» Acute Mountain Sickness (AMS) - Nature Expeditions Peru

Acute Mountain Sickness (AMS)

When you travel up into the mountains and you suddenly start suffering headache, dizziness, fatigue, shortness of breath, loss of appetite, nausea, disturbed sleep, and a general feeling of malaise you have Acute Mountain Sickness (AMS). The probability of you getting AMS depends on the altitude you are at.

Altitude is defined on the following scale:

High = 8,000 – 12,000 feet or 2,438 – 3,658 meters
Very High = 12,000 – 18,000 feet or 3,658 – 5,487 meters
Extremely High = 18,000+ feet or 5,500+ meters

Divers that are involved in altitude diving are not generally informed about AMS. That is because for a diver altitude starts at 300 meters above sea level and most altitude diving is done at more or less 1000 meters of altitude – well below the altitude wher AMS would occur. When diving however in Lake Titicaca (3812 meters) a diver would be in an environment considered by a climber or trekker as “very high” according to the above scale. That means AMS becomes an additional physical strain added to the strains of diving itself.

AMS is common at high altitudes. The occurrence of AMS is dependent upon the elevation, the rate of ascent, and individual susceptibility. At elevations over 10,000 feet (3,048 meters), 75% of people will have mild symptoms.

What Causes Altitude Illnesses?

The concentration of oxygen at sea level is about 21% and the barometric pressure averages 760 mmHg. As altitude increases, the concentration remains the same but the number of oxygen molecules per breath is reduced. At 12,000 feet (3,658 meters) the barometric pressure is only 483 mmHg, so there are roughly 40% fewer oxygen molecules per breath. (Remember: Lake Titicaca is at 3812 meters)

In order to properly oxygenate the body, your breathing rate (even while at rest) has to increase. This extra ventilation increases the oxygen content in the blood, but not to sea level concentrations. Since the amount of oxygen required for activity is the same, the body must adjust to having less oxygen.

There are no specific factors such as age, sex, or physical condition that correlates with susceptibility to altitude sickness. Some people get it and some people don’t, and some people are more susceptible than others.

Most people can go up to 8,000 feet (2,438 meters) with minimal effect. If you haven’t been to high altitude before, it’s important to be cautious. If you have been at that altitude before with no problem, you can probably return to that altitude without problems as long as you are properly acclimatized.

Acclimatization

The major cause of altitude illnesses is going too high too fast or being too active within the first day of your stay at high altitude. Given time, your body can adapt to the decrease in oxygen molecules at a specific altitude. This acclimatization generally takes 1-3 days at that altitude.

Acclimatization is height-specific!

For example, if you go up to 10,000 feet (3,048 meters), and spend several days at that altitude, your body acclimatizes to 10,000 feet (3,048 meters). If you go up to 12,000 feet (3,658 meters), your body has to acclimatize once again.

A number of changes take place in the body to allow it to operate with decreased oxygen.
• The depth of respiration increases.
• Pressure in pulmonary arteries is increased, “forcing” blood into portions of the lung which are normally not used during sea level breathing.
• The body produces more red blood cells to carry oxygen,
• The body produces more of a particular enzyme that facilitates t he release of oxygen from hemoglobin to the body tissues.

What may happen to you most probably when being at Lake Titicaca is to suffer from only mild symptoms. Nevertheless this page will also inform you about the more severe levels of Acute Mountain Sickness (AMS)

Mild AMS

Many people will experience mild AMS during the acclimatization process. Symptoms usually start 12-24 hours after arrival at altitude and begin to decrease in severity about the third day. The symptoms of Mild AMS are headache, dizziness, fatigue, shortness of breath, loss of appetite, nausea, disturbed sleep, and a general feeling of malaise. 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 within 2-4 days as the body acclimatizes. As long as symptoms are mild, and only a nuisance, ascent can continue at a moderate rate.

Moderate AMS

Moderate AMS includes severe headache that is not relieved by medication, nausea and vomiting, increasing weakness and fatigue, shortness of breath, and decreased coordination (ataxia). 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. Descending even a few hundred feet (70 -100 meters) may help and definite improvement will be seen in descents of 1,000-2,000 feet (305-610 meters). Twenty-four hours at the lower altitude will result in significant improvements. The person should remain at lower altitude until symptoms have subsided (up to 3 days). At this point, the person has become acclimatized to that altitude and can begin ascending again.

The best test for moderate AMS is to have the person “walk a straight line” heel to toe. Just like a sobriety test, a person with ataxia will be unable to walk a straight line. This is a clear indication that immediate descent is required. 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 litter evacuation).

Severe AMS

Severe AMS presents as an increase in the severity of the aforementioned symptoms, including shortness of breath at rest, inability to walk, decreasing mental status, and fluid buildup in the lungs. Severe AMS requires immediate descent to lower altitudes (2,000 – 4,000 feet [610-1,220 meters]).

Prevention of Altitude Illnesses

Before your trip, maintain a good work/rest cycle, avoiding excessive work hours and last minute packing.
Avoid tobacco, alcohol, sleeping pills or narcotics, they may decrease ventilation, intensify hypoxemia and make symptoms worse.
If you do fly or drive to high altitude, do not over-exert yourself or move higher for the first 24 hours.
If you go above 10,000 feet (3,048 meters), only increase your altitude by 1,000 feet (305 meters) per day and for every 3,000 feet (915 meters) of elevation gained, take a rest day.
It is essential that you communicate any symptoms of illness immediately to others on your trip.
”Climb high and sleep low.” This is the maxim used by climbers. You can climb more than 1,000 feet (305 meters) in a day as long as you come back down and sleep at a lower altitude.
If you begin to show symptoms of moderate altitude illness, don’t go higher until symptoms decrease.
Stay properly hydrated. Acclimatization is often accompanied by fluid loss, so you need to drink lots of fluids to remain properly hydrated (at least 3-4 quarts per day). Urine output should be copious and clear.
Take it easy; don’t over-exert yourself when you first get up to altitude. Avoid heavy exercise. Mild exercise is okay. Light activity during the day is better than sleeping because respiration decreases during sleep, exacerbating the symptoms.
Eat high-carbohydrate foods (rice, pasta, cereal – more than 70% of your calories from carbohydrates) while avoiding fatty staff.
Many hotels do provide oxygen to their clients with AMS. Oxygen will relieve symptoms. Oxygen is safe, cheap and easy to use. It can be used at night when symptoms are worse and off and on during the day as symptoms dictate.
Drink Coca leaf tea or chef dried coca leaves. Coca leaves contain 14 alkaloids, from which the most popular and broadly used is just one: the cocaine; the other ones are wasted or simply ignored. There are innumerable beneficial products made from coca leaves: from candies, cigarettes, tooth pastes. Coca leaf tea or chewing coca leafs is the absolute best prevention of AMS and also helps to relief symptoms.

Drinking coca leaf tea or chewing the leaves is perfectly legal in Peru and Bolivia but not in the United States, because the coca leaf (Erythroxylum coca) is the source of cocaine. Nevertheless it is obvious that the person chewing coca leaves or drinking coca leaf tea will not get “high” or a “dope” state because it is a natural leaves with extremely low concentrations of cocaine. Cocaine as a drug is a highly processed derivative of coca that would need a chemical process with elements such as tartic acid, pure clorhidric acid, ether, and anhydrous soda sulfate, in different determined temperatures, in order to finally produce cocaine.

Preventive Medications

Diamox (Acetazolamide) allows you to breathe faster so that you metabolize more oxygen, thereby minimizing the symptoms caused by poor oxygenation. This is especially helpful at night when respiratory drive is decreased. Since it takes a while for Diamox to have an effect, it is advisable to start taking it 24 hours before you go to altitude and continue for at least five days at higher altitude. The recommendation of the Himalayan Rescue Association Medical Clinic is 125 mg. twice a day (morning and night). (The standard dose was 250 mg., but their research showed no difference for most people with the lower dose, although some individuals may need 250 mg.)
Possible side effects include tingling of the lips and finger tips, blurring of vision, and alteration of taste. These side effects may be reduced with the 125 mg. dose. Side effects subside when the drug is stopped. Contact your physician for a prescription. Since Diamox is a sulfonamide drug, people who are allergic to sulfa drugs should not take Diamox. Diamox has also been known to cause severe allergic reactions to people with no previous history of Diamox or sulfa allergies.

Dexamethasone (a steroid) is a prescription drug that decreases brain and other swelling reversing the effects of AMS. Dosage is typically 4 mg twice a day for a few days starting with the ascent. This prevents most symptoms of altitude illness. It should be used with caution and only on the advice of a physician because of possible serious side effects. It may be combined with Diamox.

No other medications have been proven valuable for preventing AMS.

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