How does anesthesia work? - Steven Zheng

譯者: Ann Chen 審譯者: Max Chern

If you've had surgery,

假如你曾接受手術

you might remember starting to count backwards from ten,

你可能還記得從十開始倒數

nine,

九

eight,

八

and then waking up with the surgery already over before you even got to five.

在你甚至數到五之前 你已經完成手術而蘇醒了

And it might seem like you were asleep, but you weren't.

你可能覺得你睡著了 但不是這樣的

You were under anesthesia,

你被麻醉了

which is much more complicated.

這比 '睡著' 複雜多了

You were unconscious,

你失去意識

but you also couldn't move,

而且無法動彈

form memories,

無法產生記憶

or, hopefully, feel pain.

或，但願，不會感到疼痛

Without being able to block all those processes at once,

如果無法同時阻斷那些過程

many surgeries would be way too traumatic to perform.

許多手術可能會因 身心創傷太大而無法執行

Ancient medical texts from Egypt, Asia and the Middle East

來自埃及、亞洲及中東 古老的醫學文稿

all describe early anesthetics

都有描述早期的麻醉藥

containing things like opium poppy,

含有像罌粟、

mandrake fruit,

曼德拉草果實、

and alcohol.

及酒精的成分

Today, anesthesiologists often combine

現今，麻醉師常結合

regional, inhalational and intravenous agents

局部、吸入性及靜脈注射藥物

to get the right balance for a surgery.

以獲得手術需要的正確組合

Regional anesthesia blocks pain signals from a specific part of the body

局部麻醉阻斷 身體特定部位的疼痛訊號

from getting to the brain.

傳遞至腦部

Pain and other messages travel through the nervous system as electrical impulses.

疼痛及其他訊息 以電子脈衝運行於神經系統

Regional anesthetics work by setting up an electrical barricade.

局部麻醉劑是藉著 設立電流屏障而產生作用

They bind to the proteins in neurons' cell membranes

它們與神經元細胞膜的蛋白質結合

that let charged particles in and out,

而使得帶電粒子能流進與流出

and lock out positively charged particles.

並將帶正電粒子阻擋於細胞外

One compound that does this is cocaine,

Cocaine/古柯鹼 就是 執行這種機轉的一種化合物

whose painkilling effects were discovered by accident

其止痛作用是一位眼科實習醫師

when an ophthalmology intern got some on his tongue.

舌頭沾到一些，而意外發現的

It's still occasionally used as an anesthetic,

至今它仍偶爾用作麻醉劑

but many of the more common regional anesthetics

但現在有許多更常用的局部麻醉藥

have a similar chemical structure and work the same way.

具有相似的化學結構與作用機轉

But for major surgeries where you need to be unconscious,

但對於病人需要 昏迷無知覺的重大手術

you'll want something that acts on the entire nervous system,

將需要能作用於整個神經系統

including the brain.

- 包括大腦 - 的藥物

That's what inhalational anesthetics do.

吸入性麻醉劑就有這樣的作用

In Western medicine, diethyl ether was the first common one.

在西方醫學 diethyl ether/乙醚 就是最早普遍使用的一種

It was best known as a recreational drug

過去它以娛樂性藥物而聞名

until doctors started to realize that people sometimes didn't notice

直到醫師們開始瞭解 人們有時沒注意到

injuries they received under the influence.

他們是在乙醚的影響下而傷害

In the 1840s, they started sedating patients with ether

在 1840 年代，醫師開始用乙醚

during dental extractions and surgeries.

來鎮靜拔牙及手術的病患

Nitrous oxide became popular in the decades that followed

在其後數十年，Nitrous oxide/ 一氧化二氮（笑氣）變得普遍

and is still used today.

至今仍使用中

although ether derivatives, like sevoflurane, are more common.

然而乙醚的衍生物 如 sevoflurane/七氟醚 更為常用

Inhalational anesthesia is usually supplemented with intravenous anesthesia,

吸入性麻醉常會 額外加用靜脈注射麻醉

which was developed in the 1870s.

後者是在 1870 年代研發出來

Common intravenous agents include sedatives, like propofol,

常用的靜脈注射麻醉劑 包括鎮靜劑，如 propofol/異丙芬

which induce unconsciousness,

可導致昏迷無意識狀態

and opioids, like fentanyl, which reduce pain.

以及鴉片類 如 fentanyl/芬太尼 可減輕疼痛

These general anesthetics also seem to work

這些全身麻醉劑也似乎是

by affecting electrical signals in the nervous system.

藉著影響神經系統 的電子訊號發生作用

Normally, the brain's electrical signals are a chaotic chorus

通常，當大腦不同部位 之間互相交流時

as different parts of the brain communicate with each other.

大腦的電子訊號 就像一個失序的合唱團

That connectivity keeps you awake and aware.

這種連結方式讓你 保持清醒、有知覺

But as someone becomes anesthetized,

但是一旦被麻醉

those signals become calmer and more organized,

那些訊號就變得較平靜、較有秩序

suggesting that different parts of the brain

意謂大腦不同部份之間

aren't talking to each other anymore.

不再彼此溝通

There's a lot we still don't know about exactly how this happens.

這倒底是如何發生的 我們仍有許多地方不清楚

Several common anesthetics bind to the GABA-A receptor in the brain's neurons.

許多常用的麻醉劑會與 大腦神經元的 GABA-A 受體結合

They hold the gateway open,

它們維持通道開放

letting negatively charged particles flow into the cell.

讓帶負電的粒子流入細胞內

Negative charge builds up and acts like a log jam,

負電堆積就好像原木堵塞

keeping the neuron from transmitting electrical signals.

阻斷神經元電子訊號傳送

The nervous system has lots of these gated channels,

神經系統有許多這種門控通道

controlling pathways for movement,

用來控制運動、

memory,

記憶、

and consciousness.

及意識的路徑

Most anesthetics probably act on more than one,

大多數的麻醉劑可能不只一種作用

and they don't act on just the nervous system.

而且不只作用在神經系統而已

Many anesthetics also affect the heart,

許多麻醉劑也會影響心臟、

lungs,

肺臟、

and other vital organs.

及其他重要器官

Just like early anesthetics,

就如早期的麻醉劑

which included familiar poisons like hemlock and aconite,

包括熟悉的毒物，如鐵杉與烏頭

modern drugs can have serious side effects.

以及現代的麻醉劑也有嚴重的副作用

So an anesthesiologist has to mix just the right balance of drugs

所以麻醉師必須以 最恰當的比例混合藥物

to create all the features of anesthesia,

以產生麻醉的所有作用

while carefully monitoring the patient's vital signs,

同時小心地監測病人的生命徵候

and adjusting the drug mixture as needed.

及視需要調整混合的藥物

Anesthesia is complicated,

麻醉是複雜的

but figuring out how to use it

但了解如何使用它

allowed for the development of new and better surgical techniques.

讓新的及更好的外科技術得以發展

Surgeons could learn how to routinely and safely perform C-sections,

外科醫師能學會如何 例行且安全地執行剖腹產手術、

reopen blocked arteries,

打通阻塞的動脈、

replace damaged livers and kidneys,

置換損傷的肝臟及腎臟

and many other life-saving operations.

以及許多其他挽救生命的手術

And each year, new anesthesia techniques are developed

每一年，新的麻醉技術都在進步

that will ensure more and more patients survive the trauma of surgery.

這將確保更多病人 會熬過手術的身心創傷