Altitude Sickness is also known as acute mountain sickness (AMS).. It is a pathological effect of high altitude on humans, caused by acute exposure to a low partial pressure of oxygen at high altitude. It commonly occurs above 2,400m. AMS presents as a collection of non-specific symptoms, acquired at high altitude or in low air pressure, resembling a case of ‘flu, carbon monoxide poisoning or a hangover. It is hard to determine who will be affected by altitude sickness, as there are no specific factors that compare with this susceptibility to altitude sickness. However, most people can climb up to 2500m normally.
What causes it?
The body’s muscles and organs need an adequate supply of oxygen to function properly. As altitude increases, the percentage of oxygen in the air remains constant but the pressure decreases, meaning we breathe in fewer oxygen molecules with each breath. This leaves the body short of its requirements and causes altitude sickness.
Who’s affected?
It is well known that mountaineers may be affected by altitude sickness, but anyone at high altitudes can experience symptoms. This includes people who fly to high-altitude destinations and those who go on walking and trekking trips.
What are the symptoms?
How severely someone is affected by altitude sickness depends on how high they go and how quickly they ascend. It is unusual for altitude sickness to occur below 2,400m.
When altitude sickness occurs because the body is not getting enough oxygen, mild symptoms may include:
- Tiredness
- Headache
- Nausea
- Unsteadiness
For most people, symptoms start after about six hours of being at high altitude. As long as the person remains at the same altitude, the symptoms will usually disappear within one or two days.
Vomiting, chest pains and shortness of breath are signs that someone is affected more severely. These symptoms may take a day or two to appear.
Coughing up frothy sputum is a sign that fluid is collecting in the lungs, while clumsiness and difficulty walking can occur if the brain swells.
If severe cases of altitude sickness are not treated, fits, confusion and coma may follow.
What is the treatment?
It is important not to ignore altitude sickness. If symptoms are mild, rest, fluids, a light diet and painkillers will enable the body to acclimatize. One should not attempt to further ascent until all the symptoms have disappeared.
Descending to a lower altitude is often necessary when symptoms are more severe. Hospital treatment is necessary if this fails to resolve the symptoms. Any swelling of the brain is treated with oxygen, rest and drugs.
After correct treatment for altitude sickness, most people make a full recovery, and usually within a few days. However, when the condition is more severe, treatment over a longer period may be necessary.
Can it be prevented?
One can avoid altitude sickness altogether with care and proper preparations prior to treks and climbs. Climbers, in particular, are all too aware of the importance of:
Good physical fitness
Staged ascents that allow time to acclimatize
- Drinking plenty of liquid
- Being aware of the possibility and the symptoms of altitude sickness
- Not ignoring symptoms of altitude sickness if they occur
The following equipment lists are suggested and essential for both types (camping & teahouse) treks in the Himalayas country in Nepal. Make use of this list as a guideline proposal. Many adventure shops in Katmandu sell or hire Trekking equipment.