Prof Ardagh, from Christchurch, is the "champion" of the Ministry of Health target, which requires 95% of patients spend a maximum of six hours in emergency departments before being treated and discharged or transferred to a hospital bed.
Dunedin Hospital was the bottom performer in this area at the end of the last financial year and the latest report to the Southern District Health Board hospitals' advisory committee shows in September the target was met with 70.34% of patients.
Reducing long stays and overcrowding in EDs is seen as important because such factors are associated with bad experiences and outcomes for patients, as well as staff dissatisfaction.
Prof Ardagh said the approach in Dunedin Hospital had been "a little bit piecemeal", employing a "let's try this and that" approach without understanding a whole-of-system approach was needed.
He said he could understand some staff in Dunedin were getting frustrated about the speed of change.
A bit more effort was required, he said, although he accepted that was easy to say and some "big challenges" lay ahead.
Hospitals were very often reactive to an event and took a narrow focus, something all district health boards were guilty of "to a degree", he said.
In the first year of the target, which has been reported quarterly for one and a-quarter years, all boards made some progress.
Data showed the bigger the hospital, the harder it was to change, although Counties Manukau and Canterbury had both made large improvements with a comprehensive approach.
Mostly, as had been found in Dunedin, the issue was to do with the flow of patients through the hospital.
"The biggest single barrier to achieving this target is access to hospital beds beyond ED control."
How well boards met the target was an indicator of the efficiency of the whole hospital system.
It would not be solved by ED staff alone "waving the flag and battering people over the head".
A "genuine collaborative" whole-of-system, whole-of-patient-journey approach was needed.
All staff had to recognise the value of change, both for patients and themselves.
He regarded the most important initial steps for boards to take were establishing a structure to address the problem, which included clinicians and management, and identifying people who would be "champions", who could then produce a plan with priorities.
Prioritisation was important because not everything could be done at once and some aspects, such as capital developments, would not be immediate.
Prof Ardagh noted among work proposed at Dunedin Hospital was computer modelling to test various scenarios.
That would answer such questions as whether there was a need for a short-stay unit rather than building it and keeping "our fingers crossed".
Most larger hospitals had short-stay units and he could also see Dunedin could benefit from an admission/planning unit.
