There are some poly people who are into BDSM, and there are some BDSM people that are into poly. But it isn't an "automatic" interest. Just because one is into poly -- that doesn't mean they will automatically be into BDSM too. Just because someone is into BDSM -- it doesn't mean they are into poly.
Both require excellent communication to execute well.
But I don't see how multiple partner sex in a BDSM context is poly unless you already have established some kind of polyship with these people. Then you are in polyship who happen to be sharing sex in a BDSM style.
Otherwise it is multipartner sex BDSM style -- people coming together to have that single, stand alone experience. But not necessarily a polyship coming out of the shared sex experience.
Whether it is healthy or not -- that depends on all the players and their healths going in.