Dr Kerruish, who was the clinical leader of the 2008 pilot project in the department which used lean thinking methods to identify and reduce waste, said there seemed to be a lull in progress.
He wants the Southern District Health Board and executive to commit to a long-term comprehensive strategy considering all the processes patients in the region go through and transforming those processes until they were truly patient-focused.
Such a strategy would involve health care at all levels, not just in the hospitals and would ensure people got the maximum value out of money in the health budget.
"Having made that commitment, then you would work out appropriate stages to accomplish it," he said.
"If you are not steering in the right direction [you] are not going to ... make the gains you need."
Dr Kerruish's comments follow a call by ED clinical leader Dr John Chambers last week for an immediate multimillion-dollar investment in the stretched department, and chief executive Brian Rousseau saying there was no spare money.
Mr Rousseau also called for greater involvement of ED leadership in exploring all possible solutions to long stays in the department.
That comment drew further criticism from Association of Salaried Medical Specialists executive director Ian Powell, who described it as unfair and repeated his concern that senior management had not acted soon enough to improve the situation.
Dunedin Hospital has been shown as being the poorest performer in meeting the Ministry of Health target requiring 95% of patients to stay no longer than six hours in emergency departments before being discharged or transferred to a hospital bed.
Results to the end of June showed about a quarter of patients visiting the department were waiting longer than the target time.
Dr Kerruish said the target time was conventionally split into three periods. Work to be done by emergency department staff took up three hours, two hours was allowed for the in-patient team to make the decision to admit, and an hour for the physical transfer to the ward.
Emergency department staff's work consistently came in under the three-hour time, he said.
Without the introduction of an admission/planning unit and a short-stay unit (for patients whose conditions required a period of monitoring but not admission), Dr Kerruish considered it extremely unlikely the department would meet the target.
The Canterbury District Health Board had adopted that sort of comprehensive approach, using a maxim to "stop wasting patients' time".
It was not hard to find instances in Dunedin Hospital where patients' time was wasted, he said.
He cited a case where a person correctly diagnosed with appendicitis by a GP had spent 12 hours in the emergency department and then three days in a hospital bed waiting for acute surgery because there was no slot available.
In that time, the patient's condition had deteriorated to the point where open abdominal surgery rather than laparoscopic (key-hole) surgery could be used.
