Final answer:
If a synchronized cardioversion machine pauses after being activated, the nurse should shout 'all clear' while ensuring no one is touching the patient's bed when the electrical discharge occurs, then monitor the patient's cardiac rhythm.
Step-by-step explanation:
When a nurse is assisting with a synchronized cardioversion on a client in atrial fibrillation and the machine is activated followed by a pause, the appropriate action would be to ensure that all individuals in contact with or near the patient are not touching the patient or the bed and to loudly announce “all clear” before the machine discharges.
This is crucial for safety, as the electrical current used during cardioversion can cause harm if someone is in contact with the patient or the conducting surfaces. After confirming safety and the machine discharges, the nurse should monitor the patient's response to the treatment and check for the return of a normal sinus rhythm.