S9123 Nursing care, in home; by registered nurse, per hour (use for general nursing care only, not to be used when CPT codes 99500-99602 can be used).
99500-99602 are services by non-physicians rendered in the home.
If your payer accepts the S9123, and that's what was performed, and the provider is a licensed RN, then that is what you bill. However, "babysitting", for lack of a better word, is not payable. For the 12 hours to be billed, there needs to be 12 hours of care required by an RN, not just a trained medical person or aide. I do not think I have run across any patients with that diagnosis who required the services of a Registered Nurse 24 hours per day, but of course, it is possible.