Canterbury District Health Board has been told its post-operative care was unsafe, following the unexplained death of man after brain surgery.
The Health and Disability Commissioner has investigated the death of a 21-year-old man who had a defect in his brain leading to pressure buildup and headaches.
It found he should have been better monitored in the days after his operation in 2008.
The patient had alerted doctors to his breathing difficulties and childhood asthma and was awake and recovering well in the days after his operation.
However, he subsequently stopped breathing and was found dead in his hospital bed.
A post-mortem showed he died of sudden respiratory death that was not related to the operation.
The commissioner's report found that his breathing was not monitored often enough or for long enough after the operation and there was nowhere on his medical chart to document his breathing.