We all feel great when we reach high in the mountains after days of trekking or driving, but did you knew that there are risks attached to all the high altitude experiences? In this blog we will try to understand these risks.
What is Altitude?
In simple words, Altitude, is the distance above sea level. Altitude is related to air pressure. As the altitude rises, air pressure drops. In other words, the higher the altitude, lower the air pressure.
How high is ‘High Altitude?’
Have you ever wondered, how high is ‘High altitude?’ Areas that are above 8000 feet or 2400 meters are considered as "high-altitude". The altitude is defined on the following scale;
• High altitude 8,000 - 12,000 ft or 2,400 - 3,700 m,
• Very High 12,000 - 18,000 ft or 3,700 - 5,500 m, and
• Extremely High 18,000+ ft or 5,500+ m.
Since few people have been to such altitudes, it is hard to know who may be affected. There are no specific factors such as age, sex, or physical condition that correlate with susceptibility to altitude sickness. Some people get it and some people don't, and some people are more susceptible than others. Most people can go up to 8,000 feet or 2,400 meters with minimal effect.
Therefore, if you haven't been to high altitude before, it's important to be cautious. If you have been at that altitude before with no problem, you can probably return to that altitude without problems as long as you are properly acclimatized.
What happens at High altitude?
The concentration of oxygen at sea level is about 21% and the barometric pressure averages 760 mmHg. As altitude increases, the concentration remains the same but the number of oxygen molecules per breath is reduced. At 12,000 feet (3,700 meters) there are roughly 40% fewer oxygen molecules per breath. In order to properly oxygenate the body, your breathing rate (even while at rest) has to increase. This extra ventilation increases the oxygen content in the blood, but still not to the sea level concentrations. Since the amount of oxygen required for activity is the same, the body must adjust to having less oxygen.
This time that our body needs, is the time required for our body to acclimatize and continuing to higher altitudes without proper acclimatization can lead to potentially serious, even life-threatening mountain illnesses.
What is meant by Acclimatization?
Given time, your body can adapt to the decrease in oxygen molecules at a specific altitude. This process is known as acclimatization and generally takes 1-3 days at that altitude. For example, if you hike to 10,000 feet (3,000 meters), and spend several days at that altitude, your body acclimatizes to 10,000 feet (3,000 meters). If you climb to 12,000 feet (3,700 meters), your body has to acclimatize once again.
A number of changes take place in the body to allow it to operate with decreased oxygen.
• The depth of respiration increases.
• Pressure in pulmonary arteries is increased, "forcing" blood into portions of the lung which are normally not used during sea level breathing.
• The body produces more red blood cells to carry oxygen,
All these things take time and therefore it is said not to go too high too fast. Failure to acclimatize would lead to mountain sickness.
What is Acute Mountain Sickness (AMS)?
The physical distress occurring from difficulty in adjusting to lower oxygen pressure at high altitudes is called as Acute Mountain Sickness (AMS).
The occurrence of AMS is dependent upon the rate of ascent, and individual susceptibility. Many people will experience mild AMS during the acclimatization process. Symptoms usually start 12-24 hours after arrival at altitude and begin to decrease in severity about the third day. The symptoms of Mild AMS are headache, dizziness, fatigue, shortness of breath, loss of appetite, nausea, disturbed sleep, and a general feeling of malaise. Symptoms tend to be worse at night and when respiratory drive is decreased. Mild AMS does not interfere with normal activity and symptoms generally subside within 2-4 days as the body acclimatizes. As long as symptoms are mild, and only a nuisance, ascent can continue at a moderate rate. But if the symptoms become worse then, losing altitude as quickly as possible is the only solution to avoid life threatening situations.