Poor documentation and communication are believed to have led to a 75-year old patient's death in Whangarei Hospital.
The man, who died in February 2010, had undergone a total knee replacement surgery only days before his death.
The Health and Disability Commissioner said medical staff failed to respond to the man's deteriorating condition following the operation.
The man, referred to as Mr A, first sought knee joint replacement in 2006. At that time the anaesthetists considered it was not safe for him to have surgery because of his severe heart disease.
The man, who suffered from a severe heart condition and other diseases including type 2 diabetes.
His GP referred him back to the orthopaedic team in 2009 because knee pain was severely affecting his quality of life. Mr A was advised by the surgeons and anaesthetists that there was a significant risk he would not survive the surgery but he remained determined to undergo the operation and it was performed on February 15, 2010.
He was stable following the operation, but his heart and kidney function started to deteriorate. He died on February 20, the Health and Disability Commissioner said.
The commissioner found that a combination of poor documentation and poor communication led to the failure of both the orthopaedic and nursing teams to recognise and act promptly on Mr A's deteriorating condition.
The failures of the teams were service failures and so Northland DHB breached Right 4(1) of the Health and Disability Services Consumers' Rights. Northland DHB also breached Right 4(4) of the Code by failing to communicate.
Northland DHB accepted that the care the patient received was not to a high enough standard and it had apologised to Mr A's family.
Chief Medical Officer Dr Mike Roberts said significant changes had been made to improve communication among staff at the hospital.
That included educational sessions for nurses in the orthopaedic ward, use of communication tools for smooth handovers between theatre and ward staff, a 24-hour outreach service run from the intensive care unit and ICU registrars and extra time for junior doctors to handover patient care at the end of shifts.
"This sad case has led to many changes within the hospital. Standards of quality and safety within the organisation are much higher now. This is confirmed by data from the Ministry of Health which compares hospital mortality rates across the country and show that we have a significantly lower mortality rate than would be expected given the number and type of patients we treat," Dr Roberts said.