Written by: Doris McGirt, MedicalSCI
“No previously healthy person should die of hypothermia after they have been rescued and treatment has been started.” Cameron C. Bangs, M.D. The Mountaineers 1986.
To help the hypothermic patient, metabolic heat loss must be matched with metabolic heat production.
Causes of Hypothermia:
• Primary Hypothermia: normal physiological thermal regulatory responses are working but are ineffective against the environment
• Secondary Hypothermia: physiological thermal regulatory responses are impaired by injury, illness or fatigue resulting in an inability to tolerate the cold
• Clinically Induce Hypothermia: a decrease in core body temperature that is induced by surgical procedures (i.e. cardiopulmonary bypass)
Stages / Classifications of Hypothermia:
Many medical organizations have developed their own stages of hypothermia and the specific clinical symptoms patients will exhibit at each stage. The stages are differentiated by using ranges of core body temperature. A particular stage can also vary based on the presence of an injury. For example, a trauma patient is more susceptible to heat loss and may reach a “severe” stage of hypothermia at a body temperature that can be as much as 4°C warmer than a patient who has no trauma.
All of these variations may be one of the reasons health care providers get confused and are uncertain how to treat a cold patient. Our advice is, make certain the organization you are working with adopts one system of classification or at the very least modifies a clinically validated classification to make it their own. Clinical data is there for a reason, so use it.
Having little or no understanding of your patient’s level of “coldness” will lead you to not know how best to treat them.
Mechanisms of Body Heat Loss: Always remember – HEAT IS ENERGY
• Radiation Heat Loss:
o Is the heat emitted from the body’s energy – this is what you feel when you walk into a crowded room
o Is a small factor in the development of hypothermia
o Can be minimized by using reflective body covering
• Conduction Heat Loss:
o Is the transfer of body heat into a solid – this is what you feel after lying on your bed pillow for a few minutes or sitting in a chair immediately after someone else gets up
o The amount of transference is dependent upon the gradient
o The rate of transference is dependent upon the surface area
o Can be minimized by using a poor conductor and having good insulation
o Without the ability to transfer there is no conductivity of the body’s heat
• Convection Heat Loss:
o Is the transfer of body heat into a fluid – air or water
o The amount of transference is dependent upon the gradient
o The change in the surrounding temperature moves it around and replaces it with cooler fluid until it is equalized
o The rate of transference is dependent upon the surface area and density – water takes more than air – this is why you get cold faster when in water
o Can be minimized by trapping the warm fluid around the body
• Evaporation / Respiration
o Is the transfer of body heat by perspiration or exhalation – this is why we breathe on our eyeglasses to make fog before cleaning them
o The amount of transference is dependent upon the gradient
o Perspiration and exhalation leaving the body takes the body energy (heat) with it
o Can be minimized by drying the body and/or capturing the exhaled air
We are available to assist if there are any questions regarding the information above. If we do not know the answer we will do our best to get it and work to respond to all queries within 72 hours.
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