Scanning Technique

• Position the patient supine with the arm to be blocked resting comfortably on the patient's side.
• After skin and transducer preparation, a linear 7 MHz transducer is applied immediately medial to the coracoid process (COR) underneath the clavicle in a parasagittal plane to obtain the best possible transverse view of the axillary vessels and cords.

Transducer over right infraclavicular coracoid region

• Optimize machine imaging capability by selecting the appropriate depth of field (usually within 3-5 cm), focus range and gain.

Visualize the cords of the brachial plexus and axillary vessels in short axis (transverse view). Nerves in the infraclavicular region often appear hyperechoic with the lateral cord most commonly cephalad to the axillary artery (9-12 o'clock position) and the posterior cord posterior to the artery (6-9 o'clock). When visible, the medial cord is caudad to the artery (3-6 o'clock). Both the axillary artery and vein are anechoic; the artery is pulsatile and the vein is compressible. Overlying the neurovascular structures are the pectoralis major and minor muscles.

Anatomical Correlation


AA and AV = axillary artery and vein
Arrowheads = cords
PMM and PMiM = pectoralis major and minor muscles
White box = scanned area
Yellow ring = location of cords of the brachial plexus

Nerve Localization

• Perform a systematic anatomical survey from superficial to deep. The pectoralis major and minor muscles are most superficial and easily identified.
• Move the transducer cephalad to view the clavicle (optional) and laterally to view the coracoid process (optional).
• Identify the axillary artery and vein deep to the pectoralis minor muscle. The vein is almost always caudad to the artery.
• Look for hyperechoic nerve structures cephalad, posterior and caudad to the axillary artery.
• Hyperechoic density posterior to the axillary artery can be due to "acoustic enhancement", an artifact generated when beam crosses a vessel with little acoustic impedance. Angle (tilt) the transducer slightly in the parasagittal plane to check if this hyperechoic structure stays in the same location. If it does not, this is not likely to be a nerve structure.

Needle Insertion Approach

• Ultrasound guided infraclavicular block is considered an INTERMEDIATE skill level block because this is a deeper block.
• The In Plane (IP) approach is recommended to visualize the needle shaft and tip movement during needle advancement.

In Plane Approach Cephalad to Caudad Approach

• After skin and transducer preparation, a 5-7 cm 18-22 G insulated needle is inserted below the clavicle depending on the depth. A larger bore needle is preferred when the nerves are deep to facilitate visualization. Advance the needle at a 45-60 degree angle from the cephalad end of the ultrasound transducer along its long axis in the caudad direction.

• Observe real time needle advancement to the nerve target and then confirm nerve identity by electrical stimulation if desired. Always aim to place the needle and local anesthetic posterior to the axillary artery next to the posterior cord.

Arrows = block needle AA = axillary artery LA = local anesthetic Note: needle and local anesthetic posterior to artery

Out of Plane Approach

It is possible to perform ultrasound guided infraclavicular block with an out of plane approach.

Local Anesthetic Injection

• The goal is to deposit local anesthetic around all the 3 cords of the brachial plexus. Local anesthetic injected posterior to the axillary artery resulting in a U shape spread around the artery is associated with complete blockade of the arm, forearm and hand.
• Consistent success is associated with local anesthetic spread posterior to the axillary artery and a radial nerve type stimulation while inconsistent block is associated with spread anterior to the axillary artery and a median nerve type stimulation (Reg Anesth Pain Med 2007;32:130).
• In practice, it is best to inject the first 10-15 mL of local anesthetic posterior to the artery in the 6 0'clock position (posterior cord). Then inject further as the needle is withdrawn to the 9 o'clock position (lateral cord).
• If spread to the 3 o'clock position is deemed inadequate, it may be necessary to separately place the block needle between the axillary artery and vein to access the medial cord. In our experience, this maneuver is seldom necessary.
• The usual local anesthetic volume is 30-40 mL for this blockade but effective block can be achieved with a smaller local anesthetic volume. The minimum effective local anesthetic dose for this procedure has not been determined.

Post-injection Note: circumferential local anesthetic spread (arrowheads, hypoechoic ring) around the axillary artery (AA)

Clinical Pearls

Nerve Localization

1. Anatomical Variations in the Coracoid Region
There is wide anatomical variation of the brachial plexus cord locations in the lateral infraclavicular region (medial to the coracoid process) as shown below.

A = axillary artery L = lateral cord M = medial cord P = posterior cord V = axillary vein Picture from Sauter Anesth Analg 2006; (103): 1574-1576

Also, it is important to note that there may be only 2 cords and not 3 in this region due to anatomical variations.

2. The Arm Abduction Maneuver
Arm abduction to 90 degrees will stretch the brachial plexus and make it taut. This will bring the 3 cords closer together and will enhance nerve visualization.

Arm by the Side Arrowheads = nerves AA and AV = axillary artery and vein

Arm Abduction Arrowheads = nerves AA and AV = axillary artery and vein

3. Use of a Small Curved Transducer
A good alternative is to use a small curved transducer for infraclavicular scanning since it provides a wider field of view and more space for needle insertion.

	Figure A shows a sonogram of the infraclavicular region captured by a linear 12 MHz transducer. Note the field of view is narrow. The target nerves (arrowheads) are within 3 cm from the skin surface. AA and AV = axillary artery and vein
	Figure B shows a sonogram of the same region captured by a curved 8 MHz transducer. Note the field of view is wider. AA and AV = axillary artery and vein Arrowheads = nerves

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Needle Insertion [Link to top]

1. Visualizing the Needle Tip
Visualization of the block needle can be challenging due to a steep angle of insertion (> 45 degrees). One way to accurately locate the needle tip is to tilt the needle tip superficially (i.e., angle anteriorly in this case). If the needle tip is posterior to the axillary artery (6 o'clock position), one will see lifting of the artery anteriorly. If the needle tip is at the 9 o'clock position, tilting the needle will push the artery caudad.

	A. Baseline scan Arrowheads = nerves AA = axillary artery
	B. In plane needle (arrows) approach AA = axillary artery
	C. Arrowheads = nerve structures; titling the needle tip (arrow) anteriorly shows that the needle tip is too superficial; needle tip is in the pectoralis minor muscle (PMiM). AA = axillary artery
	D. The needle tip (arrow) has now reached the posterior part of the axillary artery (AA, 6 o'clock position); tilting the needle at this point will slightly compress and displace the AA anteriorly. AA = axillary artery

2. Vertical Infraclavicular Block (Out of Plane Approach)

	The site of needle insertion for the VIB is approximately the mid point of the clavicle (CL). At this location, the brachial plexus is more superficial. The pleura and lung are usually 2-3 cm from the skin surface.
	The brachial plexus (arrowheads) is commonly found lateral to the subclavian artery. Arrowheads = nerves PMM and PMiM = pectoralis major and minor muscles SA and SV = subclavian artery and vein
	Effect of arm abduction to enhance cord visualization Arrowheads = nerves SA and SV = subclavian artery and vein

3. Vertical Infraclavicular Block (In Plane Approach)

The brachial plexus can also be approached in plane with the needle pointing in a lateral to medial direction.

Catheter Insertion

• Continuous infraclavicular block (CICB) is indicated for arm and hand analgesia (see Catheter Technique).
• The in plane needle insertion approach is commonly used.
• The needle is inserted in a parasagittal plane along the long axis of the transducer (figure A).
• The block needle is advanced to reach the posterior aspect of the axillary artery (6 oíclock position, arrow = needle tip in figure B) as described for the single shot technique.
• Injection of local anesthetic (LA) or D5W solution (if nerve stimulation is desired) through the needle to distend the infraclavicular region is recommended to facilitate the ease of catheter advancement (figure C).
• Local anesthetic spread can be observed in real time during catheter injection (figure E).

	A. The block needle is advanced in the parasagittal plane inline with the transducer.
	Arrow = needle tip
	LA = local anesthetic
	D. Catheter insertion by an assistant after fluid injection and distention posterior to the axillary artery.
	E. Local anesthetic spread is observed during injection through the catheter after needle removal.
	F. Tegaderm dressing is placed over the catheter exit site.

Image Gallery

1. Local Anesthetic Spread Pattern

	A. Local anesthetic is seen ANTERIOR to the axillary artery. This type of spread is associated with a higher incidence of block failure despite a strong motor response. AA = axillary artery LA = local anesthetic PMM and PMiM = pectoralis major and minor muscles
	B. Local anesthetic is seen POSTERIOR to the axillary artery. Spread around the axillary artery in a U shape usually results in a complete block. AA = axillary artery LA = local anesthetic PMM and PMiM = pectoralis major and minor muscles

2. Local Anesthetic Injection Strategy (Curved 8 MHz Transducer)

	A. Pre-injection Scan Arrowheads = cords AA = axillary artery PL = pleura
	B. The needle (arrows) is first advanced deep to place the needle tip posterior to the axillary artery for the first part of the injection. AA = axillary artery
	C. Needle tip (arrow) is then pulled back to the 9 oíclock position and the remaining dose of local anesthetic is injected next to the lateral cord. AA = axillary artery
	D. A collection of local anesthetic (arrows) is now visualized surrounding the axillary artery (AA) and the cords. The nerve structures appear particularly hyperechoic after injection.

3. Poor Ultrasound Image in the Infraclavicular Region Captured From an Obese Patient

Note the size of the adipose layer and the depth of the axillary artery (4 cm below skin surface) The cords are not distinctly visualized. AA = axillary artery PMM and PMiM = pectoralis major and pectoralis minor muscle

4. Visualization of Rib vs. Pleura

	Figure A. A curved transducer is placed over the right infraclavicular region perpendicular to the deltopectoral fossa with the beam pointing towards the posterior chest wall.
	Figure B. A corresponding ultrasound image shows a bony shadow (white arrows) which is likely from the second rib and a pleural line (yellow arrows) more caudad. AA= axillary artery
	Figure A. The curved transducer is now angled medially over the right infraclavicular region.
	Figure B. A corresponding ultrasound image now shows a sliding pleural line. This emphasizes the risk of pneumothorax when advancing the needle medially. AA= axillary artery

5. Examination of Catheter Tip Position

	Figure A. The block needle (arrows) is inserted until its tip has reached the 9 oíclock position in relationship to the axillary artery (AA).
	Figure B. The catheter has been advanced too far and its tip (arrow) is now far from the nerves (arrowheads); pulling back the catheter is recommended.

6. Vascularity in the Infraclavicular Region

	Figure A. Vessels may be noted between the pectoral muscles. They are the pectoral branches of the thoracoacromial artery and the pectoral veins (PV). It is important to avoid puncture of these vessels during needle advancement in the cephalad to caudad direction. AA and AV = axillary artery and vein PMM and PMiM = pectoralis major and pectoralis minor muscle
	Figure B. The use of Color Power Doppler to identify the vascular structures. AA and AV = axillary artery and vein PMM and PMiM = pectoralis major and pectoralis minor muscle PV = pectoral vein

Video Gallery

Selected References

• Slater M E, Williams S R, Harris P, Brutus J P, Ruel M, Girard F, Boudreault D. Preliminary evaluation of infraclavicular catheters inserted using ultrasound guidance: through-the-catheter anesthesia is not inferior to through-the-needle blocks. Reg Anesth Pain Med 2007;32:296-302.
• Bigeleisen P E. Ultrasound-guided infraclavicular block in an anticoagulated and anesthetized patient. Anesth Analg 2007;104:1285-7.
• Dingemans E, Williams S R, Arcand G, Chouinard P, Harris P, Ruel M, Girard F. Neurostimulation in ultrasound-guided infraclavicular block: a prospective randomized trial. Anesth Analg 2007;104:1275-80.
• Hebbard P, Royse C. Ultrasound guided posterior approach to the infraclavicular brachial plexus. Anaesthesia 2007;62:539.
• Bloc S, Garnier T, Komly B, Asfazadourian H, Leclerc P, Mercadal L, Morel B, Dhonneur G. Spread of injectate associated with radial or median nerve-type motor response during infraclavicular brachial-plexus block: an ultrasound evaluation. Reg Anesth Pain Med 2007;32:130-135.
• Bigeleisen P, Wilson M. A comparison of two techniques for ultrasound guided infraclavicular block. Br J Anaesth 2006; 96: 502-507.
• Sandhu N S, Manne J S, Medabalmi P K, Capan L M. Sonographically guided infraclavicular brachial plexus block in adults: a retrospective analysis of 1146 cases. J Ultrasound Med 2006; 25: 1555-1561.
• Sandhu N S, Bahniwal C S, Capan L M. Feasibility of an infraclavicular block with a reduced volume of lidocaine with sonographic guidance. J Ultrasound Med 2006; 25: 51-56.
• Sandhu N S, Maharlouei B, Patel B, Erkulwater E, Medabalmi P. Simultaneous bilateral infraclavicular brachial plexus blocks with low-dose lidocaine using ultrasound guidance. Anesthesiology 2006; 104: 199-201.
• Sauter A R, Smith H J, Stubhaug A, Dodgson M S, Klaastad O. Use of magnetic resonance imaging to define the anatomical location closest to all three cords of the infraclavicular brachial plexus. Anesth Analg 2006; 103: 1574-1576.
• Tran d Q, Charghi R, Finlayson R J. The "double bubble" sign for successful infraclavicular brachial plexus blockade. Anesth Analg 2006; 103: 1048-1049.
• Arcand G, Williams S R, Chouinard P, Boudreault D, Harris P, Ruel M, Girard F. Ultrasound-guided infraclavicular versus supraclavicular block. Anesth Analg 2005; 101: 886-90.
• Marhofer P. Vertical infraclavicular brachial plexus block in children: a preliminary study. Paediatr Anaesth 2005; 15: 530-531.
• Porter J M, McCartney C J, Chan V W. Needle placement and injection posterior to the axillary artery may predict successful infraclavicular brachial plexus block: a report of three cases. Can J Anaesth 2005; 52: 69-73.
• Brull R, McCartney C J, Chan V W. A novel approach to infraclavicular brachial plexus block: the ultrasound experience. Anesth Analg 2004; 99: 950-951.
• Marhofer P, Sitzwohl C, Greher M, Kapral S. Ultrasound guidance for infraclavicular brachial plexus anaesthesia in children. Anaesthesia 2004; 59: 642-646.
• Sandhu N S, Sidhu D S, Capan L M. The cost comparison of infraclavicular brachial plexus block by nerve stimulator and ultrasound guidance. Anesth Analg 2004; 98: 267-268.
• Nadig M, Ekatodramis G, Borgeat A. Ultrasound-guided infraclavicular brachial plexus block. Br J Anaesth 2003; 90: 107-108.
• Greher M, Retzl G, Niel P, Kamolz L, Marhofer P, Kapral S. Ultrasonographic assessment of topographic anatomy in volunteers suggests a modification of the infraclavicular vertical brachial plexus block. Br J Anaesth 2002; 88: 632-636.
• Sandhu N S, Capan L M. Ultrasound-guided infraclavicular brachial plexus block. Br J Anaesth 2002; 89: 254-259.
• Ootaki C, Hayashi H, Amano M. Ultrasound-guided infraclavicular brachial plexus block: an alternative technique to anatomical landmark-guided approaches. Reg Anesth Pain Med 2000; 25: 600-604.