European Journal of Cardiovascular Medicine

Peripheral nerve blocks constitute a key component of contemporary regional anaesthesia practice, offering effective surgical anaesthesia while avoiding the adverse effects associated with airway manipulation and neuromuscular blockade [1]. These techniques facilitate optimal operating conditions by providing reliable muscle relaxation, maintaining stable intraoperative haemodynamics, and producing a sympathetic blockade that can minimise vasospasm. In addition to ensuring satisfactory intraoperative anaesthesia, peripheral nerve blocks also attenuate the surgical stress response and provide superior postoperative analgesia [2]. For upper limb surgeries below the shoulder, brachial plexus block is widely employed and is often regarded as the regional anaesthetic equivalent of central neuraxial blockade for the upper extremity. Multiple approaches have been described, but the supraclavicular technique has emerged as a preferred option because the plexus elements are closely clustered at this level, enabling effective blockade with a smaller volume of local anaesthetic. This approach is associated with excellent surgical conditions, stable haemodynamics, prolonged postoperative pain relief, and consistently high success rates [3]. The growing use of ultrasound guidance has further enhanced the safety and efficacy of regional anaesthesia. Real-time visualisation of neural structures and needle trajectory has reduced the incidence of nerve injury, minimised unpleasant paraesthesia, and improved block success with more rapid onset times [4-6]. Among long-acting local anaesthetics, bupivacaine remains widely utilised. It is commercially available as a racemic mixture comprising equal proportions of its S (−) enantiomer, levobupivacaine, and its R (+) enantiomer, dextrobupivacaine [7]. Although both enantiomers share identical physicochemical properties, they differ in their affinity for receptor sites, resulting in variation in both therapeutic effects and potential adverse reactions. Cardiotoxicity shows notable enantioselectivity, being more prominent with the R (+) form of racemic bupivacaine. Levobupivacaine, the pure S (−) isomer, was introduced into clinical practice because of its lower propensity to cause central nervous system and cardiovascular toxicity and its broader safety profile. Nonetheless, its clinical characteristics remain comparatively less explored [8]. Ropivacaine, another long-acting amide anaesthetic, also demonstrates reduced cardiotoxicity and neurotoxicity relative to racemic bupivacaine, making it particularly suitable for procedures requiring larger volumes of local anaesthetic. Its intrinsic vasoconstrictive properties limit systemic absorption and thereby extend the duration of analgesia. Owing to these advantages, ropivacaine has become a preferred option for postoperative pain management across several surgical settings [9-11]. The use of adjuvants can further enhance block quality by potentiating the effects of local anaesthetics and reducing the total dose required. Dexmedetomidine, a highly selective α2-adrenergic agonist, approximately eight times more selective than clonidine, exerts sedative, analgesic, antihypertensive, and anaesthetic-sparing effects when administered systemically [12,13]. When incorporated into peripheral nerve blocks, dexmedetomidine has been shown to prolong block duration and extend postoperative analgesia across a variety of regional techniques [14,15]. Despite numerous studies evaluating individual anaesthetic agents and adjuvants, there remains a paucity of direct comparisons between commonly used long-acting local anaesthetics in combination with dexmedetomidine [16,17]. Addressing this gap, the present randomised clinical trial evaluates the comparative efficacy of levobupivacaine and ropivacaine, each combined with dexmedetomidine, administered under ultrasound guidance for supraclavicular brachial plexus block, with a focus on the duration of analgesia, onset characteristics of sensory and motor blockade, and associated complications.

This randomised clinical study was conducted in the Department of Anaesthesia, Madhubani Medical College and Hospital, Madhubani, Bihar, India. Written informed consent was obtained from all participants prior to enrolment after explaining the nature and purpose of the study. All clinical procedures were performed in accordance with the ethical principles outlined in the Declaration of Helsinki. The study included patients scheduled for elective upper limb surgeries below the shoulder, conducted under ultrasound-guided supraclavicular brachial plexus block.

Sample size calculation:

The required sample size was calculated using G*Power software (version 3.1, Universität Düsseldorf, Germany) for a two-sample (independent) t-test comparing mean values between two parallel groups. The calculation was based on data from a previous study by Kulkarni SB et al. [1], which reported a mean time to first rescue analgesia of 13.23 ± 1.1651 hours. Using this standard deviation and the expected difference in means, the values were entered into the sample size formula at a 95% confidence level (α = 0.05) and 80% power (1–β = 0.80). The minimum required sample size was thus determined to be 27 patients per group. A total of 30 patients were taken per group for possible dropouts after taking written informed consent and explaining it in their language.

Inclusion criteria:

The study included adult patients of either sex, aged 20-70 years, who were classified as ASA physical status I or II and were scheduled to undergo elective unilateral upper limb surgery below the shoulder level under supraclavicular brachial plexus block.

Exclusion criteria:

Patients were excluded if they were unwilling to participate or had a documented allergy to local anaesthetics or any study-related medications. Individuals with a localised infection at the planned block site, bleeding disorders, or pre-existing neurological deficits in the operative limb were also excluded. Additional exclusion criteria comprised significant systemic illnesses, including ischaemic heart disease, severe hepatic or renal dysfunction, and conditions that could affect drug metabolism or block performance. Patients with pregnancy, chronic alcohol dependence, malnutrition, or intolerance to adjuvant agents were similarly not considered for enrolment.

Grouping and Randomisation:

Randomisation was carried out using a computer-generated allocation sequence created through an online randomisation tool. Eligible participants were assigned in a 1:1 ratio to one of two study groups:

• Group L: Received 20 mL of 0.5% levobupivacaine combined with 50 µg of dexmedetomidine.
• Group R: Received 20 mL of 0.75% ropivacaine combined with 50 µg of dexmedetomidine [18].

To ensure methodological rigor, allocation concealment was maintained using the Sequentially Numbered Opaque Sealed Envelopes (SNOSE) method. The envelopes were opened only at the time of intervention by the operating theatre technician, who prepared the study drug according to the assigned sequence. Blinding was maintained at multiple levels. The patients were unaware of the specific local anaesthetic administered, and the investigator responsible for postoperative assessment had no involvement in performing the block. All supraclavicular brachial plexus blocks were executed by experienced anaesthesiology consultants, while the outcome assessor remained fully blinded to group allocation throughout the study. A total of 75 patients were initially screened. Of these, 10 did not meet the inclusion criteria, and 05 declined to participate, resulting in 60 patients being enrolled and randomised into the two study groups. The patient selection and allocation process is detailed in the CONSORT flow diagram [Figure 1]. Participants were evaluated for the onset and duration of sensory and motor blockade and the duration of analgesia (DOA), defined as the time to first request for rescue analgesia, which served as the primary outcome measure. Secondary assessments included sedation scores and documentation of any adverse events encountered during the perioperative period.

Study Procedure:

All participants underwent a comprehensive pre-anaesthetic evaluation that included medical history, physical examination, and routine laboratory investigations. The procedure for the supraclavicular brachial plexus block, the possible use of either study drug, and the Visual Analogue Scale (VAS) for pain assessment were explained in their native language. Upon arrival in the operating theatre, Nil per Oral (NPO) status was reconfirmed. A 20-G intravenous cannula was inserted in the non-operative arm, and intravenous crystalloids were initiated. Standard monitoring: electrocardiography, non-invasive blood pressure, and pulse oximetry, was applied, and baseline haemodynamic parameters (heart rate, systolic and diastolic blood pressure, and SpO₂) were recorded. Patients were placed in the supine position with the head turned approximately 30° to the opposite side to facilitate access to the supraclavicular region. The supraclavicular block was performed using a Sonosite Edge II ultrasound machine equipped with a high-frequency linear probe (13–6 MHz). After aseptic preparation of the area with 5% povidone–iodine, local infiltration of the skin and subcutaneous tissue was carried out with 2% lignocaine. The brachial plexus was visualised, and anatomical variations, if present, were noted. A 22-G, 80-mm nerve block needle was inserted using an in-plane approach under real-time ultrasound guidance. Proper needle placement within the fascial plane was confirmed by hydrodissection with 2 mL of normal saline, which separated neural elements on the ultrasound image. A total of 20 mL of the assigned study solution was then injected incrementally under continuous sonographic visualization to ensure adequate perineural spread.

Assessment of Block Characteristics

Sensory block onset was evaluated every two minutes using a pinprick test and was defined as the time from completion of the injection to attainment of grade 3/4 on the Hollmen scale (pinprick felt as dull touch or no sensation). The duration of sensory anaesthesia was measured as the time from complete sensory block to the return of normal sensation in the distributions of the median, radial, ulnar, and musculocutaneous nerves.

Motor block onset was recorded from the end of drug administration to reaching grade 0 on the modified Bromage scale (complete inability to flex the elbow). Recovery to grade 4 (full motor function) marked the end of the motor block duration [19]. Patients with an inadequate block after 30 minutes were withdrawn from the study.

Postoperative Monitoring and Analgesia

The total duration of sensory block was defined as the interval between complete sensory blockade and the first complaint of pain. VAS scores were monitored postoperatively, and patients reporting a VAS score ≥ 3 received rescue analgesia. The time from block administration to the first analgesic requirement was documented as the duration of analgesia.

Monitoring for Adverse Events

Participants were observed for complications such as pruritus, nausea, vomiting, bradycardia, hypotension, arrhythmias, respiratory depression, pneumothorax, intravascular injection, or signs of local anaesthetic systemic toxicity (LAST).

Intraoperative sedation was determined using the Ramsay sedation scale as follows:

1. Patient anxious and agitated or restless or both;
2. Patient cooperative, oriented, and tranquil;
3. Patient responds to commands only;
4. Brisk response to light glabellar tap or loud auditory stimulus;
5. Sluggish response to light glabellar tap or loud auditory stimulus;
6. No response to light glabellar tap or loud auditory stimulus.

The maximum score was noted.

Statistical Analysis:

All collected data were compiled and analysed using Microsoft Excel and IBM SPSS Statistics software (version 26.0; IBM Corp., Armonk, NY, USA). Descriptive statistics were presented as mean ± standard deviation (SD) for normally distributed variables. Comparisons between categorical variables such as gender and ASA physical status were performed using the chi-square test. Continuous variables, including the onset and duration of sensory and motor blockade as well as duration of surgery, were analysed using the independent (unpaired) t-test for normally distributed data. Non-parametric variables, such as sedation scores, were summarised as median with interquartile range (IQR) and evaluated using the Mann–Whitney U test. A p-value < 0.05 was considered statistically significant, with all analyses conducted at a 95% confidence level.

Table 4: Comparison of duration of sensory block, motor block, and postoperative analgesia between the study groups

                    SD: Standard Deviation; P-values calculated using the unpaired t-test; * Statistically Significant.

Table 5: Comparison of sedation scores (Ramsay Sedation Scale) between the study groups

                                      P-value calculated using the Mann-Whitney

The present study compared the clinical performance of levobupivacaine and ropivacaine when combined with dexmedetomidine for ultrasound-guided supraclavicular brachial plexus block. Both groups were comparable in demographic characteristics, ensuring that the differences observed in block quality and duration could be attributed to the study drugs rather than patient-related variables. The distribution of ASA grades was also similar between groups, reflecting a homogeneous study population suitable for reliable comparison.

In the current study, the onset of both sensory and motor block was significantly faster in the ropivacaine–dexmedetomidine group than in the levobupivacaine–dexmedetomidine group (p < 0.0001). A more rapid onset with dexmedetomidine has also been highlighted in earlier studies. Agarwal S et al. and Biswas S et al. demonstrated that adding dexmedetomidine to levobupivacaine enhances the speed of block initiation, reinforcing the synergistic effect of this α2-agonist with long-acting local anaesthetics [20-22]. Similarly, studies by Mangal V et al. and Singh N et al. using 0.75% ropivacaine with dexmedetomidine reported a shortened onset profile, consistent with our findings [17,23]. Thalamati D et al. also noted that ropivacaine produced a faster sensory onset than levobupivacaine in SCPB, although they reported longer block duration with levobupivacaine [24]. In contrast to some earlier reports, the present study found that ropivacaine produced a significantly longer duration of both sensory and motor blockade compared with levobupivacaine. This prolonged action with ropivacaine aligns with previous observations by Kaur H et al. and Liu X et al., who also documented extended block duration and prolonged postoperative analgesia with ropivacaine in peripheral nerve blocks [25, 26]. Similar findings of extended sensory and motor block were also noted in studies conducted by Mangal V et al. and Singh N et al. [17, 23]. The potentiation of levobupivacaine with dexmedetomidine has likewise been demonstrated in earlier work by Agarwal S et al. and Biswas S et al., who reported increased duration of analgesia and prolonged block characteristics [21, 22]. Batool S et al. reported comparable onset times for both ropivacaine and levobupivacaine groups, but a significantly longer duration of sensory and motor block in the levobupivacaine–dexmedetomidine group, resulting in delayed need for rescue analgesia [20]. Although this differs from the current study, such variations may reflect differences in concentrations, volumes, or patient characteristics.

Overall, the findings of the present study support the superior performance of ropivacaine with dexmedetomidine in terms of faster onset, longer duration of blockade, and extended postoperative analgesia, without compromising safety or haemodynamic stability. These observations add to the growing evidence that ropivacaine, when paired with an α2-agonist like dexmedetomidine, can offer a more effective and longer-lasting regional anaesthetic profile in supraclavicular brachial plexus blocks.

Limitations of the study: This study was conducted at a single centre with a modest sample size, which may limit wider generalisation; however, it provides a strong foundation for future multicentre trials. The study focused on healthy adults, and further research, including patients with varied comorbidities, could broaden applicability. Long-term follow-up and patient-reported outcomes were not assessed, offering an opportunity for future studies to build upon these findings.

In this study, ropivacaine 0.75% combined with dexmedetomidine provided a faster onset of sensory and motor block, along with a significantly longer duration of block and postoperative analgesia compared with levobupivacaine 0.5% with dexmedetomidine. Both combinations were safe and well-tolerated, with no major complications. Overall, ropivacaine with dexmedetomidine proved to be the more effective option for ultrasound-guided supraclavicular brachial plexus block.

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