Different people under similar conditions will respond quite differently to altitude. There are no specific factors such as age, sex, or physical condition that correlate with susceptibility to altitude sickness. The response to altitude will depend on the rate of ascent, the magnitude of the ascent and individual susceptibility (genetics). The effects can be mild or severe, and are caused by the lack of oxygen to the muscles and the brain. As altitude increases the concentration of oxygen stays the same, but the number of oxygen molecules per breath is reduced as the barometric pressure drops. At 18,000 ft (5500 m), there is half the oxygen available at sea level. Kilimanjaro is 19,300 feet. In some cases altitude sickness can turn extremely severe, even fatal. For reasons not entirely understood high altitude and lower air pressures can cause fluid to leak from the capillaries and build-up in the brain and lungs. Continuing an ascent without proper acclimation can lead to a life threatening illness.
Mild symptoms of acute mountain sickness will occur in 75% of people who travel over 10,000 feet, and can affect some people at lower altitudes. These symptoms include:
- Disturbed sleep
- Loss of Appetite
These symptoms typically begin immediately after arrival and tend to worsen at night. Mild AMS does not interfere with normal activity and symptoms generally subside within 2-4 days as body acclimatizes. As long as symptoms are mild, and only a nuisance, ascent can continue at a moderate rate.
Prevention of AMS
Altitude sickness is preventable! Make sure to pay close attention to your body and the health of individuals in your group. Immediately communicate any symptoms of illness to others on your trip. Oxygen deprivation of the brain may cause individuals to deny or not recognize their own symptoms.
- STAY HYDRATED – urine output should be copious and clear. Try to drink at least 4-6 liters per day.
- AVOID tobacco, alcohol, and other depressant drugs including barbiturates, tranquilizers, and sleeping pills. They further decrease the respiratory drive during sleep resulting in a worsening of symptoms. In addition, avoid diuretics such as coffee and tea.
- “DON’T GO UP UNTIL SYMPTOMS GO DOWN” – people acclimatize at different rates, make sure your entire party is properly acclimatized before going higher. Rest at the same altitude is efficient for mild symptoms, but if they do not go away within a day or two it is essential that you descend immediately
- DIAMOX (acetazolamide) is a drug shown to be effective in minimizing the symptoms caused by poor oxygenation by helping you breathe deeper and faster. This drug is not used in treatment, it should be used as a preventative method only. The recommended dose is 125 mg twice a day, and it is advisable to start taking it 24 hours before you go to altitude and continue for at least five days at higher altitude. Side effects include tingling of the lips and finger tips, blurring of vision, and alteration of taste. If you are allergic to sulfa drugs you should not take Diamox. Use of this drug is controversial so it is advisable to research its effects prior to seeking a prescription. More information:
- EAT high-carbohydrate foods while avoiding fatty foods.
- BEFORE your trip, maintain a good work/rest cycle, avoid excessive work hours and last minute packing.
- LISTEN to your body. Do not over-do things the first day or two. Avoid heavy exercise.
HAPE results from fluid buildup in the lungs, which prevents effective oxygen exchange from the lungs to the bloodstream. This is a very serious condition and can lead to death if not treated immediately. Symptoms of HAPE include:
- Irritating Cough (can produce frothy, often blood-tinged sputum)
- Mental confusion, staggering drunken walk
- Quick Shallow Breathing, difficulty breathing
- Chest Pain
- Gurgling Noise in Chest
- Debilitating Headache and severe fatigue
- Disruption of Vision, Bladder, and Bowel Functions
- Loss of Coordination of Trunk muscles (test by walking straight line)
Although rare, HAPE frequently strikes the young and fit climbers and trekkers. If you notice any of these signs in yourself or others in your group you must descend immediately, even at night. HAPE can be fatal within a few hours if left untreated. However, if diagnosed early, recovery is rapid with a descent of only 500-1000 meters. Besides descent, treatment also includes rest, administration of oxygen and portable hyperbaric chambers.
HACE occurs when fluid leakage in the brain causes swelling which affects the central nervous system. This is considered the most serious altitude related illness. If left untreated it will lead to coma and death. HACE is thought to occur in 1% of persons above 4000 m and 3% of those with AMS, and usually occurs after a week or two at high altitudes. Symptoms of HACE can be similar to AMS and HACE and include:
- Staggered Gait (unable to walk heel-to-toe in a straight line)
- Severe weakness/fatigue
- Impaired mental processing, confusion
- Decreasing Levels of Consciousness(loss of memory, hallucinations, psychotic behavior, and coma)
- Changes in Behavior
- Difficulty Speaking
- Paralysis of a Limb
Immediate descent is the best treatment for HACE. This is of the utmost urgency, and cannot wait until morning. The moment HACE is recognized is the moment to start organizing an effort to get this person down the mountain, usually to the point where they last slept with no symptoms. It is important to recognize that persons with this illness are often confused, and may not recognize that they are ill.
*The information provided here is designed for educational use only and is not a substitute for specific training or experience. Adventures Within Reach assumes no liability for any individual’s use of or reliance upon any material contained or referenced herein.