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Lower Dolpo Trekking

Altitude sickness

What is altitude sickness?
Altitude sickness (also known as acute mountain sickness) is the name given to the physiological reactions of the human body (answers) that occur after exposure to low oxygen tension that exists at high altitude. As we climb in altitude, there is a gradual decrease in the atmospheric pressure and the partial pressure of oxygen in the air we breathe. Oxygen is essential for life and his sudden decline creates significant changes which, if sustained for too long, can even cause death. For this reason, during the climbing of the mountain, one must have several periods of acclimatization so that their body gets used to the low oxygen pressures.
When can I get altitude sickness?
The first symptoms of altitude sickness can begin to feel 2 500-3 000 meters. A man cannot live at an altitude of 5000 meters; he would eventually die because of problems at this stage. Therefore, the risk of altitude sickness in areas such as the mountains of Nepal and the Andes, where the tourist areas can be found at an altitude between 3000 and 4000 meters, is real. Every year there are at least seven deaths related to altitude in Nepal. The mortality rate is about 4%, with peak altitudes above 7000 meters.
Predisposing Factors
The high incidence of the disease varies considerably from one individual to another (individual variability). Some people are better suited than others to rapid ascents. Other influencing factors are speed climbing (the faster it is, the more the disease may occur), the length of stay at a certain height, continuous exercise at high altitude and age (young people older are more prone). Altitude sickness is not dependent on the physical form of the person and can affect even the most experienced athletes.
By lowering the pressure of oxygen in the inspired air and, consequently, in the blood, the body launches a series of mechanisms to bring more oxygen to the cells. It increases respiration and pulse and the pumping efficiency of the heart and the number of red blood cells (blood cells responsible for the ability to carry oxygen). However, the reduction of oxygen has a number of unintended consequences: increased pressure in the pulmonary circulation (pulmonary hypertension), changes in the values of blood pH (acidity), the change in the balance between fluid and electrolyte (salts) and the passage and the blood or fluid surrounding tissues (extravasation and edema fluid). Altitude sickness occurs during a rapid rise to a certain height, and you stay at this height without proper acclimatization.
How can I prevent altitude sickness?
Make a gradual ascent. First and foremost you have to climb relatively slowly, with adequate acclimatization periods at a given height (from 2000 m) before spending the night at a greater altitude. The recommended climb speed is as follows: up to 5000 meters: an average of 340-400 meters more per day of 5000 m to 6000 m, up to 250 meters per day, and over 6,000 m, up to a maximum of 150-200 m per day. In case of problems, it is necessary to descend to a lower level, to acclimatize and rest for 24 or 48 hours before resuming the climb. 
Drink plenty of fluids (at least 3 or 4 liters).
Avoid alcohol.
Food: rich in sugars and starches in particular.
Avoid getting cold.
Altitude sickness can be avoided to some extent with a drug called acetazolamide, at doses of 250 mg/12 hours or 500 mg as a single dose in the evening. Some experts suggest that because of the possible side effects of medication, it is best to do two days of testing before the trip. Possible side effects include nausea, taste disturbance, tingling in the hands and feet, frequent and copious urination, blurred vision and a rash. Using this medicine does not mean you can ignore the advice to climb slowly.
Danger signals for altitude sickness
The signs usually develop within 36 hours. They affect more than 50% of travellers over 3500 meters. A slight headache which disappears with analgesics (paracetamol, aspirin, etc).
Nausea and malaise
Difficulty sleeping
If these symptoms occur below 3000 meters above sea level you should stop and rest for a few days before continuing to climb. At heights of 3500 meters, try to get from 300 to 500 meters, and stay there for two days before continuing your ascent.
Severe symptoms of altitude sickness
A severe headache and severe pain, vomiting.
Nausea marked
Dizziness, incoordination, visual impairment
Thoracic pressure, rapid breathing and a feeling of breathlessness
Swelling or edema, usually around the eyes and in some cases, ankles and hands
Decreased urination
Confusion, disorientation. 
Psychological changes (indifference, loss of sense of danger, etc.).
When these symptoms occur, you should immediately consult a doctor and get off as quickly as possible.
Serious forms of altitude sickness
There are two severe forms of altitude sickness. They may be preceded by mild symptoms (headache, insomnia, lack of appetite, light-headedness) or suddenly appear in a previously healthy climber due to a steep rise or executed quickly. Both have a high mortality rate.
They are:
HAPE - high altitude pulmonary edema (fluid in the lungs).
OCHA - high altitude cerebral edema (fluid in the brain).
The high-altitude pulmonary edema (HAPE)
The symptoms of HAPE are serious and include severe respiratory distress, dry cough, bloody sputum, pressure or chest pain, palpitations and fatigue. You can hear a bubbling noise during breathing (pulmonary edema). The lips, the outer edges of the ears and nails may look blue (cyanotic) due to a lack of oxygen.
The high-altitude cerebral edema (OCHA)
This is the altitude sickness most severe and faster. The symptoms of HACE are mainly nausea, vomiting, headache, visual disturbances, irritability, disorganization, inattention, confusion, unconsciousness, convulsions and even coma.
If symptoms are mild, resting at the same altitude for 24-48 hours with proper hydration and a diet rich in carbohydrates is usually sufficient. Continue climbing should be prohibited for people with symptoms of altitude sickness, even minor ones, because they can develop into more severe forms.
If symptoms are more severe or worsen, you should immediately begin to descend, always accompanied. Sometimes a drop of 400 meters is usually sufficient to see an improvement.
Another measure is to be administered by an oxygen mask, the amount of 3 to 5 liters per minute at a concentration of at least 40%. For the treatment of headaches, minor pain relievers can be used (paracetamol, aspirin, etc.). As for insomnia, especially if it is caused by periodic pauses in breathing, it must be treated with acetazolamide, but never with hypnotics or sedatives such as those used for sleeping, as they can aggravate breathing more.
If a doctor is available, it can administer medication as needed. The drug does not replace the need to descend.
Who should never be exposed to high altitude?
People with heart problems / lung (angina pectoris, chronic bronchitis, emphysema, and some people with severe asthma among others).
People with anemia, including sickle cell anemia (low hemoglobin in the blood).
People with bleeding disorders with or without treatment and with a history of thrombosis (blood clots).
People who have had HAPE or OCHA before.
Who should be careful at high altitudes?
People with heart disease / lung successfully treated.
Pregnant women
People with high blood pressure
People prone to apnea sleep.
People who have had HAPE or OCHA before.
Other issues to consider in the mountains are sunburn, temporary blindness caused by snow (ophthalmic) cold and frost.