Axillary serratus anterior plane block as a novel approach to anesthetizing the intercostobrachial nerve for upper arm arteriovenous fistula creation surgery -three case reports-
Article information
Abstract
Background
Current regional anesthesia techniques used to anesthetize the intercostobrachial nerve (ICBN) for upper arm surgery either lack reliability or have increased procedural risks. Safer and more reliable regional anesthetic techniques are required to block the ICBN effectively. Here, we introduce a novel “axillary serratus anterior plane (A-SAP) block” for anesthetizing the ICBN to allow surgical anesthesia for upper arm arteriovenous fistula (UA-AVF) creation.
Case
We present 3 cases involving a 79-year-old Chinese male, a 73-year-old Malay female, and a 38-year-old Chinese male, in which the A-SAP block was utilized in UA-AVF creation surgeries. In all 3 cases, the A-SAP block was performed in combination with a supraclavicular brachial plexus block. None of the patients required local anesthetic supplementation intraoperatively.
Conclusions
The A-SAP block reliably and safely anesthetized the ICBN for UA-AVF creation surgery and is a reliable alternative to higher-risk block techniques, such as paravertebral block or neuraxial block.
Performing regional anesthesia in the upper arm can be technically challenging. The upper arm is innervated by the axillary, radial, musculocutaneous, medial brachial cutaneous, medial antebrachial cutaneous, and intercostobrachial nerves (ICBN). Most of these nerves can be anesthetized by performing a brachial plexus block. The exceptions are the medial brachial cutaneous nerve, which may be spared when the brachial plexus block is performed at the axillary level, and the ICBN, which originates outside the brachial plexus. Existing techniques for anesthetizing the ICBN such as the block of the ICBN at the level of the axillary crease and the pectoserratus plane block (PECS II) may not be entirely reliable [1,2].
In this case series, we introduce a superior regional anesthesia technique, which we refer to as the “axillary serratus anterior plane (A-SAP) block,” for anesthetizing the ICBN, to allow surgical anesthesia for upper arm arteriovenous fistula (UA-AVF) creation. This article adhered to the CAse REport guidelines for case reports. All patients provided written consent for publication.
Case Reports
Block description
The A-SAP block was administered with the patients in the supine position, with the ipsilateral shoulder abducted 90° and externally rotated. A Sonosite PX ultrasound machine (Fujifilm) was used, and a linear 15–4 MHz ultrasound transducer was placed at the mid-clavicular line, immediately caudal to the clavicle. The 2nd rib was first identified deep to the axillary vein. The probe was slid caudally to identify the 3rd rib, and then laterally towards the anterior axillary line, while keeping the 2nd intercostal space in view. The caudal end of the ultrasound probe was then rotated laterally, with the cranial end pivoting on the 2nd rib to obtain a transverse orientation, as shown in Fig. 1. The pectoralis major, pectoralis minor, serratus anterior, intercostal muscles, 2nd rib, 3rd rib, pleura, and axillary compartments could be seen in this view, as shown in Fig. 2.
Illustration of the ultrasound probe position for the axillary serratus anterior plane (A-SAP) block. A linear 15–4 MHz ultrasound transducer was placed between the 2nd and the 3rd rib, between the mid-clavicular line and anterior axillary line, in a transverse position.
A typical ultrasound image obtained while administering the axillary serratus anterior plane (A-SAP) block. The pectoralis major muscle, pectoralis minor muscle, serratus anterior muscle, 2nd rib, 3rd rib, intercostal muscles, pleura, and the axillary compartment is labelled.
A 21-gauge Sonoplex® STIM single-shot nerve block needle (PAJUNK®) was used to inject local anesthetic (LA) between the fascial plane above the serratus anterior muscle, as demonstrated in Supplementary Video 1. Using an in-plane approach, the block needle was inserted just medial to the ultrasound probe on the skin and was directed in a medial-to-lateral direction to reach the fascial plane between the pectoralis minor and serratus anterior muscles. The fascial plane was hydrodissected towards the axillary compartment, lifting it off the serratus anterior muscle, where the LA was then deposited.
Ten minutes after completion of the block, the effectiveness of the block was tested using a skin-prick test, before commencing the surgery.
Case 1
A 79-year-old Chinese male (height: 163 cm, weight: 66.4 kg, body mass index [BMI]: 25 kg/m2) was electively admitted for left arm brachiobasilic AVF superficialization with ligation of a previous brachiocephalic AVF. He was allergic to paracetamol and had a medical history of hypertension, type 2 diabetes mellitus, hyperlipidemia, left nephrectomy for left kidney renal cell carcinoma, and end-stage renal failure (ESRF). He underwent regular dialysis via a right-sided internal jugular vein tunneled hemodialysis catheter. He also had a history of non-ST-elevated myocardial infarction with extensive triple vessel disease that had not been revascularized, after discussion with the patient regarding the elevated risk associated with open-heart surgery. On echocardiographic assessment, he was found to have a moderately dilated left ventricle and low-normal left ventricular systolic function, with an ejection fraction (LVEF) of 54% and the presence of regional wall motion abnormalities. The patient was started on long-term aspirin therapy. He was admitted 1 day before his elective surgery to undergo preoperative dialysis.
The surgery was performed under regional anesthesia. An ultrasound-guided supraclavicular brachial plexus block was performed using 0.3% levobupivacaine (20 ml), and the A-SAP block was performed using 0.15% levobupivacaine (20 ml). Complete sensory loss was noted over the entire upper limb and axillary region, along with significant but incomplete motor function loss. Prior to surgical incision, the patient reported no sensation of a noxious stimulus administered at the surgical site by using surgical forceps. Surgery was performed using a medial longitudinal incision of the arm and was completed without the need for LA supplementation. At incision, he reported a pain score of 0 out of 10. He was only mildly sedated with propofol target-controlled infusion of 0.5 μg/ml intraoperatively. Following surgery, the patient was reviewed in the post-anesthesia care unit (PACU) by a block proceduralist, who claimed that he “slept comfortably throughout the surgery, without noticing that the surgery had been completed.” The postoperative precautions related to his blocked arm were reiterated, and his calm and attentive acknowledgment of these instructions provided objective evidence of his satisfaction with the care provided. The patient was reviewed by the acute pain service (APS) team on postoperative day (POD) 1. The block receded completely with no observed complications, such as pneumothorax or hematoma.
Case 2
A 73-year-old Malay female (height: 151 cm, weight: 52.4 kg, BMI: 23 kg/m2) was electively admitted for left arm brachioaxillary graft creation. She had a medical history of hypertension, type 2 diabetes mellitus, hyperlipidemia, previous stroke with good functional recovery, non-ischemic cardiomyopathy with an LVEF of 44%, and ESRF. She underwent regular dialysis via a left-sided internal jugular vein tunneled hemodialysis catheter. She was admitted 1 day before her elective surgery to undergo preoperative dialysis.
The surgery was performed under regional anesthesia. An ultrasound-guided supraclavicular brachial plexus block was performed using 0.5% ropivacaine (20 ml), and the A-SAP block was performed using 0.2% ropivacaine (20 ml). Complete motor and sensory losses were observed over the entire upper limb, including the axillary region. Prior to surgical incision, the patient reported having no sensation of a noxious stimulus delivered at the surgical site by using surgical forceps. Surgery was performed using a medial longitudinal incision of the arm and was completed without the need for LA supplementation. The patient reported a pain score of 0 out of 10 at the time of surgical incision. She was administered mild sedation with a propofol target-controlled infusion of 0.5 μg/ml intraoperatively. Following surgery, the patient was reviewed in the ward by a block proceduralist, while her daughter was at her bedside. The patient reported that, while the needle puncture for the block was mildly unpleasant, she experienced “no pain at all” during the procedure. In addition, she demonstrated satisfaction with the care received in a calm manner and acknowledged the prompt and clear communication from the team. Her daughter extended her gratitude to the medical team for their support in keeping her mother safe throughout the surgery. She was reviewed by the APS team on POD 1. The block receded completely without any observed complications.
Case 3
A 38-year-old Chinese male (height: 154 cm, weight: 53.4 kg, BMI: 22.5 kg/m2) was electively admitted for left arm brachiobasilic AVF transposition 4 months after basilic vein arterialization had been performed. He had a medical history of type 2 diabetes mellitus and had ESRF. He underwent regular dialysis via a right-sided internal jugular vein tunneled hemodialysis catheter. He was admitted 1 day before his elective surgery to undergo preoperative dialysis.
The surgery was performed under regional anesthesia. An ultrasound-guided supraclavicular brachial plexus block was performed using ropivacaine 0.5% (25 ml), and the A-SAP block was performed using ropivacaine 0.25% (15 ml). Complete sensory loss was noted over the entire upper limb and axillary region, along with significant but incomplete motor function loss. Prior to surgical incision, the patient reported experiencing no sensation of a noxious stimulus delivered at the surgical site by using surgical forceps. Surgery was performed using a medial longitudinal incision of the arm and was completed without the need for LA supplementation. The patient reported a pain score of 0 out of 10 at the time of surgical incision. He was given only mild sedation with target-controlled infusion of 1 μg/ml propofol and dexmedetomidine at a loading dose of 0.5 μg/kg, with 0.2 μg/kg/h maintenance infusion intraoperatively. Following surgery, the patient was reviewed in the PACU by a block proceduralist and was asked about his experience with the block. He stated that the supraclavicular brachial plexus block was moderately uncomfortable, whereas the A-SAP block was mildly uncomfortable; however, both were tolerable. After the block, his arm felt numb and heavy, and he did not feel the surgical excision at all. He reported that he had experienced restful sleep throughout the surgery and described an overall positive perioperative experience. The APS team reviewed the patient on POD 1. The block receded completely without any observed complications. The patient was satisfied with the experience of the block and the overall anesthetic care.
Discussion
Patients undergoing UA-AVF creation often present with preexisting comorbidities that increase their anesthetic risk; thus, avoiding general anesthesia may benefit these patients. In cases where avoidance of general anesthesia is highly desirable, some patients may undergo a paravertebral block to anesthetize the ICBN reliably, but this poses increased risks [3]. Consequently, safer and more reliable regional anesthetic techniques are required to block the ICBN effectively. In this case series, we demonstrated that our proposed A-SAP block can reliably anesthetize the ICBN for UA-AVF creation surgery and is a reliable alternative to higher-risk block techniques, such as paravertebral or neuraxial blocks.
Although significant anatomical variants of the ICBN exist, the nerve originates from the T1, T2, and T3 nerve roots in most patients, with a rare contribution from the T4 nerve root [4,5]. The nerve exits the intercostal space, pierces the intercostal muscles and the serratus anterior muscle to enter the axillary compartment. Its axillary branches innervate the axilla and its terminal branches innervate the medial arm [4]. The terminal branches travel outside of the brachial fascia and descend along the medial side of the arm [6]. Anesthetizing both the axillary and terminal branches may be required for surgical creation of a UA-AVF.
ICBN and PECS II blocks are commonly used to anesthetize the ICBN for medial arm surgery. The ultrasound-guided ICBN block described by Magazzeni et al. [7] in 2018 showed effective coverage of the upper arm for tourniquet pain. The PECS II block, described by Blanco et al. [8] in 2012, was designed to anesthetize the lateral cutaneous branches of the intercostal nerve between T2 and T6. However, a study by Quek et al. [2] in 2018 showed that, despite adding the PECS II block to the supraclavicular brachial plexus block, 33.3% of patients undergoing UA-AVF creation required LA supplementation. Another study by Eskandr et al. [1] compared the use of supraclavicular brachial plexus block combined with ultrasound-guided PECS II or ICBN block for UA-AVF creation and revealed that 30% and 20% of patients required further LA supplementation, respectively. This may be explained by the findings of a cadaveric dye study by Samerchua et al. [5], who studied the spread of LA in ultrasound-guided ICBN and PECS II blocks. According to them, after ultrasound-guided ICBN block, 100% deep staining of the terminal branch of the ICBN was observed; however, only faint or no staining of the axillary branch of the ICBN was observed in 42.9% and 57.1% of cases, respectively. The lack of proximal spread and coverage of the axillary branches of the ICBN by the LA may have contributed to the need for LA supplementation in UA-AVF creation surgery where the incisions are extended more proximally. In addition, the PECS II block resulted in deep staining of the T1 ICBN in 100% of the cadavers; however, deep staining was observed in only 85.7% of the T2 ICBN and 0% of the T3 ICBN. The T2 ICBN showed faint staining in 14.3% of cases, the T3 ICBN showed faint staining in 50% of cases, and no staining was observed in 50% of the injections. The lack of reliable staining for T2 and T3 ICBN may explain the unreliability of this block in UA-AVF creation surgery. Direct identification of the ICBN has been described; however, this technique may be limited by the anatomical variability of the ICBN, access to high-resolution ultrasound, and potential challenges in patients with obesity [9].
Another block that may anesthetize the ICBN is the serratus anterior plane (SAP) block described by Blanco et al. [10] in 2013. This block is performed at the level of the 5th–6th rib, in the mid-axillary line, either between the serratus anterior muscle and the latissimus dorsi muscle, known as the superficial SAP block, or between the serratus anterior muscle and the intercostal muscle, known as the deep SAP block. A few cadaveric studies have investigated the spread of the SAP block. Biswas et al. [11] compared the dye spread in both superficial and deep SAP blocks performed with a cephalad to caudal advanced needle, with 20 ml of dye administered at the level of the 5th rib at the mid-axillary line, with or without an additional 20 ml of dye administered at the level of 3rd rib at the anterior axillary line. The study showed minimal differences in dye spread between the superficial and deep SAP blocks. The spread of the dye was more pronounced when two injections, with a total of 40 ml of dye, were administered; however, the dye only reached the axilla in 66.6% of cases. Another cadaveric dye study performed by Kunigo et al. [12] used the SAP block at the level of the 4th rib on the mid-axillary line, but inserted the needle in the caudal to cephalad direction. They showed better dye spread in the axillary compartment, with 100% coverage of T3 and T4 intercostal nerves with only 20 ml of dye. However, dye spread to the T2 intercostal nerves was seen in only 33.3% of cases. This proportion increased to 100% when 40 ml of the dye was used.
We postulated that, although the block was delivered in the same plane, the location and direction of the injection will significantly affect dye spread, and that LA spread to the axillary region will be enhanced if the injection is performed nearer to the 2nd and 3rd rib, with the injection directed medial–laterally, which we have termed the A-SAP block. This is similar to the technique described by Seidel et al. [13] in 2017, who showed that 20 ml of methylene blue covered at least two intercostal interspaces (T2–T3), with spread restricted by the axillary fascia. Initially, our goal was to direct the needle from the inferomedial to the superolateral direction, and from the 3rd rib to the 2nd rib, to target the axillary region better. However, this approach is hindered by the pectoralis major muscle in some patients, which becomes more prominent in the shoulder-abducted position, making sonographic visualization of the area challenging. Therefore, we adopted a transverse needle orientation to overcome this limitation. In addition, no cadaveric or minimum volume studies are available to assist in determining the LA volume required to achieve an effective A-SAP block. We postulate that the volume requirement will be less than that for the PECS II block because the needle placement is more directed towards the axilla. We achieved a successful A-SAP block with an LA as low as 15 ml. Further studies should delineate the minimal volume of LA required for the A-SAP block.
In our case series, we demonstrated that the A-SAP block can provide anesthesia for UA-AVF creation surgery. In our clinical practice, we performed this block in > 20 patients undergoing UA-AVF creation surgery, none of whom required LA supplementation, and in none of whom complications were observed. Nevertheless, additional research is needed to confirm its reliability and safety as compared to the ultrasound-guided ICBN or PECS II blocks.
In conclusion, we have described the A-SAP block as a safe and reliable regional anesthesia technique for blocking the ICBN in surgeries involving the medial arm. Further studies are required to validate the reliability of this method.
Notes
Funding
None.
Conflicts of Interest
No potential conflict of interest relevant to this article was reported.
Data Availability
Data sharing is not applicable to this article as no datasets were generated or analyzed during the current study.
Author Contributions
Chi Ho Chan (Conceptualization; Investigation; Methodology; Project administration; Validation; Writing – original draft; Writing – review & editing)
Jia Yin Lim (Conceptualization; Investigation; Methodology; Validation; Writing – review & editing)
Abey M.V. Mathews (Conceptualization; Investigation; Methodology; Validation; Writing – review & editing)
Supplementary Material
Video demonstrating administration of the axillary serratus anterior plane (A-SAP) block.