Background: The dermatomal area supplied by the intercostobrachial nerve (ICBN) and medial cutaneous nerve of the arm (MCNA) are not reliably blocked by currently used approaches of the brachial plexus block. This feasibility study is aimed at determining the efficacy of the novel ultrasound-guided supraaxillary block. Patients and Methods: This prospective, observational study was conducted on patients undergoing surgeries around the elbow. Sixty American Society of Anesthesiologists Physical Status I and II patients aged between 18 and 60 years were recruited. The supraaxillary block was performed in addition to the subclavian perivascular brachial plexus block in all patients. The local anesthetic (LA) mixture was prepared with 10 ml of 2% lignocaine-adrenaline, 15 ml of 0.5% bupivacaine, and 10 ml of 0.9% saline. 20 ml of the LA solution was used for supraclavicular block, and 15 ml was injected in the supra-axillary area. Results: The onset of sensory and motor block for the subclavian perivascular block was 4.30 ± 0.891 and 8.12 ± 0.872 min, respectively. The onset of the supra-axillary block was 9.50 ± 0.707 min. Only 6.67% of the patients needed additional local infiltration. Conclusion: Ultrasound-guided single-shot injection of LA in the supra-axillary area as a supplement to subclavian perivascular brachial plexus block achieved complete anesthesia for surgical procedures around the elbow by blocking the ICBN and MCNA.
Keywords: Intercostobrachial nerve, medial cutaneous nerve, peripheral nerve block, regional anesthesia, upper limb blocks
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Sekar C, Sheela PV, Goel VK, Mistry T, Senthilkumar B, Sonawane K. Ultrasound-guided supra-axillary block as a supplement to subclavian perivascular brachial plexus block for surgeries around the elbow: A prospective feasibility study. Bali J Anaesthesiol [Epub ahead of print] [cited 2021 Apr 22]. Available from: https://www.bjoaonline.com/preprintarticle.asp?id=290533
| Introduction|| |
Upper limb fractures can result in considerable disability, especially if not treated properly. Fractures around the elbow and forearm pose a significant challenge to orthopedic surgeons and traumatologists due to the high incidence of comminution, proximity to vital nerves and vessels, and scant soft-tissue coverage. As anesthesiologist, we can contribute to better results by providing reliable surgical anesthesia and excellent postoperative analgesia for early rehabilitation.
Ultrasound-guided subclavian perivascular brachial plexus block is the preferred regional anesthesia technique for surgeries around the elbow. However, areas supplied by the intercostobrachial nerve (ICBN) and medial cutaneous nerve of the arm (MCNA) are not reliably anesthetized by any of the approaches to brachial plexus block. This is especially important in surgeries around the elbow where the incision site and tourniquet application involve the spared areas. This necessitates the use of additional local anesthetic (LA) infiltration, opioids, or conversion to general anesthesia (GA). LA infiltration needs multiple punctures, causing more pain; moreover, it may not always give a satisfactory result. To overcome this, we chose a novel ultrasound-guided supra-axillary block. This approach will allow the direct visualization of a group of four nerves: the ulnar nerve (C8, T1), MCNA (C8, T1), ICBN (T2), and the nerve to latissimus dorsi (NLD) or thoracodorsal nerve (C5–7). A single injection of LA in this area gives an excellent sensory blockade for surgeries around the elbow.
The primary endpoint of this feasibility study was to determine the success rate of the supraaxillary block. We hypothesized that ultrasound-guided supra-axillary block would provide complete anesthesia in the entire posteromedial and anteromedial surface of the arm (the areas supplied by ICBN and MCNA) for surgeries around the elbow.
| Patients and Methods|| |
This single-blind, single-arm, prospective, observational study was conducted from September to October 2018 at a tertiary orthopedic hospital after approval from our Institutional Ethical Committee and review board. The study was registered prospectively with the Clinical Trials Registry of India (CTRI/2018/08/015529). Sixty patients of either sex in the age group of 18–60 years, belonging to the American Society of Anesthesiologists Physical Status I and II, and undergoing surgeries around the elbow were included in the study pool. Patients with pregnancy, known hypersensitivity to LA, emergency surgery, uncontrolled systemic diseases, any pathology, deformity, or any history of previous surgical intervention of the supraclavicular area were excluded from the study.
After a thorough pre-anesthetic check-up, patients satisfying the eligibility criteria were selected. Written informed consent was obtained from each of the 60 enrolled patients for participation in the study. On arrival to the preoperative room, all patients were monitored for baseline parameters such as continuous electrocardiogram, heart rate, noninvasive blood pressure, respiratory rate, and peripheral oxygen saturation. Intravenous access was secured with a suitable cannula, and an infusion of Ringer's lactate was started.
Ultrasound-guided subclavian perivascular brachial plexus block was performed under all aseptic precautions in every patient through the parasagittal out-of-plane approach. Following negative aspiration, a 20 ml of LA mixture (10 ml 2% lignocaine-adrenaline, 15 ml 0.5% bupivacaine, and 10 ml 0.9% saline) was injected. Patients were evaluated for the onset of the sensory block every minute after the completion of injection for 20 min. The sensory block was assessed with pinprick sensation in the distribution of median, radial, ulnar, and musculocutaneous nerves.
The onset time of the sensory block was taken as the time from injection of LA into the brachial plexus to obtunding of pinprick sensation (Grade 0 = sharp pin sensation, Grade 1 = dull sensation felt, and Grade 2 = no sensation felt). Motor blockade was assessed using the Modified Bromage scale for upper extremities. The onset of motor block was defined as the time from injection to motor paralysis equivalent to Bromage score 2.
In the event of sensory perception (cold sensation) over the areas supplied by ICBN and MCNA, we performed the supraaxillary block in addition to the supraclavicular block. The onset time for the supraaxillary block was defined as the time interval between the injection of LA and the absence of pinprick sensation over the area supplied by ICBN and MCNA. A successful block was defined as one requiring no supplemental LA intraoperatively or no conversion to GA. Patients with inadequate dermatomal block received supplemental LA infiltration (10 ml of 1% lignocaine-adrenaline solution). All patients were observed for any symptoms of LA systemic toxicity, pneumothorax, hematoma, and neuropathy. All the blocks were performed by a single experienced anesthesiologist (CS). The anesthesiologist who was not aware of the performance of the supraaxillary block was asked to assess the effect and onset.
The position of the patient for the supraaxillary block was supine. Head was rotated towards the opposite side with the ipsilateral arm abducted to 110°, externally rotated, flexed at the elbow, and elevated above the level of the head. This positioning should be done only after performing the subclavian perivascular block to make the patient more comfortable [Figure 1] and [Figure 2]. Ultrasound-guided supraaxillary block was performed at a higher level in the axillary region where four nerves (ulnar nerve, MCNA, ICBN, and NLD) are visualized as a bunch of grapes inferior to the axillary artery, just at the lateral border of pectoralis major muscle [Figure 3].
|Figure 1: Relationship of nerves with axillary artery A: Axillary artery, MCNA: Medial cutaneous nerve of arm, UN: Ulnar Nerve, NLD: Nerve to latissimus dorsi, ICBN: Intercostobrachial nerve|
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|Figure 3: Schematic diagram of sonoanatomy PM: Pectoralis major muscle, A: Axillary artery, V: Axillary vein, N: Nerves as bunch of grapes, S: Superior or cranial, I: Inferior or caudal|
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Scanning of the supra-axillary area can be done by two different approaches. In direct approach, if the axillary triangle is mirror-imaged on to the medial side of the axilla, the apex of the triangle will represent the point of injection. The same point can be achieved by keeping the transducer vertically along the lateral border of the pectoralis major muscle [Figure 4]a and [Figure 4]b. In indirect approach, the axillary artery is traced towards the apex of axilla by moving the probe medially, starting from axillary fossa, As we cross the shoulder joint, we will see a bunch of grapes lying inferior to the artery, which represents the nerves [Figure 5]. We used a 15 ml of the LA mixture as axilla contains loose areolar tissue.
|Figure 4: Position of ultrasound transducer for supra-axillary block (a) lateral border of pectoralis major muscle (b) position of linear probe|
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|Figure 5: Scanning of supra-axillary area PM: Pectoralis major muscle, A: Axillary artery, V: Axillary vein, N: Nerves (area of local anesthetic injection)|
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Statistical analyses were performed using the Microsoft Excel 2016 for Windows 10 (Microsoft, Redmond, WA, USA). Dichotomous variables were expressed as frequency or percentage. Continuous variables were expressed as mean ± standard deviation (SD). All study variables were described by using appropriate descriptive statistical methods such as frequencies, percentages, mean, SD, minimum and maximum values.
| Results|| |
A total of sixty patients were recruited in this prospective analytical study, and none were excluded from the final analysis. The demographic profile of the patients and operative details are depicted in [Table 1] and [Table 2]. The onset of sensory and motor block for the subclavian perivascular block was 4.30 ± 0.891 and 8.12 ± 0.872 min, respectively. Moreover, the onset of the supra-axillary block was 9.50 ± 0.707 min [Table 3].
Only four patients needed a supplementary LA infiltration upon the failure of the block, and none of the patients required GA following a failed block. We did not notice any complications or side effects related to the supraaxillary block.
| Discussion|| |
In this prospective study, ultrasound-guided supra-axillary block provided anesthesia in the posteromedial and anteromedial surface of the arm (the areas supplied by ICBN and MCNA) for surgeries around the elbow. Along with subclavian perivascular block, it was possible to achieve complete anesthesia for surgeries around the elbow except in four patients.
The ICBN originates from the second intercostal nerve. MCNA is an important intermediary branch of the medial cord, which joins with the smaller ICBN to innervate the skin over the upper half of the posterior and medial aspect of the arm [Figure 1]. The size of these two nerves is inversely proportional to each other. Cadaver study reported a 90% incidence of communication between these two cutaneous nerves. Sometimes, ICBN is also reinforced by a branch from the third intercostal nerve. All these nerves cannot be blocked by conventional approaches to brachial plexus block. Hence, it is approached at the point where we block these nerves after the link with T3, ensuring the completeness of the block.
Blockade of ICBN and MCNA is usually achieved by multiple injections of LA into the subcutaneous plane above the muscle fascia by inverted U-shaped or T-shaped infiltration. However, infiltration sometimes does not provide complete anesthesia and may require additional touch-up blocks by the surgeons in the operating room. As a potential solution to this, we put forward the unique supra-axillary block.
Various studies have reported the importance of blocking ICBN and MCNA separately to achieve complete anesthesia over the inner aspect of the axilla up to the elbow., According to the literature, 87% and 77% blockade of ICBN are reported in lateral and medial techniques of the infraclavicular block, respectively. Ultrasound-guided cadaveric dye study in the subpectoral intercostal plane has also been described to anaesthetize T2 and T3 selectively. In our study, we describe the novel supra-axillary approach that allows the blockade of the two nerves concurrently using a single shot of LA. The need for a single injection and visualization of nerves are the advantages of the supra-axillary block over LA infiltration.
All the patients in our study had intact cold sensation after supraclavicular block, in the dermatomes supplied by ICBN and MCNA and required an additional supra-axillary block. Only 4 (6.7%) patients required an additional LA infiltration following the failure of the block. This could be due to the presence of septa in the area and possible anatomical variations. None of the participants required conversion to GA following the failure of the block. Because of ultrasound guidance and precise technique, the incidence of complications such as pneumothorax, Horner's syndrome, vascular puncture, recurrent laryngeal nerve or phrenic nerve palsy, and systemic toxicity of LA were not observed in our study.
There are concerns related to the intravascular injection of LA. This area is close to the axillary artery and contains small vessels. Hence, always aspirate before injection and after every 3–5 ml injection of LA. It is also important that access to injectable lipid emulsion should be easily available in case of LA toxicity.
Our study has a few limitations. A comparison of this technique with subcutaneous LA infiltration has not been studied since it was target-oriented towards two nerves – MCNA and ICBN. Since we describe a novel technique, large sample size and multiple studies are required for further confirmation of the results of our study. A dose determination study is also required to quantify the median effective dose of LA for this technique. The satisfaction level from both patients and surgeons were not evaluated.
| Conclusion|| |
We conclude that along with the subclavian perivascular brachial plexus block, the ultrasound-guided supra-axillary block will enable the blockade of ICBN and MCNA and will help to achieve reliable surgical anesthesia for procedures around the elbow.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understand that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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G 304, Jainam Planet, Tatibandh, Raipur - 492 099, Chhattisgarh
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3]