Final answer:
The most appropriate action once a choking individual collapses and becomes unresponsive is to call EMS and begin CPR. Implied consent is assumed in emergency situations when the person is not able to respond.
Step-by-step explanation:
When a person is choking and becomes unresponsive after initially refusing help, the priority is to call for emergency medical services (EMS) and begin life-saving procedures. Therefore, the most appropriate next action for the therapist would be to call EMS and begin CPR if the person is not breathing or showing signs of circulation (such as coughing, moving or breathing after collapsing).
It is critical to recognize that once the individual collapses and is unresponsive, consent is implied in life-threatening emergencies where the individual is incapable of responding. For a choking victim, this includes providing the necessary interventions to clear the airway and support breathing and circulation.
However, if the person was still conscious and merely choking (but not yet unresponsive), the first response would be abdominal thrusts, commonly known as the Heimlich maneuver, assuming no contraindications for such a procedure exist and the individual gives consent or is unable to due to the severity of their situation. But since in this scenario the person has collapsed and is likely unresponsive, CPR would be the appropriate course of action according to most protocols.