An iron lung works by lowering the pressure around your body, while keeping the pressure around your head at atmospheric pressure. That gradient pushes air into

An iron lung works by lowering the pressure around your body, while keeping the pressure around your head at atmospheric pressure. That gradient pushes air into your lungs, and then the iron lung raises pressure around your body to squeeze out that air. People who have had polio may lose function in their diaphragm muscles and require ventilation at all times. An iron lung user may exit the iron lung temporarily and use some other kind of ventilator, and some people have learned to force air into their lungs using the muscles in their mouth and throat without any machine. As you can imagine the latter can be tiring: https://en.wikipedia.org/wiki/Glossopharyngeal_breathing https://en.wikipedia.org/wiki/Glossopharyngeal_breathing