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Mountain climbing & High Altitude – health notes for trekkers & climbers
Many of our trekkers, & most mountain climbers will need to understand something about the health problems of altitude. The following section discusses aspects of altitude medicine that travellers should be aware of.
As we ascend the air contains less oxygen, & is at less pressure. Humans are designed to live at normal oxygen levels & pressure, & so a range of changes start to occur as altitude above 2000m occurs. Most people can cope with 2500m, but by 3500m, many people have some symptoms, & by 4500m most people do.
From 2500m our bodies begin to adjust to the new conditions, but the speed of ascent can mean that the acclimatisation process cannot keep up. Common symptoms of our bodies trying to acclimatise are:
• Shortness of breath on exertion
• Fast heart beat
• Poor sleep
• Headache
Normal acclimatisation takes 4-7 days for any stable altitude, but continuing to go higher means symptoms may persist. So the range of symptoms that are commonly experienced will occur in more & more percentage of people as altitude rises & also with the speed of ascent. This is called acute mountain sickness, AMS
What is altitude illness?
AMS occurs when people travel above 2500m & the body has not enough time to adjust. AMS can be mild to severe, & can be viewed as a normal pattern of response to a physical change in out environment (not enough oxygen & air pressure). Depending on altitude, it occurs between 20%-80% travel groups.
It is generally benign, will resolve through time by acclimatisation, & can be cured by descent. People with AMS have normal mental function.
People with AMS should not go higher till they have adjusted satisfactorily.
If people continue to climb, they may risk the dangerous forms of altitude illness,
• High Altitude Pulmonary Oedema, (HAPE), &
• High Altitude Cerebral Oedema, (HACE)
HAPE occurs in 1.6% travellers to altitude, & HACE occurs about half that rate. The actual incidence of both occurs more the higher the altitude.
HAPE is a serious condition of fluid accumulating in the lungs. In about half the cases, AMS symptoms will have been evident. It is characterised by shortness of breath, cough & later by drowsiness. It is an emergency, & the person should descend. Nifedipine & oxygen are usually required. HAPE is the commonest cause of death at high altitude.
HACE is caused by fluid leakage in the brain, & is characterised by decreasing mental state, starting with some confusion, right through to coma. It is a medical emergency treated with descent, oxygen, dexamethasone all required. It can occur quickly, & AMS symptoms may be missed. It can occur with HAPE.
Pressure bags may be required to simulate descent while arrangements for evacuation to lower point are being made.
Prevention of Altitude Illness
• Graded ascent helps with first night sleeping at <3000m, & daily increments of no more than 500m/night.
• No further ascent till symptoms subside
• If rapid ascent, plan rest days to commence trip
• Acetazolamide (Diamox) can be obtained from The Travel Doctor-TMVC
• Dexamethasone for specific cases
Other Medical Issues at Altitude
Dehydration, sunburn, hypothermia, & exhaustion all occur at altitude amongst trekkers & climbers especially.
Medications such as sedatives, strong pain killers, sleeping tablets an antihistamines can all cause more respiratory depression which could exacerbate altitude illness. They all should be avoided.
Aspirin & some anti-inflammatory medications that can lead to bleeding should be avoided, as retinal bleeding occurs at altitude.
Oral contraceptive pills or other hormones that increase clotting should be avoided for long stays at altitudes above 5000m
The Travel Doctor-TMVC Services.
We have many years of experience working with adventure holiday companies, & are able to tailor requirements for groups or individuals. Appropriate kits & preventive medications are available at Travel Doctor-TMVC clinics.
Click on the links below for more information specific to adventure travellers: Trekking Surfing Altitude Kokoda Trail SCUBA Diving |
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Learn about the medical requirements for your destination by checking out the Destination fact sheets
Other useful information can be found in the Travel health fact sheets
Work out your vaccine requirements by looking at the My Travel Health Planner
