The normal range of human core body temperature is 36.4°C to 37.5°C (97.5°F to 99.5°F). Body temperature is closely regulated through a balance between heat production and heat dissipation.<sup>45 Schneider S.M., Danzl D.F. Hyperthermia: From recognition to rewarming Emerg Med Reports 1992 ;  13 : 1  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> The majority of endogenous heat production results from metabolic activity in the heart and liver. The skin accounts for 90% of heat loss, and the lungs contribute the rest. Loss of heat by radiation is the primary method of thermal-load dissipation. The preoptic nucleus of the anterior hypothalamus is the thermal control center, maintaining body temperature at a given set value. In a conscious individual, the appreciation of cold induces the individual to exercise, wear more clothes, or move to a warmer environment. In response to a drop in core body temperature, the hypothalamus conserves heat by producing cutaneous vasoconstriction and stimulating muscular activity in the form of shivering.<sup>2 Bangs C.C. Hypothermia and frostbites Emerg Med Clin North America 1984 ;  2 : 475

Cliccare qui per andare alla sezione Riferimenti, 45 Schneider S.M., Danzl D.F. Hyperthermia: From recognition to rewarming Emerg Med Reports 1992 ;  13 : 1  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> Inhibition of shivering with medications such as meperidine may attenuate rewarming and worsen core temperature afterdrop in hypothermic individuals.<sup>16 Giesbrecht G.G., Goheen M.S.L., Johnston C.E. , e al. Inhibition of shivering increases core temperature afterdrop and attenuates rewarming in hypothermic humans J Appl Physiol 1997 ;  83 : 1630

Cliccare qui per andare alla sezione Riferimenti</sup> Heat production increases twofold to fourfold with shivering and exercise.

Hypothermia is defined as an unintentional decline in the core temperature below 35°C (95°F). At this temperature, the coordinated systems responsible for thermoregulation begin to fail because the compensatory physiologic responses to minimize heat loss are very limited.<sup>9 Danzl D.F., Pozos R.S., Hamlet M.P. Accidental hypothermia 3. Wilderness Medicine: Management of Wilderness and Environmental Emergencies St. Louis: Mosby (1995).  51

Cliccare qui per andare alla sezione Riferimenti</sup> Primary hypothermia (accidental hypothermia) refers to a spontaneous reduction of core body temperature, usually as a result of exposure to cold environments without adequate protection. Environmental hypothermia results from a combination of heat loss by convection (degree of wind exposure), conduction, and radiation to the surrounding ambient air. Secondary hypothermia represents a complication of an underlying disorder. Some of the disorders and conditions that may predispose an individual to hypothermia by decreasing heat production, increasing heat loss, or interfering with the central or peripheral control of thermoregulation are listed in Table 1.<sup>2 Bangs C.C. Hypothermia and frostbites Emerg Med Clin North America 1984 ;  2 : 475

Cliccare qui per andare alla sezione Riferimenti, 8 Danzl D.F., Pozos R.S. Accidental hypothermia N Engl J Med 1994 ;  331 : 1756  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti, 27 Jacobsen T.D., Krenzelok E.P., Shicker L. , e al. Environmental emergencies Dis Mon 1997 ;  43 : 809

Cliccare qui per andare alla sezione Riferimenti, 34 Lee-Chiong T.L., Stitt J.T. Disorders of temperature regulation Compr Ther 1995 ;  21 : 697

Cliccare qui per andare alla sezione Riferimenti, 35 Lee-Chiong T.L., Stitt J.T. Accidental hypothermia. When thermoregulation is overwhelmed Postgrad Med 1996 ;  99 : 77

Cliccare qui per andare alla sezione Riferimenti, 37 Manning B, Stolerman GH Hypothermia in the elderly Hosp Pract 1993 ;  May : 539

Cliccare qui per andare alla sezione Riferimenti, 45 Schneider S.M., Danzl D.F. Hyperthermia: From recognition to rewarming Emerg Med Reports 1992 ;  13 : 1  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup>.