A baby’s heart rate soared and his blood sugar level dropped dangerously low after he received fluids contaminated with insulin, a nurse’s murder trial has heard.
A medical expert told Manchester Crown Court that poisoning was the only reasonable explanation for the prematurely born twin boy’s sudden deterioration.
Lucy Letby, 32, is accused of attempting to murder the infant by adding insulin to his intravenous feed on a night shift at the Countess of Chester Hospital’s neo-natal unit in the early hours of 5 August 2015.
She is accused of trying to kill him less than 24 hours after she allegedly murdered his twin brother, Child E, by injecting air into his bloodstream.
Following the infusion after midnight, the heart rate of the youngster, referred to as Child F, surged to 200 beats a minute and his blood sugar fell to an “extremely low” reading.
His glucose levels remained low throughout the day, even after the intravenous line and the connected bag containing the nutrients was replaced.
Child F’s blood glucose rose to safe levels only after a decision to stop the nutrients from a second stock bag at 6.55pm and extra sugar was given independently, the court was told.
Giving evidence, Peter Hindmarsh, professor of paediatric endocrinology at University College London, said it was notable that low blood sugar was persistent for those 17 hours.
During that period, the boy also received twice the amount of glucose normally given to correct hypoglycaemia in a baby, he said.
Prof Hindmarsh told jurors the brain was reliant on a constant supply of glucose to function and the dangers of low blood sugar included seizures, coma and, on occasion, death.
He said Child F’s initial rise in heart rate was “consistent with the release of adrenalin, your first line of defence against a low blood glucose”.
Prof Hindmarsh concluded that a commonly used synthetic human insulin known as Actrapid – a colourless solution – was administered via the infusion.
His calculations, he said, showed the synthetic insulin remained in a steady state in Child F’s system up until 6.55pm and disappeared more than 30 minutes later.
He also calculated from a subsequent blood sample, which showed an extremely high level of insulin, that the rate it was delivered was 17 times greater than a small “appropriately therapeutic” dose given to Child F in the days after his birth.
Prof Hindmarsh agreed with prosecutor Nick Johnson that the blood glucose measurements relating to the second stock bag suggested that it too had been contaminated “more or less to the same degree”.
Mr Johnson asked the witness: “Did you conclude the explanation for (Child F’s) clinical presentation from just after midnight on August 5 to the early evening of the same day was explicable and only reasonably explicable by the fact that the fluid he was receiving was contaminated by insulin?”
Prof Hindmarsh replied: “Yes, I did.”
The witness agreed with Ben Myers KC, defending, that the blood sample reading of high insulin came from the second stock bag so could not show what level was in the first bag.
But Prof Hindmarsh said that similar blood glucose readings around the same period from a single person would be likely to mean they had a similar amount of insulin in their system earlier.
Child F went on to make a full recovery and was later discharged, the court heard.
The defendant, originally from Hereford, denies murdering seven babies and the attempted murders of 10 others between June 2015 and June 2016.
The trial continues on Monday.
