Final answer:
The appropriate first action by the nurse would be to ambulate for several minutes to improve blood flow and reduce pain in the leg.
Step-by-step explanation:
The appropriate first action by the nurse when a client calls with sudden deep throbbing leg pain would be to ambulate for several minutes. Ambulation helps to improve blood flow and can reduce pain in the leg. It is important to get the client moving to prevent blood clots and improve circulation.
Maintaining the client on bed rest may worsen the symptoms and lead to complications. Isometric exercises and applying ice to the extremity are not appropriate initial actions for sudden deep throbbing leg pain.