高山症：AMS、HAPE 和 HACE¶

徒步旅行者、滑雪者、登山者以及攀登超過 2,500 公尺（8,200 英尺）的旅行者可能會患上高原疾病，他們的身體無法適應較低的氣壓。雖然輕度急性高山症 (AMS) 會引起不適的頭痛和噁心，但在同一海拔休息後可緩解，但其兩種危及生命的進展，高海拔肺水腫 (HAPE) 和 高海拔腦水腫 (HACE)，會在數小時內使肺部充滿液體或導致致命的腦腫脹。

遵循海拔三黃金法則（及早識別症狀，切勿在出現症狀時攀登，如果症狀惡化或涉及肺部或大腦，則立即下降）是預防高山死亡的最有效方法。每個健行團體、滑雪隊和高海拔旅行者都應該知道如何進行從腳跟到腳趾的平衡測試，識別休息時的呼吸困難，並執行立即輔助下降。

現在就這樣做¶

1. 立即執行 10 秒的「腳跟到腳趾步行測試」（串聯步態測試）：在泥土或雪地上畫一條直線，並要求受試者沿著這條線從腳跟到腳趾行走，就像警察的清醒測試一樣。如果他們搖搖晃晃地偏離路線，瘋狂地揮舞手臂以保持平衡，或者閉著眼睛無法站直（共濟失調），則假設高海拔腦水腫 (HACE) 正在發展，並立即開始輔助下降。
2. 完全坐著休息10分鐘後檢查呼吸：在高海拔地區徒步上坡時，呼吸困難是正常現象。然而，如果一個人在完全靜止坐 10 分鐘後仍然氣喘吁籲、氣喘吁籲，或者靜止心率過快（每分鐘超過 110 次）且胸腔發出劈啪聲，則可能是高海拔肺水腫 (HAPE) 並立即下降。
3. 如果出現任何輕微症狀，請立即停止上升：如果該人通過了平衡測試並且在休息時呼吸舒適，但頭痛並伴有噁心、頭暈或異常疲勞，則診斷急性高山病（AMS）。立即停止所有向上行驶；不要攀登 100 米（330 英尺）高的地方到达营地或山口。
4. 針對 HAPE/HACE 立即執行 500 至 1,000 公尺（1,600 至 3,300 英尺）的輔助下降：拿起病人的背包，用兩個同伴支撐他們的重量（或用轎子或馬背），然後下降到盡可能低的高度。体力消耗会增加肺部和大脑的血压，因此患者在下降过程中必须尽可能少地工作。
5. 如果下降延遲，則使用高流量氧氣或伽莫夫袋：如果有瓶裝醫用氧氣，則透過面罩或鼻插管每分鐘輸送 4 至 6 公升氧氣。如果被暴風雪或懸崖地形困住，請將患者密封在便攜式高壓艙（伽莫夫袋）內並連續泵氣，直到天氣允許下降。
6. Activate satellite rescue and keep the patient warm: Trigger an SOS on a satellite communicator (Garmin inReach, ZOLEO, or smartphone satellite SOS) or call your local emergency number (911 in the United States and Canada, 112 across the European Union, 999 in the United Kingdom) or check 緊急號碼 if cellular coverage exists. Keep the patient warmly insulated; shivering and cold exposure constrict lung arteries and rapidly worsen HAPE.

Tactical decision flow for altitude illness triage¶

flowchart TD
    Symptom["Altitude Symptoms Above 2,500 m (8,200 ft): Headache, Fatigue, or Breathlessness"] --> Balance{"1. Heel-to-Toe Walk Test: Does Patient Stagger or Show Confusion?"}
    Balance -->|"Yes: Ataxia or Altered Mental State"| HACE["HACE (Brain Swelling): Immediate Assisted Descent 500 to 1,000 m"]
    Balance -->|"No: Normal Balance and Alert"| RestBreath{"2. Short of Breath After 10 Minutes of Complete Sitting Rest?"}
    RestBreath -->|"Yes: Breathless at Rest, Cough, or Blue Lips"| HAPE["HAPE (Fluid in Lungs): Sit Upright, Keep Warm, Descend 500 to 1,000 m Now"]
    RestBreath -->|"No: Comfortable at Rest, Headache + Nausea/Fatigue"| AMS["Mild to Moderate AMS: Stop Ascending, Rest 24 to 48 Hours, Hydrate"]
    AMS --> Worsen{"3. Do AMS Symptoms Worsen or Fail to Improve in 24 Hours?"}
    Worsen -->|"是的"| Descend["Descend at Least 500 m (1,600 ft) Until Symptoms Resolve"]
    Worsen -->|"No: Fully Resolved"| Resume["Resume Gradual Ascent: Max 300 to 500 m Sleeping Gain per Day"]
    HACE --> Rescue["Administer Oxygen (4 to 6 L/min) or Gamow Bag + Activate Mountain Rescue SOS"]
    HAPE --> Rescue

Barometric physics and physiological zones of high altitude¶

A common misconception is that the air at high mountain elevations contains a lower percentage of oxygen. In fact, atmospheric air contains the exact same 20.9 percent oxygen from sea level all the way to the summit of Mount Everest (8,849 meters / 29,032 feet). What changes is barometric pressure: as you climb higher, there is less overlying atmosphere pressing down from above, so air molecules spread farther apart. Because every lungful of thin mountain air contains fewer total oxygen molecules, the partial pressure of inspired oxygen (\(\text{PiO}_2\)) driving oxygen across your lung membranes into your bloodstream drops dramatically.

Clinical comparison: AMS vs HAPE vs HACE¶

Understanding why thin air causes fluid to leak out of capillaries into the brain and lungs helps you distinguish normal high-altitude breathing from a life-threatening emergency.

The Lake Louise AMS Self-Assessment Score and neurological checks¶

根據國際共識路易斯湖評分系統（2018 年更新）和荒野醫學協會 (WMS)，當一個人在過去 6 至 96 小時內登上 2,500 米（8,200 英尺）以上的新海拔並出現頭痛（至少 1 分）加上至少一種其他症狀時，即可診斷為急性高山病 (AMS)。 總分3分或以上：

1. 頭痛：
2. 0 = None at all
3. 1 = Mild headache
4. 2 = Moderate headache
5. 3 = Severe, incapacitating headache
6. Gastrointestinal Symptoms:
7. 0 = Good appetite
8. 1 = Poor appetite or mild nausea
9. 2 = Moderate nausea or vomiting
10. 3 = Severe, incapacitating nausea and vomiting
11. Fatigue and Weakness:
12. 0 = Not tired or weak
13. 1 = Mild fatigue or weakness
14. 2 = Moderate fatigue or weakness
15. 3 = Severe, incapacitating fatigue or weakness (reluctant to leave tent for meals or water)
16. Dizziness or Lightheadedness:
17. 0 = Not dizzy
18. 1 = Mild dizziness
19. 2 = Moderate dizziness

20. 3 = Severe, incapacitating dizziness

21. Score 3 to 5 (Mild AMS): Stop all further ascent immediately. Rest at the current elevation for 24 to 48 hours, stay hydrated, avoid alcohol and sleeping pills, and re-evaluate every 4 hours.

22. Score 6 to 12 (Moderate to Severe AMS): Treat as high risk for imminent progression to HACE. If symptoms do not rapidly improve within a few hours of rest and oxygen, descend 300 to 500 meters (1,000 to 1,650 feet) before nightfall.

How to perform the Heel-to-Toe Tandem Gait Test and Chest Auscultation¶

Because early HACE and HAPE often begin silently at dusk or during the night, expedition leaders and trekking partners should perform two 30-second physical checks every evening and morning in camp:

• The Heel-to-Toe (Tandem Gait) Balance Test for HACE: Swelling in the cerebellum (the balance center at the back of the brain) is the earliest sensitive physical sign of HACE, often appearing before obvious confusion or coma. Scratch a straight 3-meter (10-foot) line in the dirt, gravel, or snow outside the tent. Ask the climber to walk along the line placing the heel of their front boot directly touching the toe of their back boot on every step, turn around, and walk back. A healthy, acclimatized climber can walk heel-to-toe smoothly. If the climber steps off the line repeatedly, staggers sideways like a drunk person, or cannot stand still with their feet together and eyes closed without swaying (Romberg sign), they have clinical ataxia (HACE) until proven otherwise and must be taken down the mountain immediately.
• Ear-to-Chest Listening and Resting Respiratory Count for HAPE: Ask the climber to sit quietly for 10 full minutes after taking off their pack. Count how many breaths they take in 60 seconds and check their pulse. At rest in camp, a breathing rate exceeding 25 to 30 breaths per minute alongside a resting pulse over 110 to 120 beats per minute is a major red flag for HAPE. Place your bare ear directly against the skin of their back just below the shoulder blades (especially under the right shoulder blade, where early HAPE fluid often collects first in the right middle lobe) while they take a deep breath in and out: if you hear fine crackling (like rubbing hair between your fingers or opening Velcro) or wet bubbling sounds, fluid is leaking into their alveoli.

Step-by-step field management for HAPE and HACE¶

When a team member fails the heel-to-toe balance test (HACE) or becomes breathless at rest (HAPE), every hour at altitude increases mortality. Remember that HAPE accounts for the majority of deaths from altitude illness, and roughly 50 percent of climbers with advanced HAPE develop secondary HACE simultaneously because their fluid-filled lungs cannot oxygenate their brain.

1. Execute immediate, low-exertion assisted descent¶

• Why descent works like a miracle: Descending even 300 to 500 meters (1,000 to 1,650 feet) increases atmospheric barometric pressure enough to raise alveolar oxygen tension immediately. A descent of 1,000 meters (3,300 feet) frequently reverses life-threatening HAPE and early HACE within 2 to 6 hours.
• Never let a HAPE or HACE patient carry weight or hike vigorously: Physical exertion increases cardiac output and spikes pulmonary artery pressure, forcing even more serum and red blood cells through ruptured lung capillaries into the air sacs. Strip the patient of their backpack immediately, distribute their gear among healthy teammates, support the patient under both arms using trekking poles, or evacuate them on a pack animal (horse, mule, or yak), wheeled litter, or improvised rope stretcher.
• Descend at night if necessary: Do not wait until morning for a HAPE or HACE patient to "rest up." Nighttime hypoxia between midnight and 4:00 AM is the deadliest window at high camp. Put on high-output LED headlamps, harness the patient between two strong teammates, and descend the trail immediately unless a blizzard, whiteout, or technical cliff makes night movement impossible.
• Keep HAPE patients seated upright: Whenever a HAPE patient rests on the trail, sits in a tent, or rides in a stretcher, prop their torso upright or semi-upright at a 45-to-90-degree angle. Laying a HAPE patient flat on their back causes pulmonary edema fluid to spread across the upper lung fields, triggering acute suffocation within minutes.

2. Protect strictly against cold and hypothermia¶

Cold exposure triggers sympathetic peripheral vasoconstriction throughout the skin and limbs, shunting blood volume inward into the central chest cavity and sharply elevating blood pressure inside the fragile pulmonary capillaries. Clinical mountain rescue studies prove that a climber who becomes chilled or develops 低溫 at altitude is far more likely to develop acute HAPE, and shivering increases oxygen consumption by up to 400 percent.

• Dress the patient immediately in their heaviest down parka, windproof shell, insulated pants, mittens, and warm hat.
• Insulate them from snow or frozen ground with two closed-cell foam sleeping pads, place hot water bottles wrapped in socks against their armpits and chest, and have them breathe through a fleece neck gaiter or balaclava to warm and humidify inspired mountain air.

3. Operating a portable hyperbaric chamber (Gamow Bag / PAC)¶

High-altitude expeditions, Himalayan trekking lodges, and alpine mountain huts frequently stock an inflatable cylindrical nylon hyperbaric chamber (such as a Gamow bag, Certec bag, or Portable Altitude Chamber). A hyperbaric bag is a life-saving bridge when a midnight blizzard, avalanche slope, or vertical terrain prevents immediate physical descent:

1. Pre-check the patient before sealing: Have the patient urinate before entering the bag. Check that their airway is clear, explain how the chamber works to prevent claustrophobia, and instruct them to swallow, chew gum, yawn, or pinch their nose and blow gently (Valsalva maneuver) as pressure rises so their eardrums equalize comfortably. If the patient has HAPE and cannot lie flat without gasping, place the entire inflated bag on an angled 30-to-45-degree snow ramp or boulder slope with their head at the high end.
2. Zip and pressurize to simulated lower altitude: Place the patient inside wrapped in a dry sleeping bag with a headlamp and water bottle, zip the heavy airtight pressure zipper closed completely, and pump the foot or hand pump rapidly for 2 to 3 minutes until the built-in pressure relief valve begins hissing continuously (typically calibrated to 105 to 140 millibars / 1.5 to 2.0 pounds per square inch above ambient mountain air pressure). This internal pressure increase simulates an instantaneous descent of 1,500 to 2,500 meters (5,000 to 8,000 feet).
3. Pump continuously at 10 to 15 strokes per minute without stopping: Once the chamber is fully inflated, a rescuer must keep pumping 10 to 15 full strokes every minute for the entire time the patient is inside. Continuous pumping does not just keep the bag firm; it flushes the patient's exhaled carbon dioxide (\(\text{CO}_2\)) out through the bleed valve and brings fresh oxygen in. Stopping pumping while a patient is zipped inside an airtight Gamow bag causes lethal carbon dioxide suffocation within 15 to 20 minutes.
4. Use the post-chamber window to walk the patient down the mountain: After 2 to 6 hours of continuous hyperbaric treatment, HACE and HAPE patients frequently regain enough balance, mental clarity, and breathing comfort to walk down the trail with assistance. Start the physical descent immediately upon unzipping the bag, because hyperbaric relief is temporary and cerebral/pulmonary edema will rebound within hours if the patient remains at high camp.

Differentiating altitude sickness from dehydration, hypothermia, hyponatremia, and CO poisoning¶

In high mountain environments, four other acute medical emergencies produce symptoms that closely mimic AMS, HAPE, and HACE. Misdiagnosing them can lead to fatal treatment errors:

• Severe Dehydration: Cold, bone-dry mountain air and hyperventilation cause climbers to lose 3 to 5 liters (3 to 5 quarts) of water per day through insensible respiratory vapor loss and sweat. Dehydration causes throbbing headache, nausea, dark yellow urine, weakness, and orthostatic dizziness. Field differentiation: If a climber has dark concentrated urine and a mild headache with normal balance and clear lungs at rest, have them sit in the shade and drink 1 liter (1 quart) of water with electrolytes over 60 minutes. If the headache disappears completely after rehydration, the cause was dehydration; if the headache persists or worsens despite pale urine, diagnose AMS and halt ascent.
• Exercise-Associated Hyponatremia (Over-Hydration / Water Intoxication): Well-meaning trekking guides sometimes tell hikers to "drink 6 to 8 liters of plain water a day to prevent altitude sickness." Chugging excessive quantities of plain, salt-free water dilutes blood sodium levels below 130 mmol/L (hyponatremia), causing water to rush osmotically into brain cells and triggering fatal cerebral edema, confusion, staggering ataxia, vomiting, and seizures identical to HACE. Field differentiation: Ask how much the climber has been drinking and urinating. If they have been forcing down liters of plain water and passing frequent, crystal-clear urine every 30 minutes before becoming confused or clumsy, stop all plain water intake immediately, give salty broth or salted snacks if conscious, and descend.
• Tent Carbon Monoxide (\(\text{CO}\)) Poisoning: Melting snow or cooking dinner with a liquid-fuel or canister camp stove inside a zipped tent or snow cave during a storm generates odorless carbon monoxide gas, which binds to hemoglobin 200 times more tightly than oxygen. At high altitude where blood oxygen is already low, carbon monoxide poisoning causes throbbing frontal headache, nausea, vomiting, staggering ataxia, and coma within 15 minutes, mimicking severe AMS and HACE. Field differentiation: If two or three tentmates develop the exact same sudden headache and nausea right after running a stove inside a tent or vestibule, throw the tent doors wide open immediately, drag everyone into fresh outside air, administer high-flow oxygen if available, and review our carbon monoxide and smoke inhalation first aid guide。
• Wilderness Hypothermia and Exhaustion: Moderate hypothermia (core temperature below 32 degrees Celsius / 90 degrees Fahrenheit) causes the "umbles" (stumbling, mumbling, fumbling, and grumbling), apathy, confusion, and loss of balance identical to HACE. Golden rule: If you cannot be 100 percent certain whether a stumbling, confused climber at 4,000 meters (13,100 feet) has HACE or hypothermia, treat aggressively for both at the exact same time by wrapping them in dry insulation with warm water bottles while carrying or assisting them down to lower elevation.

Prevention and safe acclimatization rules¶

According to the Wilderness Medical Society (WMS), the Centers for Disease Control and Prevention (CDC, United States), and the UIAA (International Climbing and Mountaineering Federation) Medical Commission, the vast majority of severe altitude illnesses are preventable by respecting human physiological acclimatization limits:

1. Stage your initial ascent to 2,500 to 3,000 meters (8,200 to 10,000 feet): Avoid flying or driving directly from sea level to sleep above 2,800 meters (9,200 feet) in a single day. If flying into high-altitude cities such as Cusco, Peru (3,400 m / 11,150 ft), La Paz, Bolivia (3,640 m / 11,940 ft), Lhasa, Tibet (3,650 m / 11,975 ft), Leh, India (3,500 m / 11,500 ft), or high Rocky Mountain ski towns (2,800 to 3,200 m / 9,200 to 10,500 ft), descend to sleep in a lower valley (such as the Sacred Valley at 2,800 m below Cusco) for your first 2 to 3 nights whenever possible, and avoid strenuous hiking or skiing for the first 48 hours.
2. Follow the 300-to-500-meter (1,000-to-1,650-foot) sleeping rule above 3,000 meters: Once you climb above 3,000 meters (10,000 feet), never increase your sleeping elevation by more than 300 to 500 meters (1,000 to 1,650 feet) per 24-hour night.
3. Schedule a mandatory rest day every 1,000 meters (3,300 feet): Spend two consecutive nights sleeping at the same camp elevation for every 900 to 1,000 meters (3,000 to 3,300 feet) of net altitude gain (or every 3 to 4 days of upward trekking).
4. Use "Climb High, Sleep Low" judiciously (only when symptom-free): Walking up 300 to 400 meters (1,000 to 1,300 feet) onto a ridge during the afternoon and descending back to your lower camp to sleep stimulates ventilatory acclimatization. However, never "climb high" if you have even a mild headache or fatigue, as exertion at higher altitude triggers HAPE.
5. Avoid respiratory depressants (alcohol, sedatives, and opioids): Never drink alcohol or take sedative sleeping pills (such as benzodiazepines, zolpidem, or opioid painkillers) during your first several nights at a new altitude. These drugs depress your brainstem's respiratory center during sleep, causing severe nocturnal oxygen desaturation.
6. Remember that physical fitness offers zero immunity: Elite marathon runners, cyclists, and military personnel develop AMS, HAPE, and HACE at the exact same rate (and frequently higher, because they ascend steep trails too fast) as sedentary travelers. Genetics, prior history of altitude illness, and speed of ascent determine your risk.

常見問題¶

來源已檢查¶

• Wilderness Medical Society (WMS): Clinical Practice Guidelines for the Prevention, Diagnosis, and Treatment of Acute Altitude Illness (2019 and 2024 Updates).
• Lake Louise Consensus Group: The 2018 Lake Louise Acute Mountain Sickness Score Consensus Statement.
• International Climbing and Mountaineering Federation (UIAA Medical Commission): Standardized Field Recommendations for AMS, HAPE, and HACE Management (UIAA MedCom Standard No. 2).
• Centers for Disease Control and Prevention (CDC, United States): CDC Yellow Book: Health Information for International Travel: High-Elevation Travel and Altitude Illness.
• NHS (United Kingdom) and Institute for Altitude Medicine (Telluride, United States): Altitude Sickness Recognition, Acclimatisation Profiles, and Emergency Descent Guidance.

相關指南¶

• Wilderness hypothermia and cold exposure
• 體溫過低和凍傷急救
• Lost while hiking or camping survival
• Rock climbing and mountaineering accidents
• 吸入煙霧和一氧化碳中毒急救
• 按國家/地區劃分的緊急電話號碼