[Treatment of postoperative pain by balanced spinal analgesia]

Postoperative pain relief has the aim to provide patient subjective comfort, to inhibit neuroendocrine and metabolic responses to surgical injury and to enhance restoration of function by allowing the patient to breathe, cough, move more easily and to begin enteral nutrition. Opioid analgesics, independently from the route of administration, are unable to provide all this. In addition to spinal opioids other drugs, such as local anesthetics, alpha 2-agonists and cholinergic drugs, may produce an antinociceptive effect when administered by spinal route. All these drugs may be administered in combination between them, realising the so called "balanced spinal analgesia". The aim of this study is to analyse the available methods for the evaluation of pharmacological interactions, the types of interaction among different spinal antinociceptive drugs and the role of balanced spinal analgesia in the treatment of postoperative pain. Analysis of the presented data shows that the spinal synergism between opioids-local anesthetics and opioids-alpha 2-agonists can be useful in the treatment of postoperative pain, because these drug combinations are able to provide a satisfactory pain control at low doses with a reduction of the adverse effects. Furthermore, the combined use of opioids-local anesthetics proved to be effective also in abolishing postoperative incident pain and in inhibiting neuroendocrine and metabolic responses to surgical injury. Especially in high risk patients this is related to a better outcome. Finally, even if the synergism between cholinergic drugs with opioids or a2-agonists have been proved, at the moment their use in man by spinal route in the treatment of postoperative pain is not advisable.