A nurse can't explain the absence of a medical reading which she claims showed normal blood sugar levels in a critically ill woman, an inquest has heard.
Heather Bills, 64, died at Middlemore Hospital on January 2, 2013, six weeks after she suffered burns to 35 per cent of her body in an explosive house fire.
It was later discovered that she suffered a suspicious and massive hypoglycaemia-related cerebral injury, due to a high volume of insulin being "introduced to her body from the outside".
Police suspected three hospital staff members of potentially injecting Bills with the fatal dose.
The case remains open.
Registered nurse Harmeet Sokhi was Bills' primary nurse during a 7pm to 7am shift on Boxing Day, 2012.
Late that day Bills' health began to deteriorate rapidly from a then-unknown cause.
Sokhi has spent today giving evidence at a coroner's inquest in the Auckland District Court to determine the source of the insulin.
However, her evidence directly contradicts the testimony of health care assistant Sharon Connors, who was Bills' watch from 7pm to 11pm on Boxing Day, 2012.
Connors "seemed oblivious" to the situation, Sokhi said.
Sokhi later entered Bills' room just after 11pm, after heath care assistant Nirmala Salim raised the alarm, concerned over the grandma's rising heart rate.
Bills' heart rate had reached 145 beats per minute.
Her condition became critical after midnight as emergency doctors were eventually called to diagnose the decline.
During this time Sokhi said she conducted a blood sugar test with a glucometer, without the direction of a doctor.
She told the court she performed the test at about 1.40am because Bills "seemed like she had a low blood sugar" based on her symptoms.
However, according to Sokhi, the test came back normal but she couldn't specifically recall notifying the medical team.
Dr Lit Son Yoong previously told the inquest that he recalled asking for Bills' blood sugar levels and was told it was "fine".
"I recall a staff nurse said that blood sugar was 5 or 6, one of those two numbers ... We therefore concluded that she was not suffering a hypoglycaemic episode or a hypotensive," he said.
Blood tests were also conducted by the team at about the same time.
"It was just a nursing assessment that I was doing. It wasn't something that anybody needs to be alerted [to]," Sokhi said when cross-examined by Bills' daughter Michelle Maher over the glucometer test.
"It perplexes me, Ms Sokhi," Maher said, continuing to question Sokhi about the glucometer reading of 6.4 mmol/L, well within the normal range of four to 11.
However, when Bills' blood tests came back it showed a clear discrepancy to Sokhi's bedside test and indicated the blood sugar levels were critically low and the reason for the sharp drop in health.
Sokhi said she only learned of the inconsistency between the tests "way down the track".
But, the court has heard Sokhi was informed just hours later.
"You were made aware of that on the same shift, on that same night," Maher said to Sokhi.
"I cannot explain what - what I'm trying to say is I cannot recall having this conversation," the nurse replied.
Maher then asked Sokhi what her immediate reaction was to low blood sugar being found to be the cause of decline.
"What did you do?" Maher asked,
"You're asking me how did I feel?" Sokhi replied.
"No, what was your response?" Maher said.
"I would've been surprised to hear that," Sokhi said.
An emotional Maher said the glucometer reading was the "one thing that could prove that [Sokhi] acted appropriately" and that notifying doctors "could have saved her [mum's] life".
However, there is no material record of Sokhi's glucometer reading.
Despite the glucometers being able to show the results of the more than 400 most recent readings, none displayed Sokhi's 6.4 reading at 1.40am, police and DHB investigations found.
The court heard that the blood glucose reading may have been an error.
"Could be several reasons," Sokhi said, adding the error may have been because Bills' hand or finger was not cleaned properly.
The nurse said an accurate reading could've saved Bills' life.
"I'm sorry," Sokhi said.
Maher asked the nurse if she was aware of the use of insulin around the world to assist is "mercy killings".
"No," replied Sokhi.
"Did you inject my mum?" Maher continued.
She was given a warning by chief coroner Judge Deborah Marshall - and the line of questioning was objected to by Sokhi's counsel, Karen Rose.
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