Saturday, July 29

Three Dog Nights and Penguin Days

By Dr. Roberto Moreno

Although it may be springtime in the Rockies, dusting off your summer wardrobe doesnt mean you should pack away your winter clothes, if you intend on spending anytime in the great outdoors.

Hypothermia can occur in all parts of the United States, including the Sunbelt, and is always a potential risk for outdoor sports enthusiasts even if temperatures are not considered dangerously low. The majority of hypothermia cases in Colorado, occur not in midwinter but when the temperatures are between 30 and 50 degrees Fahrenheit (F).

Hypothermia is defined as a core body temperature (the temperature of the internal organs and brain) less than 95 degrees F (35 degrees Celsius). It occurs when the human body loses heat, by being unable to protect itself from the environment. Factors such as poor health and nutrition, exhaustion, alcohol and drugs, can diminish the bodies ability to maintain its own temperature and increase the incidence of hypothermia.

Body heat is lost by the following four mechanisms.

Convection is when air comes in contact with the skin and is blown away. The amount of heat lost is determined by the difference in the outside temperature and our skin, and wind speed. Thus, the colder the air and the faster the wind (wind chill) the more heat will be lost.

Conduction is the transfer of heat away from the body by objects that are in direct contact with and which are colder than the body, such as stone, ice, water, and metal. If you sat on the snow with insufficiently insulated clothes, you would lose more heat than, if you were sitting on the beach drinking a margarita.

Proper attire worn in layers minimizes sweating and heat loss

Evaporation. Sweating is a mechanism by which we cool ourselves as the sweat evaporates from our skin. Likewise, when exercising outdoors sweating can drastically lower body temperature if the proper clothing isnt worn.

Radiation is the transfer of heat through infrared energy and accounts for up to 60% of our heat loss when we are not sweating. Heat is lost from the body, through radiation, to nearby solid objects (rock, ice, walls and trees) that have a cooler temperature.

Modificacion a un ambiente frio (Adaptation to a cold environment)
The human body can do little to adapt itself to a cold environment. It will try to maintain the temperature of the body core to preserve the function of the brain and internal organs by contracting blood vessels in the skin, arms and legs so oxygen wont be lost at the core organs.

We also warm ourselves by shivering, which is the involuntary contraction of skeletal muscles. This requires a lot of fuel in the form of carbohydrates from food. When fuel is depleted, shivering will stop. If this occurs, it doesnt require extremely cold temperatures to produce hypothermia.

Sintomas (Symptoms)
All body systems are affected by hypothermia, but the brain and heart are the most sensitive. Their function progressively diminishes as the temperature decreases.

Mild Hypothermia is a core body temperature between 95 and 90 F. The victim is usually pale, confused, slow, uncoordinated and shivering.

Moderate Hypothermia is body temperature between 90 and 83 F. Cessation of shivering, irrational behavior and inability to walk or stand are all present.

Severe Hypothermia symptoms include unconsciousness, undetectable blood pressure and pulse, and often heart rhythm abnormalities (cardiac arrhythmias).

Tratamiento (Treatment)
Treatment depends on the degree of hypothermia. With all stages patients should be brought to a shelter where blankets need to be applied and warm humidified air should be breathed. All wet garments should be gently removed and replaced with dry clothes. The victim should be given sugar water and food rich in carbohydrates (granola or energy bars).

Mildly hypothermic persons should concentrate on walking and moving the extremities to generate heat. The arms and legs of moderately and severely hypothermic victims should never be manipulated.

Comatose persons are extremely sensitive to fatal cardiac rhythms triggered by toxic acids in the bloodstream produced by unnecessary body movements.

All stages of active warming such as electric blankets, hot water baths or placing victims next to a fire or stove are dangerous as complications such as rewarming shock and heart arrhythmias may occur.

Transfer to a medical center is imperative no matter how ghostly and goolish a victim appears. Many people have appeared to return from the dead after their bodies were rewarmed. Yeah, real X Files type stuff. Remember, nadie se a segura esta muerto si no esta caliente y muerto (nobody is proven dead until they are warm and dead.)

Prevencion (Prevention)
Selection of clothing is the single most important factor in maintaining a constant body temperature. Clothing should be worn in layers that can be added or taken off as needed, balancing activity, temperature, wind and precipitation, to minimize sweating and heat loss.

The inner layer should be able to wick moisture away from the body surface and dry easily. The middle layer should both insulate and ventilate well. The outer layer should be wind and water resistant to keep the body dry and minimize heat loss from convection. Your lucky cotton sweatshirt? Ni siquera piensalo! (Dont even think about it) Cotton wicks, insulates and dries poorly. The only luck youll have exercising with cotton in the cold, is bad.

Sitting down in the cold causes faster heat loss

Do not forget that exercising muscles and temperature regulations both need energy in the form of carbohydrates. A person who is in better physical condition will have a reduced need for fuel for the same level of work, and thus be safer when temperature regulation becomes critical. Fuel supplies must constantly be replaced and a convenient quantity of carbohydrates and water should always be available.

The challenge of outdoor sports is to maintain normal body temperature, conserve and replace body energy stores, and to avoid body heat loss by minimizing sweating. Clearly, mejor evitar hipotermia que tratala (hypothermia should be avoided not treated.)

Que buena onda!

Look out for the next El Medico on Preparing for High Altitudes.