Altitude Sickness Overview
At high altitudes level of oxygen lowers and atmospheric pressure decreases. The higher person ascends less oxygen he or she breathes in and starts to experience symptoms of altitude sickness. Altitude sickness occurs at more than 2000 meters (6,500 feet) above sea level when the body is not adjusted to low oxygen concentrations.
Altitude sickness includes number of potentially life-threatening conditions of which acute mountain sickness (AMS) is the most common and mildest form. More severe types of altitude sickness affect lungs and brain.
Anyone can be affected by altitude sickness but climbers, hikers and skiers most commonly develop it. However, not all individuals suffer from symptoms of altitude sickness as some adapt to “thinner” air more easily than others.
Still, the quicker and higher one ascends, more likely he or she will experience effects of this condition. Children are at highest risk of developing altitude sickness. Also, the risk is twice as high for individuals below the age of 60 years.
Causes of Altitude Sickness
Every type of altitude sickness occurs due to low oxygen levels in areas of high altitude. This makes breathing difficult and leads to hypoxia, the condition featured by reduced oxygen supply to the body tissues. Rapid ascending and exposure to cold at high altitudes are the main causes of altitude sickness.
A person can gradually get used to the effects of hypoxia to a certain point. Most people can spend several days at 3,000 meters (10,000 feet) above sea level without problems or may experience mild symptoms. On the other hand, it is impossible to survive permanently above 5,100 meters (17,000 feet).
Increased risk of altitude sickness have people who abuse alcohol or illicit drugs, overweight people and individuals suffering from chronic diseases. Also, children are at risk of developing severe forms of altitude sickness (high latitude pulmonary edema and high altitude cerebral edema) below 2,500 meters (8,000 feet).
Symptoms of Altitude Sickness
Acute mountain sickness causes symptoms at 2,000 meters (6,500 feet). The symptoms include tiredness, nausea, headaches, dizziness, disturbed sleep and shortness of breath. Swelling of the face and hands may occur as well. Acute mountain sickness is not a life-threatening type of altitude sickness and the symptoms usually resolve without treatment after a few days when a person adapts to lower air pressure.
However, AMS can sometimes indicate high altitude cerebral edema (HACE), which results from swelling in the brain. HACE causes severe headache, hallucinations, confusion, loss of memory, weakness and eventually coma and death. This condition requires immediate descending at lower altitudes.
High altitude pulmonary edema is characterized by fluid buildup in the lungs. It causes shortness of breath at rest, bluish color of the skin (cyanosis), pink or bloody sputum, weakness, confusion and coma. This condition can be fatal if an affected person is not moved to lower altitude.