Iron lung

A negative pressure ventilator, often referred to colloquially as an iron lung, is a form of medical ventilator that enables a person to breathe when normal muscle control has been lost or the work of breathing exceeds the person's ability. Examples of the device include both the Drinker respirator and the Both respirator. The negative form of pressure ventilation has been almost entirely superseded by positive pressure ventilation or biphasic cuirass ventilation.