There's always a big different from having fantasies and trying them out.
Smothering a partner and knocking them out cold, which may sounding very exciting in a story, has health consequences in real life. Read Oz's response above.
By asking your partner to do this to you, you are asking her to take on the risk of "what happens after?" The risk of "what if something goes wrong" and she is then blamed for it.
You are also asking the dommes here, to give you advice on how to potentially cause your lady to harm you.
If you want to be subdued in such a manner that you can't escape or fight your way out of the bondage, there are many ways to make that happen.
If you are trying to get off, on asking the dommes to solve this problem for you, you might have to do a bit more begging. Even then, I'm not sure you'll get an answer you were expecting.