The head of Nursing Services with the Irish Prison Service, Frances Nangle O'Connor, said medical treatment in prison is as good as that in the community.
She said the prison service had taken care of people with similar medical complaints to O'Brien.
The medical expert was speaking at the sentencing hearing.
The court earlier heard that O'Brien suffers from chronic obstructive airway disease and heart disease and requires oxygen.
Sources say that a man who had advanced Parkinson's disease received "very good" care in jail.