What are the physiological effects of high altitude on the human body at Mount Everest?

From the Guidelines

Mount Everest climbers should prioritize proper acclimatization and consider medications like acetazolamide to prevent altitude sickness, as the mountain's extreme altitude poses significant physiological challenges, including hypoxia, altitude sickness, and increased risk of pulmonary edema and cerebral edema. The physiological effects of high altitude on the human body are complex and involve multiple systems, including the respiratory, cardiovascular, and nervous systems. At high altitudes, the body responds to hypoxia by increasing respiratory rate, heart rate, and red blood cell production, which can help compensate for the reduced oxygen availability 1. However, these adaptations take time to develop, and climbers who ascend too quickly are at risk of developing altitude sickness, which can manifest as acute mountain sickness (AMS), high-altitude pulmonary edema (HAPE), or high-altitude cerebral edema (HACE) 1.

Some key points to consider when climbing Mount Everest include:

• Proper acclimatization is essential to prevent altitude sickness, and climbers should ascend gradually with rest days at intermediate elevations
• Medications like acetazolamide can help prevent altitude sickness by increasing ventilation and reducing alkalosis
• Supplemental oxygen becomes necessary above 26,000 feet in the "death zone" where sustained human life is impossible without it
• Climbers should be aware of the risks of pulmonary edema and cerebral edema, and seek medical attention immediately if symptoms develop
• The body's response to high altitude is influenced by multiple factors, including age, sex, and underlying medical conditions, and climbers should be aware of their individual risk factors 1.

In terms of specific medications and treatments, the following may be considered:

• Acetazolamide (Diamox) at 125-250mg twice daily to prevent altitude sickness
• Dexamethasone (4mg every 6 hours) to treat cerebral edema
• Nifedipine (10mg every 8 hours) to treat pulmonary edema
• Supplemental oxygen as needed to prevent hypoxia and related complications.

Overall, climbing Mount Everest is a significant undertaking that requires careful planning, preparation, and attention to the physiological challenges posed by high altitude. By prioritizing proper acclimatization and considering medications and treatments as needed, climbers can reduce their risk of altitude sickness and other complications, and increase their chances of a successful and safe climb 1.

From the Research

Mount Everest and Physiology

• Mount Everest, the highest mountain in the world, poses significant physiological challenges to climbers due to its high altitude.
• At high altitudes, the air pressure is lower, which means that there is less oxygen available to breathe 2, 3.
• This can lead to a range of health problems, including acute mountain sickness (AMS), high-altitude pulmonary edema (HAPE), and high-altitude cerebral edema 2, 4, 3.

Acute Mountain Sickness (AMS)

• AMS is a common problem at high altitudes, characterized by symptoms such as headache, nausea, fatigue, and shortness of breath 2, 5, 4.
• The risk of AMS can be reduced by ascending gradually, allowing the body to acclimatize to the higher altitude 5, 3.
• Medications such as acetazolamide and dexamethasone can also be used to prevent and treat AMS 2, 5, 4, 3.

High-Altitude Pulmonary Edema (HAPE)

• HAPE is a more serious condition that can occur at high altitudes, characterized by fluid buildup in the lungs 2, 4, 3, 6.
• The risk of HAPE can be reduced by ascending gradually and using medications such as nifedipine and dexamethasone 3, 6.
• Acetazolamide may also have some benefit in reducing the risk of HAPE, although the evidence is not conclusive 6.

Prevention and Treatment

• The best way to prevent AMS and HAPE is to ascend gradually and allow the body to acclimatize to the higher altitude 5, 3.
• Medications such as acetazolamide and dexamethasone can be used to prevent and treat AMS, while nifedipine and dexamethasone can be used to prevent and treat HAPE 2, 5, 4, 3, 6.
• In severe cases, immediate descent and/or the administration of oxygen may be necessary to treat AMS and HAPE 2, 3.