A nurse has shown an inquest how she vigorously shook a dialysis bag to ensure that her three-year-old patient was not poisoned by potassium.

Sister Sheila Sutton injected the potassium into the bag as part of Naazish Farooq's round-the-clock care at St James's hospital in Leeds.

The inquest heard yesterday that a dialysis bag injected with potassium by Sister Sutton was in place when Naazish, of Great Horton, Bradford, suffered a cardiac arrest.

Naazish's potassium level rocketed to a phenomenal 18.9 during attempts to resuscitate her. A second reading was 12.4, also lethally high. The inquest has heard that a normal level is 3.5-5.

Naazish was diagnosed with lymph cancer after she was transferred to the hospital's intensive care unit from St Luke's, Bradford, on September 24, 1999. She was desperately ill when she was transferred but she had made a remarkable improvement.

Medical staff have told the inquest at Leeds Coroner's Court of their surprise at her sudden death in the early hours of October 8, 1999.

Naazish was buried the same day but her body was exhumed when a police inquiry began following the discovery that she had more than twice the lethal level of potassium in her blood when she died.

Pathologist Christopher Milroy found that the cause of death was consistent with potassium poisoning, although it was impossible to say exactly how she died. Sister Sutton told the inquest she was caring for Naazish on a one-to-one basis the night the little girl died but she was taking a break when she went into cardiac arrest and a colleague was covering for her.

Sister Sutton showed how she lifted the dialysis bag on its end six or seven times to mix the potassium.

She then squeezed and kneaded it to thoroughly disperse the chemical in the fluid.

She said that although potassium is colourless, it is iridescent and it shimmered.

"You can see the potassium going up the bag," she said.

She said that vigorously agitating the bag to mix the potassium was ingrained in her from her student days.

She was well aware of the potential danger to a patient if potassium layered on the bottom of the bag and was taken in concentrated form. Sister Sutton said that Naazish was stable when she left her to take her break at 3.40am.

About 20 minutes later, a nurse came and told her: "I think there's something wrong with the child."

Medical staff had responded to a crash call and were attempting resuscitation on Naazish.

Sister Sutton said the 18.9 potassium level recorded at the time was "grossly high." A second blood sample taken from a central line was 12.4, also lethally high.

She said that Naazish's relatives were desperate to avoid a post mortem, saying that their daughter had been through enough.

The sister said she was shocked to learn that Naazish's condition had deteriorated so markedly in such a short time.

The inquest continues.