There were "lost opportunities" in the care of a premature baby who died after being removed from a ventilator , a coroner has said .
Rohan Rhodes, of Narberth, Pembrokeshire, was born 15 weeks early at Singleton Hospital in Swansea on August 27 2012, weighing 814g (1lb 12oz).
He was placed on a ventilator at the hospital's neonatal intensive care unit, where he was described as "doing well" for four weeks after his birth.
A heart duct which usually closes at birth had remained open and Rohan was transferred to St Michael's Hospital in Bristol for a surgical assessment.
The hospital is part of the same trust as Bristol Royal Hospital for Children, where Sir Bruce Keogh, the NHS's medical director, has ordered a review of children's cardiac services.
Flax Bourton Coroner's Court heard the medical team's plan was to keep Rohan on the ventilator ahead of his upcoming surgery.
But advanced neonatal nurse Amanda Dallorzo took the "autonomous" decision to remove the machine and put a breathing mask on Rohan instead.
Within an hour, Rohan's condition dramatically deteriorated and he developed NEC, a gastrointestinal disease, which required surgery.
Tragically, Rohan never became stable for the operation and he died, aged 36 days, in an incubator at the hospital with parents Alex and Bronwyn Rhodes close by.
Avon Coroner Maria Voisin recorded a narrative verdict following a three day inquest into Rohan's death.
She said three blood gas readings should have been taken to check Rohan's condition but were not, resulting in "lost opportunities" to treat the baby.
"Rohan Rhodes was an extremely premature baby who was at risk of developing NEC," Ms Voisin said.
"He developed this condition which caused his death on September 30.
"On September 29, there were three occasions when he should have had a blood gas test.
"It is not known what results would have been but these were lost opportunities which may have resulted in Rohan receiving earlier medical care."
She told Rohan's parents: "I am very sorry for your loss."
Ms Voisin said the blood gas tests should have been taken directly after Ms Dallorzo removed Rohan from the ventilator, at 4pm on September 29.
A second test should have been taken at 5pm, when it was noticed that a breathing mask placed on Rohan was leaking.
The final "lost opportunity" was after Rohan was put back on the ventilator, at 7.30pm that evening, Ms Voisin said.
Rohan died at 6pm the following day.