Final answer:
The appropriate action would be to remove the tube and re-intubate the child.
Step-by-step explanation:
When an air leak is heard around the intubation tube of a child with croup, it is important to address this issue promptly. In this situation, the appropriate action would be to remove the tube and re-intubate the child. An air leak around the tube can indicate that it is not properly secured or there may be a problem with the tube itself, which can compromise the child's breathing.