If you are just starting with a whole bunch of patients that are on mechanical ventilation, then you have identified a cohort and you aren't doing case-control.
However, this sounds like it could be case-control approach if you approach and analyze it as such. In a case-control approach, you identify cases by some outcome measure, and take controls from a ...
Placing bacteria filters on the tubing would be my go-to practice (I am a retired RT) but that seems ineffective since Viral load is much smaller than the sub-micro bacterial load the filters are designed for.
It’s a wet sloppy job ~ I had 35 years experience and I won’t gloss it over.
Sorry, I have no practical advice for front-line workers beyond good PPE, ...
Why aren't lung machines / ECMO widely used for COVID-19?
They are being used University of Michigan and News Medical
Beyond that, you have already suggested the "why" not being used more widely, there are far fewer ECMO devices than ventilators.
The remark about insurance companies is an inappropriate speculation.