Final answer:
The first thing that needs to be done immediately after the needle is removed from the arm and pressure is applied is to check the patient's vital signs.
Step-by-step explanation:
The first thing that needs to be done immediately after the needle is removed from the arm and pressure is applied is to check the patient's vital signs. Checking the patient's vital signs, such as their heart rate, blood pressure, and oxygen saturation, is important to monitor their overall health and ensure there are no immediate complications.