Hypothermia is an extremely life-threatening condition in which the core (internal) body temperature drops below 35°C (95°F) or much further as a result of a prolonged exposure to cold. Hypothermia happens when an individual loses his/her intrinsic ability to stabilize the core body temperature and/or when the body’s regulatory mechanism for maintaining temperature shuts down.
Urban hypothermia, an extreme exposure to cold temperatures in an urban setting, is often associated with a high mortality rate especially with elderly adults, infants/very young children, individuals with morbid conditions and homeless people are among the most susceptible. Moreover, alcohol intoxication can further aggravate cases of hypothermia since it causes systemic vasodilatation. Trauma victims are also at high risk for hypothermia resulting from treatment with cold fluids and infusions, un-warmed oxygen and exposure to a cold air- conditioned examination area during physical assessment. Usually, victims with frostbite also accompany hypothermia, however the hypothermia takes precedence in the treatment.
Assessment and Initial Findings
Hypothermia leads to several physiologic and damaging changes in all vital organ systems. There can be a noticeable and progressive deterioration of the victims physical and mental status such as impaired judgment, drowsiness, and eventual loss of consciousness. Shivering will no longer be seen if the core body temperature falls below 32.2°C (90°F), mainly because the body’s self warming mechanisms will already be rendered ineffective. Heart contractility will progressively become weaker and peripheral pulse will barely be detected followed by irregularities in cardiac rhythm and eventual arrest.
Emergency Management
Re-warming methods for hypothermia include active core (internal) re-warming and passive external or spontaneous re-warming.
Active core re-warming methods include warm fluid administration via intravenous fluids, giving warm humidified oxygen via a ventilator and the more invasive warmed peritoneal lavage. Core re-warming is normally recommended for individuals with severe hypothermia.
Passive external re-warming is usually done initially by field emergency respondents and paramedics who arrive first on the scene by covering the individual with thick warm blankets. Once transported to the emergency department, other forms of passive external re-warming methods can be done by the ED personnel such as having the victim stay on a stretcher with over-the-bed heaters while still being wrapped in warm blankets.
Active core re-warming of the extremities should be carefully monitored and must be done gradually as it can lead to a systemic metabolic response when a sudden shift of warm blood rushes quickly to the colder organs in the core can potentially cause cardiac dysfunction and electrolyte imbalance.
Supportive Management of Hypothermia
Supporting care during re-warming includes the following as directed:
- External cardiac compression (typically performed only as directed in individuals with temperatures higher than 31°C).
- Defibrillation of ventricular fibrillation for individuals whose core temperature is lower than 32°C (Individuals with core body temperature lower than 31°C will not respond effectively with defibrillation therefore re-warming procedures must be done first).
- Administration of warm intravenous fluids to correct hypotension and maintain urine output as well as core re-warming as described previously.
Initiation and constant monitoring of mechanical ventilation and heated humidified oxygen to maintain sufficient tissue oxygenation.
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