Final answer:
Decreased pain intensity is the best indication of morphine's effectiveness in pain management, although other signs such as decreased blood pressure may occur as side effects.
Step-by-step explanation:
The nurse should identify decreased pain intensity as the best indication that the morphine has been effective for the client. Morphine, being both an analgesic and narcotic, is primarily used to reduce pain without loss of consciousness at moderate doses and can cause drowsiness or loss of consciousness at higher doses. While decreased blood pressure and reduced respiratory rate can be side effects of opioid analgesics, they are not the primary indicators of pain relief. An improved appetite, though potentially a sign of general improvement, is not a direct indicator of the efficacy of morphine in pain management.
Following administration of morphine, if the client reports a lower pain score, this suggests that the medication has achieved its desired effect. However, it is also essential for the nurse to monitor for adverse effects such as respiratory depression or hypotension, which can accompany morphine use.