Altitude sickness – causes, symptoms & therapy

Altitude sickness is not only a problem for mountaineers. The ailment – called soroche – is also constantly present for residents of high regions of South America. Tibetans, on the other hand, are protected against altitude sickness by a naturally increased respiratory rate.

The complex of unspecific symptoms, which clearly indicate altitude sickness at high altitudes, includes headaches, gastrointestinal symptoms, shortness of breath, physical weakness and disturbances of consciousness. At extreme altitudes, altitude sickness can be accompanied by life-threatening accumulations of fluid in the lungs and brain (altitude cerebral edema and high-altitude pulmonary edema).

causes

Altitude sickness is caused by a pressure-related disruption in gas exchange in the lungs. The exchange of oxygen, carbon dioxide and water vapor at the border between blood and breathing air in the pulmonary alveoli is finely tuned to the air pressure conditions that prevail at the altitudes at which people normally live. The same applies to the normal concentrations of oxygen and carbon dioxide in the blood and tissues.The rapid change to other pressure conditions – be it extreme altitudes or even increased pressure during diving – upsets this balance and causes symptoms of illness. In the case of altitude sickness, the reduced oxygen partial pressure together with the general air pressure means that not enough oxygen can be absorbed through the lungs. The body reacts to the lack of oxygen with an increased respiratory rate and vasoconstriction to increase blood pressure.

At the same time, the carbon dioxide partial pressure in the outside air, which is also reduced, means that more carbon dioxide is emitted via the lungs and the carbon dioxide concentration in the blood decreases. Furthermore, altitude sickness is often characterized by dehydration , which is caused by the increased exhalation of water vapor, which is also caused by the low air pressure.

symptoms and course

Typical symptoms of altitude sickness:

• high blood pressure

• high pulse

• shortness of breath

• headache

• loss of appetite

• nausea

• muscle cramps

• disturbances of consciousness

• Edema under the skin

• dry cough

• tachycardia

• dizziness

• sleep disorders

• difficulty breathing

The majority of the symptoms of altitude sickness are caused by the lack of oxygen and the associated reduction in physical and mental performance. Lack of oxygen causes high blood pressure, increased heart rate, shortness of breath, headaches, loss of performance, loss of appetite and nausea.

The lowering of the carbon dioxide content of the blood brings with it a so-called respiratory alkalosis, an increase in the pH value of the blood. This can result in muscle cramps and clouded consciousness. Dehydration also contributes to a reduction in performance and also leads to a reduction in kidney function, the maintenance of which would be important for the regulation of alkalosis.

Another sign of altitude sickness is some bloating caused by edema – accumulation of water under the skin. The cause here is probably the increased blood pressure. In the worst case, edema can also develop in the brain and lungs.

Constant, severe headaches, severe nausea, severe drop in performance, dry cough, shortness of breath at rest, tachycardia, reduced urge to urinate, clouded consciousness, dizziness and insomnia are warning signs of a threatening altitude sickness.

Diagnose

Altitude sickness is easily recognized by its symptoms associated with being at high altitudes. A complex diagnosis is not necessary. Depending on the severity of the symptoms, an appropriate response must be taken immediately.

complications

Altitude sickness can cause a number of complications. First, the lack of oxygen leads to hyperventilation , which is accompanied by headaches, confusion and impaired consciousness. In addition, dehydration occurs and, as a result, impaired kidney performance. In extreme cases, kidney failure can occur, resulting in high blood pressure, oedema, gastrointestinal problems and cramps. In severe cases, altitude sickness can trigger pronounced breathing disorders such as Cheyne-Stokes breathing.

Depending on the altitude, breathing may stop completely. If the altitude sickness remains untreated, there is an acute risk of suffocation for those affected. Sometimes life-threatening edema develops, which is associated with serious complications. Many of those affected suffer from severe brain damage as a result of altitude sickness, which usually remains permanent.

Treating altitude sickness also carries risks. The drugs that are usually administered can have a large number of side effects and interactions. Typical symptoms are dizziness, tinnitus , itching and a drop in blood pressure (due to antihypertensive drugs such as acetazolamide) as well as asthma or damage to the gastric mucosa (due to anti-inflammatory painkillers such as Arthotec or Vimovo). Natural antidotes such as coca leaves or butter tea can also cause side effects.

treatment and therapy

In the case of mild to moderate symptoms of altitude sickness, an interruption of the ascent and a longer rest is sufficient. Headaches can be treated with ibuprofen . A remedy for nausea and medication to lower blood pressure can make it easier for the body to adapt to the unfamiliar altitude conditions. However, a doctor should be consulted about the medication beforehand, and their tolerability may also be tested in advance.

If the symptoms have not completely disappeared after a day, you should descend to lower altitudes. Immediate descent, accompanied if possible, is indicated in the case of severe symptoms. In the case of acutely threatening symptoms such as a persistent cough, rattling, heavy breath , bluish lips and confusion , immediate evacuation to the lowest possible altitude is vital. In this case, the mountain rescue service should be alerted immediately.

Medical monitoring, supplemental oxygen, and medication such as dexamethasone to treat the edema are now essential. If the descent is not fast enough, staying in a portable hyperbaric chamber can help with acute altitude sickness.

prevention

When it comes to preventing altitude sickness, time is the gold standard. If at all possible, ascents should be made on foot and not by cable car or flight. Longer preparatory stays at altitudes between 2000 and 3000 meters give the body the opportunity to adapt to the new, less oxygenated conditions by producing more red blood cells. In addition, the daily gain in altitude should ideally not exceed 500 meters.To prevent dehydration, you should drink enough, but not too much. Furthermore, the preventive administration of antihypertensive medication (acetazolamide or nifedipine) is common, and under certain circumstances dexamethasone to prevent edema. The indigenous peoples of South America traditionally use coca leaves to combat altitude sickness.