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Regional Anesthesia For the Shoulder

Table of Contents

Authors

Landon Mueller, MD

Rapid Reference

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Introduction

  • Shoulder trauma is common in the emergency department. Shoulder dislocations are the most common joint dislocation seen in the emergency department, and account for >50% of major joint dislocations.[1]Bengtzen RR, Daya MR. Shoulder. In: Walls RM, Hockberger RS, Gausche-Hill M, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. Ninth edition. Elsevier; 2018:549-568.
  • Procedural sedation is commonly used to facilitate pain control and relaxation for reduction of shoulder dislocations, with up to 57% of shoulder reductions utilizing sedation at some sites.[2]Dowson P. Shoulder Reduction Bench Project: improving care for patients with shoulder dislocations. BMJ Open Qual. 2019;8(2):e000366. doi:10.1136/bmjoq-2018-000366
  • Shoulder dislocation is one of the most common indications for procedural sedation, comprising an estimated 25-38% of all procedural sedations[3]Sacchetti A, Senula G, Strickland J, Dubin R. Procedural sedation in the community emergency department: initial results of the ProSCED registry. Acad Emerg Med Off J Soc Acad Emerg Med. … Continue reading[4]Vinson DR, Hoehn CL. Sedation-assisted Orthopedic Reduction in Emergency Medicine: The Safety and Success of a One Physician/One Nurse Model. West J Emerg Med. 2013;14(1):47-54. … Continue reading
  • While severe adverse effects with procedural sedation are rare, adverse effects including hypoxia and hypotension have an estimated 4-11% complication rate in the emergency department[5]Sacchetti A, Senula G, Strickland J, Dubin R. Procedural sedation in the community emergency department: initial results of the ProSCED registry. Acad Emerg Med Off J Soc Acad Emerg Med. … Continue reading [6]Bellolio MF, Gilani WI, Barrionuevo P, et al. Incidence of Adverse Events in Adults Undergoing Procedural Sedation in the Emergency Department: A Systematic Review and Meta-analysis. Acad Emerg Med … Continue reading [7]Smits GJ, Kuypers MI, Mignot LA, et al. Procedural sedation in the emergency department by Dutch emergency physicians: a prospective multicentre observational study of 1711 adults. Emerg Med J EMJ. … Continue reading
  • Intra-articular injections and interscalene nerve blocks provide opioid and sedation-free options for shoulder reduction
  • Interscalene nerve blocks can also be used for analgesia of the shoulder and upper arm including proximal and midshaft humeral fractures, upper extremity abscess I&D, and upper extremity laceration repair.

Anatomy

  • The shoulder and upper extremity are innervated by branches off the brachial plexus
  • The brachial plexus (BP) is a network of nerves formed by branches of the ventral (anterior) rami of cervical nerves C5, C6, C7, C8 and thoracic nerve T1
  • The cervical roots (C5-T1) converge to form three trunks: superior (C5-C6), middle (C7), inferior (C8-T1). These emerge between the anterior and middle scalenes.[8]Zisquit J, Nedeff N. Interscalene Block. In: StatPearls. StatPearls Publishing; 2020. Accessed January 26, 2021. http://www.ncbi.nlm.nih.gov/books/NBK519491
  • The trunks continue to the level of the clavicle, and then divide each into an anterior and posterior divisions -> Fibers from the divisions rearrange to form lateral, medial, and posterior cords -> peripheral nerves branch out from the three cords
[9]Hadzic A, Franco C. Essential Regional Anesthesia Anatomy. In: Hadzic A, ed. Hadzic’s Peripheral Nerve Blocks and Anatomy for Ultrasound-Guided Regional Anesthesia. McGraw-Hill Publishing; 2011. … Continue reading
  • Innervation of the shoulder joint capsule is provided by the suprascapular (C5-C6, off the upper trunk), lateral pectoral (C5-C7, off the lateral cord), and axillary nerves (C5-C6, off the posterior cord). The suprascapular nerve provides the greatest contribution to overall innervation. The supraclavicular nerve block does not provide reliable anesthesia to the suprascapular nerve, which is why the interscalene block is the gold standard block for the shoulder. [10]Okwumabua E, Thompson JH. Anatomy, Shoulder and Upper Limb, Nerves. In: StatPearls. StatPearls Publishing; 2020. Accessed January 31, 2021. http://www.ncbi.nlm.nih.gov/books/NBK526056/[11]Polcaro L, Charlick M, Daly DT. Anatomy, Head and Neck, Brachial Plexus. In: StatPearls. StatPearls Publishing; 2020. Accessed January 31, 2021. http://www.ncbi.nlm.nih.gov/books/NBK531473/[12]Laumonerie P, Dalmas Y, Tibbo ME, et al. Sensory innervation of the human shoulder joint: the three bridges to break. J Shoulder Elbow Surg. 2020;29(12):e499-e507. doi:10.1016/j.jse.2020.07.017

Interscalene Block

  • Introduction
    • The US-guided interscalene block (ISB) provides near-complete analgesia to the shoulder and upper arm
    • Widely used in the operating room for shoulder surgery, the US-guided ISB was first described for use in the emergency department in 2006, for use with anterior shoulder reduction.[13]Blaivas M, Lyon M. Ultrasound-guided interscalene block for shoulder dislocation reduction in the ED. Am J Emerg Med. 2006;24(3):293-296. doi:10.1016/j.ajem.2005.10.004
    • Analgesia for shoulder reduction remains the only studied indication in the emergency department. Literature is limited to a few single-site studies, but there is promise for its use as a sedation alternative:
      • Blaivas et al. compared ISB to procedural sedation with etomidate and found equivocal reduction success, pain scores, patient satisfaction, with overall shorter length of stay for ISB[14]Blaivas M, Adhikari S, Lander L. A prospective comparison of procedural sedation and ultrasound-guided interscalene nerve block for shoulder reduction in the emergency department. Acad Emerg Med Off … Continue reading
      • Raeyat Doost et al. compared ISB to procedural sedation with propofol and found overall shorter length of stay for ISB, but pain scores and patient satisfaction were better with sedation[15]Raeyat Doost E, Heiran MM, Movahedi M, Mirafzal A. Ultrasound-guided interscalene nerve block vs procedural sedation by propofol and fentanyl for anterior shoulder dislocations. Am J Emerg Med. … Continue reading
      • Kreutziger et al. compared ISB to procedural sedation and again found shorter length of stay for ISB, and found higher patient satisfaction rates with ISB[16]Kreutziger J, Hirschi D, Fischer S, Herzog RF, Zbinden S, Honigmann P. Comparison of interscalene block, general anesthesia, and intravenous analgesia for out-patient shoulder reduction. J Anesth. … Continue reading
    • However, there is further reason to believe interscalene block is helpful in anterior shoulder reduction:
      • Muscle relaxation has been proposed as a major component of success in anterior shoulder dislocation.[17] Lachance P-A. Reduction of shoulder dislocation: are communication and adequate relaxation more important than technique? Can Fam Physician Med Fam Can. 2012;58(11):1189-1190, e613-614.It is theorized that the spasming long head of the biceps brachii acts as a bowstring preventing the posterior movement of the dislocated humeral head.[18]Cunningham N. A new drug free technique for reducing anterior shoulder dislocations. Emerg Med Fremantle WA. 2003;15(5-6):521-524. doi:10.1046/j.1442-2026.2003.00512.x Other involved muscles include the rotator cuff muscles of the suprapsinatus, infrapsinatus, and teres minor which get stretched as they’re attached to the humeral head, causing them to spasm and pull the humeral head.[19]Baden DN, Roetman MH, Boeije T, et al. Biomechanical reposition techniques in anterior shoulder dislocation: a randomised multicentre clinical trial- the BRASD-trial protocol. BMJ Open. … Continue readingSpasming of the subscapularis (which normally acts to internally rotate the humeral head) prevents external rotation often required for reduction.[20]Cunningham NJ. Techniques for reduction of anteroinferior shoulder dislocation. Emerg Med Australas EMA. 2005;17(5-6):463-471. doi:10.1111/j.1742-6723.2005.00778.x
      • It’s been proposed that the >50 reduction techniques described in the literature are all acting to overcome the sum total force from the spasming muscles. They can be separated into three broad categories: traction, leverage, or biomechanical. Traction techniques such as the Hippocratic method, traction-countertraction use blunt force, often aided by muscle relaxation from procedural sedation to overcome the muscle spasm. Alternatively, the traction causes the muscle to tire and then relax. Leverage techniques such as Kocher often still employ a degree of traction to overcome spasm. Biomechanical techniques such as the Cunningham technique utilize muscle relaxation without sedation or minimal sedation.[21]Baden DN, Roetman MH, Boeije T, et al. Biomechanical reposition techniques in anterior shoulder dislocation: a randomised multicentre clinical trial- the BRASD-trial protocol. BMJ Open. … Continue reading
      • The interscalene block thus may aid in reduction by helping with muscle relaxation. The block should result in paralysis (or at least weakness) of muscles innervated by the nerve roots of C5, C6, and possibly C7, which covers the entire shoulder girdle.[22]Price DJ. The shoulder block: a new alternative to interscalene brachial plexus blockade for the control of postoperative shoulder pain. Anaesth Intensive Care. 2007;35(4):575-581. … Continue readingThis includes the following muscles important to shoulder reduction:[23]Miniato MA, Anand P, Varacallo M. Anatomy, Shoulder and Upper Limb, Shoulder. In: StatPearls. StatPearls Publishing; 2020. Accessed February 2, 2021. http://www.ncbi.nlm.nih.gov/books/NBK536933/
        • Deltoid: Axillary nerve (C5, C6)
        • Rotator cuff
          • Supraspinatus/Infraspinatus: Suprascapular nerve (C5, C6)
          • Teres minor: Axillary nerve (C5, C6)
          • Subscapularis: Subscapular nerve (C5-C7)
        • Biceps brachii: Musculocutaneous nerve (C5, C6)
        • Pectoralis major: Partly by lateral pectoral nerve (C5-C7)
      • Ultimately, the effect of muscle paralysis/relaxation has not been studied on shoulder reduction
    • Other potential indications for ISB include proximal and midshaft humeral fractures, upper extremity abscess I&D, and upper extremity laceration repair
  • Anatomy
    • The target of the ISB is the nerve roots of C5, C6, and C7 as they travel between the anterior and middle scalene muscles before they form trunks
    • Blockade of the superior and middle trunk are easily achievable (C5-C7), but inferior trunk blockade (C8-T1) is often more difficult to achieve due to depth[24]Zisquit J, Nedeff N. Interscalene Block. In: StatPearls. StatPearls Publishing; 2020. Accessed January 26, 2021. http://www.ncbi.nlm.nih.gov/books/NBK519491/
    • Blockade provides analgesia to the shoulder/anterior arm/lateral arm, but does not reliably block the hand due to lack of C8-T1 coverage (which becomes the peripheral ulnar nerve 
    • The phrenic nerve comes off roots C5-C7, prior to the formation of the trunks. At the level of the ISB, the phrenic nerve typically lies superficial to the anterior scalene.[25]Oliver KA, Ashurst JV. Anatomy, Thorax, Phrenic Nerves. In: StatPearls. StatPearls Publishing; 2020. Accessed January 26, 2021. http://www.ncbi.nlm.nih.gov/books/NBK513325/
    • The sternocleidomastoid muscle is superficial to the BP, and superficial to the prevertebral fascia.[26]Mian A, Chaudhry I, Huang R, Rizk E, Tubbs RS, Loukas M. Brachial plexus anesthesia: A review of the relevant anatomy, complications, and anatomical variations. Clin Anat N Y N. 2014;27(2):210-221. … Continue reading
  • Sono-anatomy and Patient Positioning
    • The interscalene block is called thus because the target BP sits between the anterior scalene muscle and the middle scalene muscle
    • The patient should be either supine or head of the bed slightly elevated, with the head turned to the opposite side.
    • Start scanning at the level of the cricoid, medial to the sternocleidomastoid muscle (SCM), with the probe in a transverse position. The goal is to visualize the carotid artery. Move the probe laterally until the anterior and middle scalene muscles are identified. Move the probe superior-inferior until at least two roots of the BP are identified. This looks like a “stoplight” with three vertically oriented nerve roots (C5-C7)
    • Trace-back method: Alternatively, place the transducer in the supraclavicular fossa. You can identify the BP at this location, lateral and superficial to the subclavian artery. Follow the BP superiorly until you get to the desired level between the scalenes.[27]Hadzic A, Franco C. Essential Regional Anesthesia Anatomy. In: Hadzic A, ed. Hadzic’s Peripheral Nerve Blocks and Anatomy for Ultrasound-Guided Regional Anesthesia. McGraw-Hill Publishing; 2011. … Continue reading
    • The BP will be about 1-3cm in depth. The lateral border of the SCM is visualized superficial to the scalene muscles. 
    • Apply color doppler to evaluate for vasculature. Vessels can mimic nerve bundles (circular and hypoechoic). There’s a high prevalence of smaller vessels traveling directly adjacent or even interposed with the BP in the interscalene and supraclavicular areas.[28]Muhly WT, Orebaugh SL. Sonoanatomy of the vasculature at the supraclavicular and interscalene regions relevant for brachial plexus block. Acta Anaesthesiol Scand. 2011;55(10):1247-1253. … Continue readingIdentification of vasculature can prevent puncture and may prevent complications including hematoma, incomplete analgesia, and local-anesthetic systemic toxicity.[29]Hahn C, Nagdev A. Color Doppler ultrasound-guided supraclavicular brachial plexus block to prevent vascular injection. West J Emerg Med. 2014;15(6):703-705. doi:10.5811/westjem.2014.5.21716[30]Kohli S, Yadav N, Prasad A, Banerjee SS. Anatomic variation of subclavian artery visualized on ultrasound-guided supraclavicular brachial plexus block. Case Rep Med. 2014;2014:394920. … Continue reading 
  • Technique
    • Obtain informed consent
    • Document an appropriate neurovascular for the procedure at hand. For shoulder reductions, document sensation over the cape of the shoulder (axillary nerve blockade, C5-C6). Test peripheral nerve motor and sensory function:
      • Median nerve – test branch of anterior interosseus nerve with “OK” sign. Test sensation to light touch over palmar 2nd digit
      • Ulnar nerve – abduct and adduct fingers. Test sensation to light touch over palmar 5th digit.
      • Radial nerve – wrist extension, thumb extension. Test sensation to light touch over dorsal 1st digit. 
    • Obtain supplies
      • 22g 3.5 in spinal needle (or similar size, spinal needle preferred)
      • Local anesthetic + appropriate size syringe
        • 15-25mL of anesthetic is appropriate for most adults. 
        • For most emergency departments, lidocaine will be the best choice due to availability, operator comfort, and length of block. We recommend 20 mL of lidocaine 1% as a good reference point. For a 70kg adult, the max dose is approximately 28 mL. 
      • Extension tubing
      • Sterile probe cover + US
      • Chloraprep
      • Assistant (to help with injection)
      • Sterile towels
    • Situate the room
      • Patient supine or head-of-bead elevated, head turned away
      • Bed height appropriate for operator comfort
      • Ultrasound machine situated on opposite side of bed (allows easy visualization of screen with in-plane technique)
      • Ensure patient is on cardiac monitor 
      • Have knowledge of/access to rescue intralipids
    • Identify target BP and mark the site of your predicted needle entry point 
    • Prepare equipment, prep skin and site, cover ultrasound probe with sterile-cover. Connect extension tubing to syringe. Prime the tubing with your anesthetic or extra sterile saline. Attach needle to opposite end of extension tubing. Hand off syringe to assistant, and use the ultrasound to identify the anatomy again.
    • Insert the needle from lateral to medial, in-plane with the ultrasound. Aim the needle tip BETWEEN the C5-C6 roots. This places the needle within the prevertebral fascia.  Aspirate to ensure no blood, and then inject 1-2 mL of anesthetic to verify needle placement. This will often displace the superficial root away from the needle. Do NOT inject against resistance. This suggests needle placement within the nerve itself.
    • Alternatively, the target for the needle tip does not need to be between the C5-C6 roots, but rather close to the roots under the prevertebral fascia. Multiple studies have confirmed the efficacy of anesthetic placement outside the brachial plexus itself.[31]Spence BC, Beach ML, Gallagher JD, Sites BD. Ultrasound-guided interscalene blocks: understanding where to inject the local anaesthetic. Anaesthesia. 2011;66(6):509-514. … Continue reading[32]Maga J, Missair A, Visan A, et al. Comparison of Outside Versus Inside Brachial Plexus Sheath Injection for Ultrasound-Guided Interscalene Nerve Blocks. J Ultrasound Med Off J Am Inst Ultrasound … Continue readingOne study group has shown that analgesia is still possible in 50% of blocks with the needle tip 8mm away in the middle scalene muscle, with the anesthetic spreading to the BP.[33]Albrecht E, Kirkham KR, Taffé P, et al. The maximum effective needle-to-nerve distance for ultrasound-guided interscalene block: an exploratory study. Reg Anesth Pain Med. 2014;39(1):56-60. … Continue readingA randomized trial by the same group demonstrated decreased diaphragmatic hemiparesis with a target distance of 4mm compared to placement directly between C5-C6. It is thus likely safer for the emergency physician who is new to regional anesthesia to be conservative with needle placement a few millimeters away from the roots, and avoid potential intraneural injection.[34]Palhais N, Brull R, Kern C, et al. Extrafascial injection for interscalene brachial plexus block reduces respiratory complications compared with a conventional intrafascial injection: a randomized, … Continue reading[35]Nagdev A, Becherer-Bailey G, Farrow R, Mantuani D. Ultrasound-Guided Nerve Blocks. In: Clsewski D, Motov S, eds. EMRA Pain Management Guide.
    • Confirm onset of block with sensory loss over the cape of the shoulder, corresponding to axillary nerve blockade (C5,C6). Additionally, motor blockade can be tested with shoulder abduction (axillary, C5-C6) or biceps flexion (musculocutaneous, C5-C6).[36] Hewson DW, Oldman M, Bedforth NM. Regional anaesthesia for shoulder surgery. BJA Educ. 2019;19(4):98-104. doi:10.1016/j.bjae.2018.12.004
  • Contraindications and Complications
    • Phrenic Nerve Paralysis
      • There is a high-incidence of phrenic nerve paralysis. Studies using landmark technique and high-volume anesthetic (34-52mL) report a 100% incidence of diaphragmatic paralysis.[37]Urmey WF, Talts KH, Sharrock NE. One hundred percent incidence of hemidiaphragmatic paresis associated with interscalene brachial plexus anesthesia as diagnosed by ultrasonography. Anesth Analg. … Continue readingUS-guided blocks report a high but smaller incidence, 79%.[38]Schubert A-K, Dinges H-C, Wulf H, Wiesmann T. Interscalene versus supraclavicular plexus block for the prevention of postoperative pain after shoulder surgery: A systematic review and … Continue reading
      • Paralysis is thought to come from anterior spread of anesthetic to hit the phrenic nerve, or possibly from rostral spreading to the nerve roots. Though, supraclavicular blocks also experience hemiparesis, and this block is more caudal away from the roots, suggesting anterior local spread is more likely the culprit.[39]Renes SH, Rettig HC, Gielen MJ, Wilder-Smith OH, van Geffen GJ. Ultrasound-guided low-dose interscalene brachial plexus block reduces the incidence of hemidiaphragmatic paresis. Reg Anesth Pain Med. … Continue reading[40]Renes SH, Spoormans HH, Gielen MJ, Rettig HC, van Geffen GJ. Hemidiaphragmatic paresis can be avoided in ultrasound-guided supraclavicular brachial plexus block. Reg Anesth Pain Med. … Continue readingHowever, there is less incidence of diaphragm hemiparesis with supraclavicular blocks. This is likely due to further separation between the brachial plexus and the phrenic nerve. At the level of the cricoid for ISB there’s only 2mm of separation, but spreads to 1.08cm at the level of the supraclavicular block.[41]Kessler J, Schafhalter-Zoppoth I, Gray AT. An ultrasound study of the phrenic nerve in the posterior cervical triangle: implications for the interscalene brachial plexus block. Reg Anesth Pain Med. … Continue reading
      • In patients with pulmonary compromise, this can be a relative contraindication. Hemidiaphragmatic paresis can result in 27% decreased forced vital capacity.[42]Urmey WF, McDonald M. Hemidiaphragmatic paresis during interscalene brachial plexus block: effects on pulmonary function and chest wall mechanics. Anesth Analg. 1992;74(3):352-357. … Continue readingWith the use of a short-acting anesthetic for the purpose of a procedure, it’s unlikely that hemiparesis would have long-lasting respiratory compromise on the majority of patients. With that said, the clinician should exercise caution with co-morbidities affecting pulmonary reserve including COPD, asthma, pulmonary fibrosis, etc, and inform the patient about the potential risks.
      • Strategies to reduce hemidiaphragmatic paresis include:
        • Using ultrasound! Compared to nerve stimulation, ultrasound results in lower incidence.[43]McNaught A, Shastri U, Carmichael N, et al. Ultrasound reduces the minimum effective local anaesthetic volume compared with peripheral nerve stimulation for interscalene block. Br J Anaesth. … Continue reading
        • Using lower volumes of anesthetic. While the protocols and anesthetics have varied, there is a trend that lower volume leads to lower incidence of paresis.[44]Lee J-H, Cho S-H, Kim S-H, et al. Ropivacaine for ultrasound-guided interscalene block: 5 mL provides similar analgesia but less phrenic nerve paralysis than 10 mL. Can J Anaesth J Can Anesth. … Continue reading[45]Riazi S, Carmichael N, Awad I, Holtby RM, McCartney CJL. Effect of local anaesthetic volume (20 vs 5 ml) on the efficacy and respiratory consequences of ultrasound-guided interscalene brachial plexus … Continue readingOne study found no difference between 10 and 20 mL however.[46]Sinha SK, Abrams JH, Barnett JT, et al. Decreasing the local anesthetic volume from 20 to 10 mL for ultrasound-guided interscalene block at the cricoid level does not reduce the incidence of … Continue reading
        • Inject anesthetic further away from the BP sheath. While only shown in one study, injecting anesthetic a few millimeters away from the nerve roots might lead to decreased paresis with equivocal analgesia[47]Palhais N, Brull R, Kern C, et al. Extrafascial injection for interscalene brachial plexus block reduces respiratory complications compared with a conventional intrafascial injection: a randomized, … Continue reading
        • Inject anesthetic deeper, away from superficial phrenic nerve. Aiming for the C7 nerve root reduces incidence of hemiparesis. Downside is riskier needle manipulation, as it’s easier to lose the needle tip.[48]Renes SH, Rettig HC, Gielen MJ, Wilder-Smith OH, van Geffen GJ. Ultrasound-guided low-dose interscalene brachial plexus block reduces the incidence of hemidiaphragmatic paresis. Reg Anesth Pain Med. … Continue reading
        • The two emergency department trials utilizing interscalene block used “20 to 30 mL” and “15-25 mL”. Neither report any patients with respiratory symptom compromise.[49]Blaivas M, Adhikari S, Lander L. A prospective comparison of procedural sedation and ultrasound-guided interscalene nerve block for shoulder reduction in the emergency department. Acad Emerg Med Off … Continue reading[50]Raeyat Doost E, Heiran MM, Movahedi M, Mirafzal A. Ultrasound-guided interscalene nerve block vs procedural sedation by propofol and fentanyl for anterior shoulder dislocations. Am J Emerg Med. … Continue reading
    • Pneumothorax
    • Infection
    • Bleeding/hematoma
    • Puncture of vascular structure
    • Local anesthetic toxicity (LAST)
    • Horner syndrome
      • Horner’s syndrome consists of unilateral miosis, ptosis, and anhidrosis, caused by ipsilateral sympathetic trunk inhibition. Spread of anesthetic from an ISB to the prevertebral space can cause Horner’ syndrome. 
      • Estimated to occur in 9-28% of surgical patients with US-guided ISB.[51]Schubert A-K, Dinges H-C, Wulf H, Wiesmann T. Interscalene versus supraclavicular plexus block for the prevention of postoperative pain after shoulder surgery: A systematic review and … Continue reading[52]Stasiowski M, Zuber M, Marciniak R, et al. Risk factors for the development of Horner’s syndrome following interscalene brachial plexus block using ropivacaine for shoulder arthroscopy: a … Continue reading
    • Hoarseness
      • Occurs from local spread of anesthetic to the recurrent laryngeal nerve.
    • Brachial plexopathy
      • ISB may cause injury through traumatic, ischemic, or toxic mechanisms. Symptoms primarily are sensory, and may be transient, permanent, or partially resolve.[53]Candido KD, Sukhani R, Doty R, et al. Neurologic sequelae after interscalene brachial plexus block for shoulder/upper arm surgery: the association of patient, anesthetic, and surgical factors to the … Continue reading
      • Estimated incidence of 1.4-3.1% in surgical patients, and is estimated to be the highest amongst peripheral nerve blocks. Permanent disability is very rare. Additionally, there are other factors with surgical patients which could affect neurapraxias including patient positioning and the surgery itself.[54]Brull R, McCartney CJL, Chan VWS, El-Beheiry H. Neurological complications after regional anesthesia: contemporary estimates of risk. Anesth Analg. 2007;104(4):965-974. … Continue reading[55]Faryniarz D, Morelli C, Coleman S, et al. Interscalene block anesthesia at an ambulatory surgery center performing predominantly regional anesthesia: a prospective study of one hundred thirty-three … Continue reading[56]Singh A, Kelly C, O’Brien T, Wilson J, Warner JJP. Ultrasound-guided interscalene block anesthesia for shoulder arthroscopy: a prospective study of 1319 patients. J Bone Joint Surg Am. … Continue reading[57]Holbrook HS, Parker BR. Peripheral Nerve Injury Following Interscalene Blocks: A Systematic Review to Guide Orthopedic Surgeons. Orthopedics. 2018;41(5):e598-e606. doi:10.3928/01477447-20180815-04
      • Rate of neurapraxia has not been studied in emergency department use
    • Contraindications
      • General regional anesthesia contraindications including patient refusal, allergy to local anesthetic, overlying skin infection, coagulopathy.[58]D’Souza RS, Johnson RL. Supraclavicular Block. In: StatPearls. StatPearls Publishing; 2020. Accessed February 14, 2021. http://www.ncbi.nlm.nih.gov/books/NBK519056/
  • Pearls and Pitfalls
    • Pearls
      • Most emergency departments do not have a standard block kit or a block cart. Consider creating a regional anesthesia cart in your emergency department which houses all these supplies for easy set-up
      • For departments without a block cart or kit, use a standard laceration tray – this will contain sterile towels, syringe, 18g needle to draw up anesthetic
      • Instead of using a marking pen to mark your target, use a ear/nasal speculum to indent the skin. This stays visible after sterilization
      • If you’re having difficulty identifying your needle tip, use “hydrolocation”. Inject a tiny amount of fluid and dissect through tissue surrounding the needle. Soundwaves are less attenuated through the fluid than tissue, enhancing needle visualization. This is known as “acoustic enhancement” or “through transmission enhancement”.
      • Using an in-plane technique, the shallower the angle of the needle, the better needle visualization as more sound waves bounce-back to the ultrasound probe. It is useful to take a shallow angle, identify the needle tip, and then make adjustments to the angle as needed. 
      • An easy rule of thumb is to combine 15cc of your preferred local anesthetic (lidocaine 1% of bupivacaine 1% or 0.5%) with 15cc of normal saline. This allows you to use a single 30cc syringe, and does not require you to weigh the patient and calculate max dose; 15cc is likely well below the toxic threshold for most adult patients. 
      • If your department has the ability to save and store ultrasound images, take a screenshot or video of your needle in position while injecting fluid. This provides documentation for billing purposes as well medicolegal proof you did not have needle placement in undesired structures.
    • Pitfalls
      • DO NOT inject against resistance. This suggests the needle tip is in an undesired location, such as intraneural. 
      • DO NOT attempt needle placement without first using color doppler to identify vascular structures.
      • DO NOT attempt an ISB without first performing and documenting a neurovascular exam. Perform a post-procedure neurovascular exam as well. 
      • Be cognisant of local anesthetic systemic toxicity (LAST). This text does not cover it, but you should be aware of signs and symptoms as well as have a plan for treatment including access to intralipids.

References[+]