The nearly obsolete negative pressure ventilator was known as the Iron Lung.  It was was first used in 1928 at Boston Children’s Hospital.  It was used on Poliomyelitis (Polio) patients to assist their breathing.  At the height of the polio outbreaks in the 1940s and 1950s iron lungs filled hospital wards.  Polio has been almost completed eradicated today through vaccination.  By 2004 there were very few of these devices remaining in use.