The parents of a toddler who died at Birmingham Children's Hospital said they were "shocked" by a coroner's decision to rule out neglect.
Samantha and Scott Douglas's 18-month-old son Dylan died at the hospital on April 26 last year, a few hours after corrective surgery to reshape the bones in his skull.
The couple, from Hill View Road, Bromsgrove, claimed staff who attended to their son after his operation failed to monitor his condition.
Speaking at the inquest, Mr Douglas said: "Samantha and I were carrying equipment and when we had the opportunity to check Dylan, Samantha found out he was not breathing. Samantha felt his face. He was pale and clammy."
However, Coroner Aidan Cotter said there was no clinical evidence to back their claims.
"I find no neglect here. There is simply no proof. Neglect is a gross failure to provide basic medical care and I do not see any evidence for this.
"I am satisfied that there was sufficient and regular monitoring while Dylan was in the recovery room.
"There is nothing in the evidence that we have heard that would suggest that there was anything wrong with the surgery.
"We know it was a long operation and a complex operation. There was nothing found after Dylan's death in the post mortem to suggest there was anything wrong in the surgery.
"Both Scott and Samantha have told us what they saw and heard in a very difficult situation and there is very little factual evidence, given what the parents say and what the witnesses say."
He agreed with consultant paediatric pathologist Tamas Marton's view of how Dylan died and recorded a verdict of a high blood potassium level.
"Dr Marton gave as a cause of death, a high potassium level," he said.
"What he did not find was any medical cause of death other than the high potassium level, which he thinks is enough."
In a joint statement Dylan's parents said they disagreed with the verdict.
"We are surprised and shocked by this. We feel let down and deeply saddened."
During the inquest Charles Ralston, medical director of the NHS trust, said: "I think this has been a devastating event for the whole cranial facial team.
"They are very well respected and in 20 years of working in the hospital, they have never had an incident like this.
"I understand it has been very difficult for the family but I know they were nothing else but highly cooperative with me when I was trying to establish what happened.
"On behalf of the whole Birmingham Children's Hospital team, I would like to say to Samantha and Scott and indeed the whole of Dylan's family, how sorry we are that Dylan died in our care."
He said an internal inquiry had been held at the hospital and was asked by Mr Cotter to read the report at the inquest.
The report identified a number of necessary changes for the treatment of patients undergoing the same operation.
Recommendations included reviewing the way staff tried to stop post-operative bleeding and guidelines for the observation of recovering patients.