He told the hospitals' advisory committee meeting yesterday the issue could not be ignored as it was "fundamental to what we're here to do" and what the hospital was doing at the moment was "clinically unsafe".
Mr Thomson said he did not want his views to be seen as a challenge to the review, but rather that the issue should form part of Southern's engagement with the review team.
The proposal under consideration by the committee will be considered by the full board today and would involve the board spending $419,000 this year for 35 hours more acute theatre time each week.
In May, the committee heard from orthopaedic clinical leader David Gwynne-Jones that fewer than half of patients requiring acute surgery at Dunedin Hospital received it within the ideal time.
Committee chairman Paul Menzies said with the National Health Board review report pending, the board did not know what it might require in terms of spending and he was not sure the committee should recommend supporting the proposal at this stage.
Mr Thomson said it was clear "we're doing very badly in this" and if the committee did not support the increased hours it would send the wrong message.
Dr Branko Sijnja agreed, saying it was important the board was not paralysed by the fact it was being analysed.
Chief executive Brian Rousseau said he felt it should be a high priority from both the clinical and patient perspective.
The board would have to answer the question of how the project would be funded because it was not included in the annual plan which was yet to gain Ministry of Health approval.
Also, there would need to be verification that the theatre was working at an efficiency level which was "at least the national average".
Any comparisons done in the past showed that the hospital was "within cooee of others".
Chief operating officer (Otago) Vivian Blake said her understanding would be that Dunedin was more efficient than other similar places, but she had not checked that data in depth.
She told the committee she felt the issue should have come to the board about three years ago, emphasising that the existing proposal had been "a work in progress since November last year".
Access to acute theatre time was one of the significant barriers to improving the time patients spent in the emergency department.
The committee agreed to recommend the board implement the proposal subject to it being satisfied about the productivity of the acute theatre in relation to the national average, and where the proposal fitted with the National Health Board review and financing of outcomes of that review.
The National Health Board assessment of Dunedin Hospital systems is expected to be in draft form for the board's consideration by the middle of this month.
