High-Altitude Travel & Altitude Illness

High-Altitude Travel & Altitude Illness is a topic covered in the CDC Yellow Book.

To view the entire topic, please or .

Relief Central with Coronavirus COVID-19 Guidelnes is a free App with a companion website developed by the staff and friends of Unbound Medicine to assist relief workers, healthcare providers, first responders, and others called to serve in disaster relief situations around the world. Explore these free sample topics:

-- The first section of this topic is shown below --

High-Altitude Travel & Altitude Illness

Environments significantly above sea level expose travelers to cold, low humidity, increased ultraviolet radiation, and decreased air pressure, all of which can cause problems. The biggest concern, however, is hypoxia. At an elevation of 10,000 ft (3,000 m) above sea level, for example, the inspired PO2 is a little more than two-thirds (69%) what it is at sea level. The magnitude of hypoxic stress depends on elevation, rate of ascent, and duration of exposure. Sleeping at high elevation produces the most hypoxemia; day trips to high elevations with return to low elevation are much less stressful on the body. Typical high-elevation destinations include Cusco (11,000 ft; 3,300 m), La Paz (12,000 ft; 3,640 m), Lhasa (12,100 ft; 3,650 m), Everest Base Camp (17,700 ft; 5,400 m), and Kilimanjaro (19,341 ft; 5,895 m; see Chapter 10, Tanzania: Kilimanjaro).

The human body adjusts very well to moderate hypoxia, but requires time to do so (Box 3-5). The process of acute acclimatization to high elevation takes 3–5 days; therefore, acclimatizing for a few days at 8,000–9,000 ft (2,500–2,750 m) before proceeding to a higher elevation is ideal. Acclimatization prevents altitude illness, improves sleep and cognition, and increases comfort and well-being, although exercise performance will always be reduced compared to what it would be at lower elevations. Increase in ventilation is the most important factor in acute acclimatization; therefore, respiratory depressants must be avoided. Expanded red-cell production does not play a role in acute acclimatization, although hemoglobin concentration is increased within 48 hours because of diuresis and decreased plasma volume.

Box 3-5. Tips for acclimatization

  • Ascend gradually, if possible. Avoid going directly from low elevation to more than 9,000 ft (2,750 m) sleeping elevation in 1 day. Once above 9,000 ft (2,750 m), move sleeping elevation no higher than 1,600 ft (500 m) per day, and plan an extra day for acclimatization every 3,300 ft (1,000 m).
  • Consider using acetazolamide to speed acclimatization if abrupt ascent is unavoidable.
  • Avoid alcohol for the first 48 hours; continue caffeine if a regular user.
  • Participate in only mild exercise for the first 48 hours.
  • Having a high-elevation exposure (greater than 9,000 ft [2,750 m]) for 2 nights or more, within 30 days before the trip, is useful, but closer to the trip departure is better.

-- To view the remaining sections of this topic, please or --

High-Altitude Travel & Altitude Illness

Environments significantly above sea level expose travelers to cold, low humidity, increased ultraviolet radiation, and decreased air pressure, all of which can cause problems. The biggest concern, however, is hypoxia. At an elevation of 10,000 ft (3,000 m) above sea level, for example, the inspired PO2 is a little more than two-thirds (69%) what it is at sea level. The magnitude of hypoxic stress depends on elevation, rate of ascent, and duration of exposure. Sleeping at high elevation produces the most hypoxemia; day trips to high elevations with return to low elevation are much less stressful on the body. Typical high-elevation destinations include Cusco (11,000 ft; 3,300 m), La Paz (12,000 ft; 3,640 m), Lhasa (12,100 ft; 3,650 m), Everest Base Camp (17,700 ft; 5,400 m), and Kilimanjaro (19,341 ft; 5,895 m; see Chapter 10, Tanzania: Kilimanjaro).

The human body adjusts very well to moderate hypoxia, but requires time to do so (Box 3-5). The process of acute acclimatization to high elevation takes 3–5 days; therefore, acclimatizing for a few days at 8,000–9,000 ft (2,500–2,750 m) before proceeding to a higher elevation is ideal. Acclimatization prevents altitude illness, improves sleep and cognition, and increases comfort and well-being, although exercise performance will always be reduced compared to what it would be at lower elevations. Increase in ventilation is the most important factor in acute acclimatization; therefore, respiratory depressants must be avoided. Expanded red-cell production does not play a role in acute acclimatization, although hemoglobin concentration is increased within 48 hours because of diuresis and decreased plasma volume.

Box 3-5. Tips for acclimatization

  • Ascend gradually, if possible. Avoid going directly from low elevation to more than 9,000 ft (2,750 m) sleeping elevation in 1 day. Once above 9,000 ft (2,750 m), move sleeping elevation no higher than 1,600 ft (500 m) per day, and plan an extra day for acclimatization every 3,300 ft (1,000 m).
  • Consider using acetazolamide to speed acclimatization if abrupt ascent is unavoidable.
  • Avoid alcohol for the first 48 hours; continue caffeine if a regular user.
  • Participate in only mild exercise for the first 48 hours.
  • Having a high-elevation exposure (greater than 9,000 ft [2,750 m]) for 2 nights or more, within 30 days before the trip, is useful, but closer to the trip departure is better.

There's more to see -- the rest of this entry is available only to subscribers.