Extreme Weather: Hyperthermia

In a previous article we covered the subject of hypothermia; now we can look at how heat can cause problems for our long suffering bodies. In many ways hyperthermia can be much more of a danger than hypothermia due to the situation and the nature of the treatment.

What is Hyperthermia?

Moving through exposed country such as this in temperatures of 40 deg. C is not for the faint of heart.

Moving through exposed country such as this in temperatures of 40 deg. C is not for the faint of heart.

Hyperthermia is the condition of having an unusually high body (core) temperature. Doesn’t sound too bad, does it? But after saying that, hypothermia didn’t! We can split this into two main stages; the first is Heat Exhaustion and the second is Heat Stroke; although these can occur by just being in high temperatures they are more commonly associated with exertion. As we know from a previous article, our normal body temperature is 37 deg. C (98.6 deg. F); this is not set in stone as everyone is different but ideally it should be between 36-38 deg. C (96.8-100.4 deg. F). Problems start to appear when outside of these figures. Before we start to look at what can be done, let’s first take a look at each one in turn to see what we are dealing with.

Heat Exhaustion

At this stage we are not necessarily looking at a serious rise in core temperature; it is a warning of what is just around the corner. In a group the guide/navigator will be on the lookout for this but if you are a lone traveller you have to be even more vigilant as this is normally the end point for self-help. Heat exhaustion is nothing more than dehydration leading to what is commonly termed ‘Volume Shock’; the correct term being Hypovolemic Shock. As the blood is made up of around 90% water, any dehydration will reduce its efficiency to do its job; as the level of dehydration increases (and the blood volume reduces) the cardio system finds it more and more difficult to pump, bringing on the condition of hypovolemic shock. The normal signs and symptoms of heat exhaustion are below.

  • A reduction in responsiveness.
  • Less coherent.
  • Skin is likely to be sweaty, clammy and pale.
  • High pulse rate.
  • High respiration rate.
  • Greatly reduced urine output.
  • Very dark urine.
  • Weakness, often throughout the whole body.
  • Nausea and vomiting.
  • Cramps due to the loss of body salts.
  • Reduced blood pressure. li>
  • Pinched skin is slow to return.
  • Swollen throat and tongue.

Heat Stroke

This is where the term hyperthermia really starts; sunstroke is the same but brought about by being in direct sunlight. If this stage is reached the casualty is likely to die unless the correct action is taken; this is extremely serious and if you are a lone traveller your chances of survival are close to none. It is often difficult to make people understand how serious this condition is; there is a complete breakdown in the body’s ability to control its own temperature. Coma and death will follow if you fail to react promptly. Many of the normal signs and symptoms of heat stroke are the same as heat exhaustion but are much more acute; additional signs and changes are below.

  • A thermometer reading of 40 deg. C (104 deg. F) or above.
  • Greatly reduced sweating.
  • Racing pulse and respiration.
  • Skin may now be hot and dry.

What Can Be Done?

The first thing is to realize that for this person the trip is over and their evacuation should be initiated. Your job now is to look after the casualty and manage the situation until help arrives; not forgetting the remainder of the group. The treatment for a heat exhaustion casualty is normally as follows.

  • Initiate evacuation.
  • Stop exercise immediately and find shade, if a short distance is to be covered share their load out amongst you.
  • Place the patient on their back and raise their feet, perhaps on a rucksack.
  • Loosen clothing and make comfortable.
  • Administer small sips of water frequently (if conscious).
  • After 15 minutes make up a drink consisting of 1 litre of water, ¾ level teaspoon of salt and 8 level teaspoons of sugar. This should ease any cramps and will help to bring salt/ sugar levels back up.
  • Regularly monitor the patient’s vital signs.
  • Continue normal hydration until urine output has returned; this will take a number of hours.
  • Evacuate patient in all cases.
  • Immersion for short, controlled periods may be needed after the initial treatment.

As we have said, heatstroke is extremely serious and requires drastic action; there is always a danger that the treatment may kill the patient at this stage. Treatment for a heat stroke casualty is normally as follows.

  • Initiate evacuation.
  • Strip the casualty down to their undergarments spray them with water (if possible) or wipe them all over with a soaking cloth. Total immersion in cold water at this stage may kill the patient or increase the core temperature further due to the body’s natural reaction to a thermal shock to the skin’s surface.
  • Fan the patient so that the moisture evaporates, taking with it body heat; remember, the patient cannot do this now by sweating.
  • Keep spraying/wetting/fanning continually.
  • If the situation is not improving you have little alternative but to immerse in cold water and risk the thermal shock, to delay further would probably result in brain damage or death anyway. Massage all parts to aid circulation and monitor vital signs continually; be ready to administer Cardio Pulmonary Resuscitation (CPR) if required. As soon as the patient’s temperature drops remove from the water but monitor this constantly and be prepared to re-immerse if required.
  • When appropriate, administer the rehydration drink as for heat exhaustion.

Top Tip

The patient may be unconscious and in the fight to save their life you may have overlooked the fact that the patient’s head may be underwater and being banged on rocks. Things are bad enough at the moment without having to treat them for drowning, concussion and a fractured skull as well! Get one of the others to hold and support their head while you do the rest.

The Navigator/Guide

Over the last few articles I have stressed the importance and value of a navigator/guide in a group. A good navigator/guide would not have let it come to this and would have planned a route that would offer a certain amount of safety if these conditions were likely to be a problem. Of course every situation is different and you are often dragged into things with a higher degree of risk; this is where sensible risk management comes in.

Should You Be Frightened?

No, you should be no more frightened of hyperthermia than hypothermia, or for that matter any of the other inordinate number of things that can kill you. Knowledge and experience are the keys to safety; treat all danger with respect and manage it accordingly.

Problem, What Problem?

If you remain properly hydrated and adjust your exertion/pace sensibly, you will avoid having to deal with it. When you are travelling or backpacking, you will find that there are plenty of problems to deal with, so manufacturing your own really isn’t necessary.

Is That It?

Well, no, not really. The body’s mechanism for maintaining its ideal temperature is complex to say the least. As we push the limits we need a greater understanding of this mechanism if we are to help our body to cope with the extremes we often venture into. As with hypothermia, don’t be frightened, be aware. Sorry, this has been a long one. Take care and keep your cool!


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