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

A. Observe the client for the presence of pain behaviors before the next analgesic dose is due: In a nonverbal client, observing for pain behaviors such as grimacing, restlessness, moaning, or changes in vital signs is crucial. If these behaviors increase before the next scheduled dose, it may suggest that the current analgesic regimen is becoming less effective, indicating tolerance. B. Review the client's laboratory values for a change in the peak and trough levels of the analgesic: Peak and trough levels are useful for monitoring therapeutic ranges for certain medications but are not reliable indicators of analgesic tolerance. Tolerance is a clinical observation based on pain behavior, not solely on drug concentration measurements. C. Prolong the interval between analgesic medication doses and monitor the client's vital signs: Extending the interval between doses risks undertreating the client’s pain and causing unnecessary suffering. Tolerance assessment should focus on evaluating pain control, not withholding medication to observe physiological responses. D. Ask family members to report behaviors suggesting that the client's pain has returned: While family members can provide valuable insight, their observations should supplement, not replace, the nurse's direct clinical assessment. Family members may miss subtle signs of pain or misinterpret behaviors unrelated to pain.