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Hypothermia Diagnosis

By Liji Thomas, MD

Hypothermia is defined as a dangerously low body temperature, below 950  F. A person with hypothermia manifests several or all of the following symptoms:

  • Sleepiness
  • Inability to think or talk clearly
  • Clumsiness
  • Pale cold skin
  • Weakness and exhaustion
  • Uncontrollable shivering
  • Slow breathing or heart rate
  • Lethargy

In infants, hypothermia may be suspected when the skin is very red and cold, and there is loss of normal activity.

Extreme cold affects brain processes, leading to confusion and poor judgment. Thus a hypothermic person fails to realize the danger of exposure, and cannot resist irrational decisions, such as going to sleep without getting into shelter and becoming warm. Shivering ceases at very low temperatures. At this stage, without prompt effective treatment, cardiac arrest occurs, resulting in death.

Protective responses occur in the early stages of hypothermia, and include:

  • Behavioral responses – walking around, waving the arms, getting under shelter.
  • Physical responses – these include shivering, the appearance of goosebumps on the skin and the closure of skin blood vessels, to shunt blood to the core. This helps to keep vital functions running.  Stress hormones are also released to burn more heat and warm the body.

Risk factors

There are several risk factors for hypothermia, such as:

  • Being very old or very young –
    • The young are less likely to protect themselves and to be able to keep themselves warm, but lose more heat because of increased metabolism.
    • The old have reduced subcutaneous fat and therefore less natural insulation against the cold. They also have slower metabolism, sense colder temperatures less well because their skin has less nerve endings and often suffer social isolation, which makes it easier for them to drift into hypothermia without anyone noticing
  • Circulatory problems, as with heart disease
  • Sickness
  • Poor nutrition
  • Fatigue
  • Drunkenness – alcohol dilates the skin vessels, increasing heat loss through the skin
  • Any condition which reduces the metabolic rate
  • Reduced consciousness
  • Reduced judgment, leading to exposure, and failure to seek proper shelter
  • Drug abuse
  • Certain medications
  • Dementia , leading to exposure
  • Being wet or sweaty for a long time
  • Immersion in water below body temperature for more than a few minutes
  • Other medical conditions which cause immobilization

Precipitating factors

When these risk factors exist, hypothermia may be precipitated by any of the following factors:

  • Getting soaked
  • Exposure to cold or wind while in wet clothing
  • Exposure to cold without sufficient clothing
  • Overexertion
  • Failure to eat or drink enough in cold weather

Severe hypothermia finally ends in death due to cardiac arrest.

Prevention of hypothermia

The following are some simple precautions against hypothermia:

  • Dress warmly, in multiple layers, including cap, mufflers, mittens and socks, if you are planning to be outside in cold weather.
  • Even if you are driving, dress warmly in case you need to leave the car.
  • Have a weatherproof outer layer to keep yourself dry, and wear insulated boots.
  • Keep extra dry warm clothes on hand in case you get wet.
  • Also have waterproof matches on hand.

Diagnosis of hypothermia

Hypothermia occurs in three phases:

Mild hypothermia

Defined as a core body temperature of 32-35 0 C, the person has pale and cool skin, with numb extremities.  The person is sluggish and drowsy, and shivers uncontrollably. The heart rate and breathing are higher than normal.

Moderate hypothermia

The core temperature drops to 28-32 0 C, and the victim lapses into unconsciousness. The shivering stops. There may be involuntary urination due to the excessive production of urine. This is because the shut-down of skin circulation frees more blood to flow through the kidneys instead. The heart rate, breathing and blood pressure drop further.

Severe hypothermia

The core temperature is very low, below 28 0 C. In severe hypothermia, the person is unconscious and cannot be roused. The heartbeat is very slow, sometimes irregular, and stops beating finally. The pupils become unreactive, while the muscles are stiff and rigid. The breathing and pulse are imperceptible.

References

Further Reading

Last Updated: Oct 12, 2015

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