Altitude Illness and "the Traveler"
by Dr. William H. Shoff, MD, Doctor of Travel Medicine and Health Asst. Professor Director, Penn Travel Medicine Dept. of Emergency Medicine, Univ. of PA Health System
Travelers are often not warned about acute mountain sickness (AMS) when traveling to altitude. AMS becomes more intense at higher altitudes because the air gets thinner and there is less oxygen to breathe.
When traveling to and sleeping at altitudes of:
- 6,000 feet, travelers run about a 12% risk of developing mild AMS;
- 8,000-10,000 feet, there is a 25% risk of developing mild-to-moderate AMS and a 0.01% risk of developing serious AMS;
- 10,000 feet, virtually everyone develops mild symptoms of AMS; and
- 10,000-14,000 feet, the risk of developing moderate AMS rises to 40%, and the overall risk of severe AMS is 0.1% to 0.6%.
Mild AMS can be managed without seeking medical attention. The symptoms of mild AMS at altitudes above 6,000 feet are headache, shortness of breath with exertion, sleep disturbance and decrease in appetite. Symptoms usually develop 6-48 hours after arrival. Headaches are usually across the forehead, but may be located anywhere. AMS is made worse by straining, lifting, coughing, hiking, running distances, skiing, or climbing. It responds to acetaminophen or ibuprofen. Light activity such as walking on the level, walking up hills (not hiking) and climbing stairs usually produces shortness of breath, but not enough to make travelers sit down. All symptoms may abate over three to five days and do not disrupt travelers' trips.
It is important that you learn to recognize worsening AMS, which requires specific treatment. When the symptoms outlined above become bad enough to disrupt daily activities, AMS is said to be "moderate AMS." Additional symptoms may include nausea, vomiting (particularly in children), complete loss of appetite, feeling lazy, feeling dizzy or unsteady, and difficulty thinking or remembering.
When AMS becomes severe, three noticeable events occur:
- Travelers are unsteady on their feet and cannot walk a straight line;
- Travelers experience shortness of breath; and
- Travelers become progressively more tired, lazy, or sleepy.
Any of the other symptoms already mentioned may become worse as well. When a traveler complains of worsening symptoms or demonstrates the events described here, immediately seek medical attention.
Treatment of worsening AMS involves descending to a lower altitude, complete rest, administering oxygen, and taking acetazolamide (125 mg to 250 mg twice a day until symptoms subside). In addition, steroids, Nifedipine, morphine, and the use of a portable hyperbaric chamber may be prescribed. Of the treatments mentioned, the most important is to descend. It may save your life!
The risk of developing AMS can be significantly decreased by ascending slowly. To decrease the risk, when planning to visit for several days at 9,000-14,000 feet, sleep two nights at around 7,000 feet en route.
Avoiding heavy exercise is another way to decrease risk. Running distances, hiking, skiing, and climbing within the first five days of arrival above 8,000 feet might precipitate acute severe AMS. It is best to increase your exercise level gradually when at altitude. Avoid any drug that sedates, including alcohol, sleeping pills, narcotic pain pills, and anxiety medications. Drugs that sedate decrease the breathing rate while asleep and increase the risk of developing AMS.
Three other important considerations that affect the development of AMS are water intake, diet, and sleeping altitude. Dehydration puts the body at risk for AMS. Water is lost faster at altitude. A good rule of thumb is to drink enough water to keep your urine light-colored. When your urine is dark, it means that you are dehydrated and more susceptible to AMS. A high carbohydrate diet (75% of calories from carbohydrate) has been shown to lessen the symptoms of AMS. The diet is best started seven days prior to going to altitude and then maintained while at altitude. Finally, the sleeping altitude is the altitude to which the body responds. Climb high and sleep low to minimize the effects of altitude.
Travelers can adapt to high altitude. Acclimatization begins as soon as travelers arrive. Travelers first notice that each breath is deeper and the rate of breathing a little faster. They may also notice that their heart rate is faster. These adaptations are made by the body to increase oxygen delivery to the organs.
All bodily changes made to adapt to altitude (above 8,000 feet) reverse upon return to a lower altitude (below 5,000 feet). If after three days travelers decide to ascend again above 8,000 feet, they must follow the guidelines all over again for preventing AMS.
Altitude illness is a real problem when ascending to altitudes above 8,000 feet. With proper planning and preparation, the problem can be minimized without compromising the trip.