Joe Massa collapsed and died in September after he and his parents waited three hours in the emergency department at Sydney's Northern Beaches Hospital.
His heart attack - caused by significant fluid loss - followed repeated failures by hospital staff to conduct basic observations or respond to concerns of his mother Elouise.
Before being peppered by questions in NSW parliament on Thursday, Healthscope chief executive Greg Horan expressed his condolences to the family for their loss and "for the care that Joe did not receive".
"I cannot imagine the grief that you're feeling right now," he said at a parliamentary hearing on Thursday.
"We are going to make sure that we (learn from) this tragic incident and ensure that it does not happen again."
The hospital's chief operating officer Peter Thomas said it was "tragic" the concerns of the boy's mother and a nurse were not actioned at all or only when it was far too late.
He said staff were working on the assumption Joe had gastro and tried to get him to sip fluids, and become somewhat fixed on this early diagnosis.
"There was a degree of anchoring bias," Dr Thomas said, describing a focus on an initial piece of information when making clinical decisions without sufficiently adjusting to later information.
"My understanding, looking at the clinical notes, is that baby Joe was taking some sips (of water) and later on, he was given IV fluids.
"But clearly ... that was too late."
IT systems provided by Telstra Health were also being reviewed after Joe's heart rate could not be logged and simultaneously flagged as concerning.
The 488-bed Northern Beaches Hospital, opened in 2018 to replace two smaller public hospitals, is one of 38 Australian run by Healthscope which is owned by a multinational private investment fund.
Parent escalation methods have already been streamlined in the hospital ahead of statewide changes agreed to by NSW Premier Chris Minns.
The premier met with the Massa family on Wednesday, agreeing to overhaul a family-led escalation pathway called REACH and rename it "Joe's Rule".
Meant to ensure staff are apprised and act upon worrying changes in a patient's condition, in practice the policy was little known and not easily understood.
"I didn't know about it as the premier and I didn't know about it as a dad who has taken my kids to emergency departments, and I think that's a problem," Mr Minns said.
The state's leader also appeared open to enshrining public hospital care in the state constitution to stop it from ending up in private hands, the family said.
That move would mimic Labor's protection of water utilities including Sydney Water in 2023.
"This government says they won't do it (privatise hospital care) and that's good," Joe's mum Eloiuse Massa told AAP.
"But what's going to happen with the next government and the next government."
Independent reviews into Joe's death, the emergency department and wider hospital were also taken on.
All aspects of the hospital contract are also being examined.
But NSW Health secretary Susan Pearce declined to tell parliament the cost of breaking Healthscope's contract, citing commercial confidentiality.
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