Iron Lung
Despite the fact there were probably thousands of iron lungs in use during the 1940's and 50's, before polio was eliminated in the United States by immunization, there are probably fewer than 20 currently on public display in the U.S.
Our iron lung was donated by the University of California, Davis, Medical Center (UCDMC) and is probably originally from the former Sacramento County Hospital, which existed in the same location as the UCDMC.
The iron lung is used to provide air exchange (breathing) for patients who have paralysis of their respiratory (breathing) muscles (intercostals and diaphragm). The patient lies in the iron lung with an airtight seal around the neck. It functions by a mechanical diaphragm at the "foot end" of the iron lung which, when it moves, pulls air into and pushes air out of the patient's lungs.
Polio patients, who the iron lung was primary used for, would remain in the iron lung constantly, with a mirror above their head being their visual contact with the "outside world". Some patients would regain the use of their respiratory muscles in weeks and be able to come out of the iron lung: yet others would spend their lifetime in one. There are still a few patients in the United States in iron lungs, but more modern and compact respirators are now available.
This massive metal apparatus is a great reminder of the diseases and their sad sequela that existed before the development of immunizations for infectious diseases...and the importance of children getting their immunizations today.