Jack Kokaua, 30, had an underlying heart disease when he died in a Sydney hospital in February 2018, but his manner of death included "exertion and use of taser," State Coroner Teresa O'Sullivan wrote in her findings on Wednesday.

The Bankstown-born man had a long history of mental health issues and was on parole when he was seen babbling in Glebe and trying to ride a hire bicycle fixed with a lock.

Constables Jessica Guthrie and Sam Marshall arrived and told the inquest earlier that it was extremely difficult to control the 130kg man who appeared intoxicated.

After an ambulance was mentioned Mr Kokaua's behaviour escalated, from thrashing his arms around to punching one officer's thighs and an urgent radio call was made for backup.

More officers arrived and eventually, Mr Kokaua was secured in the police van, but "virtually threw himself out" onto the ground, when the door was opened for paramedics to assist.

Following sedation, he was successfully transported to Royal Prince Alfred Hospital admitting that he had recently used "heaps of (the drug) ice and marijuana".

He was scheduled and placed in restraints but requested they be loosened to use the bathroom.

The registered nurse who complied was not advised it had taken seven police officers to restrain him, the inquest found.

Shortly after he escaped the hospital by jumping over a stretcher carrying another patient.

After scaling the wall at Sydney University he walked into a university lecture, and confronted staff and students.

The same detectives returned and pepper spray was first used before the first Taser was fired by Const Marshall without much warning after Mr Kokaua charged towards him.

Const Guthrie straddled Mr Kokaua who was by then face down on the ground, while Const Marshall fired his Taser for the second time less than a minute later.

"He was violently resisting us, and there was a danger, we could have been overpowered," he said.

He fired again when Mr Kokaua rolled onto his back.

The weight of several officers was used to subdue him, with one describing it as "a bit of a stacks on".

An ambulance was called and someone yelled "check his breathing".

About an hour later he was pronounced dead in hospital.

Ms O'Sullivan made a number of recommendations including that police consider calling an ambulance at the earliest available opportunity when arresting or returning a person with mental health issues to detention.

She also advised police to consider skills in de-escalation where a person's mental health problems are exacerbating the situation, their training around the use of force, and to have one officer constantly monitoring breathing when a person is placed in such a position.

Hospital workers are advised that at least two staff members should sign off on the removal of mechanical restraints, even temporarily.

Australian Associated Press