Final answer:
The statement indicating further teaching is needed for a patient about to use PCA is that they believe they should call the nurse before taking additional doses. PCA devices are set up with safety constraints to prevent overdoses and typically do not require a nurse's intervention for each dose.
Step-by-step explanation:
When teaching a client about the use of patient controlled analgesia (PCA) for post-operative care, the statement that indicates further teaching may be needed is B) "I should call the nurse before I take additional doses." PCA allows the patient to self-administer pain medication in controlled doses at fixed intervals, commonly adhering to a safety lockout mechanism to prevent overdose. The patient does not need to call the nurse before taking an additional dose, as the machine is programmed to provide doses only within safe limits.
The PCA machine can be set to deliver a continuous background infusion (indicated by A), and it is indeed designed to prevent overdose by having strict controls (indicated by D). If the pain is not well controlled, the patient should notify the healthcare team (indicated by C), but it is not necessary—or may even delay pain relief—to call before taking an additional dose if another dose is available and necessary within the set limits of the PCA programming.