How do ventilators work? - Alex Gendler

譯者: Marssi Draw 審譯者: Amanda Chu

In the 16th century, Flemish physician Andreas Vesalius

十六世紀時，一位在法蘭德斯 名叫安德雷亞斯·維薩里的醫生

described how a suffocating animal could be kept alive

描述過一種讓窒息動物不死的方式，

by inserting a tube into its trachea and blowing air to inflate its lungs.

是透過將管子插進牠的氣管，

然後灌入空氣讓牠的肺部膨脹。

In 1555, this procedure didn’t warrant much acclaim.

在 1555 年時， 這個醫療手段沒得到太多讚賞。

But today, Vesalius’s treatise is recognized

但如今維薩里的論文

被視為呼吸器的第一份記載，

as the first description of mechanical ventilation—

a crucial practice in modern medicine.

而呼吸器是現代醫學的重要醫療方式。

To appreciate the value of ventilation,

要懂得呼吸器的價值，

we need to understand how the respiratory system works.

我們必須先了解呼吸系統怎麼運作。

We breathe by contracting our diaphragms, which expands our chest cavities.

我們透過收縮橫膈膜來呼吸，

橫膈膜會擴張我們的胸腔。

This allows air to be drawn in, inflating the alveoli—

這樣能讓空氣吸進來，讓肺泡充氣，

millions of small sacs inside our lungs.

肺泡是肺裡的上百萬顆小泡囊。

Each of these tiny balloons is surrounded by a mesh of blood-filled capillaries.

每個小氣球四周 都被充滿血液的微血管網包圍。

This blood absorbs oxygen from the inflated alveoli

血液從膨脹的肺泡吸進氧氣，

and leaves behind carbon dioxide.

留下二氧化碳。

When the diaphragm is relaxed,

一旦橫隔膜放鬆，

the CO2 is exhaled alongside a mix of oxygen and other gases.

二氧化碳就會隨著 氧氣和其它氣體被吸入。

When our respiratory systems are working correctly,

我們的呼吸系統運作正常的話，

this process happens automatically.

這個過程就會自動發生。

But the respiratory system can be interrupted by a variety of conditions.

但是呼吸系統也可能 因為各種情況受阻。

Sleep apnea stops diaphragm muscles from contracting.

睡眠呼吸中止症 會讓橫隔膜的肌肉無法收縮。

Asthma can lead to inflamed airways which obstruct oxygen.

氣喘可能會造成氣道發炎， 進而阻隔氧氣。

And pneumonia, often triggered by bacterial or viral infections,

通常因細菌或病毒感染而引起的肺炎

attacks the alveoli themselves.

會攻擊肺泡。

Invading pathogens kill lung cells,

病原體侵入殺死肺細胞，

triggering an immune response that can cause lethal inflammation

引起的免疫反應可能造成嚴重發炎

and fluid buildup.

和肺部積水。

All these situations render the lungs unable to function normally.

這些情況都讓肺無法正常運作。

But mechanical ventilators take over the process,

但呼吸器接管這個程序，

getting oxygen into the body when the respiratory system cannot.

在呼吸系統失靈的時候， 將氧氣帶入身體。

These machines can bypass constricted airways,

這些機器可以繞過受阻的氣道，

and deliver highly oxygenated air to help damaged lungs diffuse more oxygen.

傳送含氧量高的空氣，

協助散布更多氧氣到受損的肺中。

There are two main ways ventilators can work—

呼吸器主要有兩種運作方式：

pumping air into the patient’s lungs through positive pressure ventilation,

用正壓呼吸器把空氣打進病人肺部，

or allowing air to be passively drawn in through negative pressure ventilation.

或用負壓呼吸器讓空氣被動吸入。

In the late 19th century,

在 19 世紀末，

ventilation techniques largely focused on negative pressure,

呼吸器技術大部分都著重在負壓，

which closely approximates natural breathing

因為這個方式較像自然呼吸，

and provides an even distribution of air in the lungs.

也讓空氣在肺部能分布得較為平均。

To achieve this, doctors created a tight seal around the patient’s body,

為了做到負壓，醫生 會用裝置密封病人身體，

either by enclosing them in a wooden box or a specially sealed room.

可能是把病人放在 木盒或特製的密封室。

Air was then pumped out of the chamber,

然後將空氣抽出，

decreasing air pressure, and allowing the patient’s chest cavity

減少氣壓，讓病人的胸腔

to expand more easily.

能更輕易的擴張。

In 1928, doctors developed a portable, metal device

1928 年，醫生製造了 可攜式金屬裝置，

with pumps powered by an electric motor.

裡面有用電動馬達驅動的幫浦。

This machine, known as the iron lung,

這個機器也就是俗稱的鐵肺，

became a fixture in hospitals through the mid-20th century.

在 20 世紀中成為醫院的固定裝置。

However, even the most compact negative pressure designs

然而，即使最完善的負壓設計，

heavily restricted a patient’s movement

都大大限制病人的行動，

and obstructed access for caregivers.

也妨礙醫護人員服務。

This led hospitals in the 1960’s to shift towards positive pressure ventilation.

這讓 1960 年代的醫院 轉而使用正壓呼吸器。

For milder cases, this can be done non-invasively.

對病情較輕的患者而言， 不需侵入他們的身體就能做到。

Often, a facemask is fitted over the mouth and nose,

一般會有面罩蓋住口鼻，

and filled with pressurized air which moves into the patient’s airway.

加壓的空氣會送進病人的氣道。

But more severe circumstances

但較嚴重的病人

require a device that takes over the entire breathing process.

需要能完全代替病人呼吸的儀器。

A tube is inserted into the patient’s trachea

插入病人氣管的管子

to pump air directly into the lungs,

會把空氣直接打進他的肺部，

with a series of valves and branching pipes

一連串的氣閥和支管

forming a circuit for inhalation and exhalation.

形成吸氣和呼氣的迴路。

In most modern ventilators,

大部分新型呼吸器會內建電腦系統，

an embedded computer system

allows for monitoring the patient’s breathing and adjusting the airflow.

能夠監控病人呼吸、調整氣流。

These machines aren’t used as a standard treatment,

這些機器不是用在一般標準治療上，

but rather, as a last resort.

而是不得已時的最後手段。

Enduring this influx of pressurized air requires heavy sedation,

要病人忍受這種加壓空氣， 需要施以高劑量鎮靜藥物，

and repeated ventilation can cause long-term lung damage.

而且重覆換氣可能 造成肺部長期損傷。

But in extreme situations,

但是在危急的情況下，

ventilators can be the difference between life and death.

呼吸器能攸關生死。

And events like the COVID-19 pandemic

像新型冠狀病毒肺炎大流行的情況，

have shown that they’re even more essential than we thought.

可以看到呼吸器 比我們想像中還要不可或缺。

Because current models are bulky, expensive,

因為目前的樣式都很笨重、昂貴，

and require extensive training to operate, most hospitals only have a few in supply.

而且需要大量訓練才能操作，

大部分的醫院只有少數幾臺可用。

This may be enough under normal circumstances,

也許在一般情況下還夠，

but during emergencies, this limited cache is stretched thin.

但是在緊急時刻， 這些儲糧僧多粥少。

The world urgently needs more low-cost and portable ventilators,

世界亟需更多低成本的 可攜式呼吸器，

as well as a faster means of producing and distributing

以及能夠快速製造、 傳播這種救命技術的方法。

this life-saving technology.