手のひら冷却で熱中症予防
1, 熱中症予防に「手のひら冷却」が注目されている
手のひらには体温調整の役割を担う血管があり、手を流水で冷やしたり、水を入れた洗面器に手を入れたりするだけで、全身を冷やす効果が期待できます。スポーツの現場にも広がっており、専門家は水分補給と合わせて、手のひら冷却を勧めています。
手のひらには動脈と静脈をつなぐ動静脈吻合（ふんごう）（AVA＝Arteriovenous Anastomoses）という体温調整を担う血管があります。通常は閉じていますが、体温が上がるとAVAが開通して一度に多くの血液を流し、手のひらから熱を逃がすことができます。
2, 洗面器に10〜15℃の水を張り、5〜10分間手をつけるというもの
氷水などに手を長時間つけることは避けましょう。冷やし過ぎは禁物。水温が冷た過ぎると、血管は収縮してしまいます。ひんやりして気持ちがいいと感じる15度程度が最適です。
AVAは、毛細血管に比べて直径が10倍と太く、血流量は約1万倍と多いため、短時間でも清涼感や皮膚温度の低下の効果が得られます。実は、こまめな手洗いでも、熱中症予防にもつながります。
3, 熱中症の症状と重症度
熱中症の初期には、めまい、立ちくらみ、足の筋肉がつる、お腹の筋肉のけいれんなどが起こります。症状が進むと、頭痛、おう吐、ぐったりした感じになります。さらに重症化すると、意識障害、全身のけいれん、全身が熱くなる高体温などが起こり、ときに死につながることもあります。
～緊急性の高い場合の見分け方～
・意識がしっかりしているかどうか？‐呼びかけに答えるか？
・自分でペットボトルをあけて、水がゴクンと飲めるかどうか？（成人）
この2つを確認してください。できない場合は、急いで医療機関に搬送してください。
熱中症は、日中に起こることが多いのですが、夜間や就寝中に発症することもあります。高齢者、小児、基礎疾患のある人、体調のすぐれない日、二日酔いの日など、個々人それぞれ自己管理して予防いたしましょう。
Preventing Heatstroke with Palm Cooling
1, “Palm cooling” has been gaining attention as a measure to prevent heatstroke
The palm of your hand contains blood vessels responsible for regulating body temperature. By simply cooling your hands with running water or submerging them in a basin of water, you can achieve an overall cooling effect on your entire body. This practice has also spread to sports fields, and experts recommend palm cooling in conjunction with proper hydration.
The blood vessels responsible for temperature regulation, known as Arteriovenous Anastomoses (AVA), connect arteries and veins in the palm. Normally, these vessels are closed, but when body temperature rises, AVA opens up, allowing a large amount of blood to flow through and release heat from the palm.
2, Recommended method is to fill a basin with water at a temperature of 10 to 15 degrees, Celsius and submerge both hands for 5 to 10 minutes
Avoid prolonged exposure of your hands to ice-cold water. Overcooling should be avoided, as excessively cold water causes the blood vessels to contract. A temperature of around 15 degrees Celsius, which feels pleasantly cool, is optimal.
Compared to capillaries, AVA has a diameter ten times larger and a blood flow rate approximately ten thousand times higher, making even short exposure effective in providing a sense of coolness and reducing skin temperature.
Interestingly, frequent hand washing can also contribute to preventing heatstroke.
3, Symptoms and Severity of Heatstroke
In the early stages of heatstroke, symptoms such as dizziness, lightheadedness, muscle cramps in the legs, and abdominal muscle spasms may occur. As the condition worsens, headaches, nausea, and a feeling of extreme fatigue may set in. In more severe cases, heatstroke can lead to loss of consciousness, full-body spasms, and extremely high body temperature, and in some cases, it can be fatal.
Identifying Urgent Cases.
If someone is suspected of experiencing heatstroke, assess the following two criteria:
・Is the person conscious and responsive when spoken to?
・Can the person open a bottle and drink water on their own? (For adults)
If the person fails to meet these criteria, it is crucial to promptly transport them to a medical facility.
Heatstroke can occur mainly during the daytime, but it may also happen at night or during sleep. It is essential for older adults, children, individuals with underlying health conditions, and those feeling unwell or experiencing a hangover to manage their condition and take preventive measures.
