circulation)
■ Excessive alcohol intake
■ Psychiatric history
Perform a physical examination and look for the following:
■ White areas (blanching) on exposed skin
■ Blebs, or "water blisters"
■ Black leathery skin fixed to deeper tissue
curled up nose to tail in a snowbank beside the Iditarod trail doesn't freeze to death as the windblown snow buries it? Ever wonder how a long-distance swimmer can survive for half a day in water so cold it's supposed to kill you and me in six hours?
Are shaking chills valuable or destructive?
The general effect of cold and a mammal's adaptation to frigid insults are fascinating topics and will complete our discussion of the body's reaction to cold. Imagine a timber wolf portrayed in a Robert Bateman painting, standing in a winterscape with its paws buried in snow. What keeps the pads of the animal's foot from freezing? The tundra and windchill factor surely plunge the temperature at paw level to what . . . twenty, thirty below? Why doesn't the water in the wolf's foot pad cells crystallize and freeze?
In the wolf's leg, the veins returning blood to the heart are wrapped about the main arteries like insulation about a water pipe. Hugging the artery in this fashion, the veins accept heat by direct transfer from the hot arterial blood coming down from the animal's warm core (its chest and abdomen). This transfer of arterial heat warms the frigid venous blood returning from the paws. Thus, the arterial blood that eventually reaches the paw has been cooled by transferring heat to the veins but is
still warm enough to prevent freezing of the paw pad. And the venous blood flows back up to the core conserving the heat it received from the arteries. Body heat is conserved centrally. Neat, eh?
Our arms and legs act in a similar fashion to conserve some heat although our thin skin—even with a layer of fat—isn't terribly effective insulation. By contrast, the sled dog doesn't die in winter because he's got a thick pelt, which traps air and remains fluffy and is augmented by that layer of soft snow that buries the animal. It's all insulation. But the system breaks down if the animal becomes wet. And that brings us to the long-distance swimmer. (You see it's not such a long trip from the Arctic to the English Channel.)
Folklore has it that long-distance swimmers are hefty athletes who sport a generous layer of adipose (fat) tissue to fight off the ravages of cold water. Without a doubt, some swimmers are cherubs, adiposidly challenged. The real speedsters are svelte, and they don't use a layer of grease either.
In 1972,1 was Davis Hart's physician when he set a world record swimming the English Channel. There wasn't much information in the medical literature at that time to use to prepare Davis for this endeavor, but we knew Davis's trim physique would leave him at risk for cold-related problems. Water conducts heat twenty-five times faster than air. Davis discovered a training program that worked for him. He swam in cold water as often as possible, but he also did a lot of warm pool swimming because of his job. What to do to acclimate to cold water? Davis began to stand in a frigid shower in a plastic garbage can filled with the cold shower water, training his nervous system to acclimate to the harsh effects of mimicked cold water submersion.
It worked. Davis tolerated 62° Channel water for nine hours and forty-four minutes. The first person in the world to swim the English Channel in under ten hours, he set a new world record.
Victims of progressive hypothermia go through three phases of progressive deterioration that blend with each other. The clinical phases of hypothermia are:
1. Excitatory. The victim increases activity and shivers to attempt to warm up; blood vessels constrict to conserve heat.
2. Adynamic. Means "without movement." This phase follows the rapid breathing of the excitatory phase; breathing slows as the respiratory center is depressed, reflecting overall metabolic slowdown.
Changes in Body Functions in Hypothermia
■ Cardiac system: Blood vessels constrict. Heart rate drops. The amount of blood eject
ed by the heart is reduced. Blood becomes thick. Ventricular fibrillation finally occurs (the heart quivers uselessly without pumping blood).
■ Nervous system: Confusion occurs with prolonged immersion or cold exposure followed by amnesia, delirium and coma. The reflexes disappear eventually, and breathing (the brain stem respiratory center) is depressed and slows.
■ Kidneys: Cold exposure and submersion in cold water both produce what doctors call a diuresis, meaning excessive urination. It may cause dehydration and aggravate other cardiovascular problems.
■ Muscular system: Discomfort and fatigue occur early on, then loss of muscular power, loss of coordination and the ability to perform simple motor tasks. Apathy occurs with severe hypothermia.
■ Skin reaction: Very much like an allergic reaction, the skin becomes red and the victim may develop wheals or "water" blebs of fluid. Skin becomes cold as blood is shunted into deeper tissues to conserve energy.
3. Paralytic. The victim becomes almost comatose as the core temperature continues to drop and neurologic signs appear.
These are the kinds of things your character might observe when she drags someone in your story from a glacial stream near Mount McKinley. A character discovered in any of the physical states mentioned above can be successfully resuscitated from extreme hypothermia if proper measures are taken.
What's going on in the victim's "core"?
A lot. And not so much. Things are slowing down. In the extreme case, sudden death may occur if an individual unaccustomed to the cold jumps or falls into frigid water. The explanation may be either that the extreme cold caused sudden cardiac arrest or the cold water produced immediate apnea (stoppage of breathing). You can place your characters
at risk by having them jump from bridges, sink their boats or tumble overboard on an Alaskan cruise. Of course, they can be saved.
Who Becomes Hypothermic?
• The foolish. They go out into hostile cold temperatures unprotected; they do not respect the potential for harm in frigid conditions.
• The unprepared. They consciously or unconsciously take risks by not preparing adequately (this includes misinformed hunters, campers and trekkers); these people believe they are ready for any eventuality when, in fact, they are not knowledgeable about wilderness survival.
• The elderly. They become exposed outdoors by dressing inappropriately or indoors because of inadequate living facilities. Elderly people often don't realize they're becoming hypothermic as their senses are blunted with aging.
• Substance abusers. Alcohol, drugs or other toxic chemicals blunt the person's level of awareness, and he ignores important symptoms such as shivering and changes in skin color and temperature changes.
• The homeless.
Shivering is a complicated phenomenon that causes muscles to contract rhythmically and repeatedly for the purpose of generating heat. You don't have to be in subzero temperatures to become hypothermic. Shivering is seen in kids during swimming lessons, in skiers at the end of the day or in your neighbor walking her dog in November without a coat as if winter wasn't in the air.
There are simple ways to safeguard against cold exposure and avoid hypothermia:
• Dress in layers. Mimic the fur of cold-tolerant animals, and trap air between clothing layers rather than wearing one thick coat.
• Avoid becoming wet. If you do, dry off immediately.
• Carry extra socks and other appropriate clothing if going away from support facilities.
• Wear head covering. At least 20 percent of all body heat loss is via the head and neck.
• Drink adequate fluid—warm when available—to avoid dehydration and to maintain core temperature.
• Avoid use of drugs and alcohol when in a cold environment.
• Plan for unexpected weather changes, and formulate a contingency
plan to get out of the cold environment.
• Gain fifty pounds!
Other Cold Injuries
Chilblain
This is a type of cold injury characterized by reddish purple bumps or small raised areas on exposed surfaces with swelling and occasionally with blistering. Occurring on the face, back of the hands and feet or any surface chronically exposed to cold but not freezing temperatures, eventually skin ulcers and bleeding may occur. Treatment includes slow rewarming, elevation of the part and protection from further abrasion.
Trench Foot
Also called cold immersion foot, this injury is seen in wet environments where actual freezing doesn't occur. For example, sailors, deep-sea fishermen and soldiers are often forced to remain wet for prolonged periods of time. Small blood vessels that supply the exposed part alternately go into spasm, then open up. This produces a cold and at times numb limb that then becomes fiery hot with a burning discomfort. Tissue damage progresses from swelling and blisters to ulcers, infection and, if the condition is severe, gangrene.
Treatment for immersion foot is similar to that for chilblains and includes slow rewarming with protection and elevation. The affected part sometimes demonstrates increased sensitivity to cold long after the injury has healed. Massaging or rubbing a body part affected by chilblains or immersion foot is to be condemned. Friction creates good fiction, but it makes frostbite injury much worse.
Extremes of temperature exist in many areas of the world and some of your characters will have to deal with the threat posed by severe cold as well as sweltering heat. Physical hardship raises the stakes in any story. At times the storm, wind chill, forest fire or frozen lake becomes another adversarial "character," a source of unpredictable conflict.
Your story's world possesses a climate of its own. Make it work for you.
Innovative technology and immeasurable courage permit humans to venture into the most hostile provinces of the earth. The price of pursuing this peripatetic impulse is measured in novel injuries and spectacular new ways to die. Of course, we're only interested in the nonlethal varieties of damage that severe environmental pressure changes wreak upon worldly adventurers.
Scuba diving and high altitude exposure share a common bond: potential oxygen deprivation. In the underwater environment, the diver carries a life-support system, which contains oxygen (compressed air) as well as other safety devices. Mountain vistas are surrounded by breathtaking views and a breath-racing lack of oxygen. Both locales place the participant at risk.
Diving accidents and high altitude medical problems form a unique and fascinating group of problems. Are any of your characters cocky? Risk takers? Unlucky?
Diving Accidents and Their Consequences
Breath-hold diving goes back to antiquity and served early cultures well in the search for valuable seafood, sponges and pearls. Over two thousand years ago the Ama, Korean and Japanese diving women, collected shells and marine plants by breath-holding. These practices continue today.
One of the first types of diving helmets was devised by Giovanni Borelli in the 1600s, and reeds and bamboo tubes were also used near the surface. Edmund Halley, after whom the comet was named, developed the first diving bell with an air supply in 1691, but it wasn't until the 1800s that the world saw the first diving suit. The rigid helmet and waterproof suit design first used by Augustus Siebe in 1837 is still employed, with modifications.
In 1943 Jacques Cousteau and Emile Gagnan invented the scuba (self-contained underwater breathing apparatus) used throughout the world. Virtually flawless at various depths, the scuba unit possesses a special valve that "steps down" compressed air tank pressure and compensates for ambient pressure differences. The valve is triggered by the inhalation effort of the diver.
Deep-diving systems developed in the 1970s and 1980s culminated in single-diver systems that descend to over a thousand feet in the ocean. New illnesses nipped at the heels of the intrepid divers who first used these new submersibles. Mixtures of oxygen and helium were necessary to permit adequate oxygenation without overwhelming problems of su-persaturation with inert gases. Research in the fie
ld of deep-diving systems continues to improve diver safety and open further fields for commercial exploitation. Although decompression sickness began to appear with "hard hat" divers, it wasn't until large numbers of people began to dive for sport that a multitude of pressure-related illnesses created a new specialty: diving medicine.
Two laws of physics are always mentioned with diving diseases and pressure-related accidents. They explain why excessive pressure is so poorly tolerated by the human body.
The first is Boyle's Law, which states that (assuming the temperature is constant) the volume of a gas is inversely related to the amount of pressure applied to it. So the volume in your lungs as you descend to greater and greater depths becomes smaller and smaller. Then, as you ascend at the end of your dive, the pressure lets up and the gas in your system expands, and if you come up too quickly the gases in your body fluids will reappear in the form of bubbles.
The second law tells us how much gas actually gets into the tissues during a dive. Henry's Law says that the amount of gas that enters a liquid depends directly on the amount of pressure applied. Assuming the temperature is constant, the amount of gas in your tissue at two atmospheres, or thirty-three feet, is half what it is at three atmospheres, or sixty-six feet. The deeper you go, the more gas that enters your body tissues from the tank on your back.
Humans are lousy breath-hold divers compared to whales and dolphins. As oxygen is used up, the diver risks shallow water "blackout" if the dive was preceded by excessive hyperventilation ("overbreathing") because the carbon dioxide drive on the brain has been removed. Dolphins can remain submerged for as long as two hours, and most diving mammals have a "diving reflex" in which the pulse rate slows with submersion, permitting more efficient oxygen use.
Three major diving problems are described to give you an idea of what your submerged characters might get into if they don't follow the rules. Each problem is related to what happens to gas under pressure in the diver's tissues.
Decompression Sickness ("The Bends")
The widespread use of compressed air in mining, tunneling and caisson work resulted in several medical investigators noticing a peculiar illness characterized by the trapping of bubbles in tissue. It wasn't long before Leonard Hill studied animals under pressure and recommended staged decompression for workers coming up from a pressurized work environment. And although a certain degree of resistance to decompression sickness can occur in individuals repeatedly exposed to pressure, the following factors make "the bends" more likely:
