Final answer:
The PT should activate the emergency response system and perform CPR while waiting for paramedics. Retrieving the AED should be done once the paramedics arrive.
Step-by-step explanation:
The first course of action by the PT should be to activate the emergency response system by calling 911. This is because the child is gasping and does not have a pulse, which indicates a medical emergency. The PT should prioritize getting professional medical help as soon as possible.
While waiting for the paramedics to arrive, the PT can also perform CPR (cardiopulmonary resuscitation) by beginning compressions and breath cycles with a ratio of 30:2. This can help maintain blood flow and oxygen circulation until the child receives advanced medical care.
Retrieving the AED or defibrillator would be the next step once the paramedics arrive, as these devices can be used to deliver an electric shock to the heart if necessary.