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Case Report

Serratus Anterior Plane Block for Awake Breast Surgery: A Case Report

Pedrosa, Filipa P. MD; Cravo, Hugo MD

Author Information
doi: 10.1213/XAA.0000000000001354
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Abstract

Thoracic fascial blocks are alternatives to classic regional anesthesia techniques such as thoracic peridural and paravertebral blocks.1,2 An understanding of the innervation of the breast and axilla is paramount for the development and application of these techniques. These blocks provide pain control in the perioperative period and decrease opioid consumption and related adverse effects.3–10 Case reports10,11 have been published depicting the successful use of anesthetic thoracic fascial blocks combined with deep sedation for breast surgery.

Serratus anterior plane (SAP) block was described in 20133 as an analgesic technique by injecting 0.4 mL/kg local anesthetic between the latissimus dorsi and the serratus anterior muscle, at the fifth rib level, over the midaxillary line. This injection covers the axilla, by blocking the intercostobrachial nerve, and the lateral thoracic wall by targeting the intercostal nerves from T2 to T6.1,3 Since its description, the SAP block has become a part of a multimodal analgesic plan for breast surgery.6,7,9

This case demonstrates a safe use of the SAP block without general anesthesia as a primary anesthetic technique for breast surgery. This is the first described case of a breast surgery performed under this technique. An informed consent was requested and signed by the patient.

CASE DESCRIPTION

A 60-year-old woman presented with a 10-mm breast mass located in the transition of the lateral quadrants of her right breast. She was scheduled to undergo lumpectomy with sentinel node biopsy.

Besides chronic hypertension, she has a congenital hemangioma of the right hemiface, extending from the right ear lobe to the right clavicle, without previous treatment or follow-up. This tumor caused dysphagia and restricted her from eating solid food or brushing her teeth because of high hemorrhagic risk. Airway evaluation showed invasion to the soft and hard palate causing a leftward shift of the uvula. She was classified as a Mallampati 3. The patient reported airway bleeding following anesthesia 10 years before, requiring an unplanned intensive care unit (ICU) admission. This patient had a large multinodular goiter without thyroid dysfunction and denied compression symptoms. Imaging of the head, neck, and thorax was requested to ascertain this anticipated difficult airway.

The computed tomography scan and magnetic resonance imaging (Figure 1) revealed a vascular tumor infiltrating the superior airway causing airway compression at the level of the hypopharynx, shift to the left side, and a reduced caliber to approximately 10–12 mm. The goiter extended into the thorax causing a tracheal compression with an 8-mm lumen.

Figure 1.
Figure 1.:
Preoperative head and neck imaging to document tumor extension and its relationship with the airway. A, Magnetic resonance imaging at the oropharynx level revealing leftward shift of the midline and reduction of the airway caliber by the tumor. B, Computed tomography imaging at the thyroid level showing a voluminous goiter with reduced airway patency.

A multidisciplinary discussion involving anesthesiology, breast surgeons, and ear, nose, and throat (ENT) teams defined the perioperative approach. Bleeding risk with airway manipulation was considered high, and a regional anesthetic thoracic fascial block was chosen. If an airway needed to be established, a tracheostomy under local anesthesia was to be performed. The patient was informed of the risks and benefits of both techniques. The ICU team was forewarned of this case.

The patient was positioned supine with right shoulder abduction with standard perioperative monitoring. Two intravenous lines were secured before the procedure. The ENT team was present in the room. An ultrasound-guided superficial approach SAP block was performed (Figure 2). A total of 25 mL of ropivacaine 0.75% was injected at 5-mL increments, between the latissimus dorsi and the serratus anterior muscles, at the level of the fifth rib, using a 22-gauge, 50-mm beveled nerve block needle. A temperature and pinprick test confirmed a blocked area from the second to the sixth intercostal space from the posterior axillary line to the midclavicular line, about 15 minutes after the technique. The area of incision and surgical dissection was blocked, and the surgery was allowed to start. Good surgical conditions were assured for around 120 minutes, and vital signs remained stable throughout. An infiltration of local anesthetic of 10 mL lidocaine 1% was needed on the medial margin of the tumor, close to the end of the surgery.

Figure 2.
Figure 2.:
Ultrasound imaging of the lateral thoracic wall at fifth rib level: (A) before and (B) after performing the block. Dashed line represents needle. LA indicates local anesthetic pocket; LD, latissimus dorsi muscle; PL, pleural line; R, rib; SAM, serratus anterior muscle.

During the perioperative period, the use of monopolar cautery was described by the patient as a warm discomfort from the chest to her right leg, where the electrode pad was placed. This was only felt when dissection was near the pectoral major muscle, because this block spares the pectoral nerves and does not anesthetize the pectoral muscles. This was easily solved by changing to bipolar cautery. Second, because axillary node dissection and margin enlargement were performed, surgery lasted longer than expected. The patient complained of right shoulder pain due to positioning. Arm abduction was slightly relieved, and light sedation was started using a total dose of ketamine (30 mg) and propofol (80 mg) over 1 hour. No opioids were administered. She remained responsive to verbal stimulation with normal vital signs.

She remained in the postanesthesia care unit for approximately 2 hours. Her postoperative multimodal analgesia protocol was intravenous acetaminophen (1 g) and ketorolac (30 mg), at fixed intervals. Tramadol (100 mg) was administered under patient request, once during the first 48 postoperative hours, to alleviate shoulder pain, reported as 4 of 10 on the numerical rating scale. Altered sensitive perception lasted for 6 hours. No postoperative nausea and vomiting (PONV) was reported. The postoperative period was uneventful, and the patient was discharged home 72 hours after surgery.

DISCUSSION

Facing a predictable difficult airway, the multidisciplinary discussion of this patient allowed a comprehensive analysis of the risks and benefits of several perioperative approaches.

Although described and used as an analgesic regional technique, the volume needed and the area of blockade of SAP block are yet to be clarified and this case report contributes to this.1,3,6 In addition, it describes a successful anesthetic technique without general anesthesia for breast lumpectomy with axillary dissection.

The SAP block covers the lateral thoracic wall and the axilla, as local anesthetic is deposited on the fascia where the muscular branches of the brachial plexus run and lateral branches of intercostal nerves arise.3 However, the innervation of the breast has different origins, and this block spares some areas of the breast. The supraclavicular branches that innervate the superior quadrants of the breast and also the medial and lateral pectoral nerves that innervate the pectoralis major and minor muscles are consistently spared. This precludes its use as an anesthetic technique for tumors of the superior quadrants of the breast or adherent to the pectoralis major muscle.2,11 In addition, anesthesia of the medial quadrants is inconsistent because their innervation is provided by the anterior cutaneous branches of the intercostal nerves that arise at the sternocostal joints.11 As such, depending on tumor location, a SAP block might have to be supplemented with the pectoralis nerves (PECS 1) block or transversus thoracic plane block to cover the surgical area.2,6

Several potential complications of this technique have been described, namely hematoma and pneumothorax, due to close anatomical relationship to the thoracodorsal artery and the pleura.3 To minimize these, an ultrasound-guided technique and incremental injection of local anesthetic was executed. Fascial blocks are volume dependent; therefore, local anesthetic systemic toxicity (LAST) is an important concern especially when anesthetic concentrations are used.1 In this case, a total of 187.5 mg in 25 mL of ropivacaine was administered, below the described toxic dose. No signs or symptoms of LAST were reported in this patient.

Thoracic peridural or paravertebral blocks are options as regional techniques for breast surgery. However, possible complications of neuraxial techniques are concerning.3,5,6,10 Thoracic fascial blocks have the advantage of avoiding the sympathetic blockade, allowing perioperative hemodynamic stability.1,5,10

Although surgical anesthesia was achieved with this block, this led to changes on surgical techniques, notably the use of bipolar cautery and the need to reduce arm abduction. Such an adjustment could be an obstacle to widespread use of this anesthetic technique, although it can be easily overcome by trained surgeons and preoperative selection of cases.

In summary, this case report describes the use of a SAP block without general anesthesia as an anesthetic technique for lumpectomy with axillary dissection, allowing good surgical conditions and patient comfort. In selected patients, this anesthetic technique is a choice, while avoiding airway manipulation. Postoperative outcomes are improved through better perioperative pain control4–10 and lessen opioid consumption,4–10 PONV,4,5,9 inpatient length of stay,4,6 and chronic pain.4

DISCLOSURES

Name: Filipa P. Pedrosa, MD.

Contribution: This author helped plan the perioperative and postoperative approach of this patient; manage the case; and write the manuscript.

Name: Hugo Cravo, MD.

Contribution: This author helped prepare preoperatively the patient; contributed to the perioperative approach; and contributed and reviewed the manuscript.

This manuscript was handled by: BobbieJean Sweitzer, MD, FACP.

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