The incorrect pain relief was given to a man after his knee surgery, ultimately resulting in his death from a gastrointestinal bleed, the Health and Disability Commissioner has found.
In a report, released on Monday, commissioner Anthony Hill says 75-year-old Mr A was referred for knee surgery in 2011.
Three years earlier, Mr A had had hip surgery and had a gastrointestinal bleed due to a type of anti-inflammatory drugs used in post-operative care.
In 2011, when Mr A attended a pre-admission clinic, neither a registrar, house officer and consultant anaesthetist reviewed Mr A's clinical records which stated he suffered a serious bleed.
Mr A was given ibuprofen - similar to what caused the previous bleed - after his knee operation and deteriorated in the days after.
Sepsis and acute kidney injury were diagnosed but Mr Hill said advice was not sought from a more senior clinician.
"No follow-up plans, further investigation, or recommendations to the orthopaedic team were documented," he said.
Mr A was transferred to ICU but had a heart attack and due to multi-organ failure, a decision was made to stop resuscitation attempts.
The failure to research the patient's history, particularly the 2008 clinical records, was "a breakdown in the DHB's systems... that could provide services with reasonable care and skill," Mr Hill said.
Failure to seek advice from senior doctors, inadequate record-keeping at the DHB, a lack of care after the knee operation and the non-recognition of a deteriorating patient were at the heart of a series of detailed recommendations Mr Hill made to the DHB involved.