[Perioperative analgesia in adults : The concept of balanced analgesia.].

The spectrum of perioperative pain treatment is discussed in the present review. The analgesic efficacy of various drugs and the dosage methods of administration and side effects reported for them in such reference works as the practical guide on the management of acute pain recently published by the International Association for the Study of Pain (IASP) are described. Effective postoperative analgesia can diminish stress reactions following surgery. Recovery and physical mobilization are improved as the result of adequate treatment. Results obtained in recent studies have demonstrated that primary adaptive hyperalgesia in the peripheral nociceptive area may develop into secondary maladaptive hypersensibility with a high degree of nociceptive excitability and pain. Chronic pain can develop following acute alterations. Increasing nociceptive activity of primary afferents induces alterations in the dorsal horn of the spinal cord. These alterations imply an increase in the excitability of nociceptive neurons, which has been described as neuronal plasticity. Clinical results have demonstrated prevention or delay of acute postoperative pain after injection of local anaesthetics, analgesic premedication or epidural injection of opioids just before the start of surgery. Continuous perioperative spinal analgesia has contributed significantly to the prevention of phantom limb pain in patients undergoing amputation of extremities. The development of pain memory may be prevented as a result of effective acute pain treatment. Several changes to the terminology of acute pain treatment for animal and clinical studies have recently been proposed, including such new terms as preemptive analgesia and pain prevention, which indicate new strategies in the treatment of postoperative pain. The concept of balanced analgesia refers to a strategy for the improvement of analgesic efficacy as a result of a combination of drugs with different local actions on nociception. The combination of systemic analgesics (opioids in low dosages) with nonsteroidal analgesics (e.g. diclofenac or ketorolac) and the combination of regional analgesic procedures with opioids have been shown to be very effective. The peripheral action of morphine offers new options in pain therapy. Different regional analgesic techniques and continuous infusions of local analgesics are described. The synergistic action of low dosages of local anaesthetics (bupivacaine 0.006%) with low dosages of fentanyl 0.0001-0.0002% are of interest for the treatment of obstetric pain and for pain in opioid-tolerant patients. Investigations performed by the author of this review have shown that epidural infusion of highly diluted mixtures of bupivacaine/fentanyl is highly effective in the analgesic treatment of patients undergoing prostatectomy, providing excellent physical mobilization. The potential dangers of drug combinations and contraindications are also discussed. The concept of using balanced analgesia to induce additive or synergistic effects following the administration of analgesic drugs requires further clinical studies.