Acuity tools for rehabilitation

I am trying to develop an acuity tool to assist with staffing in an IRF. Our acuity changes drastically from day to day and staffing levels need to be more manageable on a shift by shift basis. I would appreciate any suggestions related to desirable HPPDs, staffing levels, staffing models or acuity tools that someone has utilized successfully in rehab. I run 2 small units which make the efficiency very difficult to keep up with.
thank you