Nurses checked the man at 7.10pm, 10.45pm and 12.10am and each time his score indicated he needed more frequent checking, but this did not happen.
When a nurse checked on him at 4am she found him unresponsive with his breathing mask off. He was unable to be revived.
In his findings, Hill said the man was not monitored adequately and the DHB did not follow its Early Warning Score policy because if it had the man would have been checked by nursing staff more often.
He also criticised the DHB for not having a policy in place for monitoring personal BiPAP machines.
"It is the responsibility of Hutt Valley DHB to have in place adequate systems to ensure that an acceptable standard of care is provided to consumers. This includes having appropriate policies, having working documents that accurately reflect those policies, and ensuring that the policies are complied with," Hill said.
Hutt Valley DHB general manager of quality, service improvement and innovation Debbie Gell said it had already made a number of changes recommended by the HDC including making its early warning scores (EWS) policy and chart more consistent and clearer to understand and updating its policy around the management of patients using personal breathing devices.
Nurses has also been given additional training in relation to the processes required around early warning scores and the use of personal breathing devices.