[tremon]

it probably can reach the Internet in some way simply by being networked

That is simply untrue, you can (and in many cases should) have unroutable subnets. But even if true, that only slightly changes the question: why is operating room equipment networked in the first place? That you've never encountered a proper setup doesn't excuse not having it.

[fencepost]

I phrased that badly - it's not that they can reach the Internet, it's that with the exception of true high-security fully-airgapped locations, if the machine is networked then it's almost guaranteed that the Internet (or something on it) can effectively reach out and touch that machine even if it's only via other systems.

I don't work in a hospital environment, haven't for more than a decade and wasn't interacting with clinical systems even then, but my understanding is that a very significant amount of medical equipment was networked even then, and was at least in theory capable of streaming HL7-formatted data to other internal systems for reasons of patient care, billing, or both. How much of that happens in the real world instead of being theoretical is something I can't say, but I'm sure in the 15+ years since I was working with HL7 that hospitals and equipment haven't gotten less networked.