London - It is "incredibly worrying" that a hospital cannot explain how a pensioner was given Flash floor cleaner to drink instead of water, a coroner said on Monday.
Joan Blaber, 85, died six days after drinking a single tablespoon of the cleaning fluid while in her hospital bed a year ago.
The Flash was poured from a water jug into summer fruit cordial so she could wash down some tablets.
An earlier hearing was told some staff at the hospital spoke such poor English they needed translators, leading to fears a misunderstanding could have contributed.
Coroner Veronica Hamilton-Deeley said at the time the possibility the Flash was put in the jug deliberately "lurks on the back of one’s mind". She told the opening of the full inquest yesterday that despite almost 100 people being questioned about the tragedy – by police, the Health and Safety Executive, the hospital itself and the Care Quality Commission – there was still no explanation.
There are no plans to bring any charges as a result of the incident.
Mrs Blaber’s son Gary and her sister Rosemary Bird looked on as Miss Hamilton-Deeley told the inquest jury at the start of a week-long hearing into the death: "I think it’s probably no exaggeration to say no one knows what happened.
"This is incredibly worrying. It could happen again. We don’t know how it happened in the first place.
"Even the most rigorous police investigation hasn’t completely ascertained what actually happened.
"It’s even more important that we winkle out what may have been wrong, what may not be correct about the system in place."
The inquest heard that the widowed shopkeeper from Lewes, East Sussex, was admitted to the Royal Sussex County Hospital in Brighton after suffering a stroke. As Mrs Blaber recuperated she was given the concentrated Flash cleaning fluid from the jug placed at her bedside.
Dr Philip Thompson, a stroke consultant at the hospital, said Mrs Blaber drank around 15ml – a tablespoon – of the concentrated Flash. The liquid had been poured into a beaker with summer fruit cordial so she could take some tablets.
Minutes after swallowing the Flash she vomited brown and green liquid. She died six days later.
But it was several days before the police and other bodies were informed about the fatal incident.
Miss Hamilton-Deeley told the jury Mrs Blaber was an "extremely vulnerable woman" with many health problems and was dependent on the hospital for her care.
The inquest heard the cause of death was respiratory failure due to pneumonia caused by ingesting the cleaning fluid.
Detective Inspector Julie Wakeford, of Sussex Police, said a thorough investigation had been conducted but they were no closer to finding a suspect.
The inquest continues.