When was the iron lung invented?

Iron lung - was invented by Philip Drinker of Harvard, United States in 1929. This machine enables people whose lungs are paralysed by disease or accident to breathe. It does so by alternately reducing and increasing the air pressure round the patient's body. When the pressure is reduced, his chest expands and air streams into hi lungs through the normal air passages in his head which is outside the machine. When the pressure is increased, the chest contracts and air is automatically expelled from the lungs. This life preserving apparatus is a tube on wheels in which the patient lies on a foam rubber bed with adjustable head and foot rests. It is operated by electricity, but has a safety device which gives a warning signal in the event of a power cut. The machine can then be operated by hand. The cover on top of the iron lung can be opened to give access to the patient. When this is done, the patient's head is usually enclosed in a plastic dome in which the air pressure is alternately raised and lowered to enable breathing to continue.