Altitude acclimatization is the process of adjusting to decreasing oxygen levels at higher elevations, in order to avoid altitude sickness. Once above approximately 3,000 meters (10,000 feet = 70 kPa), most climbers and high-altitude trekkers take the "climb-high, sleep-low" approach. Mount Kilimanjaro raised 5895 meters above the sea level. Due to its high height, climbing it is probably one of the most dangerous things you will ever do. Approximately 500 climbers have been reported to be evacuated from the mountain and a maximum of 6 deaths have also reported each year. The main cause of death is altitude sickness. Tro-peaks adventure recommends to everyone climbing Mount Kilimanjaro should be familiar with the signs and symptoms of altitude sickness.

Acute mountain sickness is an illness that can affect mountain climbers, hikers or any travelers at high altitudes, usually above 10,000 feet (3,000 meters). The percentage of oxygen in the atmosphere at sea level is about 21%. As altitude increases, the percentage remains the same but the number of oxygen molecules per breath is reduced. From 10,000 feet (3,000 meters) and above there are fewer oxygen molecules per breath so the body must adjust having less oxygen. AMS is caused by reduced air pressure and lowers oxygen levels at high altitudes. The faster you climb to a high altitude, the more likely you will get AMS. According to the experience, 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. Normally climbers will start to experience the form of mild AMS from the elevation of 10,000feet (3000m) and above.

Difficulty sleeping
Dizziness or light-headedness
Loss of appetite
Nausea or vomiting
Rapid Pulse (heart rate)
Shortness of breath with exertion

Symptoms that may occur with more severe acute mountain sickness include:
Blue color to the skin (cyanosis)
Chest tightness or congestion
Coughing up blood
Decreased consciousness or withdrawal from social interaction
Gray or pale complexion
Cannot walk in a straight line, or walk at all
Shortness of breath at rest
Fluid build-up in the lungs

NOTE NO.1: Symptoms tend to be worse at night and when respiratory drive is decreased. Mild AMS does not interfere with normal activity and symptoms generally subside as the body acclimatizes. As long as symptoms are mild, and only a nuisance, ascent can continue at a moderate rate.

NOTE NO. 2: When climbing it is important to be open to the guides or other climber in your trip with any sign or symptom of illness immediately because to continue to the high altitude while effect with moderate AMS without be treated or helped can lead to DEATH.

NOTE NO. 3: Normal activity is difficult, although the person may still be able to walk on their own. At this stage, only advanced medications or descent can reverse the problem. It is important to get the person to descend before the ataxia reaches the point where they cannot walk on their own (which would necessitate a stretcher evacuation). Descending only 1,000 feet (300 m) will result in some improvement, and 24 hours at the lower altitude will result in a significant improvement. The person should remain at a lower altitude until all the symptoms have subsided. At this point, the person has become acclimatized to that altitude and can begin ascending again.

NOTE NO. 4: Severe AMS requires immediate descent of around 2,000 feet (600 m) to a lower altitude. AMS can progress to (HAPE) High Altitude Pulmonary Edema or (HACE) High Altitude Cerebral Edema which are potentially fatal. 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.

High Altitude Pulmonary Edema (HAPE) (Fluid in the lungs)
HAPE is a result of fluid accumulation in the lungs. This fluid prevents effective oxygen exchange. As the condition becomes more severe, the level of oxygen in the blood stream decreases, which leads to cyanosis, impaired cerebral function, and death on the mountain.

Symptoms and Sign of HAPE are:

Difficulty in breathing at rest
Cough which bringing up white, watery, or frothy fluid
Weakness or decreased exercise performance
Chest tightness or congestion
Crackles or wheezing (while breathing) in at least one lung field
Skin, Fingernail, and Eye color change into blue.
Rapid shallow breathing
Rapid heart rate
Confusion and irrational behavior.

NOTE: Confusion and irrational behavior are signs that insufficient oxygen is reaching the brain. In cases of HAPE, immediate descent of around 2,000 feet (600 m) is a necessary life- saving measure. Anyone suffering from HAPE must be evacuated to a medical facility for proper follow-up treatment.

High Altitude Cerebral Edema (HACE) (Swelling of Brain)
HACE is a condition in which the brain swells with fluid because of the physiological effects of traveling to a high altitude. It generally appears in patients who have acute mountain sickness. It occurs when the body fails to acclimatize.
The symptoms of HACE are:
Loss of co-ordination
Decreasing levels of consciousness
Loss of memory
Hallucinations & Psychotic behavior
NOTE: This condition is rapidly fatal unless the afflicted person experiences immediate descent. Anyone suffering from HACE must be evacuated to a medical facility for follow-up treatment.