Using ultrasound in the operating room has led to a significant change in the practice of regional anesthesia. Anesthesiologists are now going beyond landmark-based techniques, and newer techniques are being pioneered and used worldwide. Descriptions of pecs I and II blocks1,2 have encouraged anesthesiologists to look beyond the choices such as thoracic epidural or thoracic paravertebral blocks to provide regional analgesia in breast surgeries. Pecs I and II blocks aim to block lateral and medial pectoral nerves, lateral branches of the intercostals nerves, long thoracic nerve, and intercostobrachial nerve.1,2 Serratus anterior plane (SAP) block has been described and was designed to primarily block the thoracic intercostal nerves3 (Fig. 1) providing complete analgesia to the lateral part of the thorax, although this block was yet to be described in a clinical setting.
We modified the SAP block technique and used it as part of multimodal analgesia in 2 patients undergoing breast conservation surgery with axillary dissection and reconstruction with a latissimus dorsi (LD) myocutaneous pedicle flap. The aim was to block the thoracodorsal nerve, which supplies the LD muscle, along with the other nerves of the anterolateral chest wall. We believe that this is the first case reporting analgesia of the hemithorax achieved by a combination of Pecs I and SAP block. Both patients were shown the case report and gave written permission for publication.
A 48-year-old woman weighing 67 kg (patient A) diagnosed with left-sided breast malignancy and a 35-year-old woman weighing 58 kg (patient B) with right-sided breast malignancy were scheduled for breast conservation surgery with dissection of the axillary nodes followed by reconstruction using a LD pedicle flap. The surgical plan was to harvest the LD flap as the first step of the surgery followed by a crescent incision in the superolateral quadrant of the breast to remove the tumor, and axillary dissection was to be done using the same incision. The LD flap was to be harvested using a transverse incision starting at the posterior axillary line at the level of the seventh rib and extending up to the tip of scapula. The surgical analgesia needed in this procedure was over the anterior, lateral, and part of the posterior wall of the ipsilateral chest. The choice of regional analgesia techniques was thoracic epidural, thoracic paravertebral, intrapleural, and a combination of PecsI and II blocks. We considered giving a Pecs I block along with a SAP block with the intention of providing analgesia to the ipsilateral chest wall along with blocking the plexus formed by the thoracodorsal nerve in the plane between the serratus anterior (SA) and LD. Informed consent was obtained from both patients for the blocks.
Induction of anesthesia was done in both cases by 2 μg kg−1 IV fentanyl, 2 mg kg−1 propofol, and 0.9 mg kg−1 rocuronium. The airway was secured with a properly placed endotracheal tube (7.0-mm internal diameter). Anesthesia was maintained with inhaled desflurane (1 minimum alveolar concentration) in air oxygen mixture with a 40% FIO2and muscle relaxation with IV infusion of atracurium 25 mg/hr. The patients’ lungs were ventilated to normocapnia by an anesthesia ventilator (PrimusTM, Drager, Germany). Paracetamol 1 g was infused IV after induction of general anesthesia. Ultrasound-guided Pecs I and modified SAP blocks were administered with the patients in supine position. Ten milliliters of 0.25% levobupivacaine was given in Pecs I block, whereas 20 mL of the same drug was given in the SAP block (technique described below). The incisions were made about 20 minutes after block administration.
Surgery lasted for 4.5 and 4.25 hours, respectively. Both patients did not require any supplemental opioid analgesic during the entire intraoperative period as assessed by hemodynamic status. At the end of surgery, the patients were tracheally extubated and sent to the postanesthesia care unit for observation for 1 hour and then transferred to the surgical ward. Postoperative pain intensity was assessed using the visual analog scale score on an hourly basis. A visual analog scale score of >3 was noted first on the 9th and 10th hour postoperatively in patients A and B, respectively. At this point, they were given 3 mg IV morphine followed by IV morphine patient-controlled analgesia (Graseby, Smith Medical ASD, Inc., St. Paul, MN) 1 mg/mL set to deliver on-demand bolus doses of 1 mg with a 5-minute lockout period with no background infusion. Both patients also received 1 g IV paracetamol every 6 hours. Patient A required 3 boluses of morphine from the patient-controlled analgesia pump on the first postoperative day and patient B only 1. When the patients were allowed oral intake, 1 g paracetamol orally was given every 6 hours for another 48 hours. Both patients were discharged from the hospital on the fifth postoperative day. Their overall experience with pain control was satisfactory.
Description of Ultrasound Technique
After cleaning the area with 2.5% chlorhexidine in alcohol solution, an initial scan was performed with a high-frequency (12 MHz) linear array ultrasound transducer (UST) (LogiqeTM, GE, Milwaukee, WI) to note the baseline anatomy. Pecs I block was administered at the midclavicular line in the infraclavicular area with the UST held transversely (in the coronal plane). For the SAP block, we decided to place the UST in the posterior axillary line to get a better view of the LD and SA. The operating table was tilted to the contralateral side, thus raising the hemithorax, facilitating the placement of the UST in the posterior axillary line. This also helped in moving the breast away from the site of injection. The UST was placed obliquely over the sixth rib (counted by tracing from the second rib and moving posterolaterally). The LD (superficial and posterior) and SA (deep and inferior) could then be identified (Fig. 2). The thoracodorsal artery was identified at the onset of the ultrasound scanning, and care was taken so that it was not damaged. A 20-G Tuohy needle was inserted in plane of the ultrasound beam from the anteromedial to posterolateral direction toward the posterior axillary line. The needle was advanced in plane until it reached the plane between the LD and SA. Placement of the needle tip was confirmed by injecting 2 mL saline and visualizing the spread of saline in the intended plane. After confirming negative aspiration, 20 mL 0.25% levobupivacaine was injected. The depth of the muscle plane was 3 cm, and the spread of local anesthetic agent was visualized in the ultrasound monitor (Figs. 3 and 4).
Breast cancer is the most common cancer affecting women, accounting for 31% of all new cancer cases in the female population.4,5 Breast cancer surgeries cause significant acute pain and may progress to chronic pain states in 25% to 60% of patients.6
Thoracic epidural block and ipsilateral thoracic paravertebral block have been used to provide analgesia for breast reconstruction surgeries.7–9 Pecs I block and subsequently Pecs II block have been described for providing analgesia for breast surgeries including lumpectomy, wide excisions, axillary clearances, sentinel node dissection, and several types of mastectomies. The target nerves are lateral branches of the intercostal nerves (T2–T6), long thoracic nerves of Bell, and intercostobrachial nerves apart from the 2 pectoral nerves.2 A recently published clinical study has shown the effectiveness of combined Pecs I and II blocks in breast surgeries.10
SAP block has been described in which local anesthetic is injected at the mid-axillary line at the level of the fifth rib either superficial or deep to the SA muscle. The intention is to block the thoracic intercostal nerves to provide complete analgesia of the lateral part of the chest,3 but the block is yet to be clinically validated. Although this block describes the blockade of the long thoracic nerve of Bell supplying the SA muscle, there has been no mention of blocking the thoracodorsal nerve supplying the LD muscle. The thoracodorsal nerve is the sole nerve that supplies the LD muscle and forms a plexus between SA and LD muscles.11 The cutaneous nerve supply of the posterolateral thoracic wall is from the lateral cutaneous branches of the intercostal nerves.12 A recent case report has shown SAP block to be useful for the treatment of postthoracotomy pain.13 We believed that injecting the local anesthetic solution in the plane between these 2 muscles would provide adequate analgesia in surgeries involving dissection of the LD muscle as in the cases mentioned earlier.
We moved the UST to the posterior axillary line and placed it obliquely over the sixth rib. This modification gave us a better view of both muscles compared with the placement originally described by Blanco et al.3 Placing the UST over the rib also provides protection against inadvertent pleural puncture. We believe that this more distal and lateral point of injection (compared with the original technique) helped us reach the thoracodoral nerve and its plexus lying beneath the LD, thus producing remarkable analgesia for the LD area.
Our report is an early intimation of the effectiveness of SAP block for breast reconstruction surgery. This modified SAP block technique requires further study. We are about to begin a prospective single-arm study with a large number of patients undergoing breast reconstruction surgeries. We are presenting this case report as an observation and encouraging other anesthesiologists to more formally investigate and validate the efficacy of this modified SAP block approach to pain management of breast reconstruction surgeries including LD flap reconstruction.
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