This type of iron lung is called a Drinker respirator after one of its developers. Iron lungs work by alternating negative and positive pressure within their sealed body chambers—the negative pressure creates a vacuum around the patient that expands the chest cavity, compelling inhalation, and then a cycle of positive pressure compels exhalation. Negative-pressure ventilators of this type only came into use in the late 1920’s, so the acquisition of this in 1931 was quite a coup. At the time, it was one of only 36 in all of the United States and Canada. Hospital administrators publicized the new baby respirator to spur fundraising for an adult-sized one.
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Memorial Hospital System, "Infant respirator used at Memorial Hospital" (1932). Library Exhibit Images. 145.