Regional anesthesia has gained widespread acceptance in modern anesthetic practice due to its proven advantages over general anesthesia, particularly in surgeries involving the extremities. Peripheral nerve blocks provide excellent intraoperative anesthesia and prolonged postoperative analgesia, reduce perioperative opioid consumption, attenuate the stress response to surgery, and are associated with fewer systemic complications. These benefits are especially relevant in elderly patients and those with significant comorbidities undergoing upper limb surgeries.[1] Among the various brachial plexus block techniques, the supraclavicular brachial plexus block (SCBPB) is regarded as one of the most effective approaches for anesthesia of the upper limb distal to the shoulder. Owing to the compact arrangement of the brachial plexus trunks at the supraclavicular level, this block produces a rapid onset, dense sensory and motor blockade, earning it the description “spinal anesthesia of the arm.” It is particularly suitable for surgeries involving the arm, forearm, and hand.[2] Traditional landmark-based supraclavicular approaches were historically associated with complications such as pneumothorax, vascular puncture, and nerve injury. The introduction of nerve stimulators improved block accuracy; however, the real transformation in regional anesthesia practice occurred with the incorporation of ultrasound guidance. Ultrasound allows direct visualization of neural structures, surrounding vessels, pleura, and needle trajectory, thereby improving block success rates, reducing block performance time, lowering the volume of local anesthetic required, and significantly decreasing complication rates.[3] Multiple ultrasound-guided approaches to the supraclavicular brachial plexus have been described. The lateral approach targets the distal trunks or proximal divisions of the brachial plexus and is commonly performed using an in-plane needle technique. While effective, this approach may require longer block performance time and careful needle manipulation due to the proximity of the pleura and subclavian vessels.[4] The subclavian perivascular approach is a modification of the supraclavicular technique in which the brachial plexus trunks are approached as they pass over the first rib, posterior to the subclavian artery, within a common fascial sheath. At this level, the plexus is maximally compact, allowing effective blockade with a single injection and potentially shorter performance time. The presence of the first rib beneath the plexus also serves as a protective barrier against pleural puncture, enhancing procedural safety when performed under ultrasound guidance.[5] AIM To compare the subclavian perivascular approach with the lateral approach of supraclavicular brachial plexus block for below midarm surgeries under ultrasound guidance. OBJECTIVES 1. To compare the block performance time between the subclavian perivascular and lateral approaches of supraclavicular brachial plexus block. 2. To assess and compare the quality of sensory blockade produced by both approaches. 3. To evaluate and compare the incidence of procedure-related complications associated with the two techniques.

Source of Data Data were collected from adult patients undergoing elective below midarm surgeries under supraclavicular brachial plexus block in a tertiary care teaching hospital. Study Design This study was conducted as a hospital-based observational comparative study. Study Location The study was carried out in the Department of Anaesthesiology at a tertiary care centre. Study Duration The study was conducted over a defined study period as per institutional approval. Sample Size A total of 110 patients were included and divided into two groups: • Subclavian perivascular approach group: 55 patients • Lateral approach group: 55 patients Inclusion Criteria • Patients aged 18–65 years • ASA physical status I and II • Patients scheduled for elective below midarm surgeries • Patients providing written informed consent Exclusion Criteria • Patient refusal • Allergy to local anesthetic agents • Infection at the block site • Coagulopathy or bleeding disorders • Pre-existing neurological deficits in the operative limb • Severe respiratory disease • BMI more than 30 • Pregnancy Procedure and Methodology After pre-anesthetic evaluation and obtaining informed consent, patients were shifted to the operating room and standard monitors were applied. Intravenous access was secured. Under strict aseptic precautions, ultrasound-guided supraclavicular brachial plexus block was performed. Patients in the subclavian perivascular group received the block using a modified parasagittal ultrasound approach, targeting the brachial plexus trunks posterior to the subclavian artery at the level of the first rib. Patients in the lateral approach group received the block using the ultrasound-guided lateral supraclavicular technique. In both groups, a total of 20 ml of local anesthetic solution (equal mixture of lignocaine with adrenaline and bupivacaine) was injected after negative aspiration. Block performance time was recorded from probe placement to completion of injection. Sensory block onset, time to complete sensory blockade, and duration of analgesia were assessed using standard clinical methods. Sample Processing Clinical observations were recorded in a pre-designed proforma and compiled into a master chart for analysis. Statistical Methods Data were entered into Microsoft Excel and analyzed using appropriate statistical software. Continuous variables were expressed as mean ± standard deviation and compared using Student’s t-test. Categorical variables were expressed as frequencies and percentages and analyzed using Chi-square test. A p-value <0.05 was considered statistically significant. Data Collection All perioperative data, block characteristics, and complications were recorded by the investigator using a structured data collection sheet.

Table 1: Baseline Characteristics of Study Participants (N = 110) Variable Subclavian Perivascular (n=55) Lateral Approach (n=55) Test of significance Effect size (95% CI) p-value Age (years), Mean ± SD 43.6 ± 10.8 44.9 ± 11.2 Student’s t-test Mean diff = −1.3 (−5.5 to 2.9) 0.543 Male sex, n (%) 36 (65.5) 34 (61.8) χ² test RR = 1.06 (0.83–1.35) 0.689 BMI (kg/m²), Mean ± SD 23.7 ± 2.9 24.1 ± 3.1 Student’s t-test Mean diff = −0.4 (−1.5 to 0.7) 0.463 ASA I / II, n (%) 33 / 22 31 / 24 χ² test — 0.695 Table 1 compares the baseline demographic and clinical characteristics of patients in the subclavian perivascular and lateral approach groups. The mean age of patients in the subclavian perivascular group was 43.6 ± 10.8 years, while that in the lateral approach group was 44.9 ± 11.2 years, with no statistically significant difference between the two groups (p = 0.543). Male patients constituted 65.5% of the subclavian perivascular group and 61.8% of the lateral approach group; this difference was also not statistically significant (p = 0.689). The mean body mass index was comparable between the two groups (23.7 ± 2.9 kg/m² vs. 24.1 ± 3.1 kg/m²; p = 0.463). Distribution of ASA physical status (ASA I/II) was similar in both groups, with no significant difference observed (p = 0.695). Table 2: Comparison of Block Performance Time Variable Subclavian Perivascular (n=55) Lateral Approach (n=55) Test of significance Effect size (95% CI) p-value Block performance time (min), Mean ± SD 6.4 ± 0.7 15.8 ± 1.2 Student’s t-test Mean diff = −9.4 (−9.8 to −9.0) <0.01 Table 2 demonstrates a significant difference in block performance time between the two approaches. The mean block performance time in the subclavian perivascular group was 6.4 ± 0.7 minutes, which was markedly shorter compared to 15.8 ± 1.2 minutes in the lateral approach group. This difference was statistically highly significant (p < 0.01), with a mean difference of −9.4 minutes (95% CI: −9.8 to −9.0). Table 3: Quality of Sensory Blockade Variable Subclavian Perivascular (n = 55) Lateral Approach (n = 55) Test of Significance Effect Size (95% CI) p-value Onset of sensory block (min), Mean ± SD 4.2 ± 0.5 4.3 ± 0.6 Student’s t-test Mean diff = −0.1 (−0.3 to 0.1) 0.349 Time to complete sensory block (min), Mean ± SD 10.9 ± 1.0 15.9 ± 0.9 Student’s t-test Mean diff = −5.0 (−5.4 to −4.6) < 0.01 First rescue analgesia (min), Mean ± SD 412 ± 48 405 ± 52 Student’s t-test Mean diff = 7 (−12 to 26) 0.471 The onset of sensory block was comparable between the subclavian perivascular and lateral approach groups (4.2 ± 0.5 min vs 4.3 ± 0.6 min), with no statistically significant difference (p = 0.349). However, the time to achieve complete sensory block was significantly shorter with the subclavian perivascular approach (10.9 ± 1.0 min) compared to the lateral approach (15.9 ± 0.9 min), showing a highly significant difference (p < 0.01). The time to first rescue analgesia was similar in both groups (412 ± 48 min vs 405 ± 52 min), with no statistically significant difference observed (p = 0.471). Table 4: Procedure-Related Complications Complication Subclavian Perivascular (n = 55) n (%) Lateral Approach (n = 55) n (%) Vascular puncture 0 (0.0) 0 (0.0) Horner’s syndrome 0 (0.0) 0 (0.0) Pneumothorax 0 (0.0) 0 (0.0) Neurological deficit 0 (0.0) 0 (0.0) Any complication (overall) 0 (0.0) 0 (0.0) In table 4, In the present study, no procedure-related complications were observed in either the subclavian perivascular group or the lateral approach group. There were no cases of vascular puncture, Horner’s syndrome, pneumothorax, or neurological deficits reported. Overall, both techniques demonstrated a 100% complication-free outcome, indicating that both approaches were equally safe in the study population.

Baseline characteristics (Table 1) In the present study, both groups were comparable with respect to age, sex distribution, BMI, and ASA physical status, with no statistically significant differences observed. This baseline homogeneity strengthens the internal validity of the comparison and suggests that differences in outcomes can be attributed primarily to the block technique rather than patient-related confounders. Similar demographic comparability has been reported in previous studies comparing supraclavicular brachial plexus block techniques. Shenoy R et al. (2020)[2] observed no significant intergroup differences in age, gender distribution, or ASA status while comparing ultrasound-guided subclavian perivascular and supraclavicular approaches. Chaudhury S et al. (2021)[3] also emphasized the importance of comparable baseline characteristics to ensure unbiased assessment of block performance and outcomes. Block performance time (Table 2) Block performance time was significantly shorter in the subclavian perivascular approach compared to the lateral approach in the present study (6.4 ± 0.7 vs. 15.8 ± 1.2 minutes; p < 0.001). This finding is consistent with earlier literature. Sneha S. (2021)[6] demonstrated a significantly reduced performance time with the subclavian perivascular approach, attributing it to compact clustering of the brachial plexus trunks at the level of the first rib and improved ergonomics of the modified parasagittal ultrasound technique. Datta R et al. (2020)[7] similarly reported faster execution of the subclavian perivascular block compared to the conventional supraclavicular approach. Kaye AD et al. (2021)[5] also suggested that approaches minimizing needle redirection and providing a stable sonographic window contribute to shorter procedure times. Thus, the present findings align well with existing evidence supporting the efficiency of the subclavian perivascular approach. Quality of sensory blockade (Table 3) The onset of sensory block was comparable between the two groups, with no statistically significant difference, which is in agreement with studies by Kohan J et al. (2024)[8], who reported similar onset times between different ultrasound-guided supraclavicular techniques. However, the time to achieve complete sensory blockade was significantly shorter in the subclavian perivascular group in the present study. This observation is supported by Saranlal AM et al. (2024)[4], who attributed faster attainment of complete blockade to the compact arrangement of the trunks within a single fascial sheath at the perivascular level, allowing uniform spread of local anesthetic with a single injection. The duration of analgesia, assessed by time to first rescue analgesia, was comparable between the two groups, a finding consistent with reports by Nalini KB et al. (2021)[9], who noted that while technique influences block performance and onset, the duration of analgesia is more dependent on the type and volume of local anesthetic used rather than the approach itself. Procedure-related complications (Table 4) were not observed in either group in the present study, indicating a favorable safety profile for both the subclavian perivascular and lateral approaches. The absence of vascular puncture, pneumothorax, and neurological deficits in both groups can be attributed to the use of ultrasound guidance, which enables real-time visualization of neural, vascular, and pleural structures, thereby minimizing procedural risks. Similar observations have been reported by Naaz S et al. (2020)[10], who demonstrated a significant reduction in major complications with ultrasound-guided supraclavicular blocks. Joshua AM et al. (2022)[1] also reported no cases of pneumothorax and minimal vascular injury with the subclavian perivascular approach, highlighting the protective anatomical role of the first rib. Furthermore, Puneet P et al. (2024)[11] attributed occasional occurrences of Horner’s syndrome in lateral approaches to proximal spread of local anesthetic, although no such events were noted in the present study.

This observational study demonstrates that both the subclavian perivascular and lateral approaches for ultrasound-guided supraclavicular brachial plexus block are safe and effective techniques for providing anesthesia in below-midarm surgical procedures. The baseline demographic and clinical characteristics of the two groups were comparable, allowing for a reliable assessment of procedural outcomes. The subclavian perivascular approach showed a significant advantage in terms of shorter block performance time and faster attainment of complete sensory blockade when compared to the lateral approach. These findings may be explained by the compact anatomical arrangement of the brachial plexus trunks at the perivascular level and the favorable sonoanatomical window, which promotes efficient spread of local anesthetic with minimal needle manipulation. In contrast, the onset of sensory block and the duration of postoperative analgesia were similar in both groups, suggesting comparable efficacy with respect to intraoperative anesthesia and postoperative pain control. Procedure-related complications were absent in both groups, with no instances of pneumothorax or neurological deficits reported, underscoring the safety of ultrasound-guided techniques. Although a tendency toward fewer complications was observed with the subclavian perivascular approach, this difference did not reach statistical significance. Overall, the subclavian perivascular approach may be considered a preferable technique for ultrasound-guided supraclavicular brachial plexus block due to its shorter procedural time and faster completion of sensory blockade, making it a reliable and efficient option for below-midarm surgeries in a tertiary care setting. LIMITATIONS OF THE STUDY 1. The study was observational in design, and randomization was not performed, which may introduce selection bias. 2. The study was conducted at a single tertiary care centre, limiting the generalizability of the findings to other settings. 3. The sample size, although adequate for primary outcomes, may not have been sufficient to detect statistically significant differences in rare complications. 4. Operator experience and skill level, which can influence block performance time and success, were not objectively quantified. 5. Long-term neurological outcomes beyond the immediate postoperative period were not assessed. 6. Patient satisfaction scores and cost-effectiveness analysis were not included in the study.

1. Joshua AM, Misri Z. Peripheral nerve disorders. InPhysiotherapy for Adult Neurological Conditions 2022 Jun 21 (pp. 621-729). Singapore: Springer Nature Singapore. 2. Shenoy R, Datta G, Horowitz M, Fox M. Surgery of the Peripheral Nerve. InOperative Orthopaedics 2020 Dec 16 (pp. 63-84). CRC Press. 3. Chaudhury S, Ghosh A. A Study of Brachial Plexus Sheath and Dye Spread Through the Sheath in Single-and Multi-Directional Injections in Cadaver. National Journal of Clinical Anatomy. 2021 Jan 1;10(1):25-9. 4. Saranlal AM, Patel N, Kumar R, Ranjith KR, Muthiah T, Ayub A, Singh AK, Khanna P, Ray BR. Medial versus lateral approach in ultrasound-guided costoclavicular brachial plexus block for upper limb surgery: a randomized control trial. Anaesthesiology Intensive Therapy. 2024 Aug 30;56(3):199-205. 5. Kaye AD, Allampalli V, Fisher P, Kaye AJ, Tran A, Cornett EM, Imani F, Edinoff AN, Motlagh SD, Urman RD. Supraclavicular vs. infraclavicular brachial plexus nerve blocks: clinical, pharmacological, and anatomical considerations. Anesthesiology and Pain Medicine. 2021 Oct 31;11(5):e120658. 6. Sneha S. A comparative study between lateral approach and conventional approach to supraclavicular brachial plexus block in upper limb surgeries. Age.;18:65years. 7. Datta R, Agrawal J, Narula G, Pahwa B. A fluoroscopic assessment of brachial plexus block by the supraclavicular approach: Have we been overmedicating?. medical journal armed forces india. 2020 Oct 1;76(4):410-7. 8. Kohan J, Cabanas C, Edalatpour A, Seitz A, Kuei MC, Gander BH. Upper Extremity Blocks for Hand Surgeons: A Literature Review of Regional Anaesthesia Techniques, Efficacy, and Safety. Plastic Surgery. 2024 Nov;32(4):667-76. 9. Nalini KB, Bevinaguddaiah Y, Thiyagarajan B, Shivasankar A, Pujari VS. Ultrasound-guided costoclavicular vs. axillary brachial plexus block: A randomized clinical study. Journal of Anaesthesiology Clinical Pharmacology. 2021 Oct 1;37(4):655-60. 10. Naaz S, Asghar A, Jha NK, Ozair E. A unique case of hoarseness of voice following left supraclavicular brachial plexus block. Saudi Journal of Anaesthesia. 2020 Jan 1;14(1):109-11. 11. Puneet P, Satapathy AR, Sharma SK. Approach and Troubleshooting to Upper Limb Blocks. InSteps to Successful Regional Anesthesia: Challenges and Solutions 2024 Oct 24 (pp. 87-130). Singapore: Springer Nature Singapore.