The trust started using the new IT system in October 2022, two months before Ms Harkleroad’s death.
Ms Sutton said the previous RAG grading system had been “particularly effective” at times of extreme pressure in the emergency department, as a quick and clear way of identifying the most seriously ill patients.
She also said it was an important tool that could prevent future deaths.
The coroner added that a number of clinicians have expressed concerns about the new IT system, but the response so far has been that it does not have that functionality.
The coroner has written to the hospital’s board demanding action, giving it 56 days to explain what steps it is taking.