2. Pain Relief Unit, Acute and Chronic Pain Management, Donostia University Hospital, San Sebastián 20014, Spain.
Opioids have been considered the strongest option in clinical practice for the treatment of postoperative pain. However, in this setting, the spinal administration of an opioid drug does not always guarantee selective action and segmental analgesia in the spine due to partial reuptake to blood systemic circulation reaching brain receptors. Recent evidence from experimental studies indicates that bioavailability in the spinal cord biophase is negatively correlated with liposolubility, which is higher for hydrophilic opioids, than for lipophilic ones. Clinical guidelines recommend using a mixture of local anesthetic plus a strong opioid to improve the analgesic effect, minimize adverse effects and improve the overall patient´s satisfaction. Moreover, sometimes an opioid alone, typically morphine, can be administered to provide a long period of postoperative analgesia for 24 h, or even 48 h when an extended release epidural formulation is used. In all cases a vigilance protocol must be recommended to prevent either early or delayed respiratory depression.
Keywords: Spinal analgesia, epidural opioids, intrathecal opioids, and postoperative pain