The primary healthcare provider has prescribed a stat chest x-ray exam and electrocardiogram for a client with a history of heart failure. The pulse oximeter has changed from 90% to 86% oxygen saturation. Which immediate actions will the nurse take?

Tell a staff member to get the electrocardiogram machine.
Notify the x-ray department that a chest x-ray must be done stat.
Have a staff member notify the nursing supervisor of the change in client status.
Notify the health care provider of the change in oxygen saturation to ask what to do.