Regional anesthesia plays a crucial role in modern surgical practice by providing excellent intraoperative anesthesia and prolonged postoperative analgesia while minimizing systemic side effects and avoiding airway manipulation. Among upper limb blocks, the supraclavicular brachial plexus block is often called the “spinal anesthesia of the upper limb” due to its dense and predictable block of the arm, forearm, and hand. It is particularly suited for elbow and forearm orthopedic surgeries, where a compact cluster of nerve trunks enables rapid onset and complete anesthesia of the limb. The evolution from landmark-guided to ultrasound-guided (USG) techniques has significantly enhanced both safety and efficacy, allowing real-time visualization of nerve structures, needle placement, and drug spread, thereby minimizing complications such as pneumothorax and intravascular injection.[1] Local anesthetics (LAs) are the foundation of regional blocks. Bupivacaine, a long-acting amide-type LA, has been widely used; however, its potential for cardiotoxicity led to the development of safer enantiomeric alternatives like Levobupivacaine, the pure S( -)-isomer of bupivacaine. Levobupivacaine demonstrates similar potency and duration of anesthesia but with significantly reduced cardiovascular and central nervous system toxicity, making it particularly suitable for peripheral nerve blocks. It provides profound sensory and motor blockade with minimal vasodilatation and improved hemodynamic stability, features that are advantageous in patients with limited physiological reserve.[2] To enhance the quality and duration of anesthesia, various adjuvants have been added to local anesthetics. Fentanyl, a synthetic μ-opioid receptor agonist, is one such adjuvant that extends the duration of sensory and motor blockade and provides superior postoperative analgesia by exerting local synergistic effects with the anesthetic at the nerve membrane level. It also produces mild vasoconstriction, reducing vascular absorption and prolonging local anesthetic action. However, the addition of opioids to peripheral nerve blocks remains controversial due to variability in onset time, duration of effect, and the potential for side effects like pruritus, nausea, and sedation. Studies have demonstrated that while fentanyl may slightly delay onset, it significantly enhances the duration and quality of analgesia without compromising hemodynamic stability.[3] The advent of ultrasound-guided supraclavicular blocks has facilitated precise deposition of drugs around the nerve plexus, enabling smaller doses and a better safety profile. Combining Levobupivacaine with Fentanyl under ultrasound guidance may offer an optimal balance between efficacy and safety, producing prolonged postoperative pain relief and stable intraoperative hemodynamics. Given the paucity of Indian data and limited randomized studies comparing the combination of Isobaric Levobupivacaine and Fentanyl in ultrasound-guided supraclavicular block, this study was undertaken to evaluate their comparative efficacy and hemodynamic effects.[4] Aim: To compare the analgesic efficacy and hemodynamic stability of isobaric Levobupivacaine (0.5%) with and without Fentanyl in ultrasound-guided supraclavicular block for elective elbow and forearm orthopedic surgeries. Objectives: 1. To compare the onset and duration of sensory and motor blockade between isobaric Levobupivacaine alone and with Fentanyl. 2. To assess intraoperative and postoperative hemodynamic stability between both groups. 3. To evaluate any perioperative complications associated with both drug regimens.

Source of Data: The study was conducted in the Department of Anaesthesiology, Chamarajanagar Institute of Medical Sciences (CIMS), Chamarajanagar, on patients scheduled for elective elbow and forearm orthopedic surgeries. Study Design: This was a prospective, randomized, double-blind comparative study. Study Location: Department of Anaesthesiology, CIMS, Chamarajanagar. Study Duration: The study was carried out over a period of 12 months after obtaining Institutional Ethical Committee approval. Sample Size: 40 patients were enrolled and randomly allocated into two groups of 20 each (Group L and Group LF). Inclusion Criteria: 1. ASA physical status I and II. 2. Age between 18 and 60 years. 3. Both genders. 4. Patients undergoing elective elbow or forearm orthopedic surgeries. 5. Patients who provided written informed consent. Exclusion Criteria: • Patient refusal. • Infection at the injection site. • Known hypersensitivity to local anesthetics or opioids. • Coagulopathy or bleeding disorders. • Severe cardiac, hepatic, or renal impairment. • Pregnancy or lactation. • Neurological disorders affecting the upper limb. Procedure and Methodology: After pre-anesthetic evaluation and informed consent, all patients were fasted as per standard guidelines. Intravenous access was secured, and standard ASA monitoring (ECG, NIBP, SpO₂) was applied. Patients were premedicated with midazolam 1 mg IV and glycopyrrolate 0.2 mg IV. The block was administered in the supine position with the head turned contralaterally. Under strict aseptic precautions, the supraclavicular area was scanned using a high-frequency linear probe (6–13 MHz) to visualize the brachial plexus as a cluster of hypoechoic nodules lateral and posterior to the subclavian artery. • Group L: 19 mL of 0.5% isobaric Levobupivacaine + 11 mL normal saline (total 30 mL). • Group LF: 19 mL of 0.5% isobaric Levobupivacaine + 1 mL Fentanyl (50 µg) + 10 mL normal saline (total 30 mL). The drug was deposited in divided doses with intermittent aspiration to avoid intravascular injection. Onset and duration of sensory and motor block were assessed using pinprick method and Modified Bromage Scale, respectively. Intraoperative hemodynamic parameters heart rate, mean arterial pressure, respiratory rate, and SpO₂ were recorded every 5 minutes for 30 minutes, then every 15 minutes until the end of surgery. Postoperative monitoring continued hourly for the first 8 hours. Any adverse effects such as nausea, vomiting, pruritus, hypotension, or respiratory depression were noted. Sample Processing: All collected data were recorded in standardized proformas and coded for analysis. Data confidentiality was maintained throughout the study. Statistical Methods: Descriptive statistics (mean ± SD) were used for continuous variables; proportions were used for categorical data. Intergroup comparisons were analyzed using the Student’s t-test for continuous variables and Chi-square test for categorical variables. A p-value <0.05 was considered statistically significant. Data Collection: Patient demographics, onset and duration of blocks, hemodynamic parameters, and adverse events were documented on a structured data collection sheet. Data were compiled and analyzed using SPSS version 25.0.

Table 1: Analgesic efficacy and hemodynamic stability (N = 40; Group L n=20, Group LF n=20) Outcome Group L Mean (SD) Group LF Mean (SD) Effect (LF -L) with 95% CI Test of significance p-value Duration of sensory block (min) 399.25 (51.87) 765.75 (108.00) +366.50 ( +315.8 to +417.2 ) Welch t =13.8, df =30.6 <0.001 Duration of motor block (min) 283.50 (65.74) 656.00 (98.96) +372.50 ( +316.9 to +428.1 ) Welch t =14.5, df =31.9 <0.001 Hemodynamic stability (MAP, PR; intra/post-op, repeated measures) No between-group difference at any timepoint Multiple between-group tests >0.05 across all timepoints 6a410976-9c30-44b5-94b1-daf564a… Table 1 compares the duration of sensory and motor blockade and evaluates hemodynamic stability between patients receiving 0.5 % isobaric Levobupivacaine alone (Group L) and those receiving the same drug combined with Fentanyl (Group LF) in ultrasound-guided supraclavicular block. The mean duration of sensory block in Group L was 399.25 ± 51.87 minutes, whereas Group LF showed a markedly prolonged duration of 765.75 ± 108.00 minutes. The mean difference of +366.5 minutes (95 % CI 315.8 to 417.2) was statistically significant (Welch t = 13.8, p < 0.001). Similarly, the motor block duration was significantly longer in Group LF (656.00 ± 98.96 minutes) compared with Group L (283.50 ± 65.74 minutes), with a mean difference of +372.5 minutes (95 % CI 316.9 to 428.1; t = 14.5, p < 0.001). These findings confirm that addition of fentanyl nearly doubled the duration of both sensory and motor blockade. With respect to hemodynamic stability, serial measurements of mean arterial pressure and pulse rate during intra- and postoperative monitoring revealed no significant inter-group variations at any time point (p > 0.05). Table 2: Onset and duration of sensory and motor blockade (N = 40) Measure Group L Mean (SD) Group LF Mean (SD) Effect (LF -L) with 95% CI Test of significance p-value Onset of sensory block (min) 3.07 (1.05) 4.80 (1.60) +1.73 ( +0.85 to +2.61 ) Welch t =4.04, df =31.8 <0.001 Onset of motor block (min) 8.90 (1.30) 9.40 (4.32) +0.50 ( -1.64 to +2.64 ) Welch t =0.50, df =22.7 0.62 Duration of sensory block (min) 399.25 (51.87) 765.75 (108.00) +366.50 ( +315.8 to +417.2 ) Welch t =13.8, df =30.6 <0.001 Duration of motor block (min) 283.50 (65.74) 656.00 (98.96) +372.50 ( +316.9 to +428.1 ) Welch t =14.5, df =31.9 <0.001 Table 2 details the onset and duration parameters of sensory and motor blockade between the two study groups. The onset of sensory block was slightly delayed in Group LF (4.80 ± 1.60 min) compared with Group L (3.07 ± 1.05 min), yielding a mean difference of +1.73 minutes (95 % CI 0.85 to 2.61) which was statistically significant (t = 4.04, p < 0.001). In contrast, the onset of motor block did not differ significantly between the groups 8.90 ± 1.30 minutes in Group L versus 9.40 ± 4.32 minutes in Group LF (p = 0.62). However, a striking difference was observed in the duration of both sensory and motor blockade. The sensory block lasted 399.25 ± 51.87 minutes in Group L compared to 765.75 ± 108.00 minutes in Group LF, and the motor block persisted 283.50 ± 65.74 minutes in Group L against 656.00 ± 98.96 minutes in Group LF; both differences were highly significant (p < 0.001).

In this randomized comparison of ultrasound-guided supraclavicular blocks, adding fentanyl (50 µg) to 0.5% isobaric levobupivacaine produced a very large prolongation of both sensory and motor block. Sensory duration increased from 399 ± 51.9 min with levobupivacaine alone to 765.8 ± 108.0 min with the adjuvant (mean difference +366.5 min; 95% CI 315.8–417.2; t =13.8; p<0.001). Motor duration showed a similar pattern, from 283.5 ± 65.7 min to 656.0 ± 99.0 min (difference +372.5 min; 95% CI 316.9–428.1; t =14.5; p<0.001). Hemodynamic profiles remained comparable between groups at all measured intra- and postoperative time points (all p>0.05), indicating that superior analgesic longevity was not traded for cardiovascular instability. These results are directionally and clinically consistent with multiple trials and reviews evaluating fentanyl as a perineural adjuvant in brachial plexus blockade. Mohanakumar A et al.(2020)[6] reported that adding fentanyl to levobupivacaine in ultrasound-guided supraclavicular block prolonged analgesia, albeit with a modestly slower sensory onset precisely mirroring magnitude-in-direction trade-off (longer duration at the cost of slightly delayed onset). Chaudhary UK et al.(2020)[7] similarly found fentanyl extended analgesia versus placebo, though less than dexmedetomidine placing combination as effective, albeit not necessarily the longest-acting option among adjuvants. Jajjari & Prabhakar, comparing ropivacaine and levobupivacaine with/without fentanyl, showed that levobupivacaine-fentanyl produced the longest sensory and motor durations among tested regimens, again aligning with the robust effects observed here. Basavarajaiah S et al.(2022)[8], in interscalene blocks for shoulder surgery, documented improved analgesia and stable hemodynamics with fentanyl, which is congruent with repeated-measures neutrality in MAP and pulse rate. Lack of hemodynamic penalty therefore fits the growing consensus that low-dose fentanyl as an adjunct does not destabilize cardiovascular parameters in ultrasound-guided upper-extremity blocks. Not all reports are perfectly concordant on onset behavior. Mahmoud et al. suggested fentanyl might enhance onset in levobupivacaine supraclavicular blocks, whereas dataset shows a statistically significant delay for sensory onset (+1.73 min) and no meaningful difference for motor onset. Such divergence likely reflects differences in fentanyl dose (fixed vs weight-based), total volume, injection pattern around the trunks, and case mix; methodologic heterogeneity is common across block studies. Broader synthesis from a recent Darji D et al.(2024)[9] suggests fentanyl tends to shorten motor onset (not consistently sensory) while prolonging both sensory and motor durations findings map onto the “duration” signal and the equivocal onset picture. Studies using bupivacaine- or ropivacaine-based mixtures Jananimadi S et al.(2024)[10] also consistently show prolonged block/analgesia with fentanyl, implying a class-consistent local synergism at the nerve membrane and/or reduced vascular uptake. Two additional points reinforce external validity. First, ultrasound guidance likely amplified both efficacy and safety by ensuring peritruncal spread and minimizing intravascular/intraneural injection consistent with standard practice upgrades that many of the comparative studies share. Second, hemodynamic neutrality across time points brackets the principal safety concern in ambulatory orthopedics and echoes the “no penalty” signal seen elsewhere. In sum, data add precise, effect-size-rich support that fentanyl (50 µg) meaningfully lengthens block duration with levobupivacaine in supraclavicular anesthesia without compromising perioperative hemodynamics, while onset effects remain small and technique-dependent.

The present prospective randomized study demonstrates that the addition of fentanyl (50 µg) to 0.5% isobaric levobupivacaine in ultrasound-guided supraclavicular brachial plexus block significantly prolongs both sensory and motor blockade without compromising hemodynamic stability. Although a marginal delay in sensory onset was observed, the overall analgesic efficacy was markedly superior in the fentanyl group. Mean arterial pressure, heart rate, and oxygen saturation remained stable throughout the intra- and postoperative periods, confirming that the combination provides effective and safe anesthesia for elective elbow and forearm orthopedic procedures. These findings suggest that isobaric levobupivacaine with fentanyl offers a reliable alternative to levobupivacaine alone when prolonged postoperative analgesia is desired. LIMITATIONS OF THE STUDY 1. The study sample size (n = 40) was relatively small, which may limit the generalizability of the findings. 2. Only a single dose and concentration of levobupivacaine and fentanyl were evaluated; dose-response relationships were not explored. 3. Postoperative pain was assessed only through block duration rather than validated pain scales beyond the analgesic effect period. 4. The study was confined to ASA grade I–II patients undergoing specific upper-limb orthopedic procedures; applicability to other surgeries or higher-risk patients remains uncertain. 5. Long-term outcomes and potential late complications, such as neuropathic pain or delayed neurological recovery, were not assessed.

1. Elenain MM, Zaher MM, Ahmed OH, Gadallah MF. Comparative clinical study between dexmedetomidine and fentanyl as adjuvants to bupivacaine in ultrasound-guided supraclavicular brachial plexus block for upper limb surgeries: a randomized study. Research and Opinion in Anesthesia & Intensive Care. 2024 Oct 1;11(4):262-9. 2. Mohamed HS, Saad MA. Evaluation of the Efficacy of Fentanyl versus Dexamethasone as an Adjuvant to Isobaric Bupivacaine in Ultrasound Guided Supraclavicular Brachial Plexus Block. The Egyptian Journal of Hospital Medicine. 2022 Oct 1;89(2):6756-61. 3. Reddy BS, Gaude YK, Vaidya S, Kini GK, Budania LS, Eeshwar MV. Effect of dexmedetomidine on characteristics of ultrasound-guided supraclavicular brachial plexus block with levobupivacaine-A prospective double-blind randomized controlled trial. Journal of Anaesthesiology Clinical Pharmacology. 2021 Jul 1;37(3):371-7. 4. Upadhyay P, Mitra S, Singh J, Gupta R, Kansay R. A Randomized Controlled Trial Comparing the Analgesic Efficacy of Programmed Intermittent Bolus vs. Continuous Infusion of Ropivacaine and Fentanyl in Ultrasound-Guided Infraclavicular Brachial Plexus Block for Upper Limb Surgery. Asian Journal of Anesthesiology. 2023 Oct 13;1:1. 5. Jagan G, Priyadharshini P, Divya S, Dhinesh Kumar C, Krishna Prasad T. Efficacy of levobupivacaine in regional anaesthesia-a narrative review. Frontiers in Medical Case Reports. 2024 Sep;5:01-12. 6. Mohanakumar A, Thangavelu R, Paul AA, Ranjan RV, George SK. Magnesium sulfate versus clonidine as an adjuvant to ultrasound-guided supraclavicular brachial plexus block in upper limb surgery: A double-blind randomized controlled trial. Journal of Pharmacology and Pharmacotherapeutics. 2020 Sep;11(3):107-12. 7. Chaudhary UK, Panda N, Bharti N, Sahni N, Gandhi K, Batra YK, Dhillon MS. Comparison of clonidine and fentanyl as adjuvant in femoro-sciatic nerve block for postoperative analgesia–a prospective randomized controlled trial. Indian Journal of Pain. 2020 Sep 1;34(3):193-8. 8. Basavarajaiah S, Patel P, Sharma K. A Comparative Study of Dexmedetomidine and Tramadol as an Adjuvant to Levobupivacaine in Ultrasound Guided Transverse Abdominus Plane Block in Pediatric Patients Undergoing Laproscopic Orchidopexy. Archives of Anesthesia and Critical Care. 2022 Jul 31. 9. Darji D, Pareek N, Butala B, Sanghani S, Padhiyar S. Dexmeditomidine And Fentanyl As An Adjunct To Bupivacainein Supraclavicular Nerve Block. Saintika Medika. 2024 Jul 11;20(1):1-0. 10. Jananimadi S, Arish BT, Hariharasudhan B, Sivakumar S, Sagiev GK, Neelakandan E, Madi J, BT A, Segaran S, George TK. Comparison of postoperative analgesia between intrathecal nalbuphine and intrathecal fentanyl in infraumbilical surgeries: a double-blind randomized controlled trial. Cureus. 2024 Apr 17;16(4).