Prevent Altitude Sickness

 

Altitude Sickness

With increasing overseas travel and a growing interest in ‘adventure’ holidays, many people are concerned about the dangers of trekking or climbing in areas of high altitude. Altitude sickness is a very real problem that can be serious, and even life-threatening.

Causes of altitude sickness

Altitude sickness is caused by the relative lack of oxygen available from the air at high altitudes. This is due to the reduction in atmospheric pressure that occurs at high altitude compared with the pressure at sea level — the higher the altitude, the lower the atmospheric pressure.

In its mildest form, altitude sickness can occur at heights as low as 2000 metres; however, most people can ascend to 2000 metres in one day without getting sick.

Symptoms

Mild cases of altitude sickness usually involve headaches, nausea, breathlessness, palpitations (irregular or rapid heart beats) and reduced ability to exercise. This is called acute mountain sickness. It is quite common in visitors who are staying at ski resorts.

More serious forms of altitude sickness occur at higher altitude (usually defined as more than 3000 metres). In addition to the symptoms already mentioned, affected people may lose their appetite and have difficulty sleeping, and they may wake up frequently through the night due to ‘periodic’ breathing. Periodic breathing is when a person breathes normally then stops breathing for 10 to 15 seconds, which wakes them up.

Severe breathing difficulties, vomiting, frequent cough, lack of coordination and loss of consciousness are among the more serious symptoms. These serious forms of altitude sickness are called high altitude pulmonary oedema when the lungs are affected, and high altitude cerebral oedema when the brain is affected. Although both these conditions are uncommon, they are potentially fatal.Mild cases of altitude sickness usually involve headaches, nausea, breathlessness, palpitations (irregular or rapid heart beats) and reduced ability to exercise. This is called acute mountain sickness. It is quite common in visitors who are staying at ski resorts.

More serious forms of altitude sickness occur at higher altitude (usually defined as more than 3000 metres). In addition to the symptoms already mentioned, affected people may lose their appetite and have difficulty sleeping, and they may wake up frequently through the night due to ‘periodic’ breathing. Periodic breathing is when a person breathes normally then stops breathing for 10 to 15 seconds, which wakes them up.

Severe breathing difficulties, vomiting, frequent cough, lack of coordination and loss of consciousness are among the more serious symptoms. These serious forms of altitude sickness are called high altitude pulmonary oedema when the lungs are affected, and high altitude cerebral oedema when the brain is affected. Although both these conditions are uncommon, they are potentially fatal.

Risk Factors

There is no way of predicting who will, or will not, suffer from altitude sickness. Surprisingly, increased age, lack of fitness and illnesses such as asthma do not seem to make people more prone to the problem. Having had altitude sickness before does not mean that you will necessarily get it again; however, you will be more susceptible. Similarly, having been okay at high altitude previously does not guarantee that you will be okay next time.
Most people with chronic illnesses can safely travel to high altitudes, but some diseases make high altitude travel dangerous. Such diseases include sickle cell anaemia and severe lung or heart disease. If you have a chronic disease, talk to your doctor before undertaking high altitude travel.

Treating Altitude Sickness

The symptoms of acute mountain sickness will usually disappear in a few days without treatment if the person stays at the same altitude. Drinking plenty of fluids and taking pain killers (analgesics) for the headache may also help. A medicine called acetazolamide (brand name Diamox) may also be given to people who have mild to moderate symptoms, or a corticosteroid called dexamethasone may be given if symptoms are more severe.

People with serious altitude sickness need immediate descent, to be given oxygen, or to be put in a portable altitude chamber or bag (such as a Gamow bag). Air is pumped into the chamber or bag, which artificially puts the person at a higher atmospheric pressure and provides the same effect as descending. Although this may buy time, it is not a substitute for descent.

Several medicines may also be given to people with serious forms of altitude sickness. For example, dexamethasone may be used to treat both high altitude cerebral oedema and pulmonary oedema, and nifedipine, which is usually used to treat high blood pressure, may be used to treat high altitude pulmonary oedema.

Prevention

The best way to avoid altitude sickness is to ascend slowly, taking several days to get to the intended destination. This allows the body time to get used to the decreasing supply of oxygen available at high altitude and is a process is called acclimatisation. At high altitudes it can take three to five days for your body to acclimatise before you should ascend further.

If it is not possible to acclimatise — for example, if you are taking a short flight from sea-level to 3000 metres or more — acclimatisation can be helped by taking the medicine acetazolamide, which is started one day before the planned trip and continued for 2 to 3 days at altitude. Acetazolamide works by increasing a person’s breathing rate and helps with acclimatisation.

Other medicines, including nifedipine, dexamethasone, an asthma medicine called salmeterol (Serevent) and a medicine usually used to treat erectile dysfunction called tadalafil (Cialis), may also be used to prevent altitude sickness. Your doctor can advise if medicines are necessary or suitable for you.

It is important to stay hydrated when at high altitude. Dehydration is a contributing factor to altitude sickness. Much water is lost in the breath in cold, high altitudes, and also by evaporation through sweat, especially when undergoing activities such as skiing or trekking. It is also recommended that you avoid drinking alcohol or overexerting yourself for the first 24 hours at high altitude.

If you are planning a trip that involves ascending to high altitudes in a relatively short time, discuss potential problems with your doctor
 

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