The PCA pump and syringe will be connected to your IV. You may get the medicine in any of the following ways: You may have a PCA pump that will run only when you need pain relief. When you feel pain, you can push the button attached to the PCA pump. A small dose of pain medicine will be given through your IV. Your button may blink when you are able to get another dose from the pump. You may receive a small amount of pain medicine running through your IV all the time.