Final answer:
If the baby's head has been delivered and the amniotic sac is intact, the EMS provider should leave the sac intact and focus on supporting the baby's airway. They may administer oxygen if necessary.
Step-by-step explanation:
If the baby's head has been delivered and the amniotic sac is still intact, the EMS provider should leave the amniotic sac intact. Breaking the amniotic sac at this point may cause complications, such as increased risk of infection or cord prolapse. The baby can still receive sufficient oxygen through the intact sac until the rest of the body is delivered and the sac breaks naturally. The EMS provider should focus on supporting the baby's airway, ensuring that there are no obstructions, and providing any necessary respiratory assistance, such as administering oxygen if needed.