Two teenage girls held a 16-year-old girl hostage and tortured her at a London care home in a “humiliating” ordeal that was broadcast on Snapchat.

Chyane Stephenson-Dielhenn, 18, and her 16-year-old accomplice forced their victim to snort a salt and tea bag mixture, swallow her own vomit and eat noodles soaked in urine from a bowl on the floor. They tied the girl up, punched her and said that if she tried to escape they would kill her and her family.

The victim was taken prisoner in a 24-hour supported living facility in Barking and Dagenham on March 4, Snaresbrook crown court heard.

Jurors were shown clips, some filmed by Stephenson-Dielhenn, of the “cruel and sickening attack”. Instead of raising the alarm, recipients of the Snapchat videos sent suggestions about what the girls should do to their victim next.

Prosecutor James Thacker said: “This was nothing other than a wicked and despicable attack over a period of up to 10 hours. The victim was assaulted and detained against her will and told if she left then her life and the lives of her family would be in danger. Some of the degradation was filmed on a phone.”

He said the victim escaped when Stephenson-Dielhenn ordered her to take a shower and she ran to reception. “She was seen by [a member of staff] who had never seen anything like what he saw that day,” he said. “The victim was extremely frightened and sought refuge under a desk in the office.”

The 16-year-old, who cannot be named, admitted false imprisonment and assault in July. The court heard she had eight previous convictions for crimes including criminal damage, battery, robbery and theft.

This was Stephenson-Dielhenn’s first offence. She denied the charges but was found guilty of false imprisonment and assault occasioning actual bodily harm following a five-day trial last month.

Defence barrister Stephen Donnelly said she was “remorseful”.

Sentencing the pair yesterday, Recorder Shaun Murphy said: “The victim is scarred mentally and physically and this has caused her nightmares that still continue.”

Stephenson-Dielhenn, from Islington, was sentenced to three years in a young offender institution. Her co-defendant, of Tower Hamlets, received a two-and-a-half-year sentence.

Elaine Cousins, from the Crown Prosecution Service, said: “This was an unprovoked, cruel and sickening attack on an innocent young girl. The behaviour displayed was sadistic.

“Stephenson-Dielhenn and her co-defendant egged each other on and took pleasure in controlling, humiliating and degrading the young victim.

A spokesman for the supported living facility, which is council-funded but managed by an outside provider, said a “thorough” investigation had concluded that staff “acted appropriately and followed procedures once we became aware of the incident”.