右侧星状神经节阻滞引起阵发性呛咳

Distal Squeeze Technique Increases Venous Blood Flow and Allows for EasyIdentification of VeinsWith Ultrasound Accepted for Publication:8August2009To the Editor:I dentification of vascular structures dur-ing regional anesthesia procedures with ultrasound can help to identify target nerves and plan for an appropriate needle approach to avoid puncture and intravas-cular injection.Arteries can be identified by their relative resistance to collapse from pressure exerted by the ultrasound probe along with the characteristic pulsa-tileflow demonstrated by color or pulse wave Doppler.Veins often go unidentified, leading to patient morbidity1,2and poten-tial mortality.Because of their ease of collapse with minimal ultrasound probe pressure and their low-velocity-flow states that are not always well represented on ultrasound by color Doppler,veins can bedifficult to recognize with ultrasound.We describe a novel technique to identify small or collapsed veins using any standard ultrasound with color Doppler. Once an area is identified that could con-tain venous structures,color Doppler is activated.During real-time ultrasound, any distal part of the patient’s correspond-ing extremity is compressed or squeezed. This compression of the distal muscles and veins significantly increases venous bloodflow that is then represented more reliably by color Doppler on ultrasound (Fig.1).This technique may be repeated several times for complete evaluation of veins in an area and is well tolerated by patients.Other techniques can be used to visualize low-flow blood vessels such as probe tilt,adjustment of pulse repetition frequency,and increasing color gain,but none of these are effective in evaluating veins that are collapsed.Squeezing a distal extremity,as described here,results in the ability to evaluate both low-flow and com-pletely collapsed venous structures.We have found this distal compression technique to be very useful in the identification of veins that are often closely associated with nerves.We routinely use this technique in the axillaq and the popliteal regions bysqueezing the arm and calf,respectively.David B.Auyong,MDDepartment of AnesthesiologyVirginia Mason Medical CenterSeattle,WAJames G.Benonis,MDPresbyterian Anesthesia Associates,P.A.Charlotte,NCJeff Gonzales,MDPark Ridge Anesthesiology AssociatesAdvocate Lutheran General HospitalPark Ridge,ILEditor’s Note:James P.Rathmell served asthe acting editor-in-chief for this article.REFERENCES1.Dolan J,McKinlay S.Early detectionof intravascular injection duringultrasound-guided axillary brachialplexus block.Reg Anesth Pain Med.2009;34:182.2.Zetlaoui PJ,Labbe JP,Benhamou D.Ultrasound guidance for axillary plexusblock does not prevent intravascularinjection.Anesthesiology.2008;108:761.Ultrasound-GuidedInterfascial Injection forPeripheral Obturator NerveBlock in the ThighAccepted for Publication:29June2009To the Editor:W e read with interest the recent arti-cle by Sinha et al,1describing anultrasound-guided obturator nerve blockwithout the need to specifically identifyeither the anterior or the posteriorbranches of the obturator nerve.Theauthors described placement of a needleand local anesthetic injection into a fascialplane bounded by the pectineus andadductor brevis muscle followed by asecond injection into a fascial planebetween adductor brevis and adductormagnus muscles.Owing to the consider-able diversity in the sensory distributionof the obturator nerve,the authors havecorrectly taken loss of hip adduction asthe end point for a successful block.2However,the pectineus muscle,normallyinnervated by both the obturator nerveand femoral nerves,also providesan FIGURE1.A,Transverse ultrasound image of the popliteal space with superimposed color Doppler signal showing the popliteal artery in red V without compression of the calf,the vein is not readily seen.B,The same transverse ultrasound image of the popliteal space with superimposed color Doppler signal after compression of the calf showing augmented venous signal in blue.C,The simple method for squeezing the calf to augment venousflow during ultrasound imaging in the popliteal space.L ETTERS TO THE E DITORimportant contribution to hip adduction.3 Placement of local anesthetic within the fascial planes of the thigh and in the volumes described by Sinha et al may also be expected anesthetize those branches of the femoral nerve supplying pectineus muscle,thus contributing to a reduction in hip adduction.The authors may therefore have overestimated the loss of motor function attributable to obturator nerve block alone.A more accurate assessment of the contribution of the obturator nerve to hip adduction may have been achieved if blockade of the femoral nerve had been undertaken before obturator nerve block.However,one significant advantage of interfascial injection omitted in the article by Sinha et al is the ability to place local anesthetic at some distance from the peripheral nerve of interest.In this way, anesthesia can be achieved without the need for a needle to be in close contact with neural structures.Rosemary Snaith,MB,ChB,MRCP,FRCA John Dolan,BSc,MSc,PhD,MB,ChB,FFARCSIDepartment of AnaesthesiaGlasgow Royal InfirmaryGlasgow,Scotland,UKREFERENCES1.Sinha SK,Abrams JH,Houle TT,Weller RS.Ultrasound-guided obturator nerve block:an interfascial injection approach withoutnerve stimulation.Reg Anesth Pain Med.2009;34:261Y264.2.Bouaziz H,Vial F,Jochum D,Macalou D,Heck M,Meuret P,et al.An evaluation of thecutaneous distribution after obturator nerveblock.Anesth Analg.2002;94:445Y449.3.Standring S.Gray’s Anatomy.39th ed.NewY ork,NY:Churchill Livingstone;2005.Reply to Drs.Snaithand DolanAccepted for Publication:6November2009 To the Editor:W e thank Drs.Snaith and Dolan for their interest in our study and the opportunity to respond to their comments.1 The nonobturator contribution to thigh adduction was acknowledged in the intro-duction of our study,and previous stud-ies have shown that femoral nerve block can result in up to25%reduction in ad-ductor motor strength(AMS)by block-ing the adductors innervated by femoralnerve.2,3Similarly,a sciatic nerve blockmay decrease AMS by11%T7%.4Thisis specifically why we chose50%or greaterreduction in AMS to indicate successfulobturator nerve block(ONB),which standsin contrast to other investigators who haveaccepted any reduction in AMS to indicateONB.Drs.Snaith and Dolan may havemisinterpreted the intent of our study,which was not to determine B the loss ofmotor function attributable to the obtura-tor nerve,[but to identify successful ONBwith expected nociceptive block of thearticular branches to the knee.We would disagree that a superiordesign would have been to provide femoralblock before obturator block.If so de-signed,critics might suggest that the localanesthetic solution used for the femoralblock could spread to the obturator nerveand cause partial blockade.The lack ofreliable sensory distribution of the obtura-tor nerve would prevent one from rulingout such a partial blockade,and contribu-tion of the obturator nerve to adductionmight be underestimated if that were thequestion under investigation.Would notsciatic contribution to thigh adduction alsohave to be eliminated by sciatic block be-fore ONB?Finally,we would agree with thetheoretical advantage of interfascial injec-tion proposed,except that this presumesthe nerve of interest can be unequivocallyidentified before placing the needle B atsome distance[from it.Our techniqueuses ultrasound to correctly identify mus-cles and intervening fascia;no additionaltime was spent to specifically identify theobturator nerve,and although its ultra-sound appearance has been described,it isnot always obvious.Sanjay K.Sinha,MBBSJonathan H.Abrams,MDDepartment of AnesthesiologySt Francis Hospital and Medical CenterHartford,CTTimothy T.Houle,PhDRobert S.Weller,MDDepartment of AnesthesiologyWake Forest University School of MedicineWinston-Salem,NCREFERENCES1.Dolan J,Snaith R.Ultrasound-guidedinterfascial injection for peripheral obturatornerve block in the thigh.Reg AnesthPain Med.2010;35:314Y315.2.Macalou D,Trueck S,Meuret P,et al.Postoperative analgesia after total kneereplacement:the effect of an obturator nerveblock added to the femoral3-in-1nerveblock.Anesth Analg.2004;99:251Y254.3.Bouaziz H,Vial F,Jochum D,et al.Anevaluation of the cutaneous distributionafter obturator nerve block.Anesth Analg.2002;94:445Y449.4.Jochum D,Iohom G,Choquet O,et al.Addinga selective obturator nerve block to theparasacral sciatic nerve block:an evaluation.Anesth Analg.2004;99:1544Y1549.Does Lack of AnestheticAssistance Justifya SuboptimalUltrasound-Guided RegionalAnesthetic Technique?Accepted for Publication:24July2009To the Editor:W e read with interest the letter byPham Dang et al1describing aneedle-side handle as an aid when under-taking a peripheral nerve block under ul-trasound guidance.The rationale for thisincludes having one hand free for injec-tion of local anesthetic and adjustment ofthe ultrasound parameters when anestheticassistance is unavailable.Proper body er-gonomics to handle the transducer and theneedle are essential for block safety andsuccess in addition to avoiding operatorfatigue and body injury.2To provide morecontrol of the probe and a stable ultra-sound image,it is recommended that theoperator holds the probe at its distal endwith part of the hand in contact with thepatient.2In this way,the hand is comfort-ably supported while continually observ-ing and accurately positioning the needletip before and during injection of local an-esthetic.From the authors’description andillustrations provided the operator clampsthe needle side handle between second andthirdfingers of the hand.With the handnow unsupported,the freefingers hold theultrasound probe at its more proximal endwhere small movements translate into rela-tively large movements at the distal endof the transducer and thus the ultrasoundimage.Changing a recommended tech-nique to a suboptimal one risks both blockfailure and potential complications and cannever be justified even for the lack of anavailable anesthetic assistant.Aside frominjecting local anesthetic and adjusting theultrasound settings,an anesthetic assistantis also a valuable asset in monitoring andreassuring the sedated patient while theanesthesiologist concentrates more on thenerve block.Regional Anesthesia and Pain Medicine&Volume35,Number3,May-June2010Letters to the EditorACKNOWLEDGMENTThere have been no external finan-cial resources supporting this work.Rosemary Snaith,MB,ChB,MRCP ,FRCAJohn Dolan,BSc,MSc,PhD,MB,ChB,FFARCSIDepartment of Anaesthesia Glasgow Royal Infirmary Glasgow,Scotland,UKREFERENCES1.Pham Dang C,Pilet P ,Heymann eful side handle for holding needle during ultrasound-guided regional anesthesia.Reg Anesth Pain Med .2009;34:382Y 383.2.Chan VWS.Ultrasound Imaging for Regional Anesthesia.A Practical Guide .2nd ed.Toronto,Canada:Ultrasound for Regional Anesthesia,2008.Reply to Drs.Snaithand DolanAccepted for Publication:21October 2009To the Editor:Ithank Drs.Snaith and Dolan for their interest in my B home-made side handle [described to compensate the lack of anesthetic assistant during the practice of ultrasound-guided regional anesthesia (UGRA).1To their qualification of the side handle (SH)as a suboptimal tech-nique,I would like to point out some arguments showing that indeed the SHis designed to optimize the UGRA technique.Let us consider the problem with the anesthetic assistant.I believe that the assistant will not be very happy if he/she has in the same time to help and care for patient’s cardiorespiratory monitoring,se-dation,or comfort.In my institution,our anesthetist nurses care for the patient’s monitoring and comfort.I do care for all the rest in relation with UGRA,thanks to the SH.Drs Snaith and Dolan seem ignoring that,in many hospitals around the world,practitioners perform alone the single-shot regional techniques,based on nerve stimulation.The SH could allow them to move into the increasingly pop-ular UGRA with the same autonomy.The SH will permit the practitioner to free the hand that has served the needle direction and do the whole UGRA procedure by him-self.With the free hand,he/she switches and tunes himself/herself the nerve stimu-lator,feels himself/herself the pressure while injecting a chosen volume of anes-thetics around the nerve,promptly stops injecting in case of intraneural or intravas-cular or atypical spread of local anesthetics,adjusts the ultrasound parameters,writes annotation,and saves the desirable video clips.In other words,there is a continual,direct,and convenient interaction between the practitioner and the portable ultrasound machine.To my belief,this is a major tech-nical advance.As for the recommended and ref-erenced way of probe holding,2I noticed that it is to achieve a control of the probe and to avoid fatigue.The SH is designedto reach the same goal but in a different manner.The fingers of the hand holding the probe,by clamping the SH,unify the probe to the needle inserted deep in the skin and muscle.Anchored in this way,the probe is less likely to slide away.It is always possible to tilt or rotate slightly the probe unified to the needle to better visualize the relationship between target nerve and needle.The playing of fingers (video clips and photographs available on demand)is playful,and it is a child’s play.The finger movements vary with the pe-ripheral nerve block approaches.The aim is to seize the SH and achieve the B immo-bile needle technique.[3For information,there is a possibility to train oneself in the office by puncturing a sponge and moving around a computer mouse used like an ultrasound probe.The exercise consists of clamping or pinching the SH between different fingers of the hand holding the probe.The SH can be pinned flat on the probe by the first finger or immobilized by posing simply the index on the end of the long segment.Conveniently,adjust-ments are possible by pushing on the short segment with the index of the hand hold-ing the needle hub and making the SH slide over the needle to an appropriate level then turning the SH around the nee-dle to help it into the finger clamp.Consider ergonomics,the SH is a solution.Finger movements create condi-tion for hand relaxation,which is not achievable if the hand is clutching the probe.By freeing the hand that has served the needle drive,the SH in fact frees and relaxes the rest of the body.This results in a relaxed attitude for the practitioner’s neck,shoulders,and back as shown in Figure 1.This contrasts with the tense and rigid attitude usually seen,which involves 2hands,one holding the probe and the opposite holding the needle.This rigid attitude induces a stress to the 2shoulders and to the whole vertebral column.Charles Pham Dang,MDHo ˆtel-DieuCHU de Nantes,FranceREFERENCES1.Pham Dang C,Pilet P ,Heymann eful side handle for holding needle during ultrasound-guided regional anesthesia.Reg Anesth Pain Med .2009;34:382Y 383.2.Chan VWS.Ultrasound Imaging for Regional Anesthesia.A Practical Guide .2nd ed.Toronto,Canada:Ultrasound for Regional Anesthesia,2008.3.Winnie AP .An B immobile needle [for nerve blocks.Anesthesiology .1969;31:577Y578.FIGURE 1.Side handle and ergonomics.The probe is unified to the needle by the SH clamped by the fingers of the right hand in contact with the patient.The free left hand is seizing the syringe for injection.The practitioner is analyzing the Sonoscan displayed on the screen.Note the practitioner’s relaxed attitude good for ergonomics.The portable ultrasound machine is installed in line with the practitioner’s eyes and within his/her arm’s stretch.Letters to the Editor Regional Anesthesia and Pain Medicine&Volume 35,Number 3,May-June 2010Why Puncturing a Lumbar Tattoo During Epidural Analgesia Cannot Induce an Epidermoid TumorAccepted for Publication:20September 2009.To the Editor:Lumbar tattoos in young women have been at the center of an unresolved controversy since 2002.1Indeed,reported cases of epidermoid tumors caused by epidermal tissue entrapment by hollow needles after lumbar punctures have led anesthesiologists to speculate a theoreti-cal risk of introducing tattoo pigments into the epidural space during epidural analgesia,followed by potential compli-cations such as epidermal tumors and/or chemical arachnoiditis.1Based on that hypothesis,not only literature in the field of obstetrical anesthesiology but also books,media,and Internet forums have been flooded with the convincing fantasy that young parturients with lumbar tattoos could not undergo epidural analgesia.B Guidelines [have been provided,such as puncturing in a free spot within the tattoo,selecting another free vertebral interspace,nicking the skin before insertion of the needle,or even avoiding epidural anesthe-sia.2Despite rare publications discussing the true relevance of such risks,3,4precau-tionary principle still dictates blindly that the anesthesiologist avoid puncturing a lumbar tattoo.5The following images of tattooed skin are intended to show why it is irrele-vant and irrational to believe that punctur-ing a tattoo will result in the development of a B postpuncture tattoo-induced epider-mal tumor.[During tattooing,pigments areintroduced through the epidermis in the dermis.However,the pigments deposited within the epidermis just after the proce-dure are progressively lost during the heal-ing phase when the superficial layers of the epidermis peel away.6Pigments located in the dermis are mostly assimilated by macrophages and fibroblasts.Most of the macrophages migrate to the lymphatics,whereas some remain in the perivascular area,and eventually,some pigments are left free in the extracellular area within loose fibrous connective tissue (Fig.1).6Therefore,as the epidermis is devoid of tattoo pigments,it is impossible that B epi-dermal tissue coring [can include any pig-ment.Moreover,according to a forensic pathologist specializing in tattooing pa-thology,the pigments are B fixed [and sta-tionary within the dermis and cannot be mobilized by the needle or migrate along the needle track.5Therefore,if a needle is introduced through a tattoo,it would be more likely to entrap macrophages and/or fibroblasts with intracellular pigments than free the pigment itself.Potential tumoral consequences,if they do exist,will be the result of cell introduction and the epidu-ral analgesia itself rather than the pig-ments.If an anesthesiologist wants to avoid the pigments in the dermis while punctur-ing,our picture shows that he will have to make an incision to the hypodermis before puncturing.The risk of epidermoid tumor is re-lated to epidermal tissue coring during puncture not because of the presence of an underlying B harmless [tattoo.Such com-plications were reported in the 1950s in patients who had multiple punctures with hollow needles long before lumbar tattoos were fashionable.The concerns of Douglas and Swenerton 1were legitimate at first,but there is absolutely no data to support such risk.Nicolas Kluger,MDService de Dermatologie Universite ´MontpellierHo ˆpital Saint-Eloi Montpellier,France Sylvie Fraitag,MDService d’anatomopathologie Ho ˆpital Necker-Enfant MaladesParis,FranceBernard Guillot,MDService de Dermatologie Universite ´MontpellierHo ˆpital Saint-Eloi Montpellier,FranceJean-Christian Sleth,MDService d’anesthe ´sie-re ´animationPolyclinique Saint-RochMontpellier,FranceREFERENCES1.Douglas MJ,Swenerton JE.Epiduralanesthesia in three parturients with lumbar tattoos:a review of possible implications.Can J Anaesth .2002;49:1057Y 1060.2.Raynaud L,Mercier FJ,Auroy Y,Benhamou D,SOS ALR.Epiduralanaesthesia and lumbar tattoo:what to do?Ann Fr Anesth Reanim .2006;25:71Y 73.3.Sleth JC.Epidural anaesthesia and lumbar tattoo.Histology of tattoo:the missing link?Ann Fr Anesth Reanim .2007;26:266Y 267.4.Kluger N,Sleth JC,Guillot B.Lumbar tattoos and lumbar puncture:the emperor’s new clothes?Can J Anaesth .2007;54:855.5.Mercier FJ,Bonnet MP .Tattooing andvarious piercing:anaesthetic considerations.Curr Opin Anaesthesiol .2009;22:436Y 441.6.Sperry K.Tattoos and tattooing.Part II:Gross pathology,histopathology,medical complications,and applications.Am J Forensic Med Pathol .1992;13:7Y 17.Important Structures to BeKnown for a Safe Ultrasound-Guided Supraclavicular Plexus BlockAccepted for Publication:24September 2009To the Editor:We read with great interest the letter to the editor by Manickam et al 1about an incidental finding of a variant relation of the brachial plexus to the subclavian artery on the first rib.During a routine ultrasound,the authors found a surprising dissociation of the subclavian artery of 1.5cm from the brachial plexus,which ought to be adjacent to the latter structure.The dissociation was caused by a hypo-echoic structure,which was not inter-preted or named by the authors.OntheFIGURE 1.Left,Biopsy of tattooed skin (hematoxylin-eosin stain).Exogenous pigments are located in the mid and deep dermis.The epidermis is devoid of pigments.Right,Close-up view of tattoo pigments (Perls stain).Most of the pigment deposits have been assimilated by macrophages,and few pigments are left free between collagen bundles.Regional Anesthesia and Pain Medicine&Volume 35,Number 3,May-June 2010Letters to the Editorother hand,the author stated that this dissociation has never been reported in regional anesthesia literature.However,this surprising dissociation is anatom-ically easily explicable and corresponds to a very well known structure separating the artery from the brachial plexus.This structure was already mentioned 150years ago,2and this could be found in many anatomical textbooks;the scalenus mini-mus muscle.As some examples,Gray 3mentions this muscle as a frequently present muscle arising from the anterior border of the seventh cervical vertebra to run caudally and to insert on the first rib just behind the groove of the subclavian artery.Much more can be found in German literature.Hafferl 4described this structure not only as frequently present but also as a very thick and round muscular structure.The muscle’s origin can be extended to the fifth cervical vertebra.More important is that the tendon of the muscle is spread-ing shortly before the insertion on the first teral fibers might insert on the sec-ond and even third ribs,whereas the medial fibers insert in the pleural dome.As a con-sequence,the muscle reaches quite an im-pressive thickness (Fig.1)and can explain a hypoechoic structure.Because of the in-sertion in the pleural dome,this muscle is also named the B tensor pleurae muscle,[Rarely,the muscle can be replaced by liga-mentous fibers.In this case,the structure is described as the costopleurovertebral lig-ament.This ligament is one of the lig-amentous fixations of the pleural dome and is listed as the Zuckerkandl ligaments.4Other Zuckerkandl ligaments are the costopleural,vertebropleural,and esopha-gopleural ligaments.If a costopleurover-tebral ligament would be present,this would result in a hyperechoic structure.What is more,recent anatomical textbooks summarize this very frequently present muscle,providing variations,blood and nerve supply,as well as the function.5We certainly agree that,with the up-coming ultrasound techniques,some struc-tures cannot be easily assigned.Images can be misinterpreted,and structures such as the muscles might be shown as differing images from patient to patient.Neverthe-less,this is not the case for the findings mentioned by Manickam et al.1Anatomi-cal textbooks and literature provide much information about the supraclavicular region as well as about the interscalene gap.However,the correct interpretation of such findings and ultrasound images strengthens the demand for more knowl-edge of sonoanatomy,which could be provided by special workshops about this topic.As a consequence,the collaborationbetween the anesthetist and the anatomist has to be intensified.It also forces us as anatomists to incorporate our existing knowledge of sound anatomy and its vari-ations in the interpretation of ultrasound images.We would recommend researching not only anesthesiology but also anatomy literature and textbooks,which might be quite helpful.Georg C.Feigl,MD Manuel Dreu,MDInstitute of Anatomy Medical University GrazGraz,AustriaREFERENCES1.Manickam BP ,Oosthuysen SA,Parikh MK.Supraclavicular brachial plexusblock-variant relation of brachial plexus to subclavian artery in the first rib.Reg Anesth Pain Med .2009;34:383Y 384.2.Henle DJ.Muskellehre.In:Henle,ed.Handbuch der Systematischen Anatomie .1st V olume,3rd part.Braunschweig,Germany:Friedrich Viehweg und Sohn;1858:125.3.Bannister LH.Respiratory system.In:Gray’s Anatomy .38th ed.New Y ork,NY:Elsevier Churchill Livingstone;1995:1663.4.Hafferl A.Die Muskulatur.In:Hafferl A,ed.Die Anatomie der Pleurakuppel .Berlin,Germany:Julius Springer Verlag;1939:20.nz T,Wachsmuth W .Regiosternocleidomastoidea.In:Lanz-Wachsmuth,ed.Praktische Anatomie:Neck .New Y ork,NY:Springer Verlag;2004:371.Transient Cough Attacks After Right Stellate Ganglion BlockAccepted for Publication:13October 2009To the Editor:Stellate ganglion block (SGB)is a commonly used technique for a variety of diagnostic,therapeutic,and prognostic purposes.It is associated with some complications because of the anatomical properties of the ganglion.1We present a case with transient cough attacks as an unusual complication of SGB.A 69-year-old woman was diagnosed with complex regional pain syndrome and scheduled for right SGB once a day for 10days.Stellate ganglion block was performed using the paratracheal approach at the C6level.The first tree blocks wereuneventful.FIGURE 1.Ventral view of a left scalenovertebral triangle.The subclavian artery (SA)is passing the first rib (FR)as well as the brachial plexus (BP).The scalenus minimusmuscle (ScMM)disassociates both structures and inserts at the pleural dome (PD)with a very thick tendon.Letters to the Editor Regional Anesthesia and Pain Medicine&Volume 35,Number 3,May-June 2010No complication was observed during the fourth block and the patient was sent home,but2hrs after the procedure,she reported a coughing attack lasting1hr. Because the patient responded well to the blocks,we decided to continue the block on day5,and the procedure was again uneventful.Ten minutes after the sixth block,we witnessed another coughing ep-isode that lasted10mins without inter-ruption.Because the second attack was short and not life-threatening,it was de-cided to continue SGBs with smaller vol-umes,and6mL of0.25%bupivacaine was given at the seventh block.Unfortu-nately,10mins after the procedure,she had a similar cough attack lasting50mins. Result of the physical examination was unremarkable.Stellate ganglion block was stopped,and treatment continued with pregabalin.To the best of our knowledge,episo-dic coughing after SGB has been reported by Naveira and Morales2in only2patients. The authors theorized that the cough attack was due to the aspiration of saliva after recurrent laryngeal nerve paralysis.The right and left recurrent laryngeal nerves branch from the vagus nerve,but their route to reach the larynx is differ-ent.The left laryngeal nerve loops under and around the arch of the aorta(liga-mentum arteriosum)before ascending dor-sally in the left tracheoesophageal sulcus, whereas the right branch loops obliquely around the right subclavian artery and leads into the right tracheoesophageal sul-cus.When the recurrent laryngeal nerve branches at the cervical level,it is called a nonrecurrent nerve.3Nonrecurrent laryn-geal nerve mainly appears on the right side,with an incidence of0.3%to1.6%. The left nonrecurrent laryngeal nerve is rare(0.04%).4Both recurrent and nonre-current laryngeal nerves are located closer to the site of SGB on the right side and may be affected more frequently during right SGB.Our case and the other2re-ported cases had SGB on the right side.The cough reflex is initiated by ac-tivation of chemically and mechanically sensitive vagal afferent nerves.5,6The recurrent laryngeal nerve is responsible for the motor innervations of the laryngeal muscles that control the glottic opening and also carries sensitivefibers from a part of the larynx and trachea.RNL blockade after SGB leads to vocal cord paralysis and/or loss of sensation in the subglottic area.The glottis may not close tightly,which may allow aspiration of saliva into the trachea.Cough is regulated both voluntarily and involuntarily.The force and duration of cough are related to the degree of stimulus,the psychological state,and the social situation of the individual.Thenumber and the force of cough are alsounder conscious control but in ways notyet adequately quantified or described.7Because coughing may be voluntarilyinitiated or exaggerated by the patient,itmay not be considered as an importantsymptom by the clinician and not re-ported as a complication of SGB unlessit is severe.Naveira and Morales reported thatthe cough attack was ceased by inhaledlidocaine administration after SGB,butinhibition of the cough reflex is a well-known risk factor to increase lower airwayinfections.8We do not recommend inhi-biting the cough reflex unless the coughattack leads to hypoxia or hemodynamicdisturbances.In conclusion,we think that coughattack is most probably due to recurrentlaryngeal nerve anesthesia that allows as-piration into the trachea and should beconsidered as a complication of SGB.Fur-thermore,to determine whether these com-plications occur more frequently duringright SGB,studies comparing complicationfrequencies for both sides are required.Sebnem At N c N,MD,PhDKursat Akoz,MDDepartment of AnaesthesiologyDivision of AlgologyMersin UniversityFaculty of MedicineMersin,TurkeyREFERENCES1.Stanton-Hicks plications ofsympathetic blocks for extremity pain.TechReg Anesth Pain Manag.2007;11:148Y151.2.Naveira FA,Morales A.Treatment ofpersistent cough after stellate ganglion block.Reg Anesth.1993;18:312Y314.3.Toniato A,Mazzarotto R,Piotto A,BernanteP,Pagetta C,Pelizzo MR.Identification of thenonrecurrent laryngeal nerve during thyroidsurgery:20-year experience.World J Surg.2004;28:659Y661.4.Maranillo E,Vazquez T,Quer M,et al.Potential structures that could be confusedwith a nonrecurrent inferior laryngeal nerve:an anatomic ryngoscope.2008;118:56Y60.5.Canning BJ.Encoding of the cough reflex.Pulm Pharmacol Ther.2007;20:396Y401.6.Canning BJ,Mori N,Mazzoneb SB.Vagalafferent nerves regulating the cough reflex.Respir Physiol Neurobiol.2006;152:223Y242.7.Canning BJ.Anatomy and neurophysiologyof the cough reflex,ACCP evidence-basedclinical practice guidelines.Chest.2006;129:33Y47.8.Hall AP,Fox AJ,Raphael AF,Nandwani N,Smith G.Upper airway reactivity andupper respiratory tract infection:effect ofnebulized lidocaine.Br J Anaesth.1999;82:857Y860.Illusory IntravascularNeedle PlacementAn UnusualUltrasound ArtifactAccepted for Publication:27October2009To the Editor:V arious artifacts have been reportedin the literature pertaining to the useof ultrasound.1Y3We describe an appar-ent intravascular penetration during anultrasound-guided infraclavicular block.A51-year-old man presented forelective repair of a right upper-extremityarteriovenousfistula.With the ultrasoundprobe(HFL38Â/13-6MHz linear probe,SonoSite S Series;SonoSite Inc,Bothell,Wash)on the right deltopectoral groove inthe parasagittal plane,an18-gauge insu-lated Tuohy needle(StimuCath;ArrowInternational,Reading Pa),connected toa nerve stimulator(Stimuplex HNS11;B.Braun Medical Inc,Bethlehem,Pa),wasintroduced using ultrasound guidance.Thenerve stimulator was not yet switchedon at this stage.Upon approaching thelateral cord of the brachial plexus with theneedle B in plane[to the ultrasound probe,the ultrasound image appeared to show theneedle tip to be inside the axillary artery(Fig.1A).The needle was open to am-bient pressure,but there was no backflowof blood.After negative aspiration forblood,a test dose with epinephrine wasinjected through the needle with nega-tive results.Hydrodissection by the localanesthetic showed the injection to beoutside the artery,with the lateral cordbeing B pushed away[from the artery(Fig.1B).All3cords were separatelyblocked,placing10mL of0.75%ropiva-caine on each cord.No adverse effectswere noted.This case clearly illustrates that theappearance of apparent intravascular pene-tration may,in fact,be due to artifact.Apossible explanation for this appearanceis the so-called B side-lobe artifact.[Anultrasound image consists of a main beamof sound with the shape of an invertedcone(main lobe)and B side lobes.[4Sidelobes consist of beams of lesser intensityon either side of the main beam(Fig.2A).Side lobes may have sufficient intensityto produce significant echoes from strongRegional Anesthesia and Pain Medicine&Volume35,Number3,May-June2010Letters to the Editor。