Iron lung machines played pretty much similar role during polio epidemic, what modern ventilators did during covid pandemic. Present day doctors probably will fail to recognise what this machine is. But medical history will always identify an iron lung machine as a legacy version of modern ventilator. 

In the year 1940s and 1950s when polio epidemic hit the hardest, all hospital wards across many countries were loaded with iron lung machine. Numbers of lives it saved by helping polio struck patients breathe, is beyond imagination. And from there, the idea of ventilator came into existence. 

Poliovirus outbreak in earlier days :


If you ask a physician in today’s time, what a Polio patient looks like in real, s/he will mostly tell you that s/he have not seen a single case. We are privileged to live in an era where vaccines are so effective that dreadful diseases like polio are not in sight. But it was not the case in early 20th century.

Let us go in flash back to year 1900 – 1950 prior to invention of polio vaccine. It’s a time where poliovirus was spreading everywhere. It caused permanent paralysis in lacs of small children. People were so petrified that they stopped going to public places or using swimming pool or even sending their kids to school. 

How poliovirus spread and then caused permanent debility in large scale was scary. Not only paralysis of limbs or face, patient also ended up in paralysis of muscles of breathing. Thus to help a patient out to breathe a machine was used, that is called “iron lung”. 

Incredible story of Paul Alexander; the last survivor of severe paralytic polio

Iron lung machine, which was back then a showstopper in hospital wards, is now just a show piece of museum. But do you know that still somewhere someone is using it, that too day in and day out for past 70 plus years! His name is Paul Alexander. He is also famously known by the name of “Polio Paul”

When in year 1952 polio caused tons of deaths and paralysis in US, Paul got affected by paralytic polio too. He was just a 6 year old boy living in Dallas, Texas, US that time. Just in a matter of few days he lost his ability to move, speak, swallow and even breathe. 

He was then put in iron lung machine, which eventually became his home. In fact it was more than a home. For him, it was rather a virtually inseparable body part. 

In spite of having paralysis down the neck, Paul identified himself to have great potential. He went to college. Then pursued law and practiced. He soon emerged as a famous lawyer with many clients. May be ‘P’ in Paul stands for ‘Perseverance’. 

Paul is still comfortable with iron lung so much that he never thought of using any other modern technology for assisted ventilation. But why is Paul fond of this iron lung machine and not modern ventilator ? What is so special about iron lung ? Keep on reading to uncover. 

How breathing works in a normal human ?

Before trying to understand what an iron lung is and how it functions, let us know how breathing in human works? Because mechanism action of iron lung and human lung are resemblant. 

As you might know, we breathe  through an organ called lungs. Human lungs reside inside chest cavity. Just below chest cavity is the diaphragm, which act as muscle of breathing. 

Higher up in chest cavity, lies airway. Through this airway, outside air passes into lungs and exchange of O2 and CO2 takes place. So how does air goes inside lungs ?

Diaphragm is a dome shaped muscle just under lungs. When it contracts, it pulls and creates a vacuum and hence pressure drops inside chest cavity. This is called negative pressure as it is lower compared to outside pressure. 

Due to this pressure difference, air rushes from outside into lungs through airway. That’s how we breathe in. Following this, diaphragm relaxes, and goes back to original dome shape. Accordingly pressure inside chest cavity again increases, causing air to breathe out.

So to sum up 

  • Negative pressure in chest cavity -> Breathing in 
  • Positive pressure in chest cavity -> Breathing out

What is Iron lung ? And how does an iron lung machine work ?

Iron lung is in-fact a closed air tight cylindrical metal chamber. Contrary to its name, it is made up of steel instead of iron. Inside this chamber a patient is kept in such a way that only head pops out. Such that nose and air way is exposed to atmospheric pressure.


Inside the metallic cylinder chest and rest of body stays. A negative pressure is created inside the chamber. Consequently there is a negative pressure inside chest cavity. This pressure pulls air inside lung through nose and airway. Thereby an iron lung is also called as negative pressure respirator. 

Next a positive pressure is created inside metal cylinder which moves air out of lungs. This cycle is repeated. 

This differs from modern ventilators which are positive pressure respirators, where air is pushed through airway inside lungs during breathing. So unlike modern ventilators, the mechanism of iron lung echoes more with normal respiration or breathing.

Who and how invented iron lung machine ?

When polio cases soared in early 1900, and children suffered from paralysis of breathing, a machine was developed for artificial ventilation of lungs. This was called pulmotor. Pulmotor was based on positive pressure ventilation. What it used to do is, to push air into lungs of a patient in high pressure through a face mask. 

This pulmotor caused more harm to lung than good, as it resulted in pressure injuries to lungs. This brought about invention of a negative pressure respirator, popularly known as iron lung machine. 

Iron lung was invented by two scientists namely Philip Drinker and Louis Shaw in 1920s in Harvard medical school. Hence it is also called as “Drinker tank” or “Drinker respirator’. Truth to be told polio epidemic motivated scientists to build this device. 

This iron lung machine was actually first successfully used for an 8 year old polio victim in Boston children hospital in the 1928. And rest what came following it is history. 

How iron lung machines were used in polio outbreaks?

The crude version of iron lung was quite pricey, that costed around 1500$ to 2000$. Also it weighed around 500 pounds, which was too heavy to transport. 

Hence in the year 1931 John Emerson further improvised iron lung. He made it cheaper and more portable. Emerson also added window ports on both sides of machine, so that patient access is hassle-free. Maximum utility of this iron lung machine came to picture during major polio outbreak that happened in 1931. 

By the year 1939, at least 1000 iron lung machines were in use in United States alone. With due course of time, it was made even more economical and light weighted.

During 1940s to 1950s iron lung machines were used extensively in Europe, America, Australia and many other countries during polio outbreaks. Wards were packed with small kids with iron lung machines.

Patients were put to iron lung when they landed up with paralysis of breathing muscles. Physiotherapist helped in regaining breathing muscle strength through breathing exercise and practice. This would take weeks, months or even years. Once breathing is re-established they were removed out of iron lung. Nevertheless some needed iron lung lifelong. 

Here is how Bill gates explained iron lung machine.

Origin of Modern ventilator

John Emerson in 1949 employed mechanical assister for a patient. This worked on the basis of positive pressure ventilation. In initial days positive pressure respirators used face mask to push air inside lungs. As technology advanced, a tube was inserted to airway, to push air inside lungs. 

In 1952 Denmark Copenhagen showed a huge polio epidemic. In that polio outbreak positive pressure ventilator was used effectively at few places. 


However hardly anyone knew that time, that it will be a stepping stone for invention of modern ventilator and I.C.U. Wherefore modern ventilator and I.C.U. owe its origin to polio epidemic.

Evolution of Modern ventilator

Modern ventilator is a compact machine and easy to transport. We have come a long way since its conception.

In Germany first computer monitored mechanical ventilator was used. Best part is, it can modulate how much air, oxygen and pressure to be given to a patient. This settings can be individualised as per patient’s need.

Now a days ventilators are used not just for polio, but also in many other diseases when a patient needs breathing support. It is the spine of advanced critical care. 

During covid pandemic when demand of modern ventilator rose to sky high, we could appreciate its usefulness undoubtedly.


when medicine met technology, there occurred ground breaking inventions. Same is the story of modern day ventilator. 

I hope this article brings insight into an untouched yet interesting topic. Share it maximum with your friends and family members if you found it useful. 


All the informations provided here are for educational and awareness purpose only. Kindly do not use these as alternative to medical consultation.


  1. Thanks so much for sharing this. With a polio-free world around, we wouldn’t understand what people might have gone through before the vaccination. No words can define Paul Alexander’s optimism.

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