A mother who turned up at hospital with her seven-week-old baby who had stopped breathing says she was told to "sit down and wait" by a receptionist.
Daveanah Cowie took Tommy-Leigh Brewin to Royal Derby Hospital's accident and emergency unit as he was unwell but then noticed he was not breathing.
Ms Cowie, who ran past the receptionist and handed the child to doctors, said: "I didn't want him to die".
The hospital said it was now reviewing training for reception staff.
Mother-of-five Ms Cowie, of Alvaston, Derby, said Tommy-Leigh, who is seven weeks old, was not feeding properly and was concerned as his twin brother had been taken into hospital with bronchitis days before.
She took him to the children's A&E department at the hospital on 27 November.
She said when they got outside the hospital "I saw he was not breathing and I thought, 'oh my God'".
"I ran in and told the receptionist what was happening. [Tommy-Leigh] was stone white, and she just asked me questions about our names," she added.
"I thought 'what are you doing?' and when she asked for dates of birth and told us to sit down and wait I just ran off."
The 21-year-old added: "I went straight to the desk where the doctors are sat and handed him over. They rushed him to resus.
"I was just stood there in tears. It took about two or three minutes to revive him but it felt like forever.
"And he stopped breathing another six times before they got him on a ventilator."
The Derby Telegraph reported Tommy was later transferred to Nottingham's Queen's Medical Centre with bronchitis and was now recovering.
A spokesperson for Derby Teaching Hospitals said: "Our first priority is always the safe care of the babies and children brought to our Children's Emergency Department,
"We were concerned to find that a receptionist failed to immediately recognise the serious nature of this situation, as this is highly unusual for our dedicated team of reception staff.
"We immediately started an investigation and we are now reviewing the training we give to reception staff in the Children's Emergency Department.
"We are also happy to meet Ms Cowie to explain the steps we have taken."