Bonnet F, Liu N
Département d'Anesthésie-Réanimation, Hôpital Henri Mondor, Créteil.
Cah Anesthesiol. 1993;41(6):611-4.
Epidural opioids provide a potent analgesia not devoided of side effects. In addition, epidural administration of lipid soluble opioids has no clear advantage over the IV route. Combination of epidural opioids with other analgesics may strengthen analgesia and may decrease the incidence of side effects because of a reduction in the amount of opioid administered. Improvement in analgesia quality is documented when local anaesthetics are associated to opioids. Low concentrations of local anaesthetics may potentiate the effect of opioids on ions membrane channels at the level of the dorsal horn of the spinal cord. Alpha adrenergic agonists provide an alternative to local anaesthetics, allowing to improve pain control achieved with opioids. Epinephrine decreases plasma absorption of opioids and is especially useful to prolong the effect of short acting lipid soluble opioids. Alpha adrenergic agonists atc on alpha-2-adrenergic receptors of the spinal cord dorsal horn to depress pain nociceptive transmission. This effect potentiates the one of opioids at this level. Clonidine, which is a selective alpha-2-adrenergic agonist has been demonstrated to improve and to prolong analgesia produced by opioids in postoperative patients. Clonidine administration induces side effects, like sedation, bradycardia and hypotension, but allows to highly reduce the opioid dose. None of the combined techniques of analgesia implies that monitoring of the side effects of opioids has to be reduced.
硬膜外给予阿片类药物可提供强效镇痛，但并非没有副作用。此外，硬膜外给予脂溶性阿片类药物与静脉途径相比并无明显优势。硬膜外阿片类药物与其他镇痛药联合使用可能会增强镇痛效果，并可能由于阿片类药物给药量的减少而降低副作用的发生率。当局部麻醉药与阿片类药物联合使用时，镇痛质量会得到改善。低浓度的局部麻醉药可能会增强阿片类药物对脊髓背角离子膜通道的作用。α肾上腺素能激动剂可替代局部麻醉药，从而改善阿片类药物的镇痛效果。肾上腺素可减少阿片类药物的血浆吸收，尤其有助于延长短效脂溶性阿片类药物的作用时间。α肾上腺素能激动剂作用于脊髓背角的α-2-肾上腺素能受体，以抑制疼痛伤害性传递。这种作用在该水平增强了阿片类药物的作用。可乐定作为一种选择性α-2-肾上腺素能激动剂，已被证明可改善和延长术后患者阿片类药物产生的镇痛效果。给予可乐定可引起副作用，如镇静、心动过缓和低血压，但可大幅减少阿片类药物剂量。没有一种联合镇痛技术意味着必须减少对阿片类药物副作用的监测。
