Which action should the nurse take to assess for analgesic tolerance in a client who is unable to communicate?

A. Prolong the interval between analgesic medication doses and monitor the client's vital signs: Extending the time between doses to assess tolerance risks causing unnecessary pain and discomfort. Vital signs alone are not reliable indicators of pain, especially in clients unable to communicate. B. Observe the client for the presence of pain behaviors before the next analgesic dose is due: Nonverbal indicators such as facial grimacing, restlessness, muscle tension, or guarding can help assess pain in non-communicative clients. Observing these signs at the end of a dosing interval helps identify potential tolerance. C. Ask family members to report behaviors suggesting that the client's pain has returned: While family members may provide valuable insight, they may not recognize subtle or clinically significant pain cues. Direct nursing observation ensures more accurate assessment. D. Review the client's laboratory values for a change in the peak and trough levels of the analgesic: Laboratory monitoring is not a standard method for assessing analgesic tolerance, as blood levels may remain stable even if the drug’s analgesic effect diminishes over time.