According to Robert Hall author of History of the British Iron Lung, the first scientist to appreciate the mechanics of respiration was John Mayow.
John MayowIn 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 form 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.
Iron Lung Respirator - Philip DrinkerThe first modern and practical respirator nicknamed the "iron lung" was invented by Harvard medical researchers Philip Drinker and Louis Agassiz Shaw in 1927. The inventors used an iron box and two vacuum cleaners to build their prototype respirator. Almost the length of a subcompact car, the iron lung exerted a push-pull motion on the chest.
In 1927, the first iron lung was installed at Bellevue hospital in New York City. The first patients of the iron lung were polio sufferers with chest paralysis.
Later, John Emerson improved upon Philip Drinkers invention and invented an iron lung that cost half as much to manufacture.