Articles: analgesia.
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Clinically, epidural coadministration of opioids and local anesthetics has provided excellent analgesia for various types of pain. However, information about the interaction of these drugs when administered epidurally is limited. Therefore, we evaluated the antinociceptive interaction between morphine and lidocaine on both somatic and visceral noxious stimuli in the rat. ⋯ These data demonstrate that epidurally coadministered morphine and lidocaine produce synergistic analgesia and prolong the duration of analgesia in tests of somatic and of visceral nociception.
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Pain is a major factor of respiratory decompensation after chest trauma. General and/or regional analgesia improve alveolar ventilation, make physiotherapy easier and often avoid mechanical ventilation. Concerning regional techniques, epidural, intercostal and interpleural routes have their respective indications and contraindications, benefits and risks. When suitable, epidural analgesia appears to be the preferable technique.
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Prolonged administration of morphine for the treatment of chronic pain causes constipation requiring the use of laxatives, which may result in electrolyte deficits. Morphine-induced constipation is due to the binding of the drug to opioid receptors in the gastrointestinal tract and the brain, where it mimics the actions of enkephalins. The effect on the gastrointestinal tract seems to be more intense than the central effect. ⋯ Provided that the anatomical organization of the haemorrhoidal veins in the rat is similar to that in man, slow-release naloxone will be carried by the matrix, to which it is absorbed further down in the gastrointestinal tract. It may thus even reach the rectum, from where, after having been absorbed, it bypasses the liver, enters the central nervous system and reduces the antinociceptive effect of morphine. In conclusion, it can be stated that oral administration of naloxone in combination with morphine may help to prevent constipation during the treatment of chronic pain.