The nurse is evaluating the arterial blood gas and vital signs of a client admitted with abdominal pain of unknown etiology who has a nasogastric tube draining green bile. Which action should the nurse take first?

Assess the client to rule out any complications secondary to the client's pain.

Administer intravenous sodium bicarbonate to the client.

Determine the last time the client was medicated for abdominal pain.

Check the amount of suction on the client's nasogastric tube.