الفهرس 
The Vertebral ColumnOnly 14 pages are availabe for public view
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Abstract
Neuraxial block is safe, and inexpensive technique with advantage of prolonged postoperative pain relief which blunts autonomic, somatic and endocrinal response. So it can reduce the incidence of venous thrombosis, pulmonary embolism, cardiac complications, bleeding, pneumonia, and respiratory depression.
Neuraxial block is achieved by administration of local anesthetic through spinal, epidural and caudal routes which acts by blockade of voltage gated sodium channels preventing conduction of electrical impulses by the membranes of nerve and muscle.
Many factors influencing anesthetic activity including; dosage of local anesthetic, site of injection, and addition of different agents as alpha agonists(adrenaline, phenylephrine, clonidine, and dexmedetomidine.) opioids(morphine, hydromorphone, methadone, meperidine, fentanyl, and sufentanil.), NMDA receptor antagonists (ketamine, and magnesium) and others (tramadol, neostigmine, midazolam, sodium bicarbonate, and verapamil).
The great need for using additives with local anesthetics is to prolong the anesthetic action, which could allow surgery for several hours, as the duration of neuraxial block by itself can’t be extended if the operation takes longer time.
Many additives were tried to fulfill different needs as prolonging anesthetic action, prevention and relief of postoperative pain, reducing the dose of local anesthetics and allowing early ambulation after surgery.
Among these additives; opioids (morphine, fentanyl and sufentanil) and alpha agonist as clonidine has been well established to fulfill most of our needs