High Altitude

Introduction and Overview of High Altitude Sickness

During climbs to higher elevations, generally above 8000ft/2400m, the body undergoes certain physiological changes. These changes effect the way your body performs including hyperventilation/dyspnea (shortness of breath) upon exertion, increased urination, awakening many times during the night, and periodic breathing at night. These symptoms are normal upon arrival to altitude and are the natural way the body deals with a decreased oxygen environment.

Additionally, at higher elevations above 8000ft/2400m, there is a risk of altitude related sickness, Acute Mountain Sickness, (AMS) and at higher elevations and more extreme cases High Altitude Pulmonary Edema (HAPE) and/or High Altitude Cerebral Edema (HACE). There are several ways to treat the onset of AMS including drug therapy however the best prevention for AMS is a good altitude profile the allows plenty of time for acclimatization. The body will naturally adjust to the decreased oxygen environment if given enough time. For ideal acclimatization and performance at altitude it is important to average no more then 1000ft of elevation gain a day. At Alaska Mountain Guides all of our trip itineraries give priority to healthy acclimatization rather than speed of ascent. In this manner we maintain not only healthier clients throughout our climbing expeditions but also a high summit success rate.

In the more extreme cases of severe AMS, HAPE, and HACE the only genuine treatment to fully correct this problem is descent. In most cases encountering these more advanced stages of altitude illness will prematurely end the effected person’s expedition. That is why proactive recognition at the early stages of altitude illness is extremely important. An essential tool to monitor acclimatization is the pulse-oximeter. Similar to the pulse oximeters used in hospitals, the smaller, more portable versions used in the mountains give us direct information about how each persons body is adapting. By shining both red and infrared light through the fingertip (a painless process) the pulse-oximeter measures the absorption characteristics for oxyhemoglobin (the red, oxygen saturated blood) and deoxyhemoglobin (the blue, oxygen unsaturated blood). The micro-processor inside the oximeter then measures the ratio (percent) of saturated to unsaturated hemoglobin and gives the user a numeric readout.

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At Alaska Mountain Guides every trip to altitude utilizes the vital information provided by pulse-oximeters. In addition to the extensive training our guides have in recognizing the physical symptoms of altitude illness, we monitor blood-oxygen saturation twice a day so we can recognize altitude illness before it advances to a severe problem. Upon early recognition, the itinerary can be adjusted, generally by adding a day of rest and acclimatization. This allows the body to adjust naturally. In most cases, proactive, early treatment, allows the effected person to continue on the expedition and to the summit.

Symptoms and Treatment

If altitude illness remains untreated or the onset is too sudden to recognize in time it can advance to more severe stages. Symptoms of advanced altitude illness vary depending on the specific altitude related problem. For HACE they may include severe headache, nausea, vomiting, dizziness, confusion and lack of coordination. In the case of HAPE symptoms may include dry, hacking cough, frothy sputum, shortness of breath at rest, and gurgling or rattling breaths. In both of these cases the only option is descent. Prescription drugs may be able to delay permanent damage and can sometimes aid the evacuation process but they should not be used in lieu of descent.

Emergency Evacuation

In any high altitude evacuation there can be many associated technical difficulties including personal risk for the rescuers themselves. These technical difficulties can include those presented by mountainous terrain, darkness, and the volatile mountain weather. Even helicopters cannot attempt rescue at night or in bad weather. In some cases evacuation must be delayed in order to protect the safety of the patient and rescuers. The use of a Portable Hyperbaric Bag, (Gamow Bag) an artificial pressure chamber, can buy time, stabilize, or even reverse severe altitude illness while waiting for, or during descent. Without fast, immediate descent or the use of a Gamow Bag the consequences of severe altitude illness can be fatal.


At AMG, on many of our expeditions to higher, more extreme altitudes, we carry Gamow bags. We feel that this extra measure is essential to our clients safety in the mountains. We recommend that whenever you travel to high altitude you consider the risks and ask the appropriate questions of your guide service to ensure that they are taking the appropriate safety precautions. With these in place traveling to altitude and climbing to the summit of the worlds high peaks can be a safe, fun, and very rewarding experience.

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