Ascending to altitude is a great experience, the preparatory training, the challenge involved and of course those magnificent views. But spare a thought for your physiology that quietly undertakes numerous adjustments to keep you safe as you climb higher. If you take it easy and ascend slowly enough all should be well but push too hard, too high and too fast and your physiology will fail to acclimatise and high altitude illness develops. Altitude illness becomes common above 3000m and presents in the following three ways.
Acute Mountain Sickness (AMS)
AMS is reasonably common and can range from mild to severe. It is not life threatening (but left untreated it can become HACE, High Altitude Cerebral Edema) and presents with headaches plus one or more of these symptoms: nausea, loss of appetite or tiredness. The Lake Louise score is used to grade the severity of the AMS. If symptoms are mild then resting at the same, or a lower altitude till they disappear is the cure of choice. If symptoms are severe then descent is necessary.
High Altitude Cerebral Edema (HACE)
The headache is more severe and accompanied by signs of neurological disturbance such as increasing loss of coordination, reduced mental abilities and eventual loss of consciousness. The heel-to-toe walking and finger-nose tests are diagnostic aids.
High Altitude Pulmonary Edema (HAPE)
This can occur alone or along with AMS and/or HACE. Symptoms include increasing tiredness, a dry cough eventually producing frothy sputum and shortness of breath with an increased respiratory rate (check the normal rate on a well person for comparison).
HACE and HAPE can be fatal but are fortunately less common than AMS and the definitive treatment is immediate descent.
While all this may sound daunting, remember that you are walking or climbing out of our planet’s atmosphere and by the time you reach 4500m you are more than halfway to the breathable limit! If you think you or someone on your team are becoming ill, tell your leader immediately and do not ascend further with symptoms of altitude illness to prevent it from progressing to HAPE or HACE. A more detailed explanation of high altitude illness and its treatment can be found at www.treksafe.com.au
Dr. Jim Duff was an integral part of the World Expeditions team for 30 years, retiring from his role as our official medical consultant in September 2012.