[Is there an advantage to using opioid combinations by the peridural route?].

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.