Ultrasound-guided Serratus Anterior Plane Block for Accelerated Partial Breast Irradiation using Multi-catheter Interstitial Brachytherapy Technique under Anesthesia in Breast Cancer Patients: A Case Series.

In early stages of breast cancer, breast conservation therapy (BCT) with lumpectomy and adjuvant irradiation is preferred. Accelerated partial breast irradiation (APBI) is considered as an alternative to whole breast irradiation. The reasons are it requires less number of irradiation fractions, shorter treatment time, and decreased size of irradiation. The procedure includes insertion of several brachycatheters, which is associated with significant pain in the postoperative period. We report case series of 8 patients of APBI where perioperative pain management was done using ultrasound (USG)-guided serratus anterior plane (SAP) block with catheter insertion. The catheter was placed between the serratus anterior muscle and external intercostal muscle. The drug used was 0.4 mL.kg-1 of 0.375% Ropivacaine with a maximum value of 30 mL. On the day of the procedure, all patients were given two boluses of ropivacaine 20 mL each at an interval of 6 h. From the next day onward, they received ropivacaine boluses on demand basis when Numerical Rating Scale (NRS) was >4. There were no complications during the procedure. None of the patients required extra fentanyl boluses intraoperatively. One patient did not have an SAP catheter inserted during primary insertion, as she failed to give consent for block. On repositioning of catheters, she experienced severe pain with a NRS of 8/10. After obtaining proper consent, SAP catheter was inserted and she had NRS of 1/10 postoperatively. 2/8 patients received rescue analgesics in the form of diclofenac. 7/8 SAP catheters were removed on day 5. Only one SAP catheter was removed accidentally on day 3. It was concluded that USG-guided SAP catheters are a novel, safe, and effective regional anesthesia technique for perioperative pain management in breast cancer surgeries undergoing APBI. Copyright:

INTRODUCTION

Breast cancer is common in females where surgical resection is considered as the primary mode of treatment. Usually, breast conservation therapy (BCT) with lumpectomy and adjuvant whole breast irradiation is preferred as a standard therapy for early-stage breast cancer. In recent times, accelerated partial breast irradiation (APBI) has gained popularity as an alternative to whole breast irradiation.[1] APBI requires lesser number of irradiations for a shorter treatment time where irradiation is exclusively delivered around the lumpectomy site.[1] The three different approaches for APBI are external beam (which includes 3D-conformal radiation therapy and intensity-modulated radiation therapy), interstitial brachytherapy using multi-catheter and balloon catheter and intraoperative radiation therapy.[2]

Of these, multi-catheter interstitial brachytherapy has been promising with good clinical outcome. It requires multiple insertions of ultrasound (USG)-guided brachy-catheters at the lumpectomy site which is usually done under general anesthesia. The catheters are inserted at an interval of 1-1.5 cm in and around the lumpectomy bed. The number of catheters to be inserted depends upon the size and shape of tumor bed.[3] APBI procedure is considered to be less traumatic; however, these catheters can be the source of acute postsurgical pain in the postoperative period.[4] Often some of the patient requires computed tomography (CT) scanning after the insertion and at times some of the catheters need repositioning to cover the tumor bed effectively.[3] Therefore, pain is significantly associated with insertion and repositioning of these catheters.

Optimal control of pain is important, as it may progress to chronic pain. It also leads to delayed discharge, various ill systemic effects, and causes immunomodulation which has a risk of cancer recurrence.

Regional anesthesia techniques are considered to be the best to manage acute postoperative pain and reduce incidences of chronic pain in such cases.[5] One of the recent USG-guided nerve blocks used to anesthetize hemithorax is the “Serratus anterior plane (SAP) block.” Recent literature supports the effectiveness of SAP block in the management of pain in breast surgery. There are two potential spaces surrounding the serratus anterior muscle. One is superficial SAP and other is deep SAP. In our patients, we have used deep SAP for drug administration. Thus, we report a case series of eight patients undergoing APBI, where the perioperative pain was managed with deep SAP block with catheter in situ in the postoperative period.

CASE DESCRIPTION OF EIGHT PATIENTS

Eight patients after the BCT requiring APBI were included. Each patient was offered a SAP block with catheter insertion as an option for pain control. Risks and benefits were discussed with the patient before the procedure. After attaching standard monitors and securing intravenous access, anesthesia was induced with intravenous (i. v.) fentanyl (2 μg.kg−1), propofol (1–2 mg.kg−1), and vecuronium (0.1 mg.kg−1) followed by insertion of I-gel depending on patient's weight. Anesthesia was maintained with sevoflurane to achieve a minimum alveolar concentration (MAC) of 0.8–1 in 40% oxygen.

A linear high frequency (6–13 MHz) USG probe (Sonosite M-Turbo, Sonosite Inc, Bothell, WA, USA) was used for the guidance of SAP block. After induction of anesthesia, ipsilateral arm was abducted to 90° with the patient in the supine position. A wedge was placed underneath the ipsilateral shoulder. Under all aseptic precautions, scanning was done over the midaxillary line in the transverse plane. The fifth rib was identified and marked for the needle insertion [Figure 1]. The skin was anesthetized with a small volume of local anesthetic. The structures were identified in three planes using USG [Figure 2]. The subcutaneous tissue, latissimus dorsi, and serratus anterior muscle in the superficial plane, the intercostal muscle in the intermediate plane and ribs, pleura, and lungs in the deep plane were identified and appreciated.

Figure 1

SAP block with a linear USG probe and needle in midaxillary plane at fifth intercostal space. SAP = Serratus anterior plane, USG = Ultrasound

Figure 2

Real-time image of SAP block. Hydro-dissection done with saline. SAP = Serratus anterior plane

Under USG guided with in-plane approach, a 18G echogenic block needle was inserted at an angle of 45° toward the fifth rib. The tip of the needle was placed between the serratus anterior and external intercostal muscle (deep SAP). 1–3 mL of saline was injected to confirm the correct placement of the needle [Figure 2]. After adequate hydro-dissection, 0.4 mL.kg−1 of 0.375% Ropivacaine with a maximum value of 30 mL was gradually injected after frequent aspiration. The local anesthetic appeared as an expanding anechoic stripe between fascial layers. The SAP catheter of 21 Gauze was inserted through the same needle where its tip was placed at the deep serratus plane. After final confirmation by USG, it was fixed there with precautions as shown in Figures 3 and 4.

Figure 3

Drug spread in SAP with catheter in situ. SAP = Serratus anterior plane

Figure 4

SAP catheter in situ for drug delivery in the postoperative period. SAP = Serratus anterior plane

The surgical procedure for brachycatheters placement was allowed. The procedure consisted of inserting plastic hollow brachytherapy catheters into the area under USG guidance. The catheters were placed at a distance of 1–2 cm in between. Usually, 2 or more planes were used with interplane distance of about 1–2 cm.

Vitals such as heart rate (HR), systolic and diastolic blood pressure (SBP and DBP), mean arterial pressure, and ECG were monitored every 5 min throughout the intraoperative period. In case of an increase in HR and/or blood pressure by >20%, intravenous fentanyl 0.5 μg.kg−1 was administered. Total intraoperative fentanyl consumption was recorded. All patients were shifted to the postanesthesia care unit (PACU) for further monitoring, observation, pain assessment, and rescue analgesia. The patient underwent CT-based Oncentra brachytherapy planning and the dose was delivered on a Microselectron high dose rate machine. The dose given was 34 Gray in 10 fractions twice daily at least 6 h apart. After the completion of treatment, the brachycatheters were removed and patients were discharged to home.

Pain assessment was done in the immediate postoperative period after shifting the patient to PACU at 0 h and thereafter at 1, 6, 12, 18, and 24 h and then twice daily till the removal of implant catheters. The assessment was done by an independent anesthesiologist not involved in the administration of block or intraoperative management of the patient using the Numerical Rating Scale (NRS 0-10). NRS was assessed at rest and on 90° abduction of the arm ipsilateral to the side of surgery. HR, SBP, and DBP have been assessed at the same time intervals. All patients received, i.v., acetaminophen 1 g every 6 h. On pain assessment, if NRS was ≥4, 20 mL of 0.2% ropivacaine was given as bolus through SAP catheter, as shown in Figure 3. The time to first analgesic request was noted. The pain was again reassessed half an hour after giving ropivacaine bolus and if still NRS ≥4, then rescue analgesia with i. v. diclofenac 1.5 mg.kg−1 (rounded off to nearest 50 mg or 75 mg) diluted with 100 mL normal saline was administered. The second rescue analgesic was intravenous fentanyl 0.5 μg.kg−1 in case pain was not controlled within a ½-h of administration of the diclofenac.

Demographic details and results of eight patients are shown in Table 1. There were no complications during the procedure. All patients were for primary catheter implants insertion except one patient who was for catheter repositioning. None of the patients required extra fentanyl boluses intraoperatively. All patients received two boluses of ropivacaine 20 mL dose 6 h apart on postoperative day 0. The next day onward they received ropivacaine boluses on the demand basis when NRS was > 4. One patient who had repositioning done did not have an SAP catheter inserted during primary insertion. She had an NRS of 8/10 during repositioning. SAP catheter was inserted and she had NRS of 1/10 postoperatively. 2/8 patients received rescue analgesics in the form of diclofenac. 7/8 SAP catheters were removed on day 5 after the sessions. Only one SAP catheter was removed accidentally on day 3.

Table 1

Patients for accelerated partial breast irradiation under serratus anterior plane blocks

Patient demographics (years)	Intraoperative rescue fentanyl requirement	Rescue analgesia needed	SAP boluses	SAP catheter removal	Time to first rescue analgesic
41/female	Nil	No	5	5th day	Not needed as patient had adequate analgesia
67/female	Nil	No	6	5th day	Not needed
50/female	Nil	No	5	5th day	Not needed
51/female	Nil	Yes (diclofenac 75 mg)	9	5th day	8 h after brachycatheter insertion
50/female	Nil	No	5	3rd day (accidental removal)	Not needed
33/female	Nil	No	6	5th day	Not needed
46/female (reposition)	Nil	Yes (diclofenac 75 mg)	8	5th day	12 h after brachycatheter insertion
63/female	Nil	No	6	5th day	Not needed

SAP=Serratus anterior plane

DISCUSSION

The perioperative use of regional anesthesia usually combined with general anesthesia has become a standard protocol in breast cancer surgery.[6] The thoracic paravertebral block and thoracic epidural anesthesia have been used to provide perioperative analgesia in breast surgery. However, both are associated with serious complication such as spinal hematoma, injury to neuraxial structures, and Horner's syndrome.[6] Pectoral nerve blocks (PECS) I and II and SAP block are new blocks and are considered to be a better alternative for regional anesthesia techniques for breast surgery.

USG-guided SAP block was first described by Blanco in 2013.[7] Anatomically, serratus anterior muscle arises from first nine ribs and covers posteriorly on scapula to form medial wall of axilla.[7] There are two potential spaces surrounding the serratus anterior muscle where branches of the intercostal nerves are present. The superficial and deep serratus plane. Injecting local anesthetics to either plane block the lateral cutaneous branches of thoracic intercostal nerves from T2 to T12, which provide effective analgesia to anterolateral chest wall.[8] Studies are there investigating the applications of spaces above (superior) or below (deep) the serratus anterior muscle. It seems that the SAP block is successful in both cases where it is used. The literature is limited to whether the superficial or deep block should be implemented.[7] However, in our study, we have used deep SAP blocks for analgesia.

Shi et al. compared the analgesic effects of 10, 20, and 30 mL ropivacaine for deep SAP block in breast surgery. They have found a volume of 20 mL ropivacaine to be appropriate.[9] Huang et al. compared three concentrations as 0.375%, 0.5%, and 0.75% of ropivacaine in SAP block. Block with 0.5% ropivacaine was found to be superior for postoperative analgesia in breast surgery.[10] However, in our study, the volume was decided on the basis of weight of patient, as 0.4 mL.kg−1 not exceeding the volume of 30 mL and a concentration of 0.375% ropivacaine was found appropriate providing optimal analgesia in the postoperative period.

The use of SAP catheters is a relatively new technique and reports detailing the optimal local anaesthetic dosing for SAP catheter boluses and infusions for breast cancer surgery are few. In a randomized control trial by Xiao et al. in 84 breast cancer patients who underwent modified radical mastectomy, the combination of anterior serratus plane block and general anesthesia with patient-controlled anterior serratus plane block was found to be superior than control group without SAP catheter.[11] Madabushi et al. involved an SAP catheter for a patient with postthoracotomy pain.[12] In that case report, the clinicians obtained adequate analgesia without adverse effects with an initial injection of 6 mL lidocaine 1% and a continuous infusion of 0.1% bupivacaine with 1 μg.mL−1 fentanyl at 7 mL.h−1.[13] In the second case report by Kunhabdulla et al., the authors have obtained adequate analgesia in rib fractures with an initial injection of 20 mL bupivacaine 0.125% followed by a continuous infusion of 0.0625% bupivacaine with 1 μg.mL−1 fentanyl at 12 mL.h−1.[14] However, in our studies, we have not used continuous infusion, 0.4 mL.kg−1 of 0.375% ropivacaine with a maximum value of 30 mL was administered as bolus through SAP catheter on having pain with NRS >4.

Lack of randomization with small sample size was the important limitations to our study. However, the SAP block provided an optimal level of analgesia with lesser need of rescue analgesia. Advantages such as ease of catheter insertion under USG guidance, ability to be performed safely after induction of general anesthesia, safe even in patient on anticoagulation therapy, and avoidance of sympathetic blockade make SAP block a safe and effective regional anesthesia for breast cancer surgery.

CONCLUSION

USG-guided SAP catheters are a novel, safe, and effective regional anesthesia technique for perioperative pain management in breast cancer surgeries undergoing APBI. Further research is required including larger sample size in patients undergoing APBI under SAP block with catheter in situ.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.