野外與登山醫學----11--WMS 2019 update AMS/HACE prevention suggested approach 11

Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Acute Altitude Illness: 2019 Update
統一名詞翻譯
AMS 急性高山病
HACE 高海拔腦水腫
acute altitude illness 急性高海拔疾病

SUGGESTED APPROACH TO AMS/HACE PREVENTION 預防AMS/HACE 建議策略
個人之間高度適應的速率, 高海拔生理反應差異很大. 臨床醫師要認知到, 通常有效的預防方式也無法完全避免 AMS/HACE, 這些策略僅是風險狀況的其中一種功能.
Because the rates of acclimatization and physiologic responses to high altitude vary considerably between individuals, clinicians must recognize that the recommendations that follow, although generally effective, do not guarantee successful prevention in all high altitude travelers. The approach to prevention of AMS and HACE should be a function of the risk profile of the individual traveling to high altitude (Table 2).

1. 第一個原則是確保逐漸上升至目標海拔, 旅行者可選擇在中海拔地區住一晚.
The first priority should be ensuring gradual ascent to the target elevation. Travelers can lower their risk by sleeping 1 night at an intermediate altitude. For example, sea-level residents traveling to Colorado resort areas over 2800 m can spend 1 night in Denver (1600 m). It should be recognized that a large number of people will travel directly by car or plane to commonly visited mountain high altitude locations, often located between 2500 and 3000 m, and may be unable to ascend gradually because of various logistical factors. In such situations, pharmacologic prophylaxis can be considered. Such individuals should also take care to slow the rate of further ascent beyond the altitude achieved at the start of their visit. With travel above 3000 m, individuals should not increase their sleeping elevation by more than 500 m$d-1 and should include a rest day (ie, no ascent to higher sleeping elevation) every 3 to 4 d. The increase in sleeping elevation should be less than 500 m for any given day of a trip. In many areas, terrain and other logistical factors prevent strict adherence to this approach and mandate larger gains in sleeping elevation over a single day. In such cases, acclimatization days should be strongly considered before and/or after these large gains in elevation and elsewhere in the itinerary to ensuredat the very least and as an approximation of properly controlled ascentdthat the overall ascent rate averaged over the entire trip (ie, total elevation gain divided by the number of days of ascent during the trip) is below the 500 m$d-1threshold.
Prophylactic medications are not necessary in low-risk situations but should be considered in addition to gradual ascent for use in moderate- to high-risk situations (Table 2). Acetazolamide is the preferred medication; dexamethasone may be used as an alternative in individuals with a history of intolerance of or allergic reaction to acetazolamide. In rare circumstances (eg, military or rescue teams that must ascend rapidly to and perform physical work at >3500 m), consideration can be given to concurrent use of acetazolamide and dexamethasone. This strategy should be avoided except in these particular or other emergency circumstances that mandate very rapid ascent. Acetazolamide and dexamethasone should be started the day before ascent but still have beneficial effects if started on the day of ascent. For individuals ascending to and staying at the same elevation for more than several days, prophylaxis may be stopped after 2 d at the highest altitude. Individuals ascending faster than the recommended ascent rates may consider continuing preventive medication for 2 to 4 d after arrival at the target altitude, but there are no data to support this approach. For individuals ascending to a high point and then descending toward the trailhead (eg, descending from the summit of Mt. Kilimanjaro), in the absence of AMS/HACE symptoms, preventive medications should be stopped when descent is initiated.