[HocusLocus]

Learn the difference between the

Iron lung: 'negative pressure' https://en.wikipedia.org/wiki/Iron_lung Ventilator: 'positive pressure' https://en.wikipedia.org/wiki/Ventilator

Humans breathe using 'negative pressure', expanding muscles within the rib cage (principally on the back) and draw in air. Until computers and quality sensors could be given control over the breathing process, positive pressure breathing was too dangerous to even consider. While Iron Lungs were a nightmare of complexity and patient care was difficult with all or part of the body in a pressure chamber with seals around the neck... Iron Lungs were a safer alternative, especially if there is fluid in the lungs that needs to be coughed out.

I am not 100% convinced that the switch to using positive pressure exclusively was a good move, with vent damage being prevalent especially on comatose patients... and patients who would not even be in a coma but for the fact they were put on a vent.