1) "Should these be covered"? ... yes.
2) "Who decides"? ... central government.
3) "Which regulation(s) do these fall under"? ... MDR in the UK.SOR/98-282
Meanwhile ... it sounds like someone needs to get a grip of equipment purchasing where you are. Don't your biomeds insist on new (incoming) equipment being commissioned by them? Do you have (and carry out) a PM programme? If nurses are buying rubbish, and using it on the wards, if I were you I would take a good look at that stuff during my next "walk through inspection". If cheap junk "fails" in any way, I would have them remove it (or better still, bin it myself).
To my mind, the circumstances you outline illustrate in part the case for regulation ... not to mention the need for vigilance - and PM - by hospital biomeds, as well as clear policies laid down by hospital management.