Kilimanjaro Altitude Sickness

As you climb high, the percentage remains the same but the number of oxygen molecules per breath are reduced. At 12,000 feet (3,600 m) there are roughly 40% fewer oxygen molecules per breath so the body must adjust to having less oxygen.

Altitude sickness, known as AMS, is caused by the failure of the body to adapt quickly enough to the reduced oxygen at increased altitudes.

Altitude sickness can occur in some people as low as 8,000 feet, but serious symptoms do not usually occur until over 12,000 feet.

Mountain medicine recognizes three altitude categories:

  • High altitude: 4,900 to 11,500 ft (1,500 to 3,500 m)
  • Very high altitude: 11,500 to 18,000 ft (3,500 to 5,500 m)
  • Extreme altitude: 18,000 ft and above (5,500 m and above)

There are four factors related to AMS:

  • High Altitude
  • Fast Rate of Ascent
  • High Degree of Extertion
  • Dehydration

The main cause of altitude sickness is going too high (altitude) too quickly (rate of ascent).

Given enough time, your body will adapt to the decrease in oxygen at a specific altitude. This process is known as acclimatization and generally takes one to three days at any given altitude. Several changes take place in the body which enable it to cope with decreased oxygen:

  • The depth of respiration increases
  • The body produces more red blood cells to carry oxygen
  • Pressure in pulmonary capillaries is increased, “forcing” blood into parts of the lung which are not normally used when breathing at sea level
  • The body produces more of a particular enzyme that causes the release of oxygen from hemoglobin to the body tissues

Again, AMS is very common at high altitude. It is difficult to determine who may be affected by altitude sickness since there are no specific factors such as age, sex, or physical condition that correlate with susceptibility. Many people will experience mild AMS during the acclimatization process.

The symptoms of Mild AMS include:

  • Headache
  • Nausea & Dizziness
  • Loss of appetite
  • Fatigue
  • Shortness of breath
  • Disturbed sleep
  • General feeling of malaise

While hiking, it is essential that you communicate any symptoms of illness immediately to Karibu Adventures Guides.

The signs and symptoms of Moderate AMS include:

  • Severe headache that is not relieved by medication
  • Nausea and vomiting, increasing weakness and fatigue
  • Shortness of breath
  • Decreased coordination (ataxia)

Continuing on to higher altitude while experiencing moderate AMS can lead to death.

Severe AMS results in an increase in the severity of the aforementioned symptoms including:

  • Shortness of breath at rest
  • Inability to walk
  • Decreasing mental status
  • Fluid build-up in the lungs

Severe AMS requires immediate descent of around 2,000 feet (600 m) to a lower altitude. There are two serious conditions associated with severe altitude sickness; High Altitude Cerebral Edema (HACE) and High Altitude Pulmonary Edema (HAPE).

Both of these happen less frequently, especially to those who are properly acclimatized. But, when they do occur, it is usually in people going too high too fast or going very high and staying there. In both cases the lack of oxygen results in leakage of fluid through the capillary walls into either the lungs or the brain.


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