Altitude Sickness

Altitude sickness, or Mountain Sickness, is a group of symptoms caused by the rapid ascent to a higher altitude. The usual symptoms are headache, nausea, weakness, fatigue, insomnia, shortness of breath and a general feeling of rottenness. They usually occur above altitudes of 2000 meters (6000 feet) and are caused not so much by the altitude itself as by the diminished amount of available oxygen. Age and general physical fitness seems to have little to do with whether or not one gets it. But there is a genetic predilection towards it.

Depending on the severity of symptoms the disease is divided into Acute Mountain Sickness, High Altitude Pulmonary Edema (HAPE) and High Altitude Cerebral Edema (HACE). The diminished level of oxygen first in the air and then in the blood causes the capillaries (small blood vessels) in the lungs to leak fluid into the surrounding tissues. As the lungs become stiffer and the heart works harder the pressure gradient becomes greater and the fluid leakage increases. The body's response to all this is to make you breathe harder (hyperventilate) and take in more oxygen. In the process, the body loses carbon dioxide and blood vessels dilate. This is what causes the light-headedness, insomnia, fatigue, headache and loss of appetite. Unchecked, these can progress to nausea and vomiting. This usually begins within 4-12 hours and will last 24-48 hours.

If the heart and lungs cannot keep up with demand, more fluid builds up in the lungs and it becomes increasingly impossible for oxygen to get through into the blood stream. The person becomes more and more short of breath, the heart rate increases and a dry cough develops.

After a few days the blood vessels in the head also become leaky allowing pressure to build up in the brain. This can lead to difficulty walking and a host of psychiatric symptoms progressing to coma and then death.

There is also a chronic form of altitude sickness called Monge's disease, which occurs in people who live at high altitudes for long periods of time. This consists of high blood pressure, chronic headaches, vision problems and depression.

As mentioned above, there seems to be a genetic predisposition to altitude sickness. Also, someone who has suffered from it before is apt to suffer from it again if exposed to an even lower altitude. Rapid ascent and too vigorous activity also make it more likely. This is why children and young people are just as apt to suffer as out-of-shape older adults. They are more apt to overexert, not realizing that a low oxygen level is a low oxygen level, regardless of one's physical conditioning. Obesity, with more tissue to perfuse and less lung space to use, also predisposes to altitude sickness. Being cold in addition to the altitude aggravates the situation further. And for some reason women are more apt to suffer than men.

The best prevention is to just allow oneself time to acclimatize. In other words, plan a couple of days to just sit and do nothing when you first arrive. A high carbohydrate/low protein diet may help as carbohydrates produce more carbon dioxide and cause one to naturally breath harder. Protein increases ones fluid requirements and diminishes the tolerance to cold. Avoid alcohol and, despite insomnia, avoid sedatives as all of these diminish respiration and delay the time to recovery.

A drug that stimulates deep breathing, Diamoxâ (acetazolamide), can help as well. The dose is one tablet (250 mg) three times a day the day before you leave home and your first day there then once daily for five days. This acidifies the blood, makes the kidneys work overtime and by several mechanisms causes one to breathe harder and thus get a head start on the problem. Other medicines that may be used are dexamethasone (a corticosteroid) and nifedipine (a blood vessel dilator.) These are harsher on the system, however, and have more side effects so are best saved for emergencies. Drinking a lot of fluids also helps to prevent mountain sickness and the best treatment for the headache is aspirin. Aspirin, ibuprofen and other non-steroidal analgesics should be used with caution at higher altitudes (over 14,000 feet) as they can cause damage to the retina in the presence of low oxygen levels.

One folk remedy commonly recommended in the Andes is coca tea.  Brewed from the leaves of the same plant from which cocaine comes, it is reported to prevent altitude sickness about two thirds of the time.  Since only about one in three people gets symptoms anyway, it probably has no actual medicinal value.  It also does not cause the “high” that cocaine does.  If it prevents mountain sickness at all, it is likely that the mode of action is simply that the person drinking it is sitting still and admiring the scenery rather than running up and down the mountainside.  Two warnings, though.  If will show up as cocaine on a drug test, so could get you in trouble.  And tea bags of coca leaves are just as illegal crossing international boundaries as cocaine.

Adequate rest and tincture of time is usually sufficient treatment for acute mountain sickness. Pulmonary edema and cerebral edema, however, demand a prompt descent to a lower altitude. Many times a descent of as little as 1000 feet will suffice. En route, giving oxygen and wrapping the patient in a Gamow bag will help the recovery.

Short stays at altitude present no special dangers to pregnant women. High altitude trekking, however, may predispose to altitude sickness far from medical care. Women who live at higher altitudes for most of their pregnancy are at increased risk for high blood pressure, premature delivery and small-for dates babies.