The medical care provided to Grant Maynard at the North West Regional Hospital was below standard, coroner Simon Cooper said in findings published on Friday.

The 60-year-old was taken to the hospital on September 14, 2019 after his car crashed into another at slow speed.

He died three days later from multiple organ failure due to comorbidities brought on by the accident.

Shortly after Mr Maynard arrived at hospital, he was given a chest x-ray that showed a small amount of water on his lungs but no indication of rib fractures.

A subsequent CT scan, taken because Mr Maynard was at high risk of bleeding, showed he had a collapsed lung.

An autopsy found Mr Maynard also had broken ribs.

"Specifically, there was a failure on the part of medical staff to diagnose fractured ribs and a failure to recognise significant bleeding causing circulatory impairment which in turn led to acute kidney failure," Mr Cooper wrote.

He noted Mr Maynard had serious comorbidities including type-two diabetes, heart disease, liver scarring and chronic renal failure.

Mr Cooper agreed with an assessment by coronial medical adviser Dr AJ Bell, who reviewed Mr Maynard's death, that the care provided to him was below standard.

Mr Cooper made no formal recommendations.

The day after the crash, Mr Maynard was in so much pain in his left chest he needed strong painkillers, with blood tests indicating he had an acute kidney injury.

The following morning Mr Maynard was short of breath and required supplementary oxygen and was later that night admitted to intensive care.

His condition worsened and he died on September 17.

Australian Associated Press