What is an iron lung, and is it useful for people with polio?

It is a primitive negative pressure ventilator. It is basically cylinder-like rigid metal box where the patient lies so that his or her head sticks out. A vacuum pump creates a variable negative pressure inside the cylinder so that the patient’s thorax and abdomen mimic the natural breathing rhythm.

Iron lung was the first functional perpetual respirator. It was used for artificial breathing in cases, where the patient was unable to breathe on his or her own, such as respiratory paralysis, muscular dystrophy, drug overdose, poisoning etc. But being large, cumbersone and claustrophobic, it was a technological dead end.

Poliomyelitis is a virus disease where the virus attacks the motor neurones of the frontal lobe of spinal cord. By killing those neurones (nerve cells), it can cause paralysis. Polio did not only kill, it also crippled for life.

On 0.1% of all polio cases, the paralysis can spread to the bulbous medulla oblongata and the nerves which control the muscles for breathing and swallowing. If those got paralyzed, the result would be death by asphyxiation.

Iron lung was used to treat those polio patients who had it really bad and who had the disease spreading to the respiratory organs and who thus needed artificial breathing. (Another disease in which iron lung was used was ALS or Lou Gehrig’s Disease.)

Some 80% to 90% of the polio patients who were put to iron lung, died in the acute phase of the disease. They usually drowned in their own saliva because the swallowing muscles had been paralyzed, choked on carbon dioxide buildup due to clogged airways, or died from acidosis due to buildup of CO2 in bloodstream. For them, the iron lung was nothing but a terrifying and claustrophobic death chamber.

But some did survive, and they usually recovered when the surviving neurons began to re-grow axons to the muscles and began to reconnect. Yet for 1 in 10,000 the paralysis was left permanent.

Iron lung seems to be a peculiarly American contraption. They were not used much in Europe; the Europeans invented something better. Positive pressure ventilators eventually superseded iron lungs in Europe since 1952, when Björn Ibsen from Blegdamshospitalet, Copenhagen, Denmark, successfully performed tracheotomy and used positive pressure ventilation for 12-year-old Vivi Ebert, saving her life. He built a prototype using the German “Pulmotor” device and WW2 aviator respirators as the model, and he never patented it, to make it and its design spread as fast as possible.

Positive pressure ventilators had several advantages over iron lungs: they were way cheaper, easier to manufacture, easier to use, easier to maintain, more reliable, less claustrophobic, smaller, and did not require as much space. Moreover, they freed the patient to bed and the patient could be seated in semi-sitting position so that the saliva would drip in the stomach and the airways could be cleansed. The fatality rate by using positive pressure ventilation fell from 80% to 11% in the 1952 epidemic in Denmark.

There is one polio survivor from the 1950s epidemics still in Finland with respiratory paralysis alive. She uses a positive pressure ventilator integrated on her electric wheelchair.

Why the Power Symbol Looks Like this?

All of us has been seeing this icon in all our electric and electronic appliances, but do you know where does this symbol come from?

It is pretty simple. It is a combination of “I” and “O”. In electronics, people use “O”(zero) to denote an off state and “I”(one) to denote on state of any appliance. So a button/icon with the power symbol indicates that the button can be used to change the state of the appliance from on to off or vice versa.

Why did polio patients need an iron lung?

Not all needed it, but the iron lung, a behemoth of medical engineering, became the lifeline for those whose muscles had betrayed them under polio's ruthless grip.

Imagine this: your body, a prison, your breaths, shallow whispers, as polio ravages your muscles, including those you never think about because they work on autopilot—the ones that let you breathe.

The iron lung worked on a simple yet ingenious principle: negative pressure.

It mimicked the natural breathing process when the diaphragm and chest muscles failed.

The patient lay inside this cylindrical chamber, sealed except for their head poking out, looking like some sci-fi astronaut in a retro space capsule.

As the machine created a vacuum, it forced the chest to expand, pulling air into the lungs—inhale.

Then, as pressure normalized, air was pushed out—exhale.

This mechanical ebb and flow were life itself for those inside.

Sadly, being encased in metal isn't living, it's surviving.

Patients often spent weeks, months, or even years in these contraptions, lying horizontal, staring at the ceiling or into mirrors angled for a view of the world beyond their metal cocoon.

The iron lung was a stopgap until medicine caught up with polio's challenge.

Vaccines eventually relegated polio to history books and iron lungs to museums.

But for a time, they were the bodyguards against an invisible enemy, holding the line one breath at a time.

What are the advantages of using an engine with less stroke compared to one with more stroke for the same displacement?

Bore and stroke establish an engine’s displacement, but their relationship to each other also affects the engine’s operating characteristics. This is sometimes called the stroke ratio.

In general, an oversquare bore, which is an engine where the bore diameter is greater than the length of the stroke, will rev higher, and is capable of producing more horsepower, but with lower torque.

An undersquare bore, where the stroke is longer than the diameter of the bore, normally produces less peak horsepower, but more torque at lower RPM’s.

An example of an oversquare engine, which has a relatively large bore, but short stroke is the Ford 289 V8. It’s known for its exceptional ability to rev quickly and produce good horsepower at higher RPM’s.

An example of an undersquare engine, which has a longer stroke and smaller bore is the Chrysler Slant 6, which produces relatively small horsepower numbers, but comparatively high torque numbers at low RPM’s.