While You're Away: Altitude Sickness
It has now been more than 50 years since Sir Edmund Hillary and Tenzing Norgay’s ascent of Everest. Most travellers are not headed for the peak of Everest (29,036 feet), but there are many other destinations that pose a risk of altitude sickness, including the Andes, which are above 10,000 feet, the peak of Mount Kilimanjaro, at 19,340 feet, and even Aspen, which sits at 10,000 feet. In fact, symptoms may occur at any altitude above 7,000 feet.
As we ascend, the partial pressure of oxygen in the air decreases, and hence we have less oxygen for our red blood cells to deliver to vital organs such as our brain and lungs. The body responds to this challenge in a positive way by increasing the heart rate and the respiratory rate, and given time, by producing more red blood cells. However there are also deleterious changes that may occur, such as constriction of the pulmonary circulation, leakage of fluid from the blood vessels, and swelling of the brain (cerebral edema).
The symptoms of altitude sickness will vary, and may depend upon the altitude reached, the time taken to reach that altitude, and individual susceptibility. Those who spend endless hours on treadmills do not seem to be at an advantage, and in fact might be at greater risk due to their tendency to rush up the mountain. Individuals with a past history of altitude sickness, as well as those who tend to retain fluids and hypoventilate, are also at greater risk. And finally, perhaps those on a budget need to be extra careful. I am told that guides on Mt. Kilimanjaro cost $100 per day, so there might be a necessity for budget climbers to get up and hopefully down more quickly.
The mildest and most common of the altitude-related syndromes is acute mountain sickness (AMS). This resembles a hangover in many ways, with headache, nausea, vomiting, dizziness and insomnia. An annoying occurrence at high altitude is nocturnal periodic breathing. This is not a serious condition, but rather an annoying one, as you wake up feeling like you can’t get enough air. I experienced this in Bolivia, and I was annoyed!
AMS may progress to high altitude cerebral edema (HACE) if one ignores the symptoms and continues to ascend. In addition to the symptoms mentioned, unsteadiness and irrational behaviour may he characteristic. Perhaps this is the reason that unfortunate Everest climbers find themselves falling into crevasses. HACE will proceed to coma and death if it not recognized and treated promptly.
High altitude pulmonary edema (HAPE) is characterized by decreased exercise performance, a dry cough and shortness of breath. It may coexist with AMS or HACE. Once again, if it goes unrecognized, coma and death may be the end result.
My impression is that most people do OK when they fly into Cuzco or Quito, at about 10,000 feet. But La Paz or Lake Titicaca and Lhasa, at 12,000 feet can be more problematic. I recommend prophylactic Diamox for those climbing Kilimanjaro, as most people climb too fast. A 7 or 8 day climb is preferable to 5 or 6, though much more expensive. Trekking to Everest Base Camp is a gradual affair, and perhaps Diamox is not needed. Those with a track record of suffering from altitude sickness should definitely consider taking it preventatively.
So if you are intent on reaching a higher altitude, you need the proper attitude…and advice.
- Avoid rapid ascent when possible, i.e. flying directly from sea level to a high altitude. Considering this is not always possible, take a few days to acclimatize at the higher altitude.
- Climb slowly. Overexertion will not get you to the top any faster.
- Climb high, sleep low. It is the sleeping altitude that is particularly important. This should not increase by more than 1,000 feet per day. Every three days, have a day of rest. The ascent of Kilimanjaro usually involves climbing faster than the recommended guidelines.
- Avoid the use of sedatives and tranquilizers. They may depress your respiration.
- Dress warmly. Hypothermia will exacerbate the symptoms of altitude sickness.
- Avoid alcohol. Its effects might be a little more profound at high altitudes.
- Stay well hydrated. Drink enough to keep your urine clear.
- A diet high in carbohydrates and low in salt may be beneficial
- If you must ascend rapidly, or have a past history of altitude sickness, consider the use of Diamox (acetazolamide) to prevent altitude sickness. This drug contains sulfa, and should be avoided in those with sulfa allergy (this is controversial). It may cause some tingling around the mouth and extremities and you will pee more. The adult dosage is 125 mg twice a day. It may be started the day before climbing or landing at your high altitude.
- Drink the coca tea in the Andes, and the garlic soup in Nepal!
- Some people ask about taking dexamethasone for prevention. This approach is certainly not for everyone, but might be considered for the highly motivated or sulfa allergic climber.
It seems that we often don’t prevent some of the preventable things in life, so let me say a word about treatment. Mild symptoms of AMS may be treated with rest, Diamox, and simple analgesics such as acetaminophen. More severe symptoms, particularly HACE and HAPE, may need to be treated urgently with oxygen, steroids, diuretics and most importantly, rapid descent. Portable, pressurized bags (Gamow Bag) may be used when descent is not an option.
According to Dr. David Shlim, formerly of the CIWEC Clinic (their website is great) in Kathmandu, “…it is OK to develop altitude sickness, it is not OK to die from it.” Those who choose to ignore the symptoms of early altitude sickness, or who don’t know them in the first place, are the most likely to run into serious trouble. So if you want to find out what altitude sickness in its mildest form feels like, try a bottle of champagne. If you want to get to high altitudes, use your common sense!