Altitude sickness, also known as altitude illness, is a condition resulting from exposure to high elevations, typically above 8,000 feet (2,440 meters). The primary issue with altitude sickness is the decreased availability of oxygen. At sea level, oxygen makes up about 21% of the air, with a barometric pressure averaging 760 mmHg. However, as you ascend, while the oxygen concentration remains constant, the actual number of oxygen molecules per breath diminishes. For instance, at 12,000 feet (3,658 meters), the barometric pressure drops to just 483 mmHg, which means there's about 40% less oxygen per breath. To compensate, your breathing rate must increase, even at rest, to maintain adequate oxygen levels in your blood, though they will not match sea level conditions. Since the oxygen demand for activity doesn't change, your body must adapt to using less. Additionally, higher altitudes and reduced air pressure can cause fluid leakage from blood vessels, potentially leading to fluid accumulation in the lungs and brain. Climbing to greater heights without proper acclimatization can result in severe, even life-threatening conditions.Preventing altitude sickness involves two main strategies: acclimatization and preventive medication. Key acclimatization tips include:- Avoid flying or driving directly to high altitudes. Begin your journey below 10,000 feet (3,048 meters) and ascend gradually on foot.- If you must fly or drive, take it easy for the first 24 hours and refrain from gaining further altitude.- When exceeding 10,000 feet (3,048 meters), limit altitude increases to 1,000 feet (305 meters) per day, and for every 3,000 feet (915 meters) gained, take a rest day.- Follow the "Climb high, sleep low" principle used by climbers: ascend more than 1,000 feet (305 meters) in a day but return to a lower altitude to sleep.- If you notice moderate altitude illness symptoms, remain at your current altitude until they subside. If symptoms worsen, descend immediately.- Remember, acclimatization rates vary among individuals. Ensure everyone in your group is properly acclimatized before ascending further.- Stay well-hydrated, as acclimatization often leads to fluid loss. Drink plenty of fluids—at least 3-4 quarts daily. Your urine should be plentiful and clear.- Avoid exerting yourself excessively upon arrival at high altitudes. Light activities are preferable to sleeping since breathing decreases during sleep, worsening symptoms.- Steer clear of tobacco, alcohol, and depressant drugs such as barbiturates, tranquilizers, and sleeping pills, as they further reduce respiratory drive during sleep, aggravating symptoms.- Consume a high-carbohydrate diet, with over 70% of your calories coming from carbohydrates while at altitude.Acclimatization can be hindered by dehydration, overexertion, and the use of alcohol or depressant drugs. Two medications can help prevent altitude illness: DIAMOX (acetazolamide) and dexamethasone. DIAMOX enhances respiratory rate, increasing oxygen metabolism and alleviating symptoms caused by low oxygen. It's especially helpful at night when breathing slows. Begin taking DIAMOX 24 hours before ascending and continue for at least five days at higher altitudes. Dexamethasone, a steroid, reduces swelling in the brain and other areas, reversing the effects of altitude sickness. Both medications should be used cautiously and under a doctor's guidance due to potential side effects. They can be combined, but no other drugs have proven effective for altitude sickness prevention. This overview does not cover acute mountain sickness (AMS) or acclimatization in depth. For more detailed information, refer to the specific entries on Acute Mountain Sickness (AMS) and Acclimatization.
