Joseph Benett dies after inhaling laughing gas
A north London teenager died after inhaling laughing gas with his friends, a coroner's court was told.
Promising art student Joseph Benett, 17, suffered a cardiac arrest after inhaling nitrous oxide on 31 August.
The teenager, from Golders Green, fell into a coma but died last Thursday with his family at his bedside.
An interim Hertfordshire Coroner's Court report gave the cause of death as hypoxic brain injury caused by inhalation of nitrous oxide.
The inquest was opened and adjourned on 1 October. A full inquest is due to be held in 2013.
Sixth-former Joseph, who attended University College School (UCS) in Hampstead, was at a friend's house in Hertfordshire when he collapsed.
His sister Camille, 27, said: "He just never woke up. He had such terrible brain damage and his fits were getting worse.
"When he stopped breathing, my dad and I were holding his hand.
"I found it hard to leave him. As a big sister I felt a responsibility to look after my little brother."
UCS headteacher Kenneth Durham said: "They were playing with laughing gas and for some reason it had a negative reaction with serious consequences.
"Our focus is on grieving and the tragic loss.
"He was a popular, happy boy with a good sense of humour and a very talented art student.
"It's is particularly devastating for his family and close family."
The sale of nitrous oxide for recreational use is prohibited by law.