Cahiers d'anesthésiologie
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Cahiers d'anesthésiologie · Jan 1991
Review[Mechanism of action and clinical use of opioids administered by the peripheral perineural route].
Experimental studies have shown that opioids could produce two types of effect on neuronal excitability. The first one, aspecific, is a local anesthetic action on the nerve fiber with a diminution of sodium and potassium conductance. ⋯ Clinical studies have proved that opioid injection in peripheral nervous trunks and specially in the brachial plexus produce a prolonged analgesia status in the post operative period but also and mostly in the chronic pain. The more liposoluble opioids like fentanyl and buprenorphine are the more effective.
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The aim of the regional administration of opioids is to provide an efficient and prolonged analgesia. Then, opiates can be useful for postoperative analgesia and for the treatment of chronic pain of malignant origin. Analgesia is correlated with several adverse effects of which the most frequent are nausea and itching and the most severe is respiratory depression. ⋯ Opioids also act by a reduction of the motor functions of the bowel, which perhaps could reduce the incidence of anastomotic breakdowns. Finally, other effects have been reported, as anecdotes, such as the treatment of spasm after bilateral replantation of the ureters, neurologic bladder dysfunctions and enuresis. Spinal administration of opioids has also been used as a treatment of premature ejaculation.
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Cahiers d'anesthésiologie · Jan 1991
Review[Secondary effects of opioids administered by the regional route].
The administration of narcotics in the subarachnoid or the epidural space is gaining acceptance for postoperative pain relief. However, the potential side effects of intrathecal and epidural use of opioids are the following: early and late respiratory depression, pruritus, nausea and vomiting, urinary retention. ⋯ Naloxone can be used to reverse the depression. Pruritus can occur in 10 to 30% of patients receiving morphine; 10 to 30% nausea and vomiting, and urinary retention occurs in 20 to 50% of patients.
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Cahiers d'anesthésiologie · Jan 1991
Review[Opioids by the perimedullary route: mechanisms of opioid analgesia].
The identification of multiple opioid receptors and opioid peptides in the 1970 was the starting point of an increasing knowledge on opioid physiology and pharmacology. The mechanisms of action of spinally supraspinal levels. At the spinal level, opioids act by a modulation of specific supraspinal effect is the consequence of the migration of opioids, other in the bloodstream or in the cerebrospinal fluid, towards the encephalon. ⋯ At the receptor level, opioid agonists act, hypothetically via the system of adenylcylase, more certainly via a modulation of membrane tonic channels. Thus, opioids modify sodium, calcium and potassium currents, and modify the successives phases of the membrane action potential. The result is an hyperpolarization which is responsible of an inhibition of the release of various neurotransmitters such as P substance.
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Cahiers d'anesthésiologie · Jan 1991
Review[The use of opioids by the regional route in obstetrics].
Epidural and spinal administration of opioids in obstetrics can be used during labour and for cesarean section. Although these routes of administration are of limited use when opiates are employed as sole agents, the association with local anesthetics may improve the characteristics of analgesia. The administration of a local anesthetic-opiate mixture allows a reduction of the total amount of local anesthetics, thus reducing the incidence of maternal hypotension and the percentage of instrumental extraction. ⋯ Opioids may also be used for postoperative analgesia after cesarean section. Since they could be responsible for an opioid-related respiratory depression in the mother and the neonate, a strict supervision is absolutely necessary following this particular mode of administration of opiates. If human and technical means of supervision failed to bring into operation, it would be better not to use opioids by the spinal route in such a context.