Ultrasound-guided Supraclavicular Brachial Plexus Block

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1 PICTORIAL REVIEW Ultrasound-guided Supraclavicular Brachial Plexus Block 1 Faisal Rasool, 2 Armin Bartsch, 3 Aamer B Ahmed, 3 Atul Gaur IJUTPC Ultrasound-guided Supraclavicular Brachial Plexus Block 1 Specialist Registrar, Department of Anaesthesia, University Hospitals of Leicester NHS Trust, Leicester, LE3 9QP United Kingdom 2 Clinical Fellow in Anaesthesia, Department of Anaesthesia, University Hospitals of Leicester NHS Trust, Leicester, LE3 9QP United Kingdom 3 Consultant Anaesthetist, Department of Anaesthesia, University Hospitals of Leicester NHS Trust, Leicester, LE3 9QP United Kingdom Correspondence: Atul Gaur, Consultant Anaesthetist, Department of Anaesthesia, Glenfield Hospital, University Hospitals of Leicester NHS Trust, Leicester, LE3 9QP, United Kingdom, atul.gaur@uhl-tr.nhs.uk Peripheral nerve blocks have certain advantages over general anaesthesia such as associated analgesia, minimal side effects and a more rapid recovery. 1-3 The supraclavicular brachial plexus block provides reliable anaesthesia of the entire upper limb with excellent conditions for tourniquet application. Kulenkampf in 1911 described a technique based on an injection made at the supraclavicular part of the brachial plexus associated with a short onset of action. 4 Despite a few modifications, the supraclavicular approach remained risk prone owing to its association with a high incidence of pneumothorax. 5 After Grange et al performed first Doppler guided block in 1978, the evolution of real time ultrasound guided blocks (with or without nerve stimulation) resulted in ease of performance, increased safety profile, and a better quality block. 6,7 Ultrasound has played a significant role in re-establishing the supraclavicular brachial plexus block in perioperative care. However, a thorough understanding of the anatomy, sonoanatomy, sonotechniques including scanning and needling is essential to ensure a safe and high quality block. 8 ANATOMY The anterior rami of the cervical and first thoracic spinal nerves (C5-8 and T1) form the brachial plexus. The brachial plexus originates in the neck as roots and terminates in the axilla as cords, giving off various branches along its course. The roots of the brachial plexus emerge between the scalenus anterior and scalenus medius muscles to form trunks which cross the floor of posterior triangle. Each trunk divides into anterior and posterior divisions and rearranges to form the cords at the outer border of the Fig. 1: Schematic diagram of brachial plexus first rib to continue down into the axilla. Thus the roots of the brachial plexus are situated between the scalene muscles, divisions behind the clavicle and cords in the axilla. The roots and trunks along with their branches form the supraclavicular aspect whilst the cords and their branches form the infraclavicular portion of the brachial plexus (Fig. 1). The scalenus anterior muscle originates from the tubercles on the C3-6 cervical vertebrae and descends forwards and laterally to be inserted onto the scalene tubercle and adjacent part of the first rib. The phrenic nerve (C3-5) courses on the scalenus anterior within the prevertebral fascia, leaving its medial border near its lower edge and runs between the subclavian artery and vein to enter thorax. International Journal of Ultrasound and Applied Technologies in Perioperative Care, January-April 2010;1(1):

2 Faisal Rasool et al The subclavian artery arises behind the sternoclavicular joint from the brachiocephalic artery on the right side; and on the left side, more caudally in thorax directly from the aortic arch. The subclavian artery arches superiorly and laterally, anterior to the cervical pleura and behind the anterior scalene muscle. It continues as axillary artery at the outer border of first rib. The scalenus anterior divides subclavian artery into three parts; the first part lies from its origin to the scalenus anterior, second part lays posterior, and third part, lateral to the scalenus anterior up to the lateral border of first rib where it continues into axilla as axillary artery. The subclavian artery gives rise to four main branches, i.e. vertebral artery, thyrocervical trunk, internal thoracic (or mammary) artery and costocervical trunk. All branches originate from first part of the subclavian artery on the left side, and the costocervical trunk originates from the second part of the subclavian artery on the right side. The vertebral artery is the first branch of the subclavian artery which arises from its upper margin and ascends in neck between longus colli and scalenus anterior. It passes in front of the transverse process of C7 vertebra and through the transverse foramina of upper six cervical vertebrae. The sympathetic plexus runs along the vertebral artery. It is closely related to the middle and inferior cervical sympathetic ganglia which are connected by ansa subclavian. The thyrocervical trunk is the second branch which arises lateral to the vertebral artery from upper convexity of the subclavian artery. It divides into the transverse cervical, suprascapular and inferior thyroid arteries. The transverse cervical and suprascapular arteries pass laterally across scalenus anterior and the phrenic nerve and then lie in the lower part of the posterior triangle in front of the trunks of brachial plexus. The ascending cervical, a branch of either the inferior thyroid artery or thyrocervical trunk, ascends upwards and medial to the phrenic nerve. The internal thoracic artery is the third branch which originates from the inferior side of the subclavian artery. The costocervical trunk originates from first part of the subclavian artery on the left and from the second part on the right side. It courses backwards on pleura and divides into the superior intercostal and deep cervical arteries near the neck of first rib. The trunks of brachial plexus and third part of subclavian artery lie lateral to scalenus anterior in floor of posterior triangle, enclosed within prevertebral fascia. The dorsal scapular artery (DSA) occasionally originates from third part of subclavian artery. The DSA courses along with, or through, brachial plexus as it passes in front of scalenus medius before entering into the mass of levator scapulae to form scapular anastomosis. The DSA is frequently replaced by deep branch of the transverse cervical artery (TCA). Occasionally, the TCA or suprascapular artery or both directly originate from third part of subclavian artery in which case they are intimately related with the brachial plexus. Other contents of posterior triangle include the external jugular vein, accessory nerve (XI cranial nerve), lesser occipital nerve, greater auricular nerve, transverse cervical nerves and supraclavicular nerves (Fig. 2). ULTRASOUND PROBE Fig. 2: Brachial plexus The brachial plexus is scanned using a high frequency 5 to 14 MHz, linear ultrasound probe. It is important to adjust the ambient light and ultrasound machine settings by selecting appropriate depth of field, frequency, focus, and gain to optimise the ultrasound image. Probe Position (Oblique Placement) The brachial plexus can be scanned either in coronal or para sagittal planes in supraclavicular area. The ultrasound probe held in an oblique plane (coronal or sagittal) scans the brachial plexus both in longitudinal and horizontal 40 JAYPEE

3 Ultrasound-guided Supraclavicular Brachial Plexus Block directions as compared to a single (horizontal or longitudinal) plane when the probe is held either parallel or vertical to the clavicle. The sonoanatomy is more detailed when ultrasound probe is placed obliquely. Various needle approaches (anterior, posterior, medial or lateral) have been described with reference to the placement of the ultrasound probe. Sonoanatomy The subclavian artery is a prominent landmark identified immediately superior to first rib as a pulsatile hypoechoic tennis ball like image on ultrasound. The first rib appears as a bright hyperechoic rim with a drop out bony acoustic shadow. The brachial plexus normally appears superior, superolateral and/or superomedial to subclavian artery as multiple hypoechoic ovals/circles, often described as a honeycomb pattern or bunch of grapes. The brachial plexus may acquire a triangular, linear or vertical (or oblique) arrangement of trunks/division/cords around subclavian artery in supraclavicular region on ultrasound scan (Figs 3 and 4). The pleura is seen as a hyperechoic line at same level as that of the rib but appears more shiny than the rib. Pleura moves and shines more with breathing. The hyperechoic pleural shadow does not have a drop out acoustic shadow, which differentiates it from the rib shadow (Fig. 5). The scalenus anterior and medius muscles appear as hypoechoic structures on ultrasound scan and can be followed commencing from their origin to the point of insertion on first rib. The phrenic nerve lies on anterior surface of scalenus anterior from C4-7 level in neck (Fig. 6). The long thoracic and dorsal scapular nerves pass through middle scalene muscle and may appear as holes or hypoechoic structures. Often part of brachial plexus passes through scalenus anterior or medius muscles and is seen as small round or oval hyperechoic or hypoechoic structures. The thyrocervical trunk and transverse cervical artery often appear similar to nerve trunks on ultrasound scan. The pulsations of smaller arteries or branches are easily masked by the strong pulsations of subclavian artery. These vessels may fall in nerve block needle trajectory or course along or through the brachial plexus. This poses a threat of vascular injury, hematoma formation or inadvertent intravascular injection Colour Doppler may help in differentiation of brachial plexus from arteries by demonstrating colour enhancement. Thus ideally the proposed nerve block Fig. 3: Supraclavicular brachial plexus arranged in triangular pattern. Plexus is seen as rounded to oblong hypoechoic structures surrounded by hyperechoic rim. Subclavian artery (SA) is seen as large rounded hypoechoic structure which is pulsatile in real time and can be further confirmed by colour Doppler Fig. 4: Supraclavicular brachial plexus arranged as vertical/obliquely arranged circles. Plexus is seen as hypoechoic round structure (marked area) Fig. 5: Showing pleura and rib. Rib is seen as linear hyperechoic area with acoustic shadowing, pleura is visualised as hyperechoic structure without acoustic shadow. SA, subclavian artery; BPL, brachial plexus International Journal of Ultrasound and Applied Technologies in Perioperative Care, January-April 2010;1(1):

4 Faisal Rasool et al needle trajectory should be routinely scanned with Colour Flow Doppler (Figs 7A and B). In addition, veins are collapsible and may be identified by applying and releasing pressure with help of ultrasound probe while scanning. PATIENTS POSITION FOR SUPRACLAVICULAR BRACHIAL PLEXUS BLOCK The supraclavicular block may be performed with patient in supine, supine with 45 head up and in lateral positions (Figs 8A to C). Fig. 6: Showing phrenic nerve (PN) as hyperechoic structure on anterior surface of scalenus anterior (SA) muscle. IJV, internal jugular vein; CCA, common carotid artery A Patient in Supine Position The patient lays supine with head turned to the contralateral side. The pillow may be arranged as shown in Figure 8A to provide space for needle insertion. Supine Posterior Approach The ultrasound probe is held in an oblique coronal plane in supraclavicular fossa and the needle is directed medially and posteriorly as described by Chan et al (Fig. 9). In a similar approach, the ultrasound probe is held in oblique parasagittal plane and needle is directed anteriorly and caudally as described by Searle and Gopinath (Fig. 10). This technique is described in a separate article in this issue. 16 Supine Posterior Approach with 45 Head Up This position improves patient s comfort besides facilitating needle insertion. It is especially helpful when patient is unable B Figs 7A and B: Showing a branch of subclavian artery coursing through brachial plexus on colour Doppler. SA, subclavian artery Fig. 8A: Supine position 42 JAYPEE

5 Ultrasound-guided Supraclavicular Brachial Plexus Block Fig. 8B: Supine with 45 head up position Fig. 9: Showing probe placed in oblique coronal plane Fig. 8C: Lateral position Fig. 10: Showing probe placed in oblique parasagittal plane to tolerate a total supine position due to cardiorespiratory compromise or other postural issues. The ultrasound probe is placed in oblique coronal or parasagittal plane. The needle enters medially and anteriorly, or caudally and anteriorly depending on ultrasound probe placement method, as described above. Supine Anterior Approach The ultrasound probe is placed in an oblique coronal or parasagittal plane and needle is introduced from the anterior side of probe. The needle is directed posteriorly and medially to approach the brachial plexus. This approach is not in common use. The copula of the lung is located above and posterior to the subclavian artery and needle may pass very close to it. Also, the needling procedure may be challenging as needle trajectory may have to acquire a steep angle to reach brachial plexus. Coronal Placement of Probe The ultrasound probe is placed parallel to clavicle in supraclavicular fossa. The needle enters either from (a) lateral end of probe and advanced medially and posteriorly or (b) medial end of probe and advanced laterally and posteriorly using an in-plane technique. 13,6 Presence of the subclavian artery can compromise needle access to some parts of plexus which may result in higher failure rates. Manipulation of the artery to lift it away using needle tip has been described but may cause inadvertent intravascular injection or hematoma formation due to arterial puncture. Patient in Lateral Position using Posterior Approach The patient is positioned in lateral position with the side to be blocked up as described by Gaur et al. 11 This position International Journal of Ultrasound and Applied Technologies in Perioperative Care, January-April 2010;1(1):

6 Faisal Rasool et al allows the anaesthetist, needling site, line of needle insertion and ultrasound machine all to be aligned to improve nerve block procedure and operator comfort. Also, block in lateral position is ideal for pregnant patients. The probe has more space to move, angle or tilt in all directions to optimize image quality. Thus there is more freedom to obtain a safe plane of scan away from adjacent structures such as the thyrocervical trunk, pleura, etc. Fig. 11: Showing probe placed in oblique parasaggital plane in lateral position The ultrasound probe is placed in the supraclavicular fossa in an oblique parasagittal plane and needle is directed anteriorly and medially and steered towards brachial plexus (Fig. 11). A few patients have restricted neck movement or a pit in the supraclavicular fossa with a prominent trapezius muscle. It is difficult to perform the block in supine position in such patients. The lateral position still allows needle insertion through trapezius to reach brachial plexus as there is enough space on posterior aspect of the shoulder for needle maneuvering in such patients (Figs 12A to D). In addition, space on posterior side of probe and patient facilitates catheter placement when required. Needle Insertion Technique Patients are examined, informed and prepared as for traditional supraclavicular brachial plexus block. The ultrasound probe is cleaned and covered in a sterile cover, the patient s skin is prepared and procedure is performed with cap, gown and sterile gloves on. Both short bevel and Huber tip nerve block needles have been used for block procedures. Local anaesthetic is applied locally onto the skin at needle entry point. A 50 to 100 mm long needle is inserted 1 to 2 cm away from the proximal border of ultrasound probe. The needle is introduced in the Figs 12A to D: Patients with a dip in supraclavicular fossa and prominent trapezius muscle. The probe placed in oblique parasagittal plane in lateral position. (A) Patient in supine position (B) Patient in lateral position (C) Ultrasound probe in supraclavicular fossa (D) Needle is introduced through trapezius muscle due to a big dip in supraclavicular fossa 44 JAYPEE

7 Ultrasound-guided Supraclavicular Brachial Plexus Block posterior triangle near anterior border of trapezius muscle at an angle of 0 to 45 for a supraclavicular brachial plexus block. The in-plane (IP) approach is commonly used for supraclavicular brachial plexus blocks. It is safe to insert needle initially in the superficial plane until needle is visualised on ultrasound scan. Once this needle is seen as a hyperechoic line, it is steered towards the brachial plexus (Figs 13A and B). It is important to track the needle tip throughout to avoid complications such as haemothorax or pneumothorax. Often the inferior belly of omohyoid prevents smooth entry of needle towards brachial plexus; however the needle may be easily steered in from upper or lower border of omohyoid muscle. Combitech needling is a combination of landmark and ultrasound guided in-plane needling techniques. This enhances the safety of block as needle is steered in deeper planes only under ultrasound guidance. To perform combitech needling, an optimum scan of brachial plexus is obtained; a temporary landmark a blanched rectangle on skin is created by pressing firmly with ultrasound probe (Fig. 14A). Ultrasound probe is then lifted off the skin and needle is inserted in superficial subcutaneous plane in centre of the blanched rectangle (Figs 14B and C). Subsequently, ultrasound probe is replaced over needle and once needle is visualised, it is steered into deeper planes towards brachial plexus under real time ultrasound guidance (Fig. 14D). A B Figs 13A and B: (A) Showing needle as hyperechoic linear structure approaching brachial plexus using in-line needling technique, (B) Showing needle within brachial plexus using in-line needling technique. SA, subclavian artery; BPL, brachial plexus Figs 14A to D: Combitech needling (A) Ultrasound probe in parasagittal plane pressure is applied onto skin (B) Probe is lifted off the skin and a blanched rectangle is created (C) Needle is introduced subcutaneously in centre of blanched rectangle (D) Probe is replaced over needle International Journal of Ultrasound and Applied Technologies in Perioperative Care, January-April 2010;1(1):

8 Faisal Rasool et al A few specialised ultrasound needles are also available on the commercial market; however, their usefulness is yet to be demonstrated. These needles have serrations or pits on the needle surface which are claimed to improve their visibility. Sonoanatomy after LA Injection Once the needle tip is positioned near the brachial plexus, a small aliquot of 1 to 2 ml of local anaesthetic (LA) is injected to confirm the position of needle-tip by observing its spread (Fig. 15).This is followed by injection of another 10 to 30 ml of LA solution. Care must be taken not to inject when faced with a high resistance to the injection. Also, on introduction of LA, a comet tail artifact may appear at needle tip due to the deposition of multiple small air bubbles. If neither the spread of local anaesthetic nor the comet tail artifact is seen at needle tip, it is likely that the needle-shaft is being mistaken for needle-tip. In this situation probe should be moved to carefully scan, align and relocate the needletip. Initial injection of local anaesthetic can be made either (a) near the 12 to 2 o clock or (b) 4 to 6 o clock positions in reference to the subclavian artery. When local anaesthetic is initially deposited at 4 to 6 o clock position then air bubbles (accidently) introduced with the injectate do not compromise image quality during rest of the procedure. On the other hand initial injection near 12 to 2 o clock position improves image quality around 4 to 6 o clock where structures such as thyrocervical trunk or pleura are situated, hence any injury to these structures can be avoided when needle is directed in a deeper plane (Figs 16 and 17). A single injection is sufficient to produce excellent analgesia when block is performed along with a general anaesthetic. However, when the block is performed as a sole anaesthetic technique, a rapid onset is required. Multiple injections enhance the spread of local anaesthetic thus facilitate rapid onset and quality of block. 17 The needle is usually repositioned through hydrodissected areas (pockets) created by local anaesthetic around brachial plexus. 17,18 Hemidiaphragmatic paralysis is not as commonly seen after a supraclavicular approach as with the interscalene approach for brachial plexus block. Phrenic nerve paresis following supraclavicular brachial plexus has been observed in up to 67% of the patients in one series. 19 Since the phrenic nerve adheres to scalenus anterior by prevertebral fascia, this is invariably blocked when local anaesthetic spreads on the anterior surface of the muscle. After completing the local anaesthetic injection, anterior surface of scalenus anterior at C5-7 level should be scanned to detect this spread (Fig. 18). Catheter Placement The authors find that the lateral position offers a suitable alternative for catheter placement due to adequate space for needle maneuverability (Fig. 19). Local anaesthetic solution or dextrose 5% is injected to distend the sheath or space around brachial plexus prior to insertion of a catheter. Fig. 15: Showing spread of local anaesthetics as hypoechoic area bathing the plexus near needle-tip at 12 to 1 o clock position. LA, local anaesthetic; SA, subclavian artery Fig. 16: Showing spread of local anaesthetics around brachial plexus. LA, local anaesthetic; SA, subclavian artery 46 JAYPEE

9 Ultrasound-guided Supraclavicular Brachial Plexus Block Fig. 17: Showing spread of local anaesthetics around brachial plexus and needle is repositioned near 5 to 6 o clock position Fig. 18: Showing local anaesthetic spread as irregular hypoechoic area inferior to phrenic nerve (PN) and around brachial plexus at C6 level. PN, phrenic nerve; SA, scalenus anterior muscle; LA, local anaesthetic; BPL, brachial plexus Fig. 19: Showing supraclavicular block catheter placement in lateral position The correct placement of catheter is confirmed by injecting local anaesthetic and visualising its spread. The catheter produces multiple hyperechoic spots on ultrasound scan. The catheter position can also be confirmed by injecting a small volume (1 ml) of air at the end of the procedure which creates an artifact and changes the quality of the ultrasound image. 20 REFERENCES 1. Mulroy M, Larkin K, Batra M, et al. Femoral Nerve block with 0.25% or 0.5% bupivacaine improves postoperative analgesia following outpatient arthroscopic anterior cruciate ligament repair. Reg Anaesth Pain Med 2001;26 (1): Chan VW, Peng PW, Kaszas Z, Middleton WJ, Muni R, Anastakis DG, GrahamBA. A comparative study of general International Journal of Ultrasound and Applied Technologies in Perioperative Care, January-April 2010;1(1):

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