An inquest at Sheffield Coroner’s Court has heard how Cassian deteriorated rapidly on April 5 and died from a cardiac tamponade, which is when fluid builds up in the space around the heart, eventually preventing it from pumping.
On Friday, assistant coroner Abigail Combes concluded that a failure to record and share information about Cassian's care contributed to his death.
The hearing was told this week how an umbilical venous catheter inserted into Cassian's abdomen to help him feed was in a ‘suboptimal’ position near his heart when it was inserted by two junior doctors.
Neonatal consultant Dr Elizabeth Pilling told the inquest she had intended to have it repositioned within 24 hours, but waited because of the dangers of repeatedly handling a baby as premature as Cassian.
Dr Pilling said she had no explanation as to why she then forgot to make sure his feeding line was moved.
Giving her conclusion, Ms Combes said the decision to pause the procedure and reassess it in 24 hours was ‘reasonable and appropriate’, but was ‘not adequately recorded and communicated’ in Cassian's notes, or on the ward round.
The plan should have been recorded on Cassian's ‘pink sheet’, she said, and communicated to his parents.
Ms Combes said this amounted to a ‘gross failure’ in Cassian's care, which contributed to his death.
She added: "But for this incident, Cassian would not have died of what he died of, when he died."
The coroner recorded a narrative conclusion, which said Cassian's death was ‘contributed to by neglect’.
In a statement at the start of the hearing, Cassian's mother, Karolina Curry, said she and her husband James had a number of questions about her son's treatment, including reports that the unit was understaffed due to it being the Easter weekend.
But Ms Combes concluded: "There were no systemic failures in the form of staffing issues which caused or contributed to Cassian's death."
She said the staffing levels were above the national requirement that weekend, and although there were a number of junior staff present, they were ‘appropriately qualified and able to support the unit adequately’.
The medical director of Sheffield Teaching Hospitals NHS Foundation Trust, Dr Jennifer Hill, has said the trust is ‘so very sorry for what happened’ to Cassian, admitting there was ‘human error in terms of the management of Cassian's umbilical venous catheter’.
Following the inquest, Dr Hill said there had been a full review, changes had already been made and it would take on board any further recommendations from the coroner.
She said: "This was a very rare incident to have happened and everyone involved in his care is devastated.
"There has been a full review of what happened, and changes have already been made to limit the chances of this happening again including additional consultant support at weekends and ongoing improvements to the documentation used.
"We will also be taking on board any further recommendations from the coroner and ensuring we respond with appropriate actions."
Mr and Mrs Curry have said Cassian was ‘a miracle for us’ when they found out he was on his way after six cycles of IVF.
Following the conclusion, the boy's parents said: "Cassian was a beacon of light and our hearts blossomed under his pure and innocent love.
"He was everything that we dreamed of.
"Today, the coroner concluded that he died because of neglect, and had it not been for the gross failings of those in charge of his care, he would still be with us today.
"Cassian was a true miracle, and we will love and miss him forever."