Final answer:
When a baby with cleft lip and palate and a small mandible cannot breathe on their own and a seal cannot be achieved with a bag and mask, the indicated intervention is to place the baby on a ventilator to mechanically assist with breathing.
Step-by-step explanation:
A baby born at term with a bilateral cleft lip and palate and a very small mandible requires positive-pressure ventilation because they are not breathing. If a seal cannot be achieved with a bag and mask, the indicated intervention would be to place the baby on a ventilator to mechanically assist with the breathing process.