On July 29th in 1927, the first iron lung (electric respirator) was installed at Bellevue hospital in New York for the post war polio epidemic. The first iron lung was developed at Harvard University by Phillip Drinker and Louis Agassiz Shaw built with two vacuum cleaners. The iron lung is a negative pressure machine which surrounds the patient’s body except for the head, and alternates a negative atmospheric pressure with the ambient one, resulting in rhythmic expansion of the chest cage (and thus inhalation) in response to the negative extra thoracic pressure. During periods of ambient extrathoracic pressure, the lungs deflate. This type of machine is rarely used today.
The first patients of the iron lung were polio sufferers with chest paralysis.
Historically, in 1670, John Mayow demonstrated that air is drawn into the lungs by enlarging the thoracic cavity. He built a model using bellows inside which was inserted a bladder. Expanding the bellows caused air to fill the bladder and compressing the bellows expelled air from the bladder. This was the principle of artificial respiration called “external negative pressure ventilation” or ENPV that would lead to the invention of the iron lung and other respirators.
For more information visit https://en.wikipedia.org/wiki/Iron_lung