Postgraduate Medicine
ISSN: 0032-5481 (Print) 1941-9260 (Online) Journal homepage: http://www.tandfonline.com/loi/ipgm20
Hypothermia Joseph Varon MD, Nicholas Sadovnikoff MD & George L. Sternbach MD To cite this article: Joseph Varon MD, Nicholas Sadovnikoff MD & George L. Sternbach MD (1992) Hypothermia, Postgraduate Medicine, 92:8, 47-59, DOI: 10.1080/00325481.1992.11701549 To link to this article: http://dx.doi.org/10.1080/00325481.1992.11701549
Published online: 17 May 2016.
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Citing articles: 1 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ipgm20 Download by: [La Trobe University]
Date: 16 June 2016, At: 09:58
-@CME credit article
Hypothermia Saving patients from the big chill
Joseph Varon, MD
Nicholas Sadovnikoff, MD
George L. Sternbach, MD
Downloaded by [La Trobe University] at 09:58 16 June 2016
Preview Prompt recognition of hypothermia is essential to proper management, but accurate diagnosis may be difficult. Signs and symptoms are often subtle, and standard thermometers are inadequate for measuring low body temperatures. What causes hypothermia? Who is most wlnerable? The authors of this article answer these questions and discuss diagnosis, treatment, and prognosis.
The effects of cold have been recognized throughout the ages. Accidental hypothermia was common during military crusades. Alexander the Great, during his campaign into India, is said to have become unconscious from cold. 1 Scientific understanding of the effects of cold began to improve at the end of the 18th century.2 Hypothermia is commonly defined as a core body temperature below 35°C (95°F). 3 However, a more detailed scheme divides hypothermia into three levels: mild, moderate, and severe3.4 (table 1). The incidence of hypothermia is probably underestimated, because standard clinical thermometers do not measure low temperatures and there are no uniform reporting systems. 3 One of the most common errors in the management of hypothermia is failure to recognize it is present.
In the majority of cases, presentation is subtle, and the diagnosis is ofi:en made incidentally afi:er routine temperature measurement. 5 Hypothermia is seen in a variety of clinical circumstances (table 2). Primary (accidental) hypothermia is caused by sufficiently prolonged exposure to a low environmental temperature that normal heat conservation mechanisms cannot overcome. Secondary hypothermia occurs when heat conservation mechanisms are abnormal as a consequence of underlying disease. In secondary hypothermia, there may be interference with the hypothalamic temperatureregulating center or with the patient's capacity to shiver, redistribute blood, or move out of a cold environment. Induced or controlled hypothermia is occasionally employed as a therapeutic intervention in certain cardiovascular and neurosurgical
procedures.2 In all three types of hypothermia, the associated morbidity and mortality are related to the degree and especially the duration of the hypothermic state, as well as to the therapeutic approach taken.
Predisposing factors Hypothermia occurs when the thermoregulatory response is impaired, overwhelmed, or both. Extreme cold is by no means a prerequisite to the development of accidental hypothermia. Severe hypothermia may develop in persons exposed to a modestly cold environment (10° to l5°C [50° to 59°F]) for prolonged periods. 1 The incidence of hypothermia in the Sun belt of the United States underscores the fact that prolonged exposure even to cool weather may be hazardous. Hypothermia has been reported in tropical climates where ambient temperatures do not fall below l6°C (60.8°F). 6•7 Factors that predispose persons to hypothermia include age, drug intoxication, and preexisting illness. AGE-Infants and the elderly are most susceptible to hypothermia. The large ratio of surface area to mass in infants predisposes them to rapid heat loss, as does continued
VOL 92/NO 8/DECEMBER 1992/POSTGRADUATE MEDICINE • HYPOTHERMIA
47
The incidence of hypothennia in the Sunbelt of the United States underscores the fact that prolonged exposure even to cool weather may be hazardous.
Downloaded by [La Trobe University] at 09:58 16 June 2016
Table 1. Degrees and clinical manifestations of hypothermia Mild: 33°-35°C (91.4°-95°F) Amnesia Ataxia Dysarthria Normal blood pressure, pulse deficits
Moderate: 27°-32°C (80.6°-89.6°F) Progressive decrease in level of consciousness Dilated pupils Atrial fibrillation Bradycardia Susceptibility to ventricular fibrillation
Severe:
ISSN: 0032-5481 (Print) 1941-9260 (Online) Journal homepage: http://www.tandfonline.com/loi/ipgm20
Hypothermia Joseph Varon MD, Nicholas Sadovnikoff MD & George L. Sternbach MD To cite this article: Joseph Varon MD, Nicholas Sadovnikoff MD & George L. Sternbach MD (1992) Hypothermia, Postgraduate Medicine, 92:8, 47-59, DOI: 10.1080/00325481.1992.11701549 To link to this article: http://dx.doi.org/10.1080/00325481.1992.11701549
Published online: 17 May 2016.
Submit your article to this journal
View related articles
Citing articles: 1 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ipgm20 Download by: [La Trobe University]
Date: 16 June 2016, At: 09:58
-@CME credit article
Hypothermia Saving patients from the big chill
Joseph Varon, MD
Nicholas Sadovnikoff, MD
George L. Sternbach, MD
Downloaded by [La Trobe University] at 09:58 16 June 2016
Preview Prompt recognition of hypothermia is essential to proper management, but accurate diagnosis may be difficult. Signs and symptoms are often subtle, and standard thermometers are inadequate for measuring low body temperatures. What causes hypothermia? Who is most wlnerable? The authors of this article answer these questions and discuss diagnosis, treatment, and prognosis.
The effects of cold have been recognized throughout the ages. Accidental hypothermia was common during military crusades. Alexander the Great, during his campaign into India, is said to have become unconscious from cold. 1 Scientific understanding of the effects of cold began to improve at the end of the 18th century.2 Hypothermia is commonly defined as a core body temperature below 35°C (95°F). 3 However, a more detailed scheme divides hypothermia into three levels: mild, moderate, and severe3.4 (table 1). The incidence of hypothermia is probably underestimated, because standard clinical thermometers do not measure low temperatures and there are no uniform reporting systems. 3 One of the most common errors in the management of hypothermia is failure to recognize it is present.
In the majority of cases, presentation is subtle, and the diagnosis is ofi:en made incidentally afi:er routine temperature measurement. 5 Hypothermia is seen in a variety of clinical circumstances (table 2). Primary (accidental) hypothermia is caused by sufficiently prolonged exposure to a low environmental temperature that normal heat conservation mechanisms cannot overcome. Secondary hypothermia occurs when heat conservation mechanisms are abnormal as a consequence of underlying disease. In secondary hypothermia, there may be interference with the hypothalamic temperatureregulating center or with the patient's capacity to shiver, redistribute blood, or move out of a cold environment. Induced or controlled hypothermia is occasionally employed as a therapeutic intervention in certain cardiovascular and neurosurgical
procedures.2 In all three types of hypothermia, the associated morbidity and mortality are related to the degree and especially the duration of the hypothermic state, as well as to the therapeutic approach taken.
Predisposing factors Hypothermia occurs when the thermoregulatory response is impaired, overwhelmed, or both. Extreme cold is by no means a prerequisite to the development of accidental hypothermia. Severe hypothermia may develop in persons exposed to a modestly cold environment (10° to l5°C [50° to 59°F]) for prolonged periods. 1 The incidence of hypothermia in the Sun belt of the United States underscores the fact that prolonged exposure even to cool weather may be hazardous. Hypothermia has been reported in tropical climates where ambient temperatures do not fall below l6°C (60.8°F). 6•7 Factors that predispose persons to hypothermia include age, drug intoxication, and preexisting illness. AGE-Infants and the elderly are most susceptible to hypothermia. The large ratio of surface area to mass in infants predisposes them to rapid heat loss, as does continued
VOL 92/NO 8/DECEMBER 1992/POSTGRADUATE MEDICINE • HYPOTHERMIA
47
The incidence of hypothennia in the Sunbelt of the United States underscores the fact that prolonged exposure even to cool weather may be hazardous.
Downloaded by [La Trobe University] at 09:58 16 June 2016
Table 1. Degrees and clinical manifestations of hypothermia Mild: 33°-35°C (91.4°-95°F) Amnesia Ataxia Dysarthria Normal blood pressure, pulse deficits
Moderate: 27°-32°C (80.6°-89.6°F) Progressive decrease in level of consciousness Dilated pupils Atrial fibrillation Bradycardia Susceptibility to ventricular fibrillation
Severe:
