At what temperature does hypothermia happen?

Hypothermia routinely occurs at temperatures between 0 and 10 °C (32–50 °F), especially with rain, wind, wet clothing, exhaustion or immersion. It is not a below-freezing problem: most backcountry cases happen above freezing.

What are the warning signs of hypothermia?

Mild hypothermia (core 32–35 °C) brings vigorous shivering, clumsy hands, apathy, slurred speech and mild confusion. Severe hypothermia (below 32 °C) is marked by shivering that stops, rigid muscles, slow pulse, drowsiness, amnesia and heart-rhythm instability.

Is it safe to give a hypothermic person alcohol or hot drinks?

Never alcohol — it dilates surface vessels and dumps core heat. A sweet warm drink is appropriate only if the person is fully awake, alert and can swallow. Never pour fluids into a confused or unconscious patient.

Should I rub arms and legs or put them in a hot bath?

No. Rubbing drives cold blood from the limbs back to the core, and direct hot water or heating pads can burn numbed skin and trigger heart-rhythm collapse. Use a full hypothermia wrap, gentle handling and skin-to-skin rewarming instead.

失温在什么温度下发生？

失温常在 0–10 °C 之间发生，尤其在淋雨、刮风、衣物湿透、精疲力尽或落水时。它并不是冰点以下才有的问题——野外失温案例大多发生在零上气温。

失温有哪些预警信号？

轻度失温（核心温度 32–35 °C）表现为剧烈颤抖、手部笨拙、冷漠、说话含糊和轻度意识模糊；重度失温（低于 32 °C）表现为颤抖停止、肌肉僵硬、脉搏变慢、嗜睡、失忆和心律失常。

可以给失温者喝酒或热饮吗？

绝不能饮酒——酒精扩张体表血管，加速核心热量流失。含糖热饮只适合完全清醒、能吞咽的人；绝不能给意识模糊或昏迷者灌水。

应该搓揉四肢或放进热水里吗？

不要。搓揉会把四肢的冷血推回核心，直接热水袋或热水澡会烫伤麻木皮肤并诱发心律失常。正确做法是完整的失温包裹、轻柔搬运与皮肤贴皮肤复温。

Hiker wrapped in an emergency bivvy beside a misty rainy mountain trail while a partner assists

Hypothermia Risk Assessor失温风险评估器

Temperature, wind, wet clothes and fatigue — risk band, symptom staging and field rewarming steps. 气温、风、湿衣与疲劳——风险分级、症状分期与野外复温步骤。

⛑ First Aid & Health急救与健康 📅 Updated Oct 20262026 年 10 月更新

How the risk assessment works

Hypothermia is a heat-budget problem: your body loses warmth faster than it makes it. The assessor combines a physical cold component — the National Weather Service wind-chill temperature when it applies — with the four factors that dominate real backcountry cases: wetness, fatigue, exposure and injury.

The NWS wind-chill formula describes convective cooling on exposed skin from air temperature and wind speed. Its valid range is air temperature at or below 50 °F (10 °C) with wind above 3 mph; outside that range the tool falls back to plain air-temperature bands, because wind chill says nothing about rain, sweat or immersion. Crucially, most hypothermia incidents happen above freezing, in 0–10 °C rain and wind, when hikers underestimate the chill because the thermometer looks mild.

Why wetness and fatigue dominate

Water conducts heat roughly twenty-five times faster than air, so soaked clothing turns an uncomfortable afternoon into an emergency; sweat from overdressing works as well as rain. Exhaustion removes the last defenses: shivering itself is hard muscular work that burns calories and glycogen, and a tired, hungry hiker cannot generate enough heat to catch up. River immersion compresses the whole timeline into minutes.

Mild versus severe — the staging that matters

Mild hypothermia, a core temperature of roughly 32–35 °C, is a field-reversible emergency: vigorous shivering, fumbling fingers, grumpy apathy and slurred speech. Below 32 °C the picture changes — shivering stops, muscles go rigid, pulse slows and confusion deepens into drowsiness. That transition is the call-now line. Treatment is a complete hypothermia wrap: shelter, dry layers, insulation under and over the body, gentle handling, a vapor barrier such as a bivvy, and skin-to-skin contact in a sleeping bag. A sugary warm drink helps only someone fully awake and swallowing. Avoid the famous myths: no alcohol, no rubbing, no direct heat, no forced walking — and in rescue medicine, no one is dead until they are warm and dead, so CPR continues through evacuation.

风险评估是怎么算的

失温本质上是热量收支问题：身体失热速度超过产热速度。本评估器把物理寒冷分量——适用时采用美国国家气象局（NWS）风寒温度——与真实野外失温案例中最关键的四个因素合并：潮湿、疲劳、暴露与受伤。

NWS 风寒公式描述气温与风对裸露皮肤的对流冷却，适用范围是气温不高于 10 °C（50 °F）、风速大于 3 mph；超出范围时工具改用纯气温区间，因为风寒无法反映降雨、出汗或落水。必须强调：大多数失温发生在冰点以上——0–10 °C 的风雨中，徒步者看到温度计不算低就放松了警惕。

为什么潮湿和疲劳最关键

水的导热速度约为空气的 25 倍，湿透的衣物能让一个难受的下午迅速变成急症；穿太多闷出的汗和雨水效果相同。精疲力尽则撤掉了最后防线：颤抖本身是高强度肌肉劳动，消耗热量与糖原，又累又饿的人无法再产热追平失热。落水则会把整个过程压缩到几分钟内。

轻度与重度——最关键的分期

轻度失温（核心温度约 32–35 °C）在野外仍可逆转：剧烈颤抖、手指不灵活、冷漠易怒、说话含糊。低于 32 °C 时情况改变——颤抖停止、肌肉僵硬、脉搏变慢、意识混乱加深为嗜睡。这个转折就是立即求救线。处置是完整的失温包裹：遮蔽、干衣、身下与身上都隔热、动作轻柔、外层用应急睡袋等蒸汽阻隔物，并在睡袋内皮肤贴皮肤复温。含糖热饮只给完全清醒、能吞咽的人。务必避开著名误区：不饮酒、不搓揉、不直接热敷、不强迫行走；在救援医学中“未复温，不算死”，心肺复苏应在转运中持续进行。

Frequently asked questions常见问题

Can you get hypothermia above freezing?零上气温也会失温吗？

Yes — it is the classic scenario. Rain, wind, wet cotton, sweat and exhaustion routinely cause hypothermia at 0–10 °C (32–50 °F), and cases have been documented at much higher temperatures during prolonged immersion.会，而且这是最典型的情形。雨水、风、湿透的棉质衣物、出汗和疲劳常在 0–10 °C 造成失温；长时间浸泡时，更高气温下也有病例记录。

Why is stopping shivering so dangerous?为什么停止颤抖反而更危险？

Shivering is the body's emergency heat generator. When it stops despite ongoing cold, it means energy reserves and the nervous system's response are failing — a sign of severe hypothermia below about 32 °C, not improvement.颤抖是身体的应急产热机制。持续受冷时颤抖停止，意味着能量储备与神经反应正在衰竭，提示核心温度可能已低于约 32 °C，是恶化而非好转。

Does a space blanket provide enough warmth?一张急救毯够保暖吗？

A space blanket blocks wind and reflects radiant heat but has almost no insulation and none underneath. Combine it with dry insulating layers, a pad between the body and the ground, and ideally an enclosed bivvy as a vapor barrier.急救毯能挡风并反射辐射热，但几乎没有隔热能力，更不能垫在身下。要与干燥保温层、身下防潮垫配合使用，最好再加封闭的应急睡袋作为蒸汽阻隔层。

What should I do first if a partner is shivering and confused?队友又抖又迷糊，第一步做什么？

Stop moving and get them sheltered from wind and rain immediately, remove wet layers, insulate them from the ground and begin the wrap. Send for help early if severe signs appear, and never try to walk a hypothermic person out.立即停止行进、避开风雨遮蔽，脱掉湿衣、与地面隔热并开始包裹。出现重度征象尽早派人求救，绝不要让失温者自己走出去。

“Not dead until warm and dead” — what does it mean?“未复温，不算死”是什么意思？

Profoundly cold patients can appear lifeless with very slow breathing and pulse yet survive with hospital rewarming. If breathing is absent, start CPR and continue gently during evacuation until clinicians declare death after rewarming.重度低温者呼吸脉搏可能极慢、看似无生命体征，但经医院复温后仍可能存活。若无呼吸，应开始心肺复苏并在轻柔转运中持续，直到医生在复温后宣布死亡。