Signs and nature of the effects of mountain sickness

Mountain sickness can manifest itself suddenly, especially in cases where a person has significantly exceeded the limits of his individual tolerance in a short period of time, or has experienced excessive overexertion in conditions of oxygen starvation. However, most often, mountain sickness develops gradually. Its first signs are general fatigue, regardless of the amount of work performed, apathy, muscle weakness, drowsiness, malaise and dizziness. If a person continues to remain at altitude, then the symptoms of the disease increase: digestion is disturbed, frequent nausea and even vomiting are possible, respiratory rhythm disorder, chills and fever appear. The healing process is quite slow.

In the early stages of the disease, no special treatment measures are required. Most often, after active work and proper rest, the symptoms of the disease disappear - this indicates the onset of acclimatization. Sometimes the disease continues to progress, moving into the second stage - chronic. Its symptoms are the same, but expressed to a much stronger degree: the headache can be extremely acute, drowsiness is more pronounced, the vessels of the hands are overflowing with blood, nosebleeds are possible, shortness of breath is pronounced, the chest becomes wide, barrel-shaped, increased irritability is observed, and loss of consciousness is possible. These signs indicate a serious illness and the need for urgent transportation of the patient downstairs. Sometimes the listed manifestations of the disease are preceded by a stage of excitement (euphoria), very reminiscent of alcohol intoxication.

The mechanism of development of mountain sickness is associated with insufficient oxygen saturation of the blood, which affects the functions of many internal organs and systems. Of all the body tissues, the nervous tissue is the most sensitive to oxygen deficiency. In a person who finds himself at an altitude of 4000-4500 m and is prone to mountain sickness, as a result of hypoxia, excitement first arises, expressed in the appearance of a feeling of complacency and personal strength. He becomes cheerful and talkative, but at the same time loses control over his actions and cannot really assess the situation. After some time, a period of depression sets in. Cheerfulness is replaced by gloominess, grumpiness, even pugnacity, and even more dangerous attacks of irritability. Many of these people do not rest in their sleep: sleep is restless, accompanied by fantastic dreams that have the nature of forebodings.

At high altitudes, hypoxia has a more serious effect on the functional state of higher nerve centers, causing dulling of sensitivity, impaired judgment, loss of self-criticism, interest and initiative, and sometimes memory loss. The speed and accuracy of the reaction noticeably decreases; as a result of the weakening of internal inhibition processes, coordination of movements is disrupted. Mental and physical depression appears, expressed in slowness of thinking and action, a noticeable loss of intuition and the ability to think logically, and changes in conditioned reflexes. However, at the same time, a person believes that his consciousness is not only clear, but also unusually sharp. He continues to do what he was doing before he was seriously affected by hypoxia, despite the sometimes dangerous consequences of his actions.

The sick person may develop an obsession, a feeling of the absolute correctness of his actions, intolerance to critical remarks, and this, if the group leader, a person responsible for the lives of other people, finds himself in such a state, becomes especially dangerous. It has been noticed that under the influence of hypoxia, people often make no attempts to get out of an obviously dangerous situation.

It is important to know what the most common changes in human behavior occur at altitude under the influence of hypoxia. Based on the frequency of occurrence, these changes are arranged in the following sequence:

- disproportionately large efforts when performing a task;

—a more critical attitude towards other travel participants;

-reluctance to do mental work;

-increased irritability of the senses;

- touchiness;

—irritability when receiving comments about work;

-difficulty concentrating;

-slowness of thinking;

- frequent, obsessive return to the same topic;

- difficulty remembering.

As a result of hypoxia, thermoregulation can also be disrupted, which is why, in some cases, at low temperatures, the body’s heat production decreases and at the same time, its loss through the skin increases. Under these conditions, a person suffering from altitude sickness is more susceptible to chilling than other participants in the trip. In other cases, chills and an increase in body temperature by 1 - 1.5 C may occur.

Hypoxia also affects many other organs and systems of the body.

Respiratory organs. If at rest a person at altitude does not experience shortness of breath, lack of air or difficulty breathing, then during physical activity at high altitudes all these phenomena begin to be noticeably felt. For example, one of the participants in the ascent to Everest took 7-10 full inhalations and exhalations for each step at an altitude of 8200 meters. But even at such a slow pace of movement, he rested for up to two minutes every 20-25 meters of the way. Another participant in the climb, in one hour of movement and being at an altitude of 8500 meters, climbed a fairly easy section to a height of only about 30 meters.

Performance. It is well known that any muscular activity, and especially intense activity, is accompanied by an increase in blood supply to the working muscles. However, if in plain conditions the body can provide the required amount of oxygen relatively easily, then with an ascent to a high altitude, even with the maximum use of all adaptive reactions, the supply of oxygen to the muscles is disproportionate to the degree of muscle activity. As a result of this discrepancy, oxygen starvation develops, and under-oxidized metabolic products accumulate in the body in excess quantities. Therefore, a person’s performance decreases sharply with increasing altitude. So (according to E. Gippenreiter) at an altitude of 3000 m it is 90%, at an altitude of 4000 m - 80%, 5500 m - 50%, 6200 m - 33% and 8000 m - 15-16% of the maximum level of work performed at sea level.

Even after the end of work, despite the cessation of muscle activity, the body continues to be under tension, consuming an increased amount of oxygen for some time in order to eliminate the oxygen debt. It should be noted that the time during which this debt is eliminated depends not only on the intensity and duration of muscle work, but also on the degree of training of the person.

The second, although less important, reason for the decrease in the body's performance is overload of the respiratory system. It is the respiratory system, by increasing its activity up to a certain time, that can compensate for the sharply increasing oxygen demand of the body in a rarefied air environment.

Table 1

However, the capabilities of pulmonary ventilation have their own limit, which the body reaches before the maximum performance of the heart occurs, which reduces the required amount of oxygen consumed to a minimum. Such limitations are explained by the fact that a decrease in the partial pressure of oxygen leads to increased pulmonary ventilation, and therefore to increased “washing out” of CO₂ from the body. But a decrease in the partial pressure of CO₂ reduces the activity of the respiratory center and thereby limits the volume of pulmonary ventilation.

At altitude, pulmonary ventilation reaches maximum values ​​even when performing an average load for normal conditions. Therefore, the maximum amount of intensive work in a certain time that a tourist can perform in high altitude conditions is less, and the recovery period after work in the mountains is longer than at sea level. However, with a long stay at the same altitude (up to 5000-5300 m), due to acclimatization of the body, the level of performance increases.

Digestive system. At altitude, appetite changes significantly, the absorption of water and nutrients, the secretion of gastric juice decreases, the functions of the digestive glands change, which leads to disruption of the processes of digestion and absorption of food, especially fats. As a result, the person suddenly loses weight. Thus, during one of the expeditions to Everest, climbers who lived at an altitude of more than 6000 m for 6-7 weeks lost weight from 13.6 to 22.7 kg. At altitude, a person may feel an imaginary feeling of fullness in the stomach, distension in the epigastric region, nausea, and diarrhea that cannot be treated with medication.

Vision. At altitudes of about 4500 m, normal visual acuity is possible only at a brightness 2.5 times greater than normal for flat conditions. At these altitudes, there is a narrowing of the peripheral field of vision and a noticeable “fogging” of vision as a whole. At high altitudes, the accuracy of gaze fixation and the correctness of determining distance also decreases. Even in mid-altitude conditions, vision weakens at night, and the period of adaptation to darkness lengthens.

As hypoxia increases, pain sensitivity decreases until it is completely lost.

Dehydration of the body. The excretion of water from the body, as is known, is carried out mainly by the kidneys (1.5 l of water per day), skin (1 l), lungs (about 0.4 l) and intestines (0.2-0.3 l). It has been established that the total water consumption in the body, even in a state of complete rest, is 50-60 g per hour. With average physical activity in normal climatic conditions at sea level, water consumption increases to 40-50 grams per day for every kilogram of a person’s weight. In total, on average, under normal conditions, about 3 liters of water are released per day. With increased muscle activity, especially in hot conditions, the release of water through the skin increases sharply (sometimes up to 4-5 liters). But intense muscular work performed in high altitude conditions, due to a lack of oxygen and dry air, sharply increases pulmonary ventilation and thereby increases the amount of water released through the lungs. All this leads to the fact that the total loss of water among participants in difficult high-altitude trips can reach 7-10 liters per day.

Statistics show that in high altitude conditions, the incidence of respiratory diseases more than doubles. Inflammation of the lungs often takes on a lobar form, is much more severe, and the resorption of inflammatory foci is much slower than in plain conditions.

Pneumonia begins after physical fatigue and hypothermia. In the initial stage, there is poor health, some shortness of breath, rapid pulse, and cough. But after about 10 hours, the patient’s condition sharply worsens: the respiratory rate is over 50, the pulse is 120 per minute. Despite taking sulfonamides, pulmonary edema develops within 18-20 hours, which poses a great danger in high altitude conditions. The first signs of acute pulmonary edema: dry cough, complaints of compression slightly below the sternum, shortness of breath, weakness during physical activity. In serious cases, hemoptysis, suffocation, severe disturbance of consciousness occur, followed by death. The course of the disease often does not exceed one day.

The formation of pulmonary edema at altitude is usually based on the phenomenon of increased permeability of the walls of the pulmonary capillaries and alveoli, as a result of which foreign substances (protein masses, blood elements and microbes) penetrate into the alveoli of the lungs. Therefore, the useful capacity of the lungs is sharply reduced within a short time. Hemoglobin in arterial blood, washing the outer surface of the alveoli, filled not with air, but with protein masses and blood elements, cannot be adequately saturated with oxygen. As a result, a person quickly dies from insufficient (below the permissible norm) oxygen supply to the body’s tissues.

Therefore, even in the case of the slightest suspicion of a respiratory disease, the group must immediately take measures to bring the sick person down as quickly as possible, preferably to altitudes of about 2000-2500 meters.