RRTs (rapid responses) are called in the hospital when a button is pressed in the patient's room. This alerts a rapid response team to come and evaluate the patient for possible higher level of care. When the announcement is called overhead, you respond based on what hospital you are at (ask a more veteran APP if you are unsure). In the hospitals where we have a stat team they will call us once they have assessed the patient.
Things to read:
FCCS Ch. 1
ESICM: Professional Development Module: Clinical Examination section. Particular attention to primary and secondary evaluation