By Billy Hammond (Copyright AELS)

Heatstroke

Heatstroke occurs when the body’s temperature regulatory mechanisms fail and the body’s core temperature is elevated.

There are two kinds of heat stroke: Classic (non-exertional) Heatstroke and Exertional Heatstroke.

Dehydration, obesity, lack of A/C, neurological disorders, hyperthyroidism, cardiovascular disease, impaired mental function, and drugs that interfere with the release of heat such as phenothiazines, diuretics, and anticholinergenics are predisposing factors for classical heatstroke.

Exertional heatstroke is the result of overexertion in a hot environment.

In both types of heat stroke, temperatures are increased to the point where cell damage is possible. The temperature at which cell damage occurs in cell cultures is between 40 to 45 degrees Celsius or 104 to 113 degrees Fahrenheit.

The main clinical findings are (1) history of heat stress or exposure; (2) rectal temperature of >40°C; and (3) Central Nervous System (CNS) dysfunction in the forms of altered mental status, disorientation, stupor, seizures or coma). The loss of control of body movements (ataxia) may be an early indicator. Anhidrosis (the loss of the ability to sweat) is often singled out as a clue to watch for, but it has been found that it is often a late finding in the course of heat stroke. Thus, a diagnosis of heat stroke should not be ruled out in a sweating (diaphoretic) individual.

The high body core temperature can cause the failure of major body organ systems in addition to the CNS dysfunctions mentioned above. Cardiovascular collapse, liver dysfunction (elevated levels of bilirubin and transaminases) and the consumption of liver proteins, acute abdomen, bloody diarrhea and dilated loops of bowel in the GI tract, and renal (kidney) myoglobinuria are all possibilities. The electrolyte imbalance manifests itself as metabolic acidosis.

Treatment of heatstroke basically consists of rapid cooling, with the aim to bring the rectal temperature down to 38°C (100.4°F as quickly as possible). IV fluid volume replacement and electrolye stabilization are also standards.

Evaporative cooling is often used as an effective cooling method. There are variations, but a common one is to have the patient suspended in a mesh sling and while keeping the skin moist with tepid water (15°C [59°F]). Large fans are used to blow warm (45°C [113°F]) air across the skin for evaporation.

References:

Roberts, James R.; Hedges, Jerris R.. Roberts and Hedges’ Clinical Procedures in Emergency Medicine E-Book (Roberts, Clinical Procedures in Emergency Medicine). Elsevier Health Sciences. Kindle Edition.

Costanzo, Linda S.. BRS Physiology (Board Review Series). Lippincot (Wolters Kluwer Health). Kindle Edition.

熱射病(熱中症)

熱射病は身体の体温調節メカニズムが欠損し、身体の中核体温が上昇した場合に起きる。

古典的(非労作性)熱射病』と『労作性熱射病』の2種類の熱射病がある。

脱水、肥満、空調設備不足、神経疾患 、甲状腺機亢進症、心臓血管疾患、精神機能障害やフェノチアジン、利尿、抗コリン作用性の薬は古典熱射病素因とされている。

労作性熱射病は暑い環境の運動から発症する。

両方の熱射病の場合、体温は再簿損傷が起きる温度まで上昇。細胞培養では細胞損傷が起きる温度は4045°Cと証明されている。

主な臨床所見は(1)高温にさらされた歴、(2>40°Cの直腸温、(3)異常な精神状態・南力障害・昏迷・発作・昏睡のような中枢神経系障害。運動失調は初期段階の症状。しかし、よく取り上げられる.無汗症は遅い段階にも起きるので、発汗の場合には熱射病を除外しないことは大切。

高い中核体温は上記の中枢神経系障害以外には重要な臓器系の故障の原因ともなる。心血管虚脱、肝臓不全(ビリルビン値とランスアミジナーゼ値の上昇)や肝臓タンパク質の消耗、急性腹症、血性下痢や消化管の拡張腸管ループ、腎臓性ミオグロビン尿症の発症も可能。電解質インバランスは代謝性アシドーシスとして現れる。

熱射病の中心となる治療は急冷で、その目標は直腸温を出来るだけ速く38°Cに下げることだ。点滴での点滴で水分投与や電解質の安定も標準治療。

蒸発冷却は効果的な冷却方法として利用される。様々な手法があるが、よく使われるのは患者をメッシュ・ハンモックに吊るして、皮膚を15°Cの温い水を掛けながら、大型扇風機で蒸発を加速するため暖かい(45°C)空気を掛ける。

参考書:

Roberts, James R.; Hedges, Jerris R.. Roberts and Hedges’ Clinical Procedures in Emergency Medicine E-Book (Roberts, Clinical Procedures in Emergency Medicine). Elsevier Health Sciences. Kindle Edition.

Costanzo, Linda S.. BRS Physiology (Board Review Series). Lippincot (Wolters Kluwer Health). Kindle Edition.

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English books by Billy Hammond published by AELS

(AELS出版英語書籍リスト)

 

I. Majoh Gakuin and Hikari Juku – Japanese Witch Schools Trilogy

1. Majoh Gakuin & Hikari Juku – Japanese Witch Schools

2. Lost Witch (The second book)

3. Fate & Magic (The final book in the trilogy)

II. Brindle – Scryer Extraordinaire Trilogy

1. Brindle – Scryer Extraordinaire

2. Brindle – Scryer Extraordinaire – Returns

3. Brindle – Scryer Extraordinaire – Challenges (The final book in the trilogy)

III. Fantasy fiction set in Japan

1. 21st Century Ninja

2. Regressed

3. Japanese Woman

IV. Fantasy fiction set outside of Japan

1. Dimension Jumpers

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