Dear Doctors column, November 27, 2006
Rocky Mountain High: Coping with Altitude
Question:
I'm headed out West for a ski vacation. I live close to sea level and am wondering what I can expect from the altitude (the resort is at about 8000 feet) and how to prevent any ill effects.
Answer:
Although air at sea level and at high altitudes contain the same percentage of oxygen - about 21% - barometric pressure decreases as you ascend, each breath contains fewer oxygen molecules and consequently, the oxygen saturation in your blood decreases.
The red blood cells of a healthy person who is adapted to their altitude are 99% saturated with oxygen. After a rapid ascent and initial arrival at 10,000 feet, many people's red blood cell oxygen saturation drops to 90% or less. Until you adapt to high altitudes, which for most people occurs in a few days, your body has to work harder to get the oxygen it needs, and you will breathe faster and deeper than you normally do and get winded more quickly. Before you acclimatize, you also may experience other normal changes, such as an altered breathing pattern at night, waking up frequently, and increased urination, according to the International Society for Mountain Medicine (ISMM).
Altitude sickness, also called mountain sickness or acute mountain sickness, is a collection of symptoms that can occur in people who ascend to a high altitude and are not yet acclimatized to that elevation. Everyone has a different maximum acclimatization threshold, above which they will never acclimatize. Very few people have a maximum acclimatization line that is as low as 8000 feet, so at this elevation, most people will experience symptoms of altitude sickness for a few days at most.
At 8000 feet, which is close to the lower limit of what is defined as high altitude (7000-12,000 feet), about 20% of people will experience some symptoms. (Very high altitudes are elevations between 12,000-18,000 feet and extremely high altitude is 18,000 feet and higher.) The higher you go, the more likely you are to feel symptoms of altitude sickness. About 75% of people will initially notice effects at 10,000 feet or higher.
At ski resorts, the altitude at which you sleep is lower than maximum ski run elevations and most people sleep at 8000 feet or lower - altitudes that bother far fewer people. "Climb high, sleep low," is traditional advice for people at high altitude.
Susceptibility to altitude varies, and while some people may not feel any ill effects at 8000 feet, it is common to notice a few minor symptoms when you fly or drive into areas at high altitude - the rapid change in elevation doesn't give your body enough time to acclimatize. Symptoms at this elevation are typically mild and usually develop within 4 to 6 hours of arrival. Headache, nausea, loss of appetite, trouble sleeping, dizziness, fatigue, and a general feeling of malaise are the main features of mild altitude sickness.
Altitude sickness can affect people of any age or fitness level, and there is really no way to predict or prevent the condition. Mild altitude sickness typically resolves on its own in few days and does not interfere with normal activities.
There are a few simple steps you can take to minimize the effects of altitude. The faster and higher you ascend, the more likely you are to experience altitude sickness. So, when you arrive at the resort, consider taking it slow for the first day to let your body acclimatize.
Drink lots of water - twice the amount your normally drink and at least 3 to 4 quarts a day. Dehydration is extremely common at high altitude. Go easy on alcohol and caffeinated beverages, which can cause additional dehydration. Resting, drinking lots of fluid, and taking over-the-counter painkillers (which ease headache, but may increase nausea) should be adequate treatment for mild altitude sickness.
If you experience a severe headache, vomiting, or difficulty breathing, seek medical care. Descending to a lower altitude (at least 2000 feet lower) should also rapidly resolve symptoms of altitude sickness, but this is not usually necessary unless you are above 10,000 feet.
Certain conditions, including heart or lung problems, pregnancy, and high blood pressure, may exacerbate the effects of altitude. If you have any of these conditions, or other concerns about your health at altitude, consider a pretrip visit to a travel medicine specialist who can advise you about the likely effects of high elevations.
Sun and wind exposure are the other elements you really have to protect against at high altitudes. People typically get about 50% more exposure to UV radiation at high elevations, and sun and wind burns are common. Use a sunscreen with an SPF of at least 35 and reapply frequently. (Click here to read a previous Dear Doctors column on SPF.) To help prevent windburn, use an SPF with a moisturizer or frequently apply a separate moisturizer.
Hats and sunglasses also provide important protection from the elements. UV keratitis - sun damage to the eyes - is common in the mountains. (Click here to read about choosing effective eye protection.)
Most US ski resorts are based below 10,000 feet, so you will very likely experience only minor symptoms of altitude that should not interfere with your vacation. If you are traveling to destinations higher than 10,000 feet, more serious forms of altitude sickness, such as high altitude cerebral edema and high altitude pulmonary edema, can occur. Click here to read the ISSM's tutorial about altitude and these conditions.