Interscalene block

2022-10-10T19:33:43Z

JonHoll: Created interscalene block article

{{Infobox surgical procedure
| anesthesia_type =Regional
| airway =None
| lines_access =PIV
| monitors =EKG, BP, Pulse oximetry
| considerations_preoperative =
| considerations_intraoperative =Nerve injury
| considerations_postoperative =Local anesthetic systemic toxicity
}}An interscalene brachial plexus block is a form of moderate-term anesthesia and analgesia used for surgical procedures of the shoulder, proximal humerus, and/or lateral forearm. The technique consists of injecting local anesthetic around the cervical roots of the brachial plexus.<ref name=":0">{{Cite book|last=Miller|first=R.D.|title=Basics of Anesthesia|last2=Pardo Jr.|first2=M.C.|publisher=Elsevier|year=2018|location=Philadelphia}}</ref> Utilizing a posteriolateral approach provides extremity analgesia without the need for general anesthesia and a reduced risk of intravenous injection.<ref name=":0" />
==Overview==
The interscalene brachial plexus block has been performed with varying success throughout the 20<sup>th</sup> century, before being formally attributed in 1970 to Alon Winnie, who reported a percutaneous approach to the brachial plexus block with >90% effectiveness.<ref>{{Cite web|date=2018-06-24|title=Interscalene Brachial Plexus Block - Landmarks and Nerve Stimulator Technique|url=https://www.nysora.com/techniques/upper-extremity/intescalene/interscalene-brachial-plexus-block/|access-date=2022-10-04|website=NYSORA|language=en}}</ref> While peripheral nerve stimulators are used to aid with identification and isolation of C5-C7 nerve roots, the introduction and development of ultrasound imaging has resulted in ultrasound-guided regional anesthesia.
===Indications===
An interscalene brachial plexus block should be considered for surgical procedures of the shoulder and/or lateral extremity.<ref name=":0" /> The interscalene block can provide between 8-14 hours of anesthesia and analgesia, depending on the anesthetic and adjunctive medications used.<ref name=":1">{{Cite journal|last=Desai|first=N.|last2=Kirkham|first2=K. R.|last3=Albrecht|first3=E.|date=2021-01|title=Local anaesthetic adjuncts for peripheral regional anaesthesia: a narrative review|url=http://dx.doi.org/10.1111/anae.15245|journal=Anaesthesia|volume=76|issue=S1|pages=100–109|doi=10.1111/anae.15245|issn=0003-2409}}</ref> Common surgical procedures include, but are not limited to, shoulder arthroscopy, shoulder debridement, rotator cuff repair, SLAP (superior labral anterior-posterior) lesions/tears, shoulder replacement, humeral fracture repair, and/or radial fracture repair.<ref name=":2">{{Cite book|url=https://www.worldcat.org/oclc/888551588|title=Anesthesiologist's manual of surgical procedures|date=2014|others=Richard A. Jaffe, Clifford A. Schmiesing, Brenda Golianu|isbn=978-1-4963-0594-7|edition=Fifth edition|location=Philadelphia|oclc=888551588}}</ref>

The decision to perform an interscalene block requires collaborative discussion between the surgeon and regional anesthesia provider. There may be temporal or anatomical limitations to performing this block due to patient acuity. Surgeon’s preference regarding regional anesthesia may also factor into decision-making. Some procedures, such as shoulder arthroscopy, produces mild or moderate post-operative pain that can be mitigated by other management techniques.<ref name=":2" />
===Contraindications===
Absolute contraindications:<ref name=":0" /><ref name=":3">{{Cite journal|last=Löser|first=Benjamin|last2=Petzoldt|first2=Martin|last3=Löser|first3=Anastassia|last4=Bacon|first4=Douglas R|last5=Goerig|first5=Michael|date=2019-07|title=Intravenous Regional Anesthesia: A Historical Overview and Clinical Review|url=http://dx.doi.org/10.1016/j.janh.2018.10.007|journal=Journal of Anesthesia History|volume=5|issue=3|pages=99–108|doi=10.1016/j.janh.2018.10.007|issn=2352-4529}}</ref>

*Patient refusal
*Open wounds, sores, trauma, bleeding, or active soft tissue infections of the neck or extremity of interest
*Hypersensitivity/allergy to local anesthetics

Relative contraindications:<ref name=":3" />

*Uncooperative patient

*COPD
*Contralateral paresis of phrenic or recurrent laryngeal nerves
*Previous neurologic deficit of the involved arm
*Anticoagulation
**The overall incidence of bleeding complications following peripheral nerve blocks, in the anti-coagulated patient, is estimated at 0.82%. Current ASRA guidelines recommend utilizing neuraxial guidelines and precautions in the setting of peripheral nerve blocks.<ref>{{Cite journal|last=Joubert|first=F.|last2=Gillois|first2=P.|last3=Bouaziz|first3=H.|last4=Marret|first4=E.|last5=Iohom|first5=G.|last6=Albaladejo|first6=P.|date=2019-10|title=Bleeding complications following peripheral regional anaesthesia in patients treated with anticoagulants or antiplatelet agents: A systematic review|url=http://dx.doi.org/10.1016/j.accpm.2018.12.009|journal=Anaesthesia Critical Care & Pain Medicine|volume=38|issue=5|pages=507–516|doi=10.1016/j.accpm.2018.12.009|issn=2352-5568}}</ref>

==Procedure Technique==
The patient can be positioned in a supine, semi-supine, or semi-lateral decubitus position with their head rotated away from the upper extremity side being blocked.<ref name=":0" /> The semi-supine position is preferred as it allows the patient’s head to be slightly elevated, allowing for improved visualization and easy identification of the sternocleidomastoid (SCM) muscle.<ref name=":4">{{Cite web|title=Interscalene block – Technique|url=https://www.openanesthesia.org/aba_interscalene_block_-_technique/|access-date=2022-10-04|website=www.openanesthesia.org}}</ref> Once superficial landmarks are appropriately identified, the patient should be cleaned and draped in the sterile fashion. Utilizing a linear ultrasound probe, the carotid artery, anterior & middle scalene muscle, SCM muscle, and brachial plexus should be identified along the C6 transverse plane.<ref name=":0" /><ref name=":4" /> The desired view of C5-C7 nerve roots is often identified as the “stoplight” or “snowman” sign with fine-tune adjustments of the probe.<ref name=":0" /> Using a posteriolateral, in-plane approach, 2% lidocaine, or alternative, should be administered to the superficial area. Utilizing the same injection site, the block needle is inserted in-plane, towards the brachial plexus, along the same posteriolateral approach. Direct visualization of the needle and needle tip should be maintained throughout the procedure. Once the needle tip is approximated near the C5-C7 nerve roots, the provider aspirates to ensure the needle tip is not located within a blood vessel.<ref name=":4" /> Once aspiration-negative, the provider can inject 3-5ml of local anesthetic to ensure proper placement of the needle, appropriate hydro-dissection, and local anesthetic spread.<ref name=":0" /> The provider can then inject, redirect, and inject further local anesthetic, taking care to aspirate after every 3-5ml of injected local anesthetic or immediately following needle repositioning. The overall effectiveness of an interscalene block varies upon where local anesthetic is located. Two common areas of injection are between the middle scalene muscle and brachial plexus sheath (peri-plexus) versus an injection within the brachial plexus sheath (intra-plexus).<ref name=":5">{{Cite journal|last=Spence|first=B. C.|last2=Beach|first2=M. L.|last3=Gallagher|first3=J. D.|last4=Sites|first4=B. D.|date=2011-05-16|title=Ultrasound-guided interscalene blocks: understanding where to inject the local anaesthetic|url=http://dx.doi.org/10.1111/j.1365-2044.2011.06712.x|journal=Anaesthesia|volume=66|issue=6|pages=509–514|doi=10.1111/j.1365-2044.2011.06712.x|issn=0003-2409}}</ref> While there is no difference between the block onset and block quality with either approach, intra-plexus blocks have been shown to last 2-3 hours longer than peri-plexus blocks.<ref name=":5" />

Procedural sedation can be considered for patients undergoing interscalene blocks. Commonly used medications include Midazolam (0.5-4 mg IV as needed) and Fentanyl (25-100 mcg IV as needed).

===Choice of Local Anesthetic===
The choice of local anesthetics (LA) is determined by the goal of the block (operative analgesia) and desired block duration. 0.5% Bupivacaine is one of the most common choices for interscalene blocks, but availability of this medication for regional anesthesia may vary.

'''Choice of local anesthetic''' — Choices of LA for interscalene block varies, but include:<ref>{{Cite web|title=UpToDate|url=https://www.uptodate.com/contents/interscalene-block-procedure-guide#H3179671851|access-date=2022-10-04|website=www.uptodate.com}}</ref>

· Pre-operative anesthesia: 2% lidocaine, 0.5% bupivacaine, or 1.5% mepivacaine.

· Post-operative analgesia: 0.25-0.5% bupivacaine or 0.5% ropivacaine.

2-5ml of 2% lidocaine, for the standard 70kg patient, is a common choice for superficial local anesthesia/analgesia prior to performing the interscalene block.

For a 70kg patient, the minimum effective volume of 0.5% bupivacaine (with adjunct epinephrine (1:200,000)) was reported to be 0.95ml, with adequate postoperative analgesia obtained with approximately 2.34ml.<ref>{{Cite journal|last=Falcão|first=L.F.R.|last2=Perez|first2=M.V.|last3=de Castro|first3=I.|last4=Yamashita|first4=A.M.|last5=Tardelli|first5=M.A.|last6=Amaral|first6=J.L.G.|date=2013-03|title=Minimum effective volume of 0.5% bupivacaine with epinephrine in ultrasound-guided interscalene brachial plexus block|url=http://dx.doi.org/10.1093/bja/aes419|journal=British Journal of Anaesthesia|volume=110|issue=3|pages=450–455|doi=10.1093/bja/aes419|issn=0007-0912}}</ref> However, provider experience, preference, patient’s anatomy, adjunct medication(s), and overall successful spread of local anesthesia should be considered. It is therefore reasonable to prepare and inject between 10-25ml of local anesthesia, monitoring for effective volume spread and the toxic dose limit of the local anesthetic.<ref>{{Cite web|date=2018-09-16|title=Ultrasound-Guided Interscalene Brachial Plexus Nerve Block|url=https://www.nysora.com/techniques/upper-extremity/intescalene/ultrasound-guided-interscalene-brachial-plexus-block/|access-date=2022-10-04|website=NYSORA|language=en}}</ref>

===Adjunct Medications===
Many agents have been studied as adjunct medications administered in regional blocks. The intent of adjunct medications is to increase the duration of analgesia of the nerve block without prolonging motor blockade.<ref name=":6">{{Cite journal|last=Desai|first=N.|last2=Albrecht|first2=E.|last3=El-Boghdadly|first3=K.|date=2019-09|title=Perineural adjuncts for peripheral nerve block|url=http://dx.doi.org/10.1016/j.bjae.2019.05.001|journal=BJA Education|volume=19|issue=9|pages=276–282|doi=10.1016/j.bjae.2019.05.001|issn=2058-5349}}</ref> Various medications have been studied, including clonidine, dexmedetomidine, and dexamethasone, providing between 2- 8 hours of additional analgesia.<ref name=":6" /> Epinephrine is reported to increase the mean duration of a nerve block by 1 hour, likely due to decreased systemic uptake of the anesthetic agent, rather than direct sensory and/or motor blockade.<ref name=":1" />
==Potential Complications==
===Major Adverse Events===
Local anesthetic systemic toxicity (LAST) is one of the greatest risks associated with any form of regional nerve blocks due to intravenous anesthetic injection.<ref name=":0" /> Possible intravenous anesthetic injection sites include the nearby carotid or vertebral artery.<ref name=":7">{{Cite book|url=https://www.worldcat.org/oclc/1012014941|title=A practical approach to regional anesthesiology and acute pain medicine|date=2018|others=Joseph M. Neal, De Q. H. Tran, Francis V. Salinas, Michael F. Mulroy|isbn=978-1-4698-9683-0|edition=Fifth edition|location=Philadelphia|oclc=1012014941}}</ref> LAST can presents with various signs and symptoms, but is commonly associated with perioral paresthesias, audio-visual disturbances, sudden change in mental status, or seizures.<ref>{{Cite journal|last=El-Boghdadly|first=Kariem|last2=Pawa|first2=Amit|last3=Chin|first3=Ki Jinn|date=2018-08|title=Local anesthetic systemic toxicity: current perspectives|url=http://dx.doi.org/10.2147/lra.s154512|journal=Local and Regional Anesthesia|volume=Volume 11|pages=35–44|doi=10.2147/lra.s154512|issn=1178-7112}}</ref> While LAST is extremely uncommon, regional anesthesia providers and teams should be observant for any signs of LAST during and following the procedure.<ref>{{Cite journal|last=Sites|first=Brian Daniel|last2=Taenzer|first2=Andreas H.|last3=Herrick|first3=Michael D.|last4=Gilloon|first4=Constance|last5=Antonakakis|first5=John|last6=Richins|first6=Janeen|last7=Beach|first7=Michael L.|date=2012|title=Incidence of Local Anesthetic Systemic Toxicity and Postoperative Neurologic Symptoms Associated With 12,668 Ultrasound-Guided Nerve Blocks|url=http://dx.doi.org/10.1097/aap.0b013e31825cb3d6|journal=Regional Anesthesia and Pain Medicine|volume=37|issue=5|pages=478–482|doi=10.1097/aap.0b013e31825cb3d6|issn=1098-7339}}</ref> Intravenous lipid emulsion therapy should be readily available where regional blocks are being performed to rapidly manage LAST.

===Minor Adverse Events===
Horner’s Syndrome (Stellate Ganglion block) is another well-known side-effect of the interscalene block of the brachial plexus and occasionally, epidural analgesia. While this presentation is often transient, cases of long-lasting Horner’s syndrome have been reported.<ref>{{Cite journal|last=Alzahrani|first=Traiq|last2=Alnajjar|first2=Mouhannad|last3=Algarni|first3=AbdulrahmanD|last4=Al-Ahaideb|first4=Abdulaziz|date=2014|title=Delayed Horner′s syndrome following ultrasound- guided interscalene brachial plexus block|url=http://dx.doi.org/10.4103/1658-354x.125972|journal=Saudi Journal of Anaesthesia|volume=8|issue=1|pages=121|doi=10.4103/1658-354x.125972|issn=1658-354X}}</ref> Laryngeal nerve block and/or phrenic nerve block sequala have also been reported despite the use of ultrasound imaging.<ref>{{Cite journal|last=Cugnin|first=Nina|last2=Le Gaillard|first2=Benjamin|last3=Souza Neto|first3=Edmundo Pereira de|date=2021-03|title=Permanent hemidiaphragmatic paresis after interscalene brachial plexus block: a case report|url=http://dx.doi.org/10.1016/j.bjane.2021.02.009|journal=Brazilian Journal of Anesthesiology (English Edition)|volume=71|issue=2|pages=175–177|doi=10.1016/j.bjane.2021.02.009|issn=0104-0014}}</ref> Given an increased risk of incidental or secondary phrenic nerve block, interscalene nerve blocks should be avoided in patients with documented pulmonary compromise if unable to tolerate up to a 30% decreased in vital capacity or forced expiratory volume over 1 second (FEV<sub>1</sub>).<ref name=":7" />

Additional adverse events include accidental vascular puncture or neuraxial injections.<ref name=":7" />

===References===
<references />

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Interscalene block