Mountain Sickness

Mountain sickness, first described and named by the Spaniard Acosta, who observed it in himself and his companions in the mountains of Peru. He was also the first to recognize the cause of the disease in the rarefied state of mountain air. Mountain sickness is connected not only with ascents into mountains, but generally develops with ascents to great heights (e.g., among balloonists, as well as in a chamber with rarefied air). The disease has been observed at an altitude of 2,150 feet above sea level, but usually develops at an altitude of 4,000-5,000 m. Only very few people can ascend to 6,000-7,000 and even 7,250 m without significant health disturbances. This difference depends not only on the individuality and behavior of different people, but also on the additional influences of the mountain climate. For example, ascents in the Alps and Caucasus are tolerated more difficultly than in the Andes and especially in the Himalayas. Ascents by balloon and rarefaction of air in a chamber are tolerated more easily. Mountain sickness occurs not only in humans, but also in animals. Symptoms of mountain sickness. Depending on certain conditions, the disease can manifest in different forms. If the ascent into the mountains is made on foot, then excessive muscle weakness appears first. Shortness of breath and palpitations develop. Dizziness, nausea, vomiting, and fainting occur. Body temperature sometimes rises to feverish levels (by 0.3-1.7°). In the most severe cases, nasal, pulmonary, and other hemorrhages appear. At rest, these phenomena mostly pass quickly. In the case of mountain sickness developing under conditions of rest (ascent by balloon, to mountains by railway), cerebral phenomena predominate. General weakness and drowsiness develop. The will weakens, apathy sets in. Thinking is difficult. Appetite may disappear completely. Sometimes Cheyne-Stokes breathing develops, a feeling of heaviness in the head and mild pain in the forehead and temples. When attempting any physical movements, the picture changes: extreme weakness and dizziness immediately appear, headache joins in, a feeling of the head being constricted by a hoop, suffocation, palpitations, sometimes nausea. Physiological data. The volume of respiratory ventilatory air in mountain sickness is increased in most cases, but with fatigue of the respiratory muscles and with decreased excitability of the respiratory center, it can also decrease. In more severe cases, decreased excitability of the respiratory center is expressed in the appearance of Cheyne-Stokes breathing. Cold, wind, bright light, and ultraviolet rays at high altitudes stimulate respiration and thus contribute to increased absorption of O₂. But these same factors, by increasing metabolism, also increase the body's need for O₂, and this need may not be covered by increased absorption of O₂. The heart in mountain sickness easily expands. The pulse becomes small, usually quickens, more rarely slows down. Experiments on animals subjected to air with low O₂ content showed that in them small vessels in the lungs, liver, adrenal glands, and other organs greatly expand, and hemoglobinuria may appear. These phenomena make understandable the hemorrhages observed in severe cases of mountain sickness and connect them with oxygen deficiency. Under mountain altitude conditions to this is added the influence of dry air and cold. The expenditure of protein in the body in mountain sickness increases, and the nitrogen balance is negative. The same was found in animals when inhaling air with low O₂ content. Urine becomes rich under-oxidized products, the percentage of ammonia relative to the total nitrogen in urine increases, the alkaline reserve of blood decreases. In the liver of animals, the amount of residual nitrogen increases. These findings are consistent with the degenerative phenomena in the liver in such animals. Causes of mountain sickness. The totality of observations on mountain sickness and related physiological research forces most authors (Zuntz, Loewy, Kestner) to join the long-expressed view of Bert (P. Bert) and see the cause of mountain sickness in the oxygen starvation of the body. This starvation is caused by the discrepancy between the body's need for oxygen and its presence in the rarefied air. At an altitude of 4,560 m, Zuntz and Loewy found the oxygen pressure in alveolar air to be only 38-61 mm Hg instead of the normal 101-109 mm; meanwhile, the stimulating factors of the mountain climate require an increased delivery of O₂ to the body compared to the usual norm. Besides many facts cited earlier, a weighty argument in favor of this view of the origin of mountain sickness is the healing effect of inhaling O₂, under the influence of which all symptoms of the disease usually quickly disappear. Another interpretation of the phenomena of mountain sickness is given by the known theory of Mosso. Cases of the absence of a beneficial effect from inhaling O₂ in mountain sickness and, conversely, relief from it under the influence of small muscle movements led Mosso to seek the cause of the disease not in a deficiency of O₂, but in a decrease in the content of CO₂ in the blood, which is observed at high altitudes. This state of the body he called acapnia (see) and considers it a primary phenomenon arising under the influence of the rarefied state of the air. Since CO₂ is a strong stimulant for the heart and respiratory center, acapnia, according to Mosso, should lead to disorders of circulation and respiration. The sometimes observed beneficial effect of muscular work Mosso connects with the enrichment of the blood with CO₂. Inhaling CO₂ (according to experiments by Mosso and Loewy) also acts beneficially in mountain sickness. However, it has been established that for stimulating respiration and circulation, it is not the amount of CO₂ in the blood that is important, but its tension. The decrease in the latter, as it turns out, is not always encountered at high altitudes, and no parallelism has been found between this decrease and the development of mountain sickness. The decrease in CO₂ is explained more simply as a result of increased respiration (hyperventilation) under the influence of oxygen deficiency, and is thus a secondary phenomenon. - Phenomena of adaptation to high altitudes. In people and animals remaining at high altitudes for a long time, adaptation to the rarefied air gradually develops, and they cease to suffer from mountain sickness. Adaptation begins to manifest itself after a few days, but full acclimatization requires months (Poppig). The mechanism of adaptation consists in deepening of respiration, in increased work of the heart, and in an increase in the number of erythrocytes and Hb (Zuntz and Loewy and others). The increase in the number of erythrocytes and the amount of Hb is initially relative, but later it becomes absolute. This is proven by changes in the bone marrow, abundant increase in erythrocytes with granulo-filamentous substance in the blood, and an increase in the absolute amount of hemoglobin in the body. Dangers of high altitudes. High altitudes place increased demands on the viability and adaptability of the organism. Here already at rest the organism is constantly in a state of increased vital activity, and in case of work its expenditures are excessively increased, exceeding the amount of energy that is expended for the same work in lowlands. Blood pressure increases in this case and can reach high figures. Staying at high altitudes is therefore a more or less heavy load even for strong and acclimatized people. It is not surprising, therefore, that according to Mosso, among native mountain dwellers, especially men, heart diseases occur more frequently than among those living in lowlands. The effect of altitudes should be even more unfavorable on people who, due to their constitution or as a result of certain diseases, are less adapted to struggle with the deficiency of O₂. These include, for example, people of weak build and elderly age, people suffering from severe anemia, acute inflammatory conditions of the respiratory tract and lungs, emphysematics, cardiac patients, hypertensives (especially with renal insufficiency), gout sufferers. Even those small altitudes (up to 2 thousand m), which due to their moderate stimulating properties act beneficially on other patients and on healthy people, in these cases prove harmful and even dangerous. Besides the easily occurring general phenomena of O₂ deficiency, staying at these altitudes in these cases can particularly sharply affect the state of the cardiovascular apparatus. Prevention and treatment of mountain sickness. All measures for the prevention of mountain sickness are based on the maximum provision of tissues with oxygen. They can be presented in the form of the following rules. 1. Before ascending to great altitudes, training at medium altitudes is useful. 2. The ascent should be made slowly and gradually, frequent rests and stops are necessary. 3. It is more useful to make ascents on horseback, and not on foot and not on a rapidly moving train. 4. Breathing should be calm and deep, conversations should be avoided. 5. Do not make ascents in a state of fatigue or after a poorly spent night. 6. Protect oneself from intense sunlight and avoid conditions of overheating. 7.

Ensure adequate and appropriate nutrition: during the journey—frequent, very light meals; the main meal at the campsite—after rest and not abundant; the food should be easily digestible and not impede breathing due to its volume or subsequent development of intestinal gases. 8. Clothing should be warm, light, and not constricting the body. 9. Great positive importance is attached to good psychological condition (cheerfulness of spirit, faith in one's own strength), and the presence of a guide. Empirically, natives chew coca leaves (Bolivia, Peru), eat sour fruits, rub the mouth, nose, and ears with garlic, and other stimulating agents. In case of already occurring symptoms of Mountain Sickness, rest is primarily recommended, which is sometimes sufficient for the symptoms of Mountain Sickness to disappear. In more severe cases, repeated inhalation of oxygen—pure or, better, with the addition of a few percent of carbon dioxide—is used. Severe headache is relieved by phenacetin and similar preparations. In extreme cases, when all measures prove unsuccessful, according to Tsunts and Levi, the last resort remains descending to lower altitudes in order to, after some time, again attempt the ascent.