Approaches of Brachial Plexus Block

Abstract

Pain is as old as life. Man, as we think, as the highest developed organism, is the strongest feeler of pain. It has been man’s endeavour to kill and lessen pain from the very early ages. For the upper limb surgeries brachial plexus block has evolved into valuable and safe alternative to general anesthesia. It is a great tool in the anesthetic armamentarium for relief of pain preoperatively, perioperatively and postoperatively. Since its introduction by “William Steward Halsted” in 1885, who performed the block by exposing the roots, it has undergone many modifications and changes to arrive at a better technique. It is possible and desirable for the patient to remain ambulatory. Patient who arrive at the operation theatre with full stomach face less danger of aspiration, if they vomit. Post anesthetic nausea, vomiting and other side effects of general anesthesia such as atelectasis, hemodynamics instability, ileus, dehydration and deep vein thrombosis are reduced. In the new trend of day care surgeries, brachial plexus block seems to be a better alternative to general anesthesia with minimal hospital stay and less financial burden on the patients. Brachial plexus block is used widely today to provide anesthesia for upper extremity. There are several techniques for blocking the nerves of the brachial plexus. These techniques are classified by the level at which the needle or catheter is inserted for injecting the local anesthetic-interscalene block on the neck, supraclavicular block immediately above the clavicle, infraclavicular block below the clavicle and axillary block in the axilla (armpit). Modern local anesthetics are safer then their predecessors, but risks persist, and even the experienced practitioner using the correct dose may provoke a fatal reaction. The cornerstone of safe practice is a thorough understanding of the pharmacology and toxicity of the agents used, in particular, dose and concentration required, likely speed of onset and duration of action. Toxic effects primarily involve the central nervous system (CNS) and cardiovascular system (CVS). Factors affecting the anesthetic activity of local anesthetics include the dissociation constant (pKa), protein binding, lipid solubility, pH, and vascularity at the injection site. Ultrasound for peripheral nerve localization is becoming increasingly popular; it may be used alone or combined with other modalities such as nerve stimulation. The use of ultrasound can make it easier to locate the brachial plexus, especially in obese patients. It also allows practitioners to see that the local anesthetic is going where they intend it to. Unlike nerve stimulation alone, ultrasound guidance allows for a variable volume of local anesthetic to be injected, with the final amount determined by what is observed under direct vision. This technique usually results in a far lower injected volume of local anesthetic. Patient cooperation and participation are keys to the success and safety of every regional anesthetic procedure; patients who are unable to remain still for a procedure may be exposed to increased risk.