Sunday, March 22, 2009

There is less oxygen in your blood in mountain- says research

There is less oxygen in your blood in mountain- says research
Dr. Nitish Priyadarshi

Climbers summiting Mount Everest have as little oxygen in their bloodstream as residents of coastal areas who are in cardiac arrest- or who have even dead. Four physicians from University College London trekked up Everest and drew their own blood for analysis. They found that because of the altitude, they had about a quarter less oxygen in their blood than is normal for people at sea level. The analysis also confirmed other effects of being at high altitudes, such as the increase in hemoglobin to ferry as much oxygen as possible.

The number of people travelling to the high altitude regions, especially South America, Nepal, and India, has risen enormously in the past 10 years. Without special climbing ability these trekkers can be exposed to altitudes they will not have encountered in their home countries.

In India tourists traveling towards remote areas of Leh and Laddakh region of Jammu and Kashmir state complain of breathlessness and fatigue.

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 (3,658 meters) the barometric pressure is only 483 mmHg, so 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 not to sea level concentrations. Since the amount of oxygen required for activity is the same, the body must adjust to having less oxygen. In addition, for reasons not entirely understood, high altitude and lower air pressure causes fluid to leak from the capillaries which can cause fluid build-up in both the lungs and the brain. Continuing to higher altitudes without proper acclimatization can lead to potentially serious, even life-threatening illnesses.
The major cause of altitude illnesses is going too high too fast. 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.
Lack of oxygen causes high-altitude sickness. As altitude increases, the air becomes "thinner," which means less oxygen is in the atmosphere. You get less oxygen in your lungs with each breath, so the amount of oxygen in your blood declines. (This is called hypoxia). All people can experience mountain sickness, but it may be more severe in people who have heart or lung problems.

What are the symptoms?
Symptoms usually begin within 48 hours of arriving at high altitude. The higher the altitude, the greater the effects. People can notice effects when they go to an altitude of 7,000 to 8,000 feet. If you have heart disease (such as heart failure) or lung disease (such as emphysema), you may have symptoms at lower altitudes. Symptoms include headaches, breathlessness, fatigue, nausea or vomiting, inability to sleep swelling of the face, hands and feet.
Both heart rate and breathing rate increase as the body tries to send more oxygen to its tissues. At very high altitudes, body fluid can leak into the brain (called brain or cerebral edema) or into the lungs (pulmonary edema). Both these conditions can be serious or even life-threatening.
How can we prevent high-altitude illness?
You can do two important things to prevent high-altitude illness:
1. Take your time traveling to higher altitudes. When you travel to a high altitude, your body will begin adjusting right away to the lower amount of oxygen in the air, but it takes several days for your body to adjust completely. If you're healthy, you can probably safely go from sea level to an altitude of 8,000 feet in a few days. But when you reach an altitude above 8,000 feet, don't go up faster than 1,000 feet per day. The closer you live to sea level, the more time your body will need to get used to a high altitude. Plan your trip so your body has time to get used to the high altitude before you start your physical activity.
2. Sleep at an altitude that is lower than the altitude you are at during the day. For example, if you ski at an elevation of 10,000 feet during the day, sleep the night before and the night after at an elevation of 8,500 feet.

L. Jordan, March 2009. Scientific American, India. pp.19
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