Mr Thomson, speaking at yesterday's HAC meeting in Invercargill, returned many times to a theme he has expounded at previous meetings - a lack of reported information provided for committee members.
While Mr Thomson's concerns have been picked up by managers, who are still looking at how to provide more comprehensive reports, Mr Thomson seemed unhappy with progress yesterday.
"Why bother having a HAC? Just send a note with a couple of tick-boxes and say 'it's all tickety-boo'."
Inadequate reports were compromising not just board members but the public's right to know how well the DHB was performing, he said.
At three paragraphs, Southland's chief medical officer's report took such documents to a "new level of brevity".
"What percentage of what we do is medical? It's a huge percentage.
"For me as a board member, I consider this almost a dereliction of duty."
Chairman Paul Menzies told Mr Thomson that he ought to have "some faith" in management bringing issues to the committee's attention when it was warranted.
Mr Thomson told Mr Menzies he did not share his confidence.
Earlier, Mr Thomson took issue with a lack of information pertaining to a flagged issue in children's health, a report on which said a staff vacancy, and upcoming sabbatical leave requirements, meant the outpatient service needed to review waiting list management over the next few months.
That statement did not actually say what had been done to remedy the issue, and if it had been resolved, Mr Thomson said.
In response, Otago chief operating officer Vivian Blake said she accepted Mr Thomson's point, and told him a review was under way and would be reported to the committee as soon as possible.
Mr Thomson also complained about scanty information pertaining to CT and MRI radiology services. Wait times "remain high" a brief staff report said.
Such information used to be more detailed, including information on waiting times, Mr Thomson said.
