Brachial plexus block

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Brachial plexus block
Video of a brachial plexus block, using a portable ultrasound scanning device for localization of the nerves of the brachial plexus
ICD-9-CM04.81
MeSHD009407

Brachial plexus block is a

regional anesthesia technique that is sometimes employed as an alternative or as an adjunct to general anesthesia for surgery of the upper extremity. This technique involves the injection of local anesthetic agents in close proximity to the brachial plexus, temporarily blocking the sensation and ability to move the upper extremity. The subject can remain awake during the ensuing surgical procedure, or they can be sedated or even fully anesthetized
if necessary.

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 for example is considered the second most complete postoperative analgesia,[1] supraclavicular block immediately above the clavicle, infraclavicular block below the clavicle and axillary block in the axilla (armpit).[2]

Indications

General anesthesia may result in low blood pressure, undesirable decreases in cardiac output, central nervous system depression, respiratory depression, loss of protective airway reflexes (such as coughing), need for tracheal intubation and mechanical ventilation, and residual anesthetic effects. The most important advantage of brachial plexus block is that it allows for the avoidance of general anesthesia and therefore its attendant complications and side effects. Although brachial plexus block is not without risk, it usually affects fewer organ systems than general anesthesia.[3]

Brachial plexus blockade may be a reasonable option when all of the following criteria are met:[citation needed]

Anatomy

Main article: Brachial plexus

The brachial plexus is formed by the

ventral rami of C5-C6-C7-C8-T1, occasionally with small contributions by C4 and T2. There are multiple approaches to blockade of the brachial plexus, beginning proximally with the interscalene block and continuing distally with the supraclavicular, infraclavicular, and axillary blocks. The concept behind all of these approaches to the brachial plexus is the existence of a sheath encompassing the neurovascular bundle extending from the deep cervical fascia to slightly beyond the borders of the axilla.[2]

Dorsal scapular nerve (rhomboids, levator scapulae)Suprascapular nerve (supraspinatus, infraspinatus)Nerve to subclavius (subclavius)Lateral pectoral nerve (pectoralis major)Musculocutaneous nerve (coracobrachialis, brachialis, biceps brachii)Axillary nerve (deltoid, teres minor)Median nerve (forearm flexors except FCU and ulnar part of FDP, thenar muscles)Ulnar nerve (FCU and ulnar part of FDP, most intrinsic hand musclesMedial cutaneous nerve of forearmMedial cutaneous nerve of armRadial nerve (triceps brachii, supinator, anconeus, forearm extensors, brachioradialis)Lower subscapular nerve (lower part of subscapularis, teres major)Thoracodorsal nerve (latissimus dorsi)Medial pectoral nerve (pectoralis major, pectoralis minor)Upper subscapular nerve (upper part of subscapularis)Long thoracic nerve of Bell (serratus anterior)Cervical spinal nerve 5Cervical spinal nerve 6Cervical spinal nerve 7Cervical spinal nerve 8Thoracic spinal nerve 1
Anatomical illustration of the brachial plexus with areas of roots, trunks, divisions and cords marked. Clicking on names of branches will link to their Wikipedia entry.

Techniques

Brachial plexus block is typically performed by an

muscle may be elicited.[4] Modern portable ultrasound devices allow the user to visualize internal anatomy, including the nerves to be blocked, neighboring anatomic structures and the needle as it approaches the nerves. Observation of local anesthetic surrounding the nerves during ultrasound-guided injection is predictive of a successful block.[5] Appropriate block per site-specific procedure are listed in the following table:[6]

Procedure Site Interscalene Supraclavicular Infraclavicular Axillary1
Shoulder2 ++ +3
Arm2 + ++ +
Elbow2 ++ ++ +
Forearm2 + ++ ++
Hand2 + + ++

1. Include musculocutaneous nerve 2. Include T1-T2 if block is anesthetic 3. Include C3-C4 if block is anesthetic

Interscalene block

Left: the red line corresponds to the course of the subclavian artery, while the yellow line represents the brachial plexus and the "X" represents the site of entry of the needle when performing an interscalene block. Right: diagram of the course of the brachial plexus in relation to other important anatomic structures in the right side of the neck.

The interscalene block is performed by injecting local anesthetic to the nerves of the brachial plexus as it passes through the groove between the

middle scalene muscles, at the level of the cricoid cartilage. This block is particularly useful in providing anesthesia and postoperative analgesia for surgery to the clavicle, shoulder, and arm. Advantages of this block include rapid blockade of the shoulder region, and relatively easily palpable anatomical landmarks. Disadvantages of this block include inadequate anesthesia in the distribution of the ulnar nerve, which makes this an unreliable block for operations involving the forearm and hand.[2]

Side effects

Temporary paresis (impairment of the function) of the thoracic diaphragm occurs in virtually all people who have undergone interscalene or supraclavicular brachial plexus block. Significant respiratory impairment can be demonstrated in these people by pulmonary function testing.[7] In certain people — such as those with severe chronic obstructive pulmonary disease — this can result in respiratory failure requiring tracheal intubation and mechanical ventilation until the block dissipates.[8] Horner's syndrome may be observed if the local anesthetic solution tracks cephalad and blocks the stellate ganglion. This may be accompanied by difficulty swallowing and vocal cord paresis. These signs and symptoms are transient however, and do not commonly result in any long-term problems, although they may be significantly distressing to patients until the effects subside.[citation needed]

Contraindications

Contraindications include severe chronic obstructive pulmonary disease,[8] and paresis of the phrenic nerve on the opposite side as the block.[9]

Supraclavicular block

Providing a rapid onset of dense anesthesia of the arm with a single injection, the supraclavicular block is ideal for operations involving the arm and forearm, from the lower humerus down to the hand. The brachial plexus is most compact at the level of the trunks formed by the C5–T1 nerve roots, so nerve block at this level has the greatest likelihood of blocking all of the branches of the brachial plexus. This results in rapid onset times and, ultimately, high success rates for surgery and analgesia of the upper extremity, excluding the shoulder.[10]

Surface landmarks can be used to identify the appropriate location for injection of local anesthetic, which is typically

lung are located at this level). Palpation or ultrasound visualization of the subclavian artery just above the clavicle provides a useful anatomic landmark for locating the brachial plexus, which is lateral to the artery at this level.[10] Proximity to the brachial plexus can be determined using by elicitation of a paresthesia, use of a peripheral nerve stimulator, or ultrasound guidance.[11]

Compared to the interscalene block, the supraclavicular block — despite eliciting a more complete block of the median, radial ulnar and musculocutaneous nerves — does not improve postoperative analgesia. However, the supraclavicular block is often quicker to perform and may result in fewer side effects than the interscalene block. Compared to the infraclavicular block and axillary blocks, the successful achievement of adequate anesthesia for surgery of the upper extremity is about the same with supraclavicular block.[11]

Unlike the interscalene block — which results in diaphragmatic hemiparesis in all subjects — only half of those who undergo supraclavicular block experience this side effect. Disadvantages of the supraclavicular block include the risk of pneumothorax, which is estimated to be between 1%–4% when using paresthesia or peripheral nerve stimulator guided techniques. Ultrasound guidance allows the operator to visualize the first rib and the pleura, thereby helping to ensure that the needle does not puncture the pleura; this presumably reduces the risk of pneumothorax.[11]

Infraclavicular block

Left: the red line corresponds to the course of the subclavian artery, while the yellow line represents the brachial plexus and the "X" represents the site of entry of the needle when performing an infraclavicular block. Right: diagram of the course of the brachial plexus in relation to other important anatomic structures in the right infraclavicular fossa.

For infraclavicular block, current evidence suggests that — when using a peripheral nerve stimulator for nerve localization — a double-stimulation technique is better than a single-stimulation technique. When compared to a multiple-stimulation axillary block, infraclavicular block provides similar efficacy. However it may be associated with a shorter performance time and less procedure-related pain for the patient.[11]

Axillary block

Left: the red line corresponds to the course of the axillary artery, while the "X" represents the site of entry of the needle when performing an axillary block. Right: diagram of the course of the axillary artery in relation to the brachial plexus in the right axilla.

The axillary block is particularly useful in providing anesthesia and postoperative analgesia for surgery to the elbow, forearm, wrist, and hand. The axillary block is also the safest of the four main approaches to the brachial plexus, as it does not risk paresis of the phrenic nerve, nor does it have the potential to cause pneumothorax.[12] In the axilla, the nerves of the brachial plexus and the axillary artery are enclosed together in a fibrous sheath which is a continuation of the deep cervical fascia. The easily palpated axillary artery thus serves as a reliable anatomical landmark for this block, and the injection of local anesthetic close to this artery frequently leads to a good block of the brachial plexus. The axillary block is commonly performed due to its ease of performance and relatively high success rate.[4]

Disadvantages of the axillary block include inadequate anesthesia in the distribution of the musculocutaneous nerve. This nerve supplies motor function to the

Subcutaneous injection of local anesthetic over the medial aspect of the arm in the axilla helps patients tolerate an arm tourniquet by blocking these nerves.[13]

Single-injection techniques provide unreliable blockade in the areas supplied by the musculocutaneous and radial nerves. Current evidence suggests that a triple-stimulation technique — with injections on the musculocutaneous, median and radial nerves — is the best technique for the axillary block.[11]

Methods of nerve localization

Despite the fact that people have been performing brachial plexus blocks for over a hundred years,[14] there is as yet no clear evidence to support the assertion that one method of nerve localization is better than another. There are however numerous case reports documenting cases in which use of a portable ultrasound scanning device has detected abnormal anatomy that would otherwise not have been evident using a "blind" approach. On the other hand, use of ultrasound may create a false sense of security in the operator, which may lead to errors, especially if the needle tip is not adequately visualized at all times.[10]

For interscalene block, it is not clear whether nerve stimulation provides a better interscalene block than elicitation of paresthesiae.[11] However, a recent study using ultrasound to follow the spread of local anesthetic demonstrated an improved success rate of the block (relative to blocks done with nerve stimulator alone) even at the inferior roots of the plexus.[2]

For supraclavicular block, nerve stimulation with a minimal threshold of 0.9 mA can offer a dependable block.[11] Although ultrasound-guided supraclavicular block has been shown to be a safe alternative to the peripheral nerve stimulator guided technique, there is little evidence to support that ultrasound guidance provides a better block, or is associated with fewer complications.[10] There is some evidence to suggest that the use of ultrasound guidance in combination with nerve stimulation can shorten the performance time of supraclavicular block.[11]

For axillary block, success rates are greatly improved with multiple injection techniques whether using nerve stimulation or ultrasound guidance.[12]

Special situations

The duration of a "single-shot" brachial plexus block is highly variable, commonly lasting anywhere from 45 minutes to 24 hours. The block can be extended by placing an indwelling catheter, which may be connected to a mechanical or electronic infusion pump for continuous administration of local anesthetic solution. A catheter may be inserted at the interscalene, supraclavicular, infraclavicular or axillary location, depending on the desired location of nerve block. Specific branches of the brachial plexus can also be blocked individually, for example the suprascapular nerve.[15] The infusion of local anesthetic can be programmed to be a continuous flow or patient-controlled analgesia. In some cases, people can maintain the catheters and infusions at home after release from the facility where the surgery was performed.[2]

Complications

As with any procedure involving disruption of the integrity of the skin, brachial plexus block can be associated with infection or bleeding. In people who are using anticoagulant agents, there is a greater risk of complications related to bleeding.[2]

Complications associated with brachial plexus block include intra-arterial or intravenous injection, which can lead to

cardiac dysrhythmia, cardiac arrest and death may occur.[17] Other rare but serious complications from brachial plexus block include pneumothorax and persistent paresis of the phrenic nerve.[18]

Complications associated with interscalene and supraclavicular blocks include inadvertent

subarachnoid or epidural injection of local anesthetic, which can result in respiratory failure.[18]

Because of the close proximity of the lung to the brachial plexus at the level of the clavicle, the complication most often associated with this block is pneumothorax — with a risk as high as 6.1%.[10] Further complications of supraclavicular block include subclavian artery puncture, and spread of local anesthetic to cause paresis of the stellate ganglion, the phrenic nerve and recurrent laryngeal nerve.[10]

Alternatives

Depending on the circumstances, alternatives to brachial plexus block may include general anesthesia, monitored anesthesia care, Bier block, or local anesthesia.[citation needed]

History

In 1855,

Harvey Cushing (1869–1939) — who was at that time one of Halsted's surgical residents — applied cocaine to the brachial plexus prior to dividing it, during a forequarter amputation for sarcoma.[26]

The first

spinous process.[29]

By the late 1940s, clinical experience with brachial plexus block in both peacetime and wartime surgery was extensive,[30] and new approaches to this technique began to be described. For example, In 1946, F. Paul Ansbro was the first to describe a continuous brachial plexus block technique. He secured a needle in the supraclavicular fossa and attached tubing connected to a syringe through which he could inject incremental doses of local anesthetic.[31] The subclavian perivascular block was first described by Winnie and Collins in 1964.[32] This approach became popular due to its lower risk of pneumothorax compared to the traditional Kulenkampff approach. The infraclavicular approach was first developed by Raj.[citation needed] In 1977, Selander described a technique for continuous brachial plexus block using an intravenous catheter secured in the axilla.[33]

See also

Notes

  1. ^ Panchamia, Jason, Olsen, David, Sanchez-Sotelo, Joaquin, MD, PhD, Amundson, Adam. Combined Selective Nerve Blockade and Local Infiltration Analgesia in a Total Shoulder Arthroplasty Patient With Chronic Pain and Severe Restrictive Lung Disease: A Case Report. A&A Case Reports. 2017;9(12):360-363. doi:10.1213/XAA.0000000000000617.
  2. ^
    ISBN 978-1-4160-5279-1. Archived from the original
    (PDF) on 2019-12-16. Retrieved 2012-06-09.
  3. ^ Boedeker, BH; Rung, GW (1995). "Regional anesthesia" (PDF). In Zajtchuk, R; Bellamy, RF; Grande, CM (eds.). Textbook of Military Medicine, Part IV: Surgical Combat Casualty Care. Vol. 1: Anesthesia and Perioperative Care of the Combat Casualty. Washington, DC: Borden Institute. pp. 251–86. Archived from the original (PDF) on 2012-05-17. Retrieved 2012-06-09.
  4. ^
    ISBN 9780721611723
    .
  5. S2CID 24839528
    .
  6. ISBN 978-0071423588
    .
  7. ISBN 978-0387375595
    .
  8. ^
    ISBN 9781416023920
    .
  9. ^ Amutike, D (1998). "Interscalene brachial plexus block". Practical Procedures. 1998 (9). Archived from the original on 2011-09-26.
  10. ^ a b c d e f Macfarlane, A; Brull, R (2009). "Ultrasound guided supraclavicular block" (PDF). The Journal of New York School of Regional Anesthesia. 12: 6–10.[permanent dead link]
  11. ^
    S2CID 4711427
    .
  12. ^
    PMID 21716725
    .
  13. ^ Tschaikowsky, K. and Hemmerling, T. (1998), Comparison of the effect of EMLA and semicircular subcutaneous anaesthesia in the prevention of tourniquet pain during plexus block anaesthesia of the arm. Anaesthesia, 53: 390-393. https://doi.org/10.1046/j.1365-2044.1998.00301.x
  14. ^ a b c Kulenkampff, D (1911). "Zur anästhesierung des plexus brachialis" [On anesthesia of the brachial plexus]. Zentralblatt für Chirurgie (in German). 38: 1337–40.
  15. S2CID 237539656
    .
  16. S2CID 36915462. Archived from the original
    (PDF) on 2012-11-19.
  17. S2CID 34745265.[permanent dead link
    ]
  18. ^ a b Urmey, WF (2009). "Pulmonary complications of interscalene brachial plexus blocks" (PDF). Lecture notes: 2009 symposium. New York: The New York School of Regional Anesthesia. Retrieved 2012-06-02.[permanent dead link]
  19. S2CID 86030231
    .
  20. PMID 13395966
    .
  21. ^ Koller, K (1884). "Über die verwendung des kokains zur anästhesierung am auge" [On the use of cocaine for anesthesia on the eye]. Wiener Medizinische Wochenschrift (in German). 34: 1276–1309.
  22. ISBN 978-0849397752
    .
  23. ^ Halsted, WS (1885-09-12). "Practical comments on the use and abuse of cocaine; suggested by its invariably successful employment in more than a thousand minor surgical operations". New York Medical Journal. 42: 294–5.
  24. ^ Crile, GW (1897). "Anesthesia of nerve roots with cocaine". Cleveland Medical Journal. 2: 355.
  25. S2CID 19403814
    .
  26. PMID 17861171
    .
  27. S2CID 41966814
    .
  28. ^ Hirschel, G (1911-07-18). "Die anästhesierung des plexus brachialis fuer die operationen an der oberen extremitat" [Anesthesia of the brachial plexus for operations on the upper extremity]. Munchener Medizinische Wochenschrift (in German). 58: 1555–6.
  29. PMID 17865904
    .
  30. PMID 17859253
    .
  31. PMID 20983091
    .
  32. S2CID 36275626
    .
  33. S2CID 8164535
    .

Further reading

External links
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