The HDC's investigation found during a two-month period in 2017 the man had two falls and developed pressure injuries which were not properly documented and his family weren't told about.
It also found that when the man was transferred to hospital level care, the rest home failed to document the extent of the pressure injuries to the new provider.
Deputy Health and Disability Commissioner Rose Wall were critical of the rest home for failing to provide services to the man with reasonable care and skill.
Wall highlighted the importance of providers communicating effectively with one another and with the consumer's family, and of ensuring that clinical assessments and care plans were comprehensive and actioned.
It's critical that documentation was completed to a good standard to support care and decision-making, including on the transfer of care to another provider, Wall said.
The man's daughter believed that failures at the rest home caused her father's "health and wellbeing to plummet dramatically over this period of time and cause his unnecessary demise".
Wall noted that the man's family were very involved in his care and would have expected pertinent information to be conveyed to them.
She said: "I consider that information pertaining to a change in health condition, such as falls and pressure areas, is significant, and information that a family would expect to receive. I am critical that this did not occur".
Wall recommended the rest home apologise to the man's family which has been done.
The deputy Health and Disability Commissioner also advised the rest home consider gaining access to a more specialised level of nursing, clarify guidelines for accessing specialist advice, schedule regular and ongoing education sessions on specified topics and report back to HDC on the effectiveness of these changes and the results of audits in relation to the changes.
