Altitude Sickness or Acute Mountain Sickness

Altitude sickness or Acute mountain sickness (AMS) comprises of a group of medical conditions that commonly affect the people travelling from sea level to a high altitude area (more than 3500 meters). In most of the cases, it is a self-limiting condition, and recovery usually occurs within 48 hours without any serious progression.

The symptoms include exertional breathlessness, headache, fatigue, sleep pattern disturbances, nausea and palpitations within 24-36 hours of arrival at the high altitude. However, these unpleasant effects of lack of oxygen usually wade off after 2-3 days.

Most of the travellers experience some degree of sickness at 3500 meters above sea level, and almost all the travellers experience the sickness if they ascend rapidly to 5000 meters. Once acclimatized in this way, further height gain is possible, but then the symptoms may recur.

There is no way of predicting who will develop acute mountain sickness, since there is no correlation with fitness levels and smoking habit. Strenuous exercise at the altitude worsens the condition, both in fit as well as non-fit subjects.

Complications

In most of the cases, resolution happens spontaneously, usually without any serious progression. However, some or the other complications may occur, which might be serious.

Pulmonary oedema occurs in almost about 2% of cases. The symptoms of which include breathlessness and expectoration of frothy sputum.

Cerebral oedema may occur as a result of fluid collection in the brain, which causes drowsiness, confusion and double vision. Returning to low altitudes and corticosteroids treat it.

Signs of peripheral or facial oedema and small retinal hemorrhages may also occur which usually resolve completely without any treatment.

Treatment

Adequate hydration and oxygen should be given and the subject should be descended to lower altitude. Azetazolamide, taken as a prophylactic for few days before ascent, reduces the incidence of altitude sickness.

In majority of the cases, full recovery occurs with some or all of the above treatments. Recurrence may occur on repeat exposure to high altitude.