A dui that results in substantial bodily harm or death carries a mandatory minimum of 2 years in prison and a maximum of 20 years in prison. If the person had a prior dui felony that the penalty can be even more severe.
If you were given an own recognizance release, the terms are that you appear in court for your hearings. Normally no other restrictions apply so leaving the state would be fine. You will need to appear for the preliminary hearing or trial. The best thing to do is consult with your attorney to make sure that you have no restrictions on your ability to leave the state.