[Clinical experience in the use of clonidine in regional anesthesia and early postoperative period (1984-1989)].

Clonidine attracts attention as a sole agent for local anesthesia. This review analyzes the role of alpha 2-adrenergic agents in modern regional anesthesiology, both practical and experimental. Recent controlled studies showed that an alpha 2-adrenoreceptor clonidine administered spinally is characterized by a dose-dependent antinociceptive effect and is as effective as epinephrine in prolonging local anesthetic blocks. Moreover, in combination with spinal opioids, intraspinal clonidine possesses a synergic analgesic effect, potentiating the intensity and duration of opioid anesthesia. Use of clonidine as an adjuvant to various plexus blockades and for caudal block in children is discussed. Regional administration of clonidine involves side effects, such as hypotension, bradycardia, and sedation. Minimization of the dose of alpha 2-adrenergic agonists minimizes the complications. Regional clonidine effects (analgesia, hemodynamic changes, and sedation) and their recognized mechanisms of action are described.