Baby

Our case this week involves a premature baby who experienced lack of blood flow to the brain, and thus has a very poor neurologic prognosis. To prevent possible seizures, the baby was given a loading dose of Phenobarbital, and currently the blood levels are slightly above the therapeutic range. The baby is now on a ventilator, and there is a possibility that the family will request terminal extubation. Is that ethically permissible, in the context of a medication which can suppress a patient's drive to breathe?