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Minimizing Altitude Sickness Symptoms on Mountain Trips

By Kent Trulsson

The Dallas Sierra Club sponsors a number of trips to the mountains of Colorado and New Mexico each year. Some of these trips involve a sudden change in altitude, from just 600’ above sea level in Dallas, to a trailhead elevation of 8,000’ or 9,000’ about 12 hours later, to a camp elevation of 10,000’ or 11,000’ just 24 hours after leaving Dallas. In particular, our bus trips to Taos and the Pecos, Sangre de Cristo and Wemunuche Wilderness areas can trigger symptoms of “altitude sickness” for some participants. This article answers the most frequently asked questions our trip leaders get about altitude sickness.

What is altitude sickness? Altitude sickness is a general term for several related illnesses caused by either sudden or extended exposure to high altitudes (over 8,000’). All of these illnesses spring from the same cause: low air pressure and oxygen concentrations at high altitudes, resulting in low blood oxygen levels. The most common and least severe form is called Acute Mountain Sickness (AMS). Much more severe and dangerous are High Altitude Pulmonary Edema (HAPE), fluid collection in the lungs, and High Altitude Cerebral Edema (HACE), brain swelling due to fluid collection.

Is some form of altitude sickness common on Dallas Sierra Club bus trips? For the conditions found on mountain Dallas Sierra Club bus trips, from 10% to 30% of the participants will experience some (usually mild) symptoms of AMS during the first one or two days at altitude; the higher the trip altitude, the greater the number of participants that will experience problems. We have never had a known case of either HAPE or HACE on a Dallas Sierra Club bus trip, mainly because our trip altitudes are moderate and our trips of short duration. We do send participants with persistent AMS symptoms down to lower attitudes before the AMS progresses to the more severe HAPE or HACE.

What are the symptoms of Acute Altitude Sickness? The initial symptoms of AMS usually occur within 6 to 12 hours of the arrival at altitude, but may not start until 48 hours after arrival. The first symptom is usually a mild, generalized headache which does not respond to over-the-counter medications. This may be followed by fatigue, appetite loss, dizziness or nausea. It is common for the face and fingers to swell. Occasionally, vomiting can result from the nausea. At night, restless sleep and irregular breathing may occur. In rare cases, these symptoms may get progressively more severe after the first 24 hours. For most people, the symptoms disappear completely after 24 to 48 hours, as their bodies acclimatize to the lower oxygen concentration.

Are some people more prone to get AMS than others? Yes, some people almost always get some symptoms, for a given altitude, while others do not seem to ever be bothered. A person that is first affected by AMS at about 10,000’ altitude is likely to be similarly affected at about the same altitude on the next trip. Fitness and training do not seem to matter. AMS affects both sexes equally. Younger people are generally more affected. People who have recently had colds or gotten little sleep are more likely to have AMS symptoms. That said, it is impossible to predict if a person will be affected by AMS symptoms on a given trip.

What can I do to minimize or prevent the symptoms of AMS? There are steps an individual can take to minimize the chance of getting AMS symptoms, or at least limit the severity and duration of those symptoms. In selecting or planning a trip, pick a lower altitude trip if you know you are more susceptible to AMS. Before the trip, drink plenty of fluids and avoid drinking alcohol or taking sedatives or sleeping pills. Get adequate sleep, and stay in good health. During the trip, continue to drink plenty of fluids—enough to produce copious amounts of clear urine. Continue to avoid alcohol. Eat a high calorie, high carb diet. Spread out the effort of the first day’s hike, and avoid getting out of breath. Stop hiking early on the first day of the trip, and try to camp at the lowest possible altitude on the first night. If possible, hike to higher altitudes during the day than the final camp altitude. At night, do not completely zip up the door of your tent, and do not bury your head into your sleeping bag. If some symptoms persist on the second day of the trip, avoid or minimize strenuous activity. Plan to do the highest altitude section of the trip, such as peak-bagging, on the third or fourth day at altitude. Once exceeding a 10,000’ altitude, increase camp elevations by no more than 1,000’ per night. If all of these steps are followed, it is rare for AMS to progress to more serious conditions.

What should I do if the AMS symptoms get worse? If your AMS symptoms do not diminish after 48 hours, or if they seem to be getting progressively worse, you should move immediately to a lower altitude, usually at the trail head. If the symptoms persist even after reaching the trailhead, find a way to get below 8,000’ in altitude. When altitude sickness symptoms are rapidly getting worse, it is very important to move lower as quickly as possible, especially if there are any of the HACE symptoms as described below.

What are the symptoms of HAPE and HACE, and what should I do if I have these symptoms? It is very important that every person who hikes to high altitudes know the symptoms of these potentially fatal high-altitude illnesses.  HAPE, a fluid buildup in the lungs, usually does not occur below elevations of 10,000’ or before three days at altitude. HAPE symptoms usually progress from a shortness of breath in the absence of exercise, to dry cough, chest pain, rapid pulse, and in advanced cases, sounds of fluid buildup in the lungs. HACE, a swelling of the brain, usually does not occur below 12,000’, or before four days at altitude. HACE symptoms include a severe headache, confusion, vomiting, irregular breathing with breathing stops, staggering gait, inability to balance, and finally, unconsciousness. For both of these illnesses, the most important treatment is to descend as much as possible (at least 2,000’ to 3,000’) as quickly as possible, and seek medical attention immediately.

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