When to shut down a scene

When is it to intense for submissive to use of safe word?
What are the symptoms to look for?

The submissive safe because she has her safe word. True but what happens in the scene gets to intense and the submissive lost power of rational volition?

Here are some things to look for:

Loss of rational speech - Is her speech mumbled, incoherent and off - topic. Then you need to shut down the scene.

Irrational demands for "more, harder." If you pushed her to her previous limits a place beyond her tolerance and continues to moans "more, harder" the she dropped to deep into subspace to be rational player in the scene you to shut the scene down.

What is your name? If she slipped away ask her name. If she can't answer immediately shut the scene down.

Safe word if nothing else ask your safe word if she doesn't answer immediately or coherently shut the scene down.

Now what you give her aftercare drink and hydration, a damp towel, under the covers with lots of cuddles and while talking to her softly letting her know your there.