4 Supraclavicular and Infraclavicular Techniques of Brachial Plexus Block
Just above the clavicle, each of the trunks splits into an anterior and a posterior division:
The three posterior divisions combine to form the posterior cord.
The anterior divisions of the upper and middle trunks form the lateral cord.
The lateral cord lies most superficially (lateral to and in front of the subclavian artery).
The posterior cord is found a little deeper and slightly lateral to the lateral (!) cord (lateral to and behind the subclavian artery).
The subclavian artery and the brachial plexus run medial to the coracoid process to the axilla.
Note the 90° rotation of the cords around the subclavian artery from the infraclavicular to the axillary region. While the posterior cord lies furthest lateral (but deeper) compared with the lateral cord in the infraclavicular region, the designations of the cords reflect their actual positions in the axillary region.
The medial cord passes below the artery and then lies medial to the artery, giving off a medial root that joins the lateral root of the lateral cord to form the median nerve.
4.2 Supraclavicular Block Techniques
The supraclavicular block of the brachial plexus, similarly to the infraclavicular block, has the advantage that the nerves supplying the arm are bundled very compactly in the area where the trunks separate into the cords. However, the classical supraclavicular block techniques by Kulenkampff (Kulenkampff 1911) and later Winnie and Collins (1964) have been used less than the infraclavicular block in recent decades due to the increased risk of pneumothorax. The introduction of ultrasound-guided techniques has, at least theoretically, the advantage of minimizing the risk of pneumothorax, although a pneumothorax cannot be completely precluded even with ultrasound (Bhatia et al 2010).
Sensory and motor effects, indications and contraindications, and complications, side effects, and method-specific problems are, unless specified otherwise, similar to those of the infraclavicular block techniques (Chapter 3.2.3).
The supraclavicular plexus block should be performed only under ultrasound guidance and possibly with a nerve stimulator as well.
4.2.1 Ultrasound-Guided Supraclavicular Block of the Brachial Plexus
Linear transducer: 10 to 12 MHz
Needle: 6 to 10 cm
Visualization of the Brachial Plexus Using Ultrasound
As already described for the trace-back method for locating the interscalene brachial plexus (Chapter 3.2.3), the transducer is placed immediately above and parallel to the clavicle in the supraclavicular fossa and the beam is directed obliquely under the clavicle toward the thorax (not perpendicularly; Fig. 4.9).
First the subclavian artery (round, pulsating, hypoechoic structure) is visualized. If the finding is unclear, color Doppler can be used to clarify the situation. Lateral and slightly anterior to the subclavian artery is the brachial plexus, visible as a bundle of small, hypoechoic circles (grapelike structure; Fig. 4.9)
The in-plane needle approach from lateral to medial is preferred to avoid a pneumothorax (Fig. 4.10). The needle is inserted at the lateral end of the transducer and advanced in the beam strictly along the transducer axis up to the desired structures. As in the interscalene block, a slight loss of resistance is felt when the fascia surrounding the plexus (prevertebral fascia) is penetrated. This phenomenon is also visible in the ultrasound image as a slight depression of the fascia followed by recoil (loss of resistance).
A few milliliters are injected to check whether the local anesthetic spreads in the correct compartment. It is crucial that the local anesthetic also spreads into the deep nerve structures in the angle between the first rib and the subclavian artery (corner pocket; Fig. 4.9), as there may otherwise be an incomplete block in the region of the ulnar nerve (Fig. 4.10). Information on the required volume of local anesthetic to be applied fluctuates between 15 mL (Soares et al 2007) and 30 mL (Fredrickson et al 2009, Perlas et al 2009).
A catheter can be placed using the technique described here, but is less successful than infraclavicular catheter placement with respect to postoperative analgesia (Mariano et al 2011). The reason for this is the unfavorable angle between the needle and the course of the brachial plexus for advancing the catheter.
Tips and Tricks
The ultrasound-guided supraclavicular block can be performed in combination with nerve stimulation. As described above, a response in the hand should be striven for. Note: After administration of local anesthetic and/or normal saline, the function of the nerve stimulator is impaired! Use dextrose 5% if necessary.
The targeted application of the local anesthetic in the corner pocket between the first rib and the subclavian artery should lead to a very reliable block with rapid onset (Soares et al 2007, Tran et al 2006). However, a comparative study of this method with the “in plane” infraclavicular plexus anesthesia showed a better block in the region of the ulnar nerve with the same onset time (30 min; Fredrickson et al 2009) in favor of the infraclavicular block.
In the same visualization of the supraclavicular brachial plexus as described above (in the short axis), an out-of-plane puncture similar to the perivascular supraclavicular block described by Winnie and Collins (Tran et al 2008) is also possible. The angle to the transducer should be as steep as possible. Using continuous small movements (local tissue movement, see Chapter 1), the practitioner can determine the position of the tip of the needle. The risk of a pneumothorax may be greater than in the in-plane technique. A catheter is easier to place.
4.3 Vertical Infraclavicular Block According to Kilka, Geiger, and Mehrkens
In contrast to the other infraclavicular techniques, the vertical infraclavicular block (VIB) described by Kilka et al (1995) has clear landmarks.
These landmarks are the anterior end of the acromion and the middle of the jugular notch. The midpoint of the line connecting these two points marks the injection site, which here lies just below the clavicle (Fig. 4.11 and Fig. 4.12).
The patient lies supine; special positioning of the arm is not necessary. If possible, the patient′s hand should lie comfortably on his or her abdomen (Fig. 4.13).
4.3.2 Needle Approach
After penetrating clavipectoral fascia, which is often very tough, there is a stimulus response after 2.5 to 4 cm. Peripheral muscle contractions in the fingers are striven for as a response indicating success (posterior cord/radial nerve, lateral cord/median nerve, medial cord/ulnar nerve). Stimulation of the lateral cord only, which leads to contraction of the biceps muscle and/or pronator teres, may result in an incomplete block. In order to obtain a successful response, the needle in this case must be withdrawn to a subcutaneous position, and after moving the skin slightly more laterally (0.5 to 1.0 cm) it should be advanced again vertically to the underlying surface. The desired response is about 0.5 cm deeper and is then usually in the region of the posterior cord, which here lies laterally (care !) and deeper than the lateral cord.
A 4 to 6 cm long insulated needle is used; a catheter technique is possible. The needle is inserted just below the clavicle strictly vertical (perpendicular) to the surface the patient is lying on.
Tips and Tricks
Because of the potential danger of a pneumothorax, a medial needle direction, a puncture site too far medially, and excessively deep puncture should be avoided at all costs (Fig. 4.16). The depth of puncture must never be more than 6 cm even in large patients. In slim patients where the distance between the acromion and the jugular notch is short (< 20 cm), the risk of a pneumothorax is increased, as the plexus is sometimes located at a depth of < 3 cm (Neuburger et al 2001). Even when all the rules are followed, a pneumothorax cannot always be avoided (Neuburger et al 2000).
When the distance from the acromion to the jugular notch is < 20 cm it is advisable to move the puncture site further laterally by 0.3 cm for each centimeter by which the distance falls below 20 cm (e.g., jugular-acromion distance 17 cm; puncture site not 8.5 cm but 7.6 cm from the anterior end of the acromion or 9.4 cm from the middle of the jugular notch on the J–A line; Neuburger et al 2003).
The injection point is largely identical with the medial boundary of the “infraclavicular fossa” (clavipectoral trigone or Mohrenheim fossa). The plexus emerges under the clavicle exactly at the lateral margin of the superficial part of pectoralis major. The so-called “finger point” (Fig. 4.17) acts as an additional orientation and thus provides certainty that the correct injection site has been defined. The anesthetist′s index finger (right index finger when the right limb is to be blocked, left index finger when the left limb is to be blocked) is placed in the gap between the deltoid and pectoralis major muscles and pressed laterally on the coracoid process. The tip of this finger encounters the clavicle and its ulnar border marks the medial margin of the infraclavicular fossa (deltopectoral groove) and thus the puncture site (Neuburger et al 2003).