16 Upper Limb
16.1 Supraclavicular Block of the Brachial Plexus
The three trunks of the brachial plexus run distally from where they exit the interscalene groove toward the first rib (Fig. 2.3). The upper trunk arises from roots of C5 and C6, the middle trunk is formed from the C7 nerve root, and the lower trunk consists of the roots of C8 and T1 (Fig. 2.1). The brachial plexus crosses the first rib lateral to the subclavian artery. The pleural dome is in the immediate vicinity of the supraclavicular brachial plexus (Fig. 2.11). It extends clearly beyond the first rib.
In the clavicular region, each trunk splits into an anterior and a posterior division and these form the cords. All posterior divisions unite to form the posterior cord (C5–C8, T1). The anterior divisions of the upper and middle trunks form the lateral cord (C5–C7) and the medial cord arises from the anterior divisions of the lower trunk (C8, T1; Fig. 2.1).
A linear transducer is placed directly supraclavicular, parallel to the clavicle, and is directed toward the thorax in the coronal plane (Fig. 16.1). The subclavian artery is visualized in the short axis. The supraclavicular brachial plexus is usually found lateral to the subclavian artery and appears as a (grapelike) cluster of round, hypoechoic structures with a hyperechoic border (Fig. 16.2). As the subclavian artery is usually examined from a slightly oblique direction, it is not seen as round, hypoechoic structure, but shows blurring at the edges. The vessel can be safely identified based on the visible pulsations or by using color Doppler.
The first rib is found in the ultrasound image below, that is, distal to the plexus from the transducer, which thus provides a degree of protection against accidental pleural puncture, as the pleura is in close proximity to the subclavian artery and the brachial plexus. The pleura should always be visualized.
16.1.3 Technique of Supraclavicular Brachial Plexus Block
Clavicle, the subclavian artery, and first rib in ultrasound visualization.
The child lies supine, the ipsilateral arm is adducted, and the head is turned slightly to the contralateral side. Due to the limited space in the supraclavicular region, particularly in small children, the shoulder girdle should be padded with a towel roll so that there is a sufficient hyperextension of the neck.
The clavicle is palpated and the transducer is placed parallel and directly cranial to the clavicle (Fig. 16.1). The brachial plexus is sought lateral to the subclavian artery in the short axis. Subsequently, the pleura is identified (Fig. 16.2). Then the region is disinfected, draped, and the transducer is covered with a sterile sleeve. The transducer is placed again at the previously determined position. After a stab incision with a lancet, the regional anesthesia needle is inserted for an in-plane technique on the narrow side of the transducer and the needle is advanced under repeated aspiration from lateral to medial to the plexus (Fig. 16.3).
An in-plane technique should always be used for a single-shot method. Even for a catheter method, in-plane needle guidance should be preferred; however, an out-of-plane technique is possible in exceptions. It is advisable to place a local anesthetic depot between the brachial plexus and first rib. Another depot can be injected above the plexus. Throughout the whole block process, the pleura must be visualized and kept in view.
If a continuous technique is planned, the catheter is then advanced 1 to 3 cm beyond the end of the needle.
Local Anesthetic, Dosage
Administer 0.4 to 1 mL/kg body weight of a long-acting local anesthetic (e.g., ropivacaine 0.2 to 0.5% [2–5 mg/mL]), maximum 20 mL.
The maximum permissible local anesthetic dose per kilogram body weight must be observed!
Maximum dosage for infants, toddlers, and children older than 6 months is 0.4 mg/kg body weight per hour of ropivacaine.
16.1.4 Indications and Contraindications
All interventions in the area of the entire arm, especially the upper arm (“spinal anesthesia of the arm”; Tsui and Suresh 2010).
General contraindications (Chapter 20.2).
Owing to the risk of pneumothorax, no bilateral block should be conducted and no block at all if there is contralateral pneumothorax. This technique should also not be used in children with severe respiratory failure or contralateral paresis of the diaphragm or vocal cords.