Protection and treatment of hypothermia in ... - Umeå universitet

important to stress that thermoregulatory responses are induced long before body
core temperature declines below the level defined as hypothermia. Beyond the two
classifications mentioned above, to be more applicable in a prehospital rescue
scenario, yet another method of staging hypothermic patients is recommended by
the International Commission for Alpine Rescue (ICAR) (28). Using this method,
degree of consciousness, presence or absence of shivering, cardiac activity, and
body core temperature are taken into consideration when deciding hypothermia
level. Table 1.1.
The human body maintains an average core temperature near 37 °C in various
thermal conditions (41). However, extreme thermal exposure as well as certain
medical conditions can lead rapidly to dangerous deterioration of body core
temperature. Because the speed of chemical reactions vary with temperature and
because the enzyme systems of the body have narrow temperature ranges in which
their function is optimal, normal body function depends on finetuned temperature
regulation. A deviation of about 2 °C above or below normal body core temperature
is well tolerated but a deviation of about 3 °C begins to threaten normal body
function.
Thermoregulatory mechanisms are not fully developed until after puberty and
from about seventy years of age thermoregulatory capacity is decreased, having the
consequence that children and elderly are more vulnerable to cold stress (41).
There are also differences between men and women (41). Women, as a group,
have, compared to men, a greater surface-area-to-mass ratio, a greater percentage of
subcutaneous and total body fat, a greater resting vasoconstriction in hands and feet,
a higher setpoint for cutaneous vasodilation and onset of sweating, and also cyclic
hormonal changes that influence thermoregulation. However, when individual
differences are accounted for, thermoregulatory gender differences are negligible.
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