Altitude sickness Altitude sickness refers to the physiological reaction the body experiences when reaching a certain altitude (often above 2700 meters), characterized by difficulty in adapting to the high altitude due to changes such as dry air, exposure to ultraviolet radiation, and cold temperatures, leading to a decrease in air pressure and oxygen levels. This condition can trigger a series of symptoms and metabolic changes, and it is the most common type of high-altitude illness.

Altitude sickness refers to the physiological reaction the body experiences when reaching a certain altitude (often above 2700 meters), characterized by difficulty in adapting to the high altitude due to changes such as dry air, exposure to ultraviolet radiation, and cold temperatures, leading to a decrease in air pressure and oxygen levels. This can trigger a series of symptoms and metabolic changes, and it is the most common type of high-altitude illness. The main symptoms of altitude sickness include headache, dizziness, lightheadedness, ringing in the ears, insomnia, and fatigue. It may also include symptoms such as chest tightness, difficulty breathing, nausea, vomiting, palpitations, and edema. Most changes are physiological and tend to affect organ function less frequently.

Altitude sickness can be divided into acute and chronic types based on the course of the disease, both of which are functional disorders and generally do not affect work and daily life. Therefore, whether it is acute altitude sickness or chronic altitude sickness, it does not usually leave any sequelae.

Acute Altitude Sickness

It is a series of acute hypoxic reactions caused by the body's inability to adapt to the natural environment at high altitudes. It is a common and frequently occurring disease in high-altitude areas. If not treated in a timely manner, it can prolong the duration of altitude sickness and can lead to high-altitude pulmonary edema, high-altitude cerebral edema, and even life-threatening conditions. Usually, the symptoms of patients can gradually diminish or disappear within 2 weeks. In a very small number of patients, the symptoms of acute altitude sickness may persist for more than 3 months, leading to chronic altitude sickness.

Chronic Altitude Sickness

It is mostly due to the continuous presence of symptoms from acute altitude sickness. Some patients may have an insidious onset, with the disease occurring after more than 4 months at high altitude, and mild abnormalities in certain organs or systems may be observed, such as hypotension, reduced pulse pressure, and myocardial hypoxia. With treatment over a month, most patients can be cured, but some may develop organic damage in certain organs or systems.

Altitude: The higher the altitude, the higher the incidence of altitude sickness. According to statistics, for every 1000 meters increase in altitude, the oxygen content in the air decreases by 10%.

Temperature: The climate in high-altitude areas is cold, with large temperature variations between day and night. People who are new to high-altitude areas cannot adjust promptly, which can easily trigger or exacerbate altitude sickness.

Humidity: The climate in high-altitude areas undergoes dramatic changes, and due to the influence of the greenhouse effect, the higher the altitude, the lower the humidity in the air, making the body prone to dehydration, and even leading to conditions such as thrombosis, memory decline, intellectual decline, and anemia.

Air pressure: The higher the altitude, the lower the atmospheric pressure, and the lower the oxygen partial pressure, resulting in oxygen deficiency in high-altitude areas. Additionally, the higher the altitude, the lower the boiling point, making it difficult to cook food and leading to digestive system diseases.

Radiation: The radiation intensity in high-altitude areas is high, making it highly susceptible to skin and ophthalmic diseases.

Transportation: Research has shown that the probability of developing altitude sickness is lower for those who travel to high-altitude areas by train compared to those who travel by air.

Body weight: Overweight individuals are more susceptible to acute altitude sickness due to hypoxia, especially during sleep.

Gender: The probability of altitude sickness is higher in males than in females, and the specific mechanism is not yet clear.

Psychological factors: Fear of high altitudes, excessive tension, and similar factors can increase the likelihood of altitude sickness. Therefore, maintaining a positive mindset is essential to prevent altitude sickness.

Acclimatization: It refers to a reversible physiological change process that the body undergoes to adapt to the environment. The duration of acclimatization is related to the severity of altitude sickness. The longer the acclimatization period, the milder the altitude sickness.

The use of components such as ginseng, astragalus, and poria cocos or similar traditional Chinese medicine has a significant effect in preventing or alleviating acute altitude sickness, but they should be used judiciously.

Acute altitude sickness can lead to serious conditions such as high-altitude pulmonary edema and high-altitude cerebral edema, with an incidence rate of 3%, which is relatively low, but has a rapid onset and a high mortality rate. It is more likely to occur in individuals at altitudes above 4000 meters, often rapidly occurring between 3 to 48 hours after ascending, or delayed onset between 3 to 10 days.

High-Altitude Pulmonary Edema

High-altitude pulmonary edema often occurs 2 to 5 days after entering high-altitude areas, and excessive fatigue, cold, diet, respiratory tract infections, and rapid ascent speeds can all trigger this condition. Early symptoms may include difficulty breathing, fatigue, and dry cough. Later, patients may experience difficulty breathing during simple activities or rest, along with cyanosis and coughing up pink frothy sputum.

High-Altitude Cerebral Edema

High-altitude cerebral edema is the terminal stage of acute altitude sickness and often occurs 1 to 3 days after entering high-altitude areas. Only a small number of patients with acute altitude sickness will develop high-altitude cerebral edema, and not all patients with high-altitude cerebral edema will necessarily have symptoms of acute altitude sickness before the onset. Clinical manifestations of high-altitude cerebral edema include headache, vomiting, ataxia, hallucinations, and speech disorders, and in severe cases, drowsiness, coma, and convulsions may occur.

Patients should pay attention to rest and keep warm, monitor weather changes, and adjust clothing according to temperature changes to prevent catching a cold.

Patients should avoid vigorous activities such as fast walking or running, but can engage in moderate exercise. After a week, they can gradually increase their activity level. However, if the altitude sickness is severe, they should not exercise and should stay in bed rest.

Oxygen therapy can be administered to correct hypoxia and prevent altitude sickness. It can also improve and alleviate headaches, thereby improving sleep quality. The duration of oxygen therapy should be gradually reduced after 3 days.

Upon arrival at high altitudes, reduce intake of water and salt to prevent pulmonary edema. If appetite decreases, consume appetizers to increase appetite.

Due to the dry air at high altitudes, the body loses a lot of water. Unless there are specific discomforts, it is important to drink plenty of water.

What should high altitude sickness patients pay attention to in their daily life management?

Enhance nutrition and pay attention to dietary hygiene, with a diet consisting of high carbohydrates, low fat, and moderate protein. Avoid raw, cold, hard, and spicy foods.

Patients with acute altitude sickness initially show signs of anxiety, restlessness, tension, fear, denial, etc. Patients should familiarize themselves with the environment and their condition, have a correct understanding of their illness, and build the courage and confidence to overcome it. Maintain an optimistic, positive, and cooperative attitude towards treatment.

Avoid going out at noon, use sun umbrellas and sunscreen, and wear dark sunglasses when outdoors. If the skin is sunburned, keep it clean and apply cold compresses to prevent further damage. After cold compressing a large area of redness, apply hydrocortisone cream.

Try to minimize smoking and abstain from excessive drinking to avoid reducing oxygen consumption. Seek immediate medical attention if there is persistent coughing, a feeling of throat congestion, or difficulty expelling phlegm or coughing up frothy pink sputum, as this may indicate the onset of pulmonary edema.

Before entering high altitude areas, undergo a comprehensive physical examination. Pregnant women, as well as patients with hypertension, epilepsy, severe neurasthenia, active gastrointestinal ulcers, and severe anemia, are not suitable for high altitude areas.

Avoid deliberate physical exercise before entering high altitude areas. At least half a month before entering high altitudes, refrain from training to avoid increasing oxygen consumption, increasing cardiac burden, and causing altitude sickness.

People who have recovered from a cold should avoid entering high altitude areas immediately, as their physical functions are compromised and their resistance to disease is weakened, making them highly susceptible to other high altitude illnesses, especially pulmonary edema.

Upon arrival in high altitude areas, avoid vigorous exercise and heavy physical labor initially, gradually increasing the amount of exercise based on adaptability.

Do not overeat or overdrink upon entering high altitude areas. Consume more vegetables and fruits, supplement with vitamins, and drink plenty of water.

Try to bathe as little as possible or not at all upon arrival in high altitude areas to avoid catching a cold or experiencing altitude sickness due to excessive physical exertion.

Keep warm, add clothing to avoid catching a cold, adjust sleep time reasonably, and ensure adequate sleep.

Pay attention to sun protection, wear UV-protective sunglasses, dark long-sleeved shirts, wide-brimmed hats, and apply sunscreen 30 minutes before going out.

Take acetazolamide every night after entering high altitude areas, which can effectively prevent the onset of acute mountain sickness (ineffective if taken before ascending). People allergic to sulfonamides should not take it.

Upon arrival at high altitudes, there may be varying degrees of dizziness, difficulty breathing, and other signs of hypoxia. Severe symptoms may include headaches, muscle aches, and insomnia. Patients should minimize activity, maintain regular eating habits, take medication to alleviate altitude sickness, and seek medical attention promptly. They should also leave by flight as soon as possible.

Maintain a positive mindset, have a correct understanding of the high altitude environment, and avoid being overly anxious.

When entering high altitude areas, it is preferable to choose transportation such as trains or cars, as arriving at high altitudes quickly increases the likelihood of acute altitude sickness.