Dehydration occurs when then amount of liquid a person loses is more than the amount they gain. It is a common fact that our bodies are around two thirds water, and we use this is all sorts of cell-level chemical processes necessary for our survival. When performing such demanding tasks as hiking or climbing through mountains, it is easy to get hot and sweat a lot. At altitude things are much worse because of the decreased pressure, which makes you breathe deeper and faster. More gas exchange means that more water vapour is lost, as it is a waste product of breathing. On top of this making the body work harder inevitably makes a person hot. The body’s natural response to this is to activate the mechanisms to regain normal temperature. Losing heat in this case involves sweating, which again loses vital water stores.
There are three stages in dehydration:
- Mild (where you can lose 3% to 5% of your body weight)
- Moderate (6% to 9%)
- Severe (10% or more)
At the moderate stage dehydration can cause abnormalities in the sodium and potassium levels in the body, changes which can lead to problems in the heart’s rhythm. To counter the effects on the body it is important to drink plenty to replace the lost fluids. These effects include, in order:
- Dry mouth, lips and nose
- Fatigue and lethargy
- Deep, rapid breathing
- Rapid, weak pulse of 100bpm at rest
- Dizziness and feeling light-headed
- Temperature drop, especially the extremities
- Sunken, dry eyes
- Blue lips
- Low blood pressure
- Muscles cramping
- Painful kidneys
Dehydration is a serious condition and can need hospitalisation. If you judge the condition to have reached a serious stage, where re-hydrating techniques do not seem to be working, then begin descent immediately, and seek medical advice.
Another reason it is important to stay hydrated is that the symptoms are similar to Acute Mountain Sickness (AMS.) Failure to diagnose AMS can lead to High Altitude Pulmonary Edema (HAPE) and or High Altitude Cerebral Edema (HACE), both potentially life-threatening illnesses. Confusion with dehydration can be avoided by staying hydrated, allowing for easy recognition of AMS.
To prevent dehydration the obvious answer is to drink as much as possible. Although this does not include alcohol, energy drinks, tea, coffee or other caffeine-containing fluids (diuretics, which will cause you to lose water) it does include:
- Oral Re-hydrating Solutions (ORS) which contain carbohydrates or electrolytes (body salts)
- Fruit and fruit juice
- Herbal teas
- Flavoured water
If you aren’t drinking enough and think you might be dehydrated then there are two simple tests:
- Examine your urine. Clear or straw-coloured urine denotes sufficient liquid intake. A dark orange or yellow tint means waste is concentrated and so you should drink more, even if you don’t feel thirsty.
- Lightly pinch a soft area of skin such as the back of you hand and it doesn’t return to its normal position quickly then it is likely that you are dehydrated.