Medical problems associated with altitude include several uncomfortable symptoms and can ultimately become life threatening. All are due to decreased oxygen concentration in the blood caused by the lower atmospheric pressure at altitude.
The effects of altitude tend to make themselves felt at around 2800-3200m (8-9000′) whilst rapid ascent above 4300m (14000′) without prior acclimatisation is dangerous.
There is wide variation in an individual’s ability to acclimatise – in absolute terms (i.e. whether they ever do or not) and in time it takes them to achieve a given level of tolerance and in performance on different expeditions. Previous lack of difficulties should not lead to over confidence in this area.
Other generalised observations are:
Individuals over 25 have fewer problems – probably due to maturity of bone marrow. Children are particularly susceptible.
Yearly exposure over a number of years (i.e. experience) decreases the likelihood of altitude problems – probably due to better precautions rather than any physiological effect.
Physical fitness has no positive effect on acclimatisation. Marathon runners in fact often have more problems by virtue of their (usual) ability to retain water under specific physiological stress.
In other words, no matter how fit you are, if you have had little or no experience of trekking at altitude, you may be just as susceptible as someone of lesser fitness.
Slow ascent is the only way to acclimatise. The old adage ‘climb high, sleep low’ is a good idea although lower on the mountain, a gradual daily increment is generally acceptable. The ‘acclimatisation profile’ plot of altitude .v. expedition day does not exceed accepted limits for this trip.
Symptoms of altitude sickness.
Some symptoms are described below to allow personal monitoring of your acclimatisation.
Fatigue – Undue tiredness in relation to work put in. Our altitude itineraries are planned with this in mind.
Headaches – Drink copious quantities of fluid – 6 litres per 24 hours if you can manage it; one should pass a clear stream of urine 3 or 4 times a day. Take a mild pain killer if a bad headache does develop.
Nausea – Replace fluids if you are sick. Use isotonic fluids such as ‘Dioralyte’.
Anorexia – Loss of appetite. (A sign of acclimatisation is when it returns in a big way!)
Breathlessness – Quick breathing, blue lips.
Photosensitivity – Sneezing in bright sunlight.
Cheyne-Stokes Breathing – Irregular, cyclic breathing pattern, especially at night. Listen to partners who may suddenly inhale deeply and sharply.
Oedema – Swollen wrists (watch too tight?) puffy eyes etc.
In fact the best description of initial mountain sickness is probably best provided by a bad whisky hangover after a good tramp across the winter hills!
Altitude also affects the higher brain centres and can lead to depression and irritability especially at the end of a long day. Vivid dreams and anxiety are also fairly common.
Very few of these symptoms should be experienced by the majority of expedition members.
Diamox (Acetazolamide) is a drug that has gained a certain vogue for mitigating the effects of altitude even though it is contra-indicated for certain kidney, eye and liver conditions. Your doctor’s advice should be taken prior to its use. It functions by affecting the acid-base balance in the body at a time when normal balances are already stressed by altitude.
Once symptoms of acute mountain sickness do develop the only treatment is immediate descent – to less than 3000m (10000′) if need be – although even a descent of a few hundred metres can make a marked difference. It is sometimes forgotten that Acute Mountain Sickness (AMS) is a life threatening condition and descent is the only reliable cure.