Hypothermia

Hypothermia is defined as a core temperature of less than 35°C. Hypothermia may be caused prolonged exposure to cold. A high wind chill in cold weather can increase the risk of developing hypothermia. This is exacerbated when surrounded by cold wet clothing or water. 

As the core temperature falls, numerous compensation mechanisms will try to counteract this. The patient will be peripherally shut down (vasoconstricted) in an attempt to maintain their core temperature. This relative increase in the core circulating volume may generate a need to pass urine. The patient may also be shivering, an action to generate heat from muscle movement. It is important to note that the shivering response is absent at lower temperatures and so its absence does not rule out hypothermia. 

As the patient’s temperature falls, there are increasing impacts on other body systems, with deterioration until cardiac arrest.

Step to manage of Hypothermia:

1. The first step is to remove the patient from the cold environment, remove any wet clothes and gently dry the skin. Wet clothes should be cut off rather than stripped to minimise patient movement. This should be done in conjunction with a ABCDE assessment and the patient rewarmed.
2. For mild hypothermia, it may be adequate to remove wet clothes, dry the patient and simply wrap the patient up/dress them in warm clothes. It is particularly important to ensure that their head is covered as this is an important area for heat loss.
3. For more marked hypothermia, it may be appropriate to actively warm the patient using a warm water bath. Clearly this is only an option if the patient has a normal level of consciousness and no other ABCDE issues requiring treatment.
4. During the rewarming process it is important to monitor the heart rate, and conscious level, as marked blood vessel dilation (vasodilatation) may occur.
5. It is important that any patient with hypothermia is observed closely in case a rapid deterioration in their condition occurs.
6. It is also important that the patient is handled gently, since inappropriate stimulation may cause the patient to deteriorate into cardiac arrest.
7. Any patient with all but the mildest hypothermia, should be transferred as soon as possible to an appropriate emergency department.