Anesthesia of the brachial plexus

The fact that the nerves of the brachial plexus are grouped together acts as a benefit as well. Local anesthetics such as lidocaine or bupivacaine can be injected in close proximity to these nerves, rendering an entire arm insensate and immobile. The process of injecting local anesthetic for this purpose is called regional nerve blockade or more simply, a nerve block, and it is a common procedure in anesthesia. After an onset time of approximately 10 to 15 minutes, the targeted arm will be fully anesthetized and ready for surgery. The patient can remain awake during the ensuing surgical procedure, or he can be sedated with medications or fully anesthetized with general anesthesia as the situation requires.

Peripheral nerve blockade

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The use of peripheral nerve blockade (in this case, a "brachial plexus nerve block") offers several advantages when compared to general anesthesia or local anesthesia:

• The patient can remain awake and breathing on their own, thus protecting themselves from aspiration of stomach contents into the lungs. By avoiding general anesthesia, patients with adverse reactions to general anesthetics (viz. malignant hyperthermia, severe post-operative nausea and vomiting, known hypersensitivity to agents) can be successfully treated. Similarly, patients who experience nuisance side effects from general anesthesia such as nausea, vomiting, or excessive sleepiness can minimize these symptoms.
• There is no need to perform an endotracheal intubation, the procedure of inserting a breathing tube into the trachea. Occasionally, such intubation is unexpectedly difficult to perform, causing injury to the patient.
• The affected limb's sympathetic nerves are anesthetized, leading to vasodilation. This improves blood flow to the affected limb and makes microvascular surgical procedures technically simpler.
• The limb can remain numb for several hours after surgery, providing excellent pain relief.
• Deep and superficial structures of the limb are similarly anesthetized, allowing extensive surgical exploration and correction to occur. This is in contrast to locally injected local anesthetics, which tend only to numb superficial structures in the immediate vicinity of the injection.

Brachial plexus blockade

Brachial plexus blockade is the preferred anesthetic technique when:

• Surgery is expected to be limited either to a region between the midpoint of the humerus and the fingers (in which case the brachial plexus block should be either a supraclavicular, infra-clavicular, subcoracoid, or axillary block), OR surgery is expected to be limited to a region between the midpoint of the humerus and the shoulder (in which case the brachial plexus block should be an interscalene block). Because of the distribution of the local anesthetics on the various portions of the brachial plexus, surgeries crossing the midpoint of the humerus often reveal patchy, unanesthetized portions of the arm. Such procedures probably should not be performed under regional nerve block alone.

AND

• There are no contra-indications to a block such as infection at the intended injection site, significant anti-coagulation, allergy or hypersensitivity to local anesthetic medications, or disproportionate risk in the event of a local anesthetic toxic reaction (seizure) such as gastric aspiration in a patient who has not adequately fasted,

AND

• There will not be a need to perform a neurologic examination immediately following the surgical procedure,

AND

• Patient prefers this technique over other available and reasonable approaches.

References