الفهرس 
PHYSIOLOGY OF PAINOnly 14 pages are availabe for public view
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Abstract
The trend in the last 10 years towards more outpatient surgery and faster rehabilitation has created more interest in methods of postoperative pain control that will decrease the dependency on narcotics and their adverse effects such as drowsiness, nausea, constipation, and malaise.
The superiority of regional anesthesia to all other modalities of acute pain management cannot be doubted. However, one of the major problems with regional anesthesia is that the acute pain usually outlasts the nerve block. To counter this problem, various maneuvers and techniques to increase the duration of single injection nerve blocks have been developed and tried over the years. These ranged from searching for longer-acting regional anesthetic agents to postulating the theory of pre-emptive analgesia.
A recent method is the continuous peripheral nerve blockade, also called “perineural local anesthetic infusion”. It involves the percutaneous insertion of a catheter directly adjacent to the peripheral nerve(s) supplying a surgical site. Local anesthetic is then infused via the catheter providing site-specific analgesia.
Various equipments are used for performing such blocks. These include peripheral nerve stimulator for accurate localization of the target nerve, needle and catheter sets with various types and sizes according to the approach and finally infusion systems for maintainance of the block which may be used for inpatients and even for outpatients for patient controlled analgesia at home.
These technique can be applied to different anatomical territories to serve many surgical indications. It can be widely applied to the brachial plexus through various approaches as interscalene, supraclvicular, infraclavicular and axillary. When so, it can be used for providing anesthesia and postoperative analgesia in the upper limb surgeries as rotator cuff repair, shoulder arthroplasty and other surgeries involving the proximal part of the upper limb. When these technique are applied to the lumbar plexus, sacral plexus, femoral and sciatic nerves, it can be used for lower extremity surgeries as hip replacement or knee arthroscopy.
Serious complications following continuous peripheral nerve blocks are extremely rare. The complications related to such blocks fall into one or more of the following categories: complications related to the local anesthetic toxicity, hemorrhagic complications, infectious complications and nerve injury as a result of needle trauma or injected medications. However, continuous plexus and peripheral nerve blocks offer the potential benefits of prolonged analgesia with fewer side effects, greater patient satisfaction, and faster functional recovery after surgery.
The success of these techniques is infact multifactorial. The anesthesiologist is required to have a basic knowledge of the physiology of pain with good understanding of the pathways of sensory perception. Moreover, studying the pharmacology of local anesthetic drugs, will provide a chance for wise choice of the appropriate local anesthetic for each patient.
Other factors contributing in the success of such procedures are: the appropriate technical skills of the anesthesiologist’s placement of the catheter, the appropriate choice and understanding of the equipments used, precise knowledge of the anatomy of the involved territory, good understanding of the basic catheter technique and experienced mastering of the procedure.
Continuous peripheral nerve blocks have become an important and effective approach for perioperative pain treatment; however, these techniques are more effective when included in a multidisciplinary and multimodal approach to the patient’s pain management. All specialists, including surgeons, anesthesiolgists, recovery and ward nurses, physical therapists, and pharmacists who care for patients must work together throughout the perioperative period to improve the patient’s well-being and outcome.
Continuous peripheral nerve blockade is an effective and safe technique for postoperative analgesia, even when administered at home. To optimize this technique, further studies are needed to help minimize the risk of side effects, improve techniques to locate the targeted nerve and choose less toxic drugs with more effective infusion regimens.