KEY POINTS

1. The process of nociception is not a hard-wired characteristic but is a plastic and dynamic process (i.e., neuroplasticity) with multiple points of activation and modulation. Persistent noxious input may result in relatively rapid neuronal sensitization and possibly in chronic pain.
2. Postoperative pain, especially when poorly controlled, results in harmful acute effects (i.e., adverse physiologic responses) and chronic effects (i.e., delayed long-term recovery and chronic pain).
3. By preventing central sensitization, preemptive analgesia may reduce acute and chronic pain. Although experimental studies overwhelmingly support the concept of preemptive analgesia, clinical trials are equivocal because of methodologic issues.
4. By allowing individual titration of analgesic agents, use of PCA (intravenous or epidural) may provide several advantages over traditional provider-administered analgesia (e.g., intramuscular injections) in the management of postoperative pain.
5. The incidence of respiratory depression from opioids does not appear to be significantly different among the various routes of administration (i.e., intravenous versus intramuscular versus subcutaneous versus neuraxial). Appropriate monitoring of patients receiving opioid analgesics is essential to detect patients with opioid-related side effects such as respiratory depression. Whether patients receiving neuraxial opioid analgesics require monitoring in an

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   intensive care unit is debatable, although there is literature demonstrating the relatively safe use of single dose and continuous infusions of neuraxial opioids on routine surgical wards under appropriate monitoring conditions.
6. Judicious use of adjuvant agents, such as NSAIDs, may improve postoperative analgesia and diminish analgesic-related side effects.
7. Compared with systemic opioids, perioperative epidural analgesia may confer several advantages, including a facilitated return of gastrointestinal function and decrease in the incidence of pulmonary complications, coagulation-related adverse events, and possibly cardiovascular events, especially in higher-risk patients or procedures. However, the risks and benefits of epidural analgesia should be evaluated for each patient, and appropriate monitoring protocols should be employed when using postoperative epidural analgesia.
8. Epidural analgesia is not a generic entity because different catheter locations (catheter-incision congruent versus catheter-incision incongruent), durations of postoperative analgesia, and analgesic regimens (local anesthetics versus opioids) may differentially affect perioperative morbidity.
9. Postoperative pain management should be tailored for special populations (e.g., ambulatory surgical, elderly, opioid-tolerant, pediatric, obese, OSA patients) who may have different anatomic, physiologic, pharmacologic, or psychosocial issues.