Following days of sedation in the Royal Darwin Hospital emergency department and high-security Joan Ridley Unit, Pukamani Alimankinni stopped breathing while sleeping in a bean bag on August 8, 2021.
Northern Territory Coroner Elisabeth Armitage was told during a four-day inquest on Tuesday Pukamani's death was as a result of over-sedation.
In the days leading up to her death the 47-year-old was given "high doses" of varying antipsychotics and sedatives, including ketamine, during a Careflight from Tiwi to Royal Darwin Hospital.
She spent three days in the hospital's emergency department, at times under the watch of security guards, because there were no beds available in the mental health unit.
Once transferred to the mental health unit her compulsory 15-minute observations were done via CCTV footage and when she was found non-responsive medical teams delayed CPR.
"This death was preventable. We know that," counsel assisting Beth Wild told the court.
During the final days of the inquest her tiny grandchildren sat in the first row of the court room trying to peer between lawyers sitting at the bar who debated the inadequacy of Pukamani's care.
"NT Health take full responsibility for the shortcomings in the care that was provided to Pukamani," chief psychiatrist David Mitchell wrote in his institutional response.
Ms Wild said the department had reviewed more than nine hours of CCTV in the lead-up to Pukamani's death.
"The nine hours of footage that follows there is no further contact between any of the nurses on shift," Ms Wild told the coroner.
Several nurses gave evidence they monitored Pukamani by CCTV until about 6am when one of them realised she was unresponsive and "could not see her chest moving".
CPR was started but later stopped while the mental health team waited for a specialist team to arrive from the main hospital to resume compressions.
Pukamani had lived with a schizo-affective disorder since 1998 and was described as "very well" for extensive periods in the 20 years before her death.
The inquest is expected to continue on Wednesday morning with further evidence from a doctor and oral closing submissions.
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