> Do we have any "iron lung" negative displacement ventilators still in service or did every single one get phased out? I've heard those are easier on the lung

> Do we have any "iron lung" negative displacement ventilators still in service or did every single one get phased out? I've heard those are easier on the lungs in concept and I'm wondering if some got dug out of basements to fight covid-19 and their success rates. I wonder if it would make more sense for non-medical-device companies like GM to produce that type of ventilator, rather than the more modern types. The technology is simpler and the required manufacturing process are probably closer to their core competencies.