**3.6 USG anterior approach to AN block**

With the arm positioned parallel to the thoracic wall with internal rotation and forearm pronated on the abdomen, a US probe is placed below and parallel to the clavicula identifying the coracoid process and lesser tubercle and intertubercular (bicipital) groove; then the arm is externally rotated, pushing the subscapular muscle rostrally and identifiable under the deep lamina of the deltoid fascia; the first portion of the AN is present between the deep lamina of the deltoid fascia and the superficial lamina of the subscapular muscle, where needle tip is placed. Interfacial position is confirmed after injection of 2 mL of normal saline, then 10 mL of 0.25% bupivacaine is injected. Rotating caudally the medial side of the probe and abducting the limb permits to directly visualize the AN and posterior circumflex humeral artery.

The injection is distributed on the anterior surface of the subscapular muscle and around the proximal insertion of the coracobrachialis and biceps brachial muscles. The sensory block is detected in AN area and areas supplied by the branches of the musculocutaneous nerve, lateral pectoral nerve, lateral supraclavicular nerve, and intercostobrachial nerve.

A complete AN blockade could provide anesthesia to the anteroinferior and lateral edges, and to part of the posterior aspect. of the shoulder joint capsule.

#### **Figure 11.**

*AN US images at axillary fossa. A. Transducer position 1. The US imagen corresponds to D. B. Transducer position 2. The US imagen corresponds to E. C. Anterior view of axilla showing the quadrangular space; AN emerges posterior to brachial plexus and enters the QS divided in anterior and posterior ramus. D. Scanning starts viewing the brachial plexus at the axillary level, observing the fascia of the teres major muscle. E. Moving proximally the transducer (towards the axillary fossa) shows the teres major muscle fascia deepening and the subscapular muscle tendon; the QS is seen. F. with 180° arm extension, the teres major muscle closes the QS. G and H. the axillary nerve is observed above the subscapular muscle as a hyperechoic image next to the circumflex humeral artery.*

The remaining shoulder joint areas are innervated by the SSN, which must be blocked if complete anesthesia of the shoulder is to be achieved. The LPN, or its articular branches, can be blocked by PECS I block or at the space between the coracoid process and clavicle (**Figure 12**) [41, 42].

*Regional Anesthesia for Shoulder and Clavicle Surgery DOI: http://dx.doi.org/10.5772/intechopen.101939*

#### **Figure 12.**

*US-guided anterior approach to AN blockade. A. Axillary nerve and its relations to subscapular, deltoid, and pectoralis muscles, axillary and circumflex humeral arteries, coracoid process, and humerus bone. B. Sagittal oblique ultrasound anatomy of the anterior axilla. C. Ultrasound scan: Transducer between coracoid process (medial) and the lesser tubercle of the humerus. Arm adducted and internal rotation. D. Transducer parallel to the inferior border of the clavicle, ultrasound mark is lateral. E and F. arm rotated externally/no abduction; subscapular muscle appears over humeral head. G and H. full external rotation and abduction of the arm. The medial side of the transducer is rotated inferiorly to obtain a sagittal oblique view of the axilla. The subscapular muscle is pushed rostrally and is identifiable under the deep lamina of the deltoid fascia. The cephalic vein is seen in the groove between deltoid and pectoralis major muscles. The axillary artery appears in the image and laterally to it, the axillary nerve is located. The needle shows the injection around the axillary nerve, on the surface of the subscapular muscle.*

### **4. Surgery involving the collarbone**

Clavicle fractures account for 2.6–4% of fractures in adults and 35% of shoulder injuries. The annual incidence is estimated between 29 and 64 per 100,000, and

#### **Figure 13.**

*The peri clavicular fascial plane or clavipectoral planes block (CPB). A: Scan throughout all clavicle surface, identifying the fracture site (proximal segment is displaced upward) B: Initiate the US scan in a sagittal paramedian position C: Tilting the ultrasound probe, is positioned on the upper surface of the clavicle D: Identify the anterior and posterior borders of clavicle E: 25 G needle tip positioned between bony surface and periosteum (if seen: By the fractured site, the periosteum is usually detached F: After 1-2 ml injected, the periosteum is further disengaged G: A second hyperechoic line appears, which correspond to clavipectoral fascia H: Needle tip positioned in the gap between periosteum and clavipectoral fascia I: Initial injection under clavipectoral fascia. Track Injectate spread in caudal and cephalic way along the anterior surface of clavicle I: Alternatively, Clavipectoral fascia scanning and needle in plane insertion from caudal to cephalic over clavipectoral fascia between pectoral major and minor muscles; this plane is the target for injection of local anesthetic.*

are distributed as follows: diaphysis 69-82%, lateral end 21-28%, and medial end 2-3%. There is often caudal displacement of the lateral fragment under the shoulder weight and elevation of the medial fragment by traction by the SCM. Infrequently,

#### *Regional Anesthesia for Shoulder and Clavicle Surgery DOI: http://dx.doi.org/10.5772/intechopen.101939*

posterior displacement of the medial end can cause compression of the mediastinum and main vessels requiring urgent intervention. Non-displaced fractures are managed without surgery, while surgical management is preferred in cases of displaced fractures in active adults [43].

Innervation of the skin above the second rib is supplied by the supraclavicular nerves of the SCP. Terminal branches of suprascapular, subclavian, lateral pectoral, and long thoracic nerves pass through the plane between the clavipectoral fascia and the clavicle and, theoretically, contribute to collarbone innervation.

Common approaches in anesthesia for clavicle fracture surgery are GA, regional anesthesia techniques such as ISBP block combined with SCP block. The clavipectoral fascial plane (CPB) block (**Figure 13**) is accomplished by injecting 10 to 15 mL of LA deep to the clavipectoral fascia on the medial and lateral side of the fracture site. A SCP or supraclavicular nerves block should be implemented to provide a sensory block of the skin of the shoulder. This nerve block can potentially involve the PN if the injection is not performed accurately in the proper subcutaneous plane and using low volumes. The block can be used for diaphysis and lateral end interventions, but as isolated block for surgical anesthesia, it only works for diaphysis fractures (**Figure 13**) [44].

For lateral fractures, including acromioclavicular and coracoacromial ligaments, articular branch of lateral pectoral nerve should be blocked. Likewise, if the surgery involves the acromioclavicular joint, the SSN should be blocked. Yamak Altinpulluk states that in the description of Ince et al., the LA was injected between the periosteum of the clavicle and the surrounding fascia (assumed as the clavipectoral fascia), but cadaveric dissections show that the spread is between the clavicle and fascia of the pectoralis major muscle in the upper and anterior aspect of the clavicle, with anesthetic spread under the deep layer of superficial cervical fascia and the superficial layer of pectoralis major fascia. The naming of this block as CPB is misleading and suggests that this block should be named as peri clavicular block (PB) [45]. The publication of a series of cases by Kukreja et al., shows the injection of the LA between the clavipectoral fascia and the pectoralis major muscle, resolving the previous objections described by Yamak Altinpulluk et al. [46].

#### **5. Interscalene brachial plexus (ISBP) block**

ISBP block targets the roots and trunks of the BP in the interscalene groove between ASM and MSM, and is directed towards C5-C6 nerve roots or UT. With higher volumes, C7 and even C8 nerve roots may be blocked. The block provides analgesia and anesthesia to the shoulder, lateral two-thirds of the clavicle, proximal humerus, and shoulder joint surgeries. Continuous infusion of 0.15% bupivacaine or ropivacaine (vs GA or intravenous anesthesia) provides adequate pain relief, similar side effects, and high patient satisfaction. ISBP block is associated with a high risk of PN blockade and HDP. Persistent PN palsy after ISBP block has recently gained wider recognition (reported incidence of 1:2000). Phrenic nerve palsy could be due to direct needle trauma or intraneural injection during landmark guided ISB but this complication has not been described with USG ISBP block. More peripheral BP nerve blockades are alternatives in scenarios in which avoiding PN palsy is critical, without clinically meaningful analgesic differences compared with ISBP block, except during recovery room stay [47]. Vocal hoarseness and Horner's syndrome are due to selflimiting temporary blockade of the ipsilateral recurrent laryngeal nerve and stellate ganglion [48]. ISBP block cannot reliably block the C8 and T1 ventral rami [48, 49].

ISBP Blockade relies on the visualization of the relevant anatomy, needle-tip position and LA spread using USG plus peripheral nerve stimulation with or

without injection pressure monitoring. USG allows fewer needle passes, lower volumes of LA, and better postoperative analgesia [1].

**Figure 14** shows the scan process of interscalene space: At cricoid cartilage level, with transverse scan, identify the carotid artery and move the transducer laterally

**Figure 14.** *Interscalene brachial plexus block.*

#### *Regional Anesthesia for Shoulder and Clavicle Surgery DOI: http://dx.doi.org/10.5772/intechopen.101939*

to locate the sonographic image of C5 and C6 TP; C5-C6 nerve roots are seen between the anterior and posterior tubercles and are traced in the groove between ASM and MSM, deep to the prevertebral fascia. The SCM lies superficially, and the PN runs medially over the ASM, away from the C5 root. Below the C6 TP and nerve root, C7 TP appears and the C7 nerve root can be seen anteriorly as hypoechoic round structure, lateral to vertebral vessels (identified by doppler color scan); meanwhile C5 and C6 nerve trunk are merging to conform to the UT; inferiorly to C7 transverse process, C7 nerve root conforms the MT. The dorsal scapular nerve (DSN) arises from the C5 nerve root and is imaged as a hyperechoic structure traversing the MSM, accompanied by LTN. Both must be avoided not needling through MSM. The block is performed positioning the tip deep to the C6 nerve root or UT and seeking the spread of LA anterior and posterior to the nerves, within the interscalene groove, and then repositioning of the needle superficial to the C5 nerve root or UT to obtain a satisfactory spread of LA. Do not needle between C5 and C6. 10-15 mL of LA (ropivacaine 0.75%) produce surgical anesthesia. Supraclavicular nerves blockade is added aimed to provide complete anesthesia to the shoulder cap.

The PN diverges at a rate of 0.3 mm per cm below the cricoid cartilage. Its blockade is reported in as 100% with a traditional landmark-based approach using volumes greater than 20 mL, and between 25 and 50% with lower volumes. Forced expiratory volume in 1 s (FEV1) may be reduced by up to 40%, and patients with comorbidities (obesity and respiratory disease) may develop troublesome dyspnea. ISBP block has been associated with an incidence of temporary neurological dysfunction in up to 14% at 10 days. Hypotension and bradycardic events occur in up to 20% during shoulder surgery, typically in the sitting position, and at around 30 min after the placement of an ISBP block. High circulating catecholamine concentrations and an underfilled, hyper contractile ventricle (induced by venous pooling) stimulates intramyocardial mechanoreceptors resulting in an abrupt reduction in sympathetic tone together with increased vagal tone. Prompt treatment with an antimuscarinic (ideally atropine) with or without sympathomimetic drugs is indicated [1].

Selective trunk block (SeTB) targets injection around individual trunks, with small volumes of LA. Produces anesthesia of the entire upper extremity (C5-T1) except the ICBN innervated area (T2). Is performed as one injection targeting UT and MT at interscalene and another one targeting LT at the corner pocket of the supraclavicular fossa (Up to 25 ml of LA are used). Produces HDP similar to UT approach [49, 50].
