Acute mountain sickness

Japanese: 急性高山病 - きゅうせいこうざんびょう（英語表記）Acute mountain sickness

What is the disease?

Acute mountain sickness is a syndrome characterized by acute respiratory, circulatory, and central nervous system symptoms caused by the hypoxic environment that occurs when rapidly reaching high altitudes.

There are two types of acute mountain sickness: mild and spontaneously improves in 1-2 days. Mountain Drunk ( Yamayo ) The condition, also known as "dysentery," requires immediate treatment. High altitude pulmonary edema ( Kochi is a hot spring ) "or" High altitude cerebral edema ( Kochi city ) This includes serious conditions such as " (Table 17).

Usually, when a person who has not been acclimatized to high altitude reaches an altitude of 2500m or more within a few hours, acute hypoxemia occurs, resulting in altitude sickness. The onset of altitude sickness often occurs within 2 to 3 days after reaching high altitude, and severe cases are often seen in young men.

What is the cause?

As altitude increases, the partial pressure of inhaled oxygen decreases. This results in insufficient ventilation, which causes hypoxemia and leads to the onset of altitude sickness. The incidence, severity, and duration of altitude sickness depend on the height and speed reached. In addition, environmental factors such as fatigue and dehydration due to mountain climbing, cold and dryness, individual differences in the degree of altitude acclimatization and cardiopulmonary function, drinking alcohol or taking sedatives at high altitude, and lack of sleep also contribute to the promotion of onset and progression of the disease. At present, it is difficult to accurately predict the onset of altitude sickness.

How symptoms manifest

Mountain sickness usually occurs within a few hours to a day after reaching altitudes of 2500m or higher. As the altitude increases, high altitude pulmonary edema, high altitude cerebral edema, and high altitude retina ( Also well ) Complications such as bleeding may occur (Table 18).

Testing and diagnosis

The manifestation of clinical symptoms (Table 18) is the deciding factor for diagnosis (Figure 9). Laboratory findings (Table 19) are useful for understanding the pathology.

Treatment methods

Early detection and early treatment are the golden rules of treatment. The basic first aid measures are rest, keeping warm, oxygen inhalation, and prompt descent from the mountain (Figure 10).

Prevention measures

It is necessary to slowly ascend to altitude while taking rest periods. Alcohol use, sedatives, excessive physical exertion, and cold weather at altitude are all factors that can prevent this. exposure ( Bakuro ) Also, you should avoid sleep deprivation. One preventative measure is to take acetazolamide (Diamox) orally (250 mg per day) about 12 hours before starting the climb.

Table 17. Classification and severity of acute mountain sickness
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Table 17. Classification and severity of acute mountain sickness

Table 18. Clinical symptoms of acute mountain sickness
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Table 18. Clinical symptoms of acute mountain sickness

Figure 9. Key points for diagnosing acute mountain sickness
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Figure 9. Key points for diagnosing acute mountain sickness

Table 19. Test findings for acute mountain sickness
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Table 19. Test findings for acute mountain sickness

Figure 10. Flowchart of emergency treatment for acute mountain sickness
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Figure 10. Flowchart of emergency treatment for acute mountain sickness

Source: Houken “Sixth Edition Family Medicine Encyclopedia” Information about the Sixth Edition Family Medicine Encyclopedia

Japanese:

どんな病気か

　急性高山病は、急速に高地に到達した際に、その低酸素環境により生じる急性の呼吸・循環・中枢神経症状を主体とした症候群です。

　急性高山病には、1～2日で自然に軽快する軽症の「山酔(やまよ)い」とも呼ばれる病態から、早急に治療を必要とする「高地肺水腫(こうちはいすいしゅ)」や「高地脳浮腫(こうちのうふしゅ)」などの重症の病態まで含まれます（表17）。

　通常、高地に順化していない人が、海抜2500m以上の高所へ数時間のうちに到達した場合に、急性の低酸素血症が生じ、その結果高山病が発症します。高山病の発症は、高地到達後2～3日以内のことが多く、重症例は若年の男性に多くみられます。

原因は何か

　高度の増加に伴い吸入酸素分圧が低下します。その結果、換気不足に陥り低酸素血症が引き起こされ高山病が発症します。高山病の発症率、重症度、罹患期間は、到達する高さ、到達速度に左右されます。また、登山による疲労や脱水、寒冷や乾燥などの環境要因、高地順応の程度や心肺機能などの個体差、高地での飲酒や鎮静薬の服用、さらに睡眠不足なども発症の促進や病態の進展に関与します。現在のところ、高山病の発症を正確に予測することは困難です。