Clinical meaning
Opioid analgesics produce their effects primarily through mu (μ) receptor agonism in the CNS. Mu-1 receptors mediate supraspinal analgesia, while mu-2 receptors mediate respiratory depression, constipation, and physical dependence. Kappa receptors contribute to spinal analgesia and dysphoria. The nurse must understand equianalgesic dosing for opioid rotation, the multimodal analgesia approach combining opioids with non-opioid agents (acetaminophen, NSAIDs, gabapentinoids) to reduce opioid requirements, and patient-controlled analgesia (PCA) management. Opioid-induced respiratory depression remains the primary safety concern, monitored through the Pasero Opioid-Induced Sedation Scale (POSS) and continuous pulse oximetry or capnography.
Exam relevance
Risk factors: - Opioid-naïve patients (highest risk for respiratory depression) - Concurrent CNS depressants (benzodiazepines, gabapentin, alcohol) - Obesity and obstructive sleep apnea - Advanced age (>65) with altered pharmacokinetics - Hepatic or renal impairment affecting drug metabolism/excretion - Chronic respiratory disease (COPD, asthma) - History of substance use disorder - Post-operative patients receiving neuraxial opioids (epidural/intrathecal)