I am not an expert either. I would be surprised if they put someone on a ventilator just because his O2 level was low without first putting him on O2 and maxin

I am not an expert either. I would be surprised if they put someone on a ventilator just because his O2 level was low without first putting him on O2 and maxing out the flow. Little experience that I do have is that people are first put on O2, then if their saturation remains low they increase the flow until they can increase no more. At that moment they are a candidate for a ventilator. Maybe they "relaxed" the criteria after a while if ventilators showed bad outcomes but when people are maxed out on O2, there is little you can do.