The care in the unit was poorly documented, with low oxygen saturations being recorded but no record was made of oxygen provided.
Just before being discharged from the unit, Matthew coughed up blood-stained sputum and/or pink froth, an event attributed to his having been intubated. This incident was not documented.
He was taken to the children's ward, with instructions to have his oxygen saturation level maintained at 94 per cent or greater. The anaesthetist prescribed 2 to 10 litres of oxygen. At the time of discharge the boy's oxygen saturation was noted to be 96 per cent on 8 litres of oxygen.
The children's ward night-duty nurse documented his oxygen level as consistently 95 per cent overnight. At around 2am she reduced the oxygen to 3 litres. At 5am she turned off the oximeter machine - which measures a patient's oxygen saturation level - as she had to care for a new admission. She did not assess Matthew again until 6.30am when she found him unresponsive.
He was resuscitated and flown to Christchurch Hospital's intensive care unit where he died from the brain injury induced by lack of blood flow and oxygen.
Mr Hill found the anaesthetist, two nurses and the DHB breached the code of patients' rights. He referred the night nurse to his director of proceedings for a decision on whether any proceedings - such as a case before the Health Practitioners Disciplinary Tribunal - should be taken. The tribunal can fine, suspend or de-register nurses it finds guilty of professional misconduct.
Mr Hill said the night nurse's reduction in oxygen at 2am, inadequate monitoring, failure to obtain a medical review, and cessation of monitoring by oximeter were serious departures from accepted standards.
He also criticised the nurse for what he said were her failures to make a full, prompt and truthful explanation to Matthew's parents and to the DHB about when she ceased the oximeter monitoring.
Staff orientation and training at Grey Base Hospital were sub-optimal, policies were inadequate and the pattern of sub-optimal clinical documentation by multiple staff members was of concern.
He recommended the DHB and the staff involved make written apologies to the family.
Mr Meates said: "We deeply regret that in this instance our systems did not support staff responsible for caring for Matthew to provide care of an acceptable quality. The West Coast DHB accepts all the HDC's findings."
"We have made significant progress in implementing changes which will reduce the possibility of something similar happening in the future."