His condition deteriorated quickly about six hours after arriving and he passed away at 8.49pm despite efforts to save him.

According to coronial findings, Mr Patterson was diagnosed at the hospital as having atypical pneumonia causing confusion and hypoglycaemia.

"This diagnosis was incorrect and Mr Patterson, in fact, was bleeding from a duodenal ulcer with a large artery in its base," coroner Olivia McTaggart said.

If he had been correctly diagnosed with gastrointestinal bleeding, appropriate emergency treatment would have followed, Ms McTaggart said.

"This should have included urgent transfer for endoscopy or other surgical options to control the bleeding," she said.

"Assuming a correct diagnosis and rapid escalation of care, Mr Patterson would have had a chance of survival.

"As the diagnosis was missed, his death was, unfortunately, a certainty."

An expert medical panel that reviewed his death said there had been "premature diagnostic closure" and clinicians failed to communicate key information.

There was ineffective communication between clinicians about Mr Patterson's elevated blood urea levels, a significant diagnostic sign, the panel said.

Two of four recommendations made by the panel, including for a scoring scale to manage suspected upper gastrointestinal haemorrhages at the hospital, have been implemented.

A department of health spokesman said the remaining two recommendations were due to be completed by the end of December.

"The department of health and Mersey Community Hospital extends its sincere condolences to the family and loved ones of Mr Patterson," the spokesman said.

"We are committed to continuously improving the health services provided in Tasmania.

"We carefully review all coroner’s findings to learn from what has happened, and to implement appropriate changes."