Ultrasound Techniques

Ultrasound-guided Infraclavicular Brachial Plexus Block - Single Injection

Figure 1

The patient is in supine position with the head facing away from the side to be anesthetized. The premedication of an adult, average size patient typically consists of 4-6 mg of midazolam. In addition, 500mg -750mg of alfentanyl can be administered just before insertion of the needle. This typically produces tranquil and analgesic patient for the procedure.

TIP: Visualization of the brachial plexus can be challenging in patients who are tense, moving or exhibit guarding. Proper sedation can go a long way toward obtaining quality images.
Figure 2

Equipment:

Ultrasound machine + 8-12 MHz probe

Nerve block tray with following equipment items:

  1. Betadine soaked sponges
  2. 4”x4” gauze packs
  3. Sterile gel for the ultrasound probe
  4. Local anesthetic (30-40ml)
  5. Insulated nerve stimulator needle (50-100 mm)
  6. Injection pressure monitor (optional)
  7. Sterile gloves
  8. Surface electrode (optional)
  9. Nerve stimulator (optional)
  10. Ruler and skin marker
  11. Remote controller (foot pedal) for the nerve stimulator (optional)
Figure 3

Identify the orientation of the probe, e.ie., which end of the probe corresponds to the right, left and upper (superficial) part of the screen. After applying a sterile large “Tegaderm” and sterile gel to the probe, touch the end of the probe with the finger and observe the position of the shadow created with touching of the probe.

TIP: Make sure that there is no air trapping between the “Tegaderm” and the probe to avoid “shadowing” due to the poor acoustic impedance  of the trapped air.

Figure 4

The ultrasound probe (10-12MHz) is applied in the parasagital probe in the vicinity to the coracoid process and angled to best visualize the axillary artery.

TIP: when the axillary artery is not visualized, the most common cause is too inferior position of the probe. Solution – move the probe cephalad to almost “ride” the inferior edge of the clavicle.
Figure 5

Typical view of the brachial plexus in the infraclavicular region.

Parasagital view of the axillary artery and the brachial plexus in the infraclavicular region. Shown are skin, pectoralis major muscle, pectoralis minor muscle and deep (minor) pectoralis fascia. The axillary artery and brachial plexus are positioned bellow the (deep) fascia of the pectoralis minor muscle. The cords of the brachial plexus are positioned around the axillary artery with the lateral cord (L) being superficial and lateral to the artery, medial cord (M) medial and in line with the artery, and the posterior cord (P) close to the posterior wall of the artery. The cords in this image are seen as hypoechoic structures.

TIPS:

  • The cords of the brachial plexus in this location may appear hypo or hyper echoic.
  • Vary the pressure on the probe to distinguish between the artery, vein, and the cords of the brachial plexus.
  • Of these three structures, only the veins will collapse when applying a firm pressure on the probe.

Figure 6 &7

A 50-100 mm stimulating needle is inserted immediately next to the ultrasound probe at approximately 60°-70° angle and in line with the longitudinal axis of the probe. The needle insertion angle should be in parallel to the long axis of the probe in order to visualize the path of the needle on the ultrasound image.

TIPS:

  • When the ultrasound probe in this view (parasagital) is oriented properly, the shadow of the needle will be first seen entering from the upper left corner of the ultrasound screen (Figure 8)
  • To avoid the risk of pneumothorax, always check the depth of the axillary artery on the ultrasound image before inserting the needle. Limit the depth of needle insertion accordingly.




Figure 8
Insertion of the needle is visualized on the ultrasound image as an oblique shadowing (blue arrows) extending from the left upper most corner toward the axillary artery.
Figure 9-12

Injection of local anesthetic is best made in at least two locations with intention to inject  ½ of the planned volume of local anesthetic lateral to the axillary artery and close to the posterior cord (Figure 9) and the other ½ medial to the artery in the vicinity of the medial cord (Figure 10). Figures 11and 12 demonstrate slight lateral (Figure 11) and medial (Figure 12) needle orientation to accomplish the two injections on both sides of the artery.

TIP: Nerve stimulator can be used in conjunction with the ultrasound localization to assure that what is seen on the ultrasound image indeed represents the elements of the brachial plexus. Any twitch of the brachial plexus at any current 0.2mA-0.8mA is adequate for this purpose.

* The areas shaded in blue represent the pread of the local anesthetic after the laterasl and medial injections.

Figure 9Figure 10
Figure 11Figure 12
Figure 13

The injection of the local anesthetic is made slowly with frequent aspiration. Since the tip of the needle is rarely visualized and multiple injections are often made, avoidance of excessive resistance (>20 psi) to injection is essential to avoid an intraneural injection.

Figure 14

Typical indications for this block are surgery on the elbow, forearm, wrist and hand.

 

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DISCLAIMER: The material presented on this Web page has not been peer-reviewed. The indications, techniques and dosages on this Web page have been recommended in the medical literature and/or conform to OUR clinical practice. The medications and equipment have not necessarily been approved by the Food and Drug Administration (FDA) for use in the techniques and dosages for which they are recommended. The package insert for each drug and/or equipment should be consulted for use and dosage as recommended by the FDA. Because standards, practices and recommendations change, it is advisable to keep abreast of revised recommendations, particularly those concerning new drugs and techniques. While the techniques and dosages described are successfully used in our practice, they should be followed with a discretion since their complications may be dependent on the operator, patient and/or other accompanying clinical circumstances. The development and maintenance of this web page has not been supported by any pharmaceutical or medical manufacturing industry. The medications and/or equipment discussed in the web page is shown solely for teaching purposes. Similar equipment or medications from other manufacturers may produce similar clinical results to ours.