Overuse of ventilators in the first wave probably killed a ton more people than expected. Once they dialed back ventilator use and established cortison treatments and normal oxygen instead death rates lowered.
- are intended for use for a few days, not a few weeks. The artificial air pressure destroys lung cells and capillaries
- patients are sedated to avoid pulling out tubes. This weakens both their lung function and the rest of their body due to immobilization, including bed sores. Usually their trachea is damaged and they cannot talk after removing the tubes for a period of time, and must do physical rehabilitation afterwards.
- doctors and nurses consider patients on ventilators the sickest in the hospital, followed by recent ventilator patients
- being in a hospital for a month or more exposes patients to other infections, which are not immediately apparent in a sedated patient
- China warned about ventilator use being usually unproductive with corona very early in 2020, so it took a while for US doctors to understand that the low oxygen levels measured in corona patients was not a critical thing in most cases if they could still breathe on their own.
ER doctors are not researchers, so they follow previous recommendations until told otherwise.
Doctors didn't dare to go against the guidelines, even with their reservation (they could be held responsible if they did).
Some people I know wrote a book on the subject and are claiming we should held governments accountable for those dead in the first wave (and they've been promptly censored and facebook-banned out of existence). I tend to err on the side of incompetence more than malice.
That said, there is plenty of ignorant people claiming ventilators kill based on statistics - but it's usually the other way round: once you need a ventilator you're either dead 100% or you can get a 40% survival rate with a ventilator.