Doctors treating polio patients found that while many sufferers were unable to breathe in the acute stage, when the action of the virus paralyzed muscles in the chest, those who survived this stage usually recovered completely. Such observations indicated the need to develop strategies to maintain respiration until the patient could breathe independently again.
In 1927, chemical engineers Philip Drinker (1894-1972) and Louis Agassiz Shaw, from Harvard University, devised a tank respirator to maintain respiration. In the device, the patient's head stuck out of the end of the tank, with a sponge rubber seal to make it airtight. Air was then pumped from the tank to produce negative pressure causing the chest to expand and thus produce breathing.
The first iron lung was installed in 1927 at Bellevue Hospital, New York, and in 1928 the first patient was an eight-year-old girl with polio, comatosed from lack of oxygen. One minute after the device was switched on, she regained consciousness and asked for ice cream. Further refinements included a garage mechanic's "creeper" that allowed patients to slide out of the tank, and boat "portholes" through which medical staff provided treatment. Equipment designer John Haven Emerson produced an iron lung that could vary the respiration rate, with the added advantage that it cost half as much to manufacture.
The iron lung helped to save thousands of lives during the polio outbreaks of the 1940s and 1950s. In 1959, 1,200 people were using tank respirators in the United States, but with the advent of the polio vaccine this figure had fallen to thirty by 2004.
