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Evaporation 蒸發 is the principal mechanism of heat loss in a hot environment
but this becomes ineffective above a relative humidity of 75% 濕度太高蒸散不易
When the ambient temperature rises to >35°C (>95°F), the body can no longer
radiate heat to the environment and becomes dependent on evaporation for heat transfer.
Medications : Anticholinergic agents, diuretics, phenothiazine, β-blockers, CCB, sympathomimetic agents.
Anticholinergic agents impair sweating and the cardiovascular response to heat
藥物 也可能會影響人體散熱的效能
- 長期服用抗膽鹼藥物可能會抑制排汗
- 降血壓藥物如抗交感神經藥物也可能會影響心血管系統對體溫的調節
- 娛樂性藥物如安非他命容易讓身體產熱
Minor (heat edema, prickly heat, heat cramps, and heat exhaustion)
Major (heat stroke)
Heat edema
self-limited
mild swelling of the feet, ankles, and hands
appears within the first few days of exposure to a hot environment
cutaneous vasodilatation and orthostatic pooling
Prickly heat
lichen tropicus, miliaria rubra, or heat rash
pruritic, maculopapular, and erythematous rash over
normally clothed areas of the body
antihistamines, Calamine lotion, topical steroids, and oral vitamin C
Heat cramps 小腿抽筋
painful, involuntary, spasmodic contractions of skeletal muscles,
usually calves, may involve thighs and shoulders
Self-limited and do not cause significant morbidity
Rhabdomyolysis is rare
Hyponatremia and hypochloremia
relative deficiency of sodium, potassium, or magnesium and fluid at muscle level
fluid and salt replacement (PO or IV) and rest
熱衰竭 Heat exhaustion < 40 度
可某種程度上視為中暑前兆
Water and sodium depletion
do not manifest signs of CNS impairment
** 沒有超過 40 度 ; 沒有 CNS signs **
- 頭暈, 頭痛, 無力虛弱
- 大量出汗, 皮膚溼冷, 臉色蒼白
- 心跳加速, Orthostatic hypotension or near-syncope
- 噁心嘔吐
- 肌肉抽筋
- 熱痙攣 (heat cramps), 熱暈厥 (heat syncope)
- Rhabdomyolysis is rare
- 不一定抽血有電解質異常
Volume and electrolyte replacement and rest.
中暑 Heat stroke > 40 度
Acute life-threatening emergency with high mortality
** 超過 40 度 + AMS **
體溫調節失控及中樞神經系統受到影響
- 影響到中樞神經而有 CNS symptoms (意識混亂, 意識不清, 情緒不穩, 說話不清)
- 皮膚可能因無法出汗而呈現無汗 Anhidrosis
Sweat is present in over half of patients with heat stroke 還是可以有流汗
- 脫水, 急性腎衰竭, 心律不整, 橫紋肌溶解症, 肝臟損傷, 休克, 抽筋, 昏迷, 甚至死亡
Cerebellum is highly sensitive to heat, and ataxia can be an early neurologic finding
Decorticate and decerebrate posturing, hemiplegia, status epilepticus, and coma.
Seizures are quite common, especially during cooling.
Currently, only physical methods of cooling are recommended,
goal is to reduce the core temperature to approximately 39C (102.2F)
and to avoid overshoot hypothermia.
目標是降溫到 39 度 !!!!
脫衣服, 灑水, 吹電風扇
To prevent hypothermic overshoot,
some recommend using either tepid water warmed to 40°C or exposing the patient to hot air (45°C) with the fan
Evaporative 脫衣服灑水 : 強烈建議, 最大的問題是 shivering
Shivering is treated primarily with short-acting benzodiazepines and secondarily with phenothiazines.
NG, Foley 灌冷水 : 有效但是缺乏實證安全性
血壓低可以選 Dopamine or dobutamine
Norepinephrine 會讓周邊血管收縮, 不好降溫
嚴重脫水會高血鈉 ; 也可能因為有口服補充水分而呈現低血鈉
Thrombocytopenia, DIC
Hepatic damage is almost always reversible, with a full recovery
Seizures may occur during cooling and can be controlled with benzodiazepines.
中暑病人初步處置 ：
1. 將病人移至通風陰涼處
2. 減少與鬆開衣物
3. 評估意識狀態及生命現象
4. 若有嘔吐, 則側躺以避免吸入性肺炎, 採頭低腳高姿勢, 預防低血壓造成腦部灌流不足
5. 熱痙攣時不可強力按摩與拉扯痙攣的肌肉
6. 測量體溫, 如果大於 39.5度, 灑水淋濕以電扇吹拂, 並將冰袋置於頸部, 腋窩及鼠膝
7. 若過多汗液和尿液已排出時, 補充含鹽水份(每公斤水含 0.1-0.15 克的鹽)
8. 若尿量排出減少, 給予冰電解質溶液, 千萬不要給予純水
9. 聯繫 119, 盡速送醫處理
10. 送醫期間持續降溫
(若個案發現至到院前, 已超過 1 小時以上, 個案腋溫已降至 38.5℃, 則停止降溫)
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