Final answer:
The nurse should include the statement, wait until the pain is severe before using the PCA pump, in the teaching. Option a can lead to medication overdose, and option d is a valid statement to limit access to the pump.
Step-by-step explanation:
The nurse should include the statement, Wait until the pain is severe before using the PCA pump, in the teaching. This is because the PCA pump is designed to provide controlled doses of pain medication to the patient, and it is most effective when used at the onset of pain or discomfort.
Pressing the button as often as desired without limits, as mentioned in option a, can lead to the overdose of medication. Option c, asking the nurse for help if the pump is not working, is important, but it is not the most crucial information to include in the teaching. Option d, family members should not touch the PCA pump, is a valid statement as it is essential to limit access to the pump to ensure proper administration of medication.