[The pre-emptive analgesia in the treatment of postoperative pain].

The term "pre-emptive analgesia" implies the hypothesis that an analgesic treatment, given before nociceptive stimuli reach the Central Nervous System, could prevent or reduce the subsequent pain. The rational basis of this phenomenon, giving rise to much interest in the last years, comes from the finding that noxious stimuli cause wind-up and receptive fields expansion phenomena in the dorsal horn neurons of the spinal cord leading to hyperalgesia. Recently, many clinical trials to verify the existence of a pre-emptive effect regarding the management of postoperative pain by the administration of non steroidal antiinflammatory drugs (NSAIDs), local anesthetics and opioids have been conducted. As regards NSAIDs to date no study demonstrated a pre-emptive effect. Conflicting results emerged from trials employing local anesthetics, opioids or associations of the three classes of drugs. Thus, the "pre-emptive analgesia" represents a very important phenomenon for the basic research, but further trials must investigate its clinical impact.