SAR Day 7: Hypothermia

On Tuesday the team trained for treating hypothermia.

Hypothermia affects people year round. In a seminar a few years ago a BC Ambulance paramedic told us that older people who are in trouble because they have fallen inside their houses are almost always hypothermic after just a few hours. The upshot is that an immobile person is extremely vulnerable to cold.

Here on the wild west coast we get a lot of rain. Wet people in wet clothes loose the ability to keep warm. One warm August evening we were called out to find a group who had one member injured and decided to stay with that person. The team ended up finding four mildly hypothermic people. It did not help that they were very lightly dressed.

The basic mechanics are that people head out for a hike on a warm day wearing clothing appropriate for the weather — at sea level. With altitude it gets colder, approximately 1 degree C per 1000ft, but the people don’t really notice as long as they can move. If trouble happens and they are immobilized, they don’t get the benefit of warmth generated by exercising muscles. If they don’t have enough food or water they don’t get the calories to generate more heat. The evening brings cooling temperatures. Shivering often makes people panicky (and being cold affects the mental process as well). This often leads people to try moving at night, which gets them even more lost.

Although hypothermia is quite common, luckily treating it, from the point of view of a SAR member in the field, is extremely easy. In every case we apply warmth; warming is the treatment for all hypothermia. Depending on other factors (mobility, hydration, injuries) we will either re-warm on site until the patient can move on their own, or load them into a stretcher and begin a carry.

Now some may find the above statement controversial; that rewarming is always the correct treatment. The context is as follows:

There is an effect for profoundly hypothermic patients called “afterdrop” where during re-warming their core temperature will drop a few degrees. This can cause medical complications. Because of this, in the past wilderness first aid manuals and courses have wrongly stated that one should not attempt to rewarm extremely cold patients in the field, and would even go so far as to ask rescuers to take the core body temperature before treating.

While afterdrop is a real phenomenon, it is only a concern in a clinical environment for this simple reason: in the field it is not actually possible to rewarm a person to the point where afterdrop will take effect. When a SAR member reaches a hypothermic patient, we can use several techniques to apply warmth, but the immediate effect of the heat is to slow the cooling process. It has been shown that even while being treated, patient’s core temperatures will continue to drop for a period before it stops, and then only slowly will the temperature rise. In the case of profound hypothermia, this patient is so critically ill that evacuation is urgent; packaging for transportation in a hypothermia bag with charcoal burning heaters is the best one can do.

If a patient is profoundly hypothermic the amount of time, and heat needed to re-warm completely is beyond the ability for a field member to supply. So we rest assured that we can treat with the techniques we have, and work on evacuation as soon as possible. We let the physicians in critical care handle the possibility of afterdrop in the hospital.

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