As the final countdown to departure looms closer, I have focused my energy on understanding what I can expect in terms of the possible (likely) responses to high altitude, namely acute mountain sickness (AMS).
AMS refers to an umbrella of symptoms experienced by unacclimatized individuals with initial exposure to high altitude. The cluster of AMS symptoms are headache, gastrointestinal symptoms, fatigue, dizziness/light-headedness, and overall poor sleep quality.
For unacclimatized individuals (such as yours truly), exposure to low oxygen (hypoxic) environments triggers a physiological response intended to increase the amount of oxygen breathed in by the lungs. These adjustments to breathing in response to low oxygen induces a number of physiological changes that are thought to lead to the characteristic symptoms of ‘high altitude sickness’ and more serious health complications found in individuals who ascends too quickly or ignore/mismanage initial symptoms.
Generally speaking, how fast you ascend, the altitude reached, the altitude that you sleep at, and individual physiological differences determine the likelihood of developing AMS. At altitudes above 3000 m, the incidence of AMS is around 40 – 50%; however, there currently aren’t any strong predictors of who will get sick. Fitness, age, gender, previous high altitude experience, and a host of other individual factors appear to have no conclusive bearing on whether an individual will develop these symptoms in high altitude.
As such, the ascent profile of our trek has been designed to provide the best opportunity for acclimatization and hopefully reducing AMS symptoms. This includes slow ascent (< 600 m per day) and rest days at 3340 m, 3860 m, and 4240 m. Further, we’ll be taking daily doses of a drug called acetazolamide (Diamox), which has been shown to speed up the acclimatization process and reduce incidence of AMS.
How my body will respond to high altitude is one of the the biggest unknowns as I prepare for this trip. I have been to altitudes of 2500 – 2700 m on multiple occasions and felt fine; however, given that our trek begins at 2840 m, I guess I’ll have to wait and see how my body deals with a low oxygen environment.