Altitude sickness



What is Altitude Sickness?
"Altitude Sickness" refers to the group of illnesses due to exposure to high altitude, especially those consequent to exposure to reduced oxygen pressure, (hypobaric hypoxia). The incidence & severity of illness increases with altitude & the symptoms largely reflect the various organs response to inadequate oxygen supply. The main systems affected are the lungs & the brain.


What are the main types of Altitude Sickness?
The commonest from is known as Acute Mountain Sickness, AMS, which is usually a benign illness occurring at altitudes beyond 2000 - 2500 meters. This is characterized by headache, insomnia, tiredness & mild shortness of breath & is generally self limiting, acclimatisation occurring in 2-5 days with resolution of symptoms. AMS occurs in about 40% of individuals ascending rapidly to 3000m & 75% of those rapidly ascending to 4500m.


Severe forms of altitude sickness occur at higher altitudes. High Altitude Cerebral Oedema, HACE, occurs in 1-2% of short term travellers to 3-5000m & is characterized by progressive cerebral dysfunction, ataxia, confusion & unusual behavior & can lead to coma & death. High Altitude Pulmary Oedema, HAPE, occurs in 2% of climbers to 6000m & is the commonest cause of fatal altitude sickness. Symptoms include shortness of breath, a cough & blood stained sputum


What are the treatments of Altitude Sickness?
The treatment of all forms of altitude sickness is primarily rest, oxygen & descent. For AMS, rest, fluids & simple analgesics is usually adequate to allow acclimatisation. Sedatives should be avoided. Oxygen is occasionally required & descent considered if symptoms persist.
Dexamethasone has a role in the treatment of HACE & nifedipine is used to treat HAPE.


Who gets Altitude Sickness?
Anybody may be at risk of altitude illnesses. Males & females of all ages are equally effected & illness occurs in children as the same in adults. However, symptoms can be harder to recognize in children. General fitness is not a prevention. Having altitude illness previously, is pre-disposing to repeat illness.


Is there prevention for Altitude Sickness?
All travellers to altitude should be warned about the potential for altitude illnesses especially AMS. Rapid ascent increases the risk, so planning itineraries with gentle ascent is helpful. Allow one night for each rise at 500m above 2000m.
Drinking plenty of water, avoiding alcohol, high carbohydrate diet & moderate exercise is helpful to assist acclimatisation. Acetazolamide can be used to speed acclimatisation in some individuals.