Nurse Lucy Letby tried to kill a premature baby by giving her fluids contaminated with insulin, according to her murder trial.
The boy’s blood sugar fell dangerously low and his heart rate rose sharply after Letby intentionally added insulin to his intravenous supply during an overnight shift, Manchester Crown Court heard.
Letby, 32, is accused of attempting to kill the boy, known as Child F, less than 24 hours after he allegedly murdered his twin brother, Child E, by injecting air into his blood.
The children’s real names cannot be revealed for legal reasons.
The nurse, from Hereford, denies killing seven babies and attempting to kill 10 others between June 2015 and June 2016.
Peter Hindmarsh, professor of pediatric endocrinology at University College London, told the court on Friday that poisoning was the only reasonable explanation for Child F’s sudden deterioration in the neonatal unit at the Countess of Chester in the early hours of August 5, 2015.
After the nutrient infusion, which began after midnight, the boy’s heart rate jumped to 200 beats per minute and his blood sugar dropped to an “extremely low” level.
By intravenous route, we mean a way of administering a substance using a needle or a tube inserted into a vein.
Professor Hindmarsh said a commonly used synthetic human insulin known as Actrapid – a colorless solution – was given by infusion.
He said the brain depends on a “constant supply” of glucose to function and the dangers of low blood sugar include seizures, coma and sometimes death.
The boy’s glucose levels remained low throughout the August 5 day shift, even after the intravenous line and connected bag containing the nutrients had been replaced.
“Low blood sugar for 17 hours”
Child F’s blood sugar did not reach safe levels until after the decision to stop nutrients from a second bag at 6:55 p.m. and independently give him extra sugar, the court heard.
Prof Hindmarsh said it was clear the boy’s hypoglycaemia was “persistent” during those 17 hours.
Meanwhile, child F received twice the amount of glucose normally given to correct low blood sugar in a baby, he said.
Child F has fully recovered
The witness agreed with Letby’s attorney, Ben Myers KC, that the high insulin blood sample reading was from the second bag of stock and therefore could not show what the level was in the first bag attached to the early hours of August 5.
But Prof Hindmarsh said similar blood sugar readings from around the same time a person was likely to mean they had a similar amount of insulin earlier in their system.
Child F later recovered fully and was later released, the court heard.
The trial will continue on Monday.