Low On 02

The ultimate guide to living at altitude.

Into Thin Air

Demystifying Acute Mountain Sickness.

What is AMS?
A person has acute mountain sickness (AMS) if he has a headache plus at least one other symptom, such as nausea, fatigue, and

dizziness, while at altitude. Researchers don't know exactly what causes AMS, but many believe that hypoxia (low oxygen) causes blood vessels in the brain to dilate in an attempt to get more oxygen.

The process of dilation causes a headache in most people; the increased blood flow from the dilation also causes swelling in the brain, which may be worse in those that eventually come down with AMS. The brain swelling is thought to be the origin of the other AMS symptoms as well.

How can I prevent AMS?
A gradual ascent to higher altitudes is the key to thwarting AMS. Take your visiting flatlander family too high, too quick, and you're begging for someone to get sick. Instead of taking them to, say, Breckenridge (9,603 feet above sea level), have them spend their first night in Colorado at an intermediate altitude such as Denver (5,280 feet) or Idaho Springs (7,526 feet) before heading higher into the I-70 corridor. (Some Denver hotels, like the Hotel Teatro, even offer discounted "acclimatization packages" to get you to stay in Denver for a night before heading up the hill.)

Beyond planning a deliberate rate of ascent, you'll want to keep your lowlanders hydrated—forcing them to down 100 ounces of water a day will help with acclimatizing—and help them avoid overexertion for the first 48 hours at altitude. (That means no crazy hiking at 9,600 feet, folks.) Also, remind your family to stay away from alcohol and sleeping pills in the benzodiazepine family (like Halcion and Restoril), as both suppress breathing and result in lower blood-oxygen levels.

People who know they are susceptible to altitude sickness—meaning they've acquired it repeatedly—can ask a doctor to prescribe Diamox. By increasing the amount of bicarbonate excreted in your urine, Diamox makes your blood become more acidic. Acidifying the blood stimulates breathing, which increases the amount of oxygen in the blood. Taken 24 hours before arrival at altitude and every

12 hours for the first two days at altitude, the drug can be up to 75 percent effective in preventing AMS, depending on dose, rate of ascent, and susceptibility.

How can I ID the symptoms of AMS?
The Lake Louise Score is the gold standard for putting a numerical value on the severity of AMS symptoms, such as headache, gastrointestinal distress, and fatigue. A score of four or higher, and you've got AMS. Download the Lake Louise Score sheet at www.high-altitude-medicine.com.

How do I treat AMS?
The best remedy is to descend to lower altitude. But if you can't go lower or simply want to tough out mild symptoms, the next best treatment is rest, liberal use of ibuprofen or acetaminophen, and time (AMS usually gets better within 24 to 48 hours). If you have AMS symptoms, do not go higher; if you, or someone in your party, is very sick, descend immediately. Of course, if you have access to bottled oxygen, sucking down those Os will decrease AMS symptoms quickly.