With the level of control over her body and nervous system, I think Susannah could definitelly have used the Dogan to commit suicide. Set the 'heart beat' panel to 0, whatever. (Sure there wasn't a heart beat panel, but she could create one.)

Not that she would have, but it was certainly possible. I think Mia might have stepped in and prevented her though if she realised what was happening. I say 'might' as I'm not convinced she would be successful, the dogan being Susannah's sanctuary, a place Mia likely couldn't penetrate.