ORIGINAL ARTICLE |
https://doi.org/10.5005/jp-journals-10089-0126 |
Comparison of Efficacy of Levobupivacaine 0.375% and Levobupivacaine 0.25% along with a Fixed Dose of Dexmedetomidine for Ultrasound-guided Supraclavicular Brachial Plexus Block
1,3Department of Anesthesia & Critical Care, Medanta Hospital, Ranchi, Jharkhand, India
2Department of Neuroanesthesia & Critical Care, Medanta Hospital, Ranchi, Jharkhand, India
4Department of Cardiac Anesthesia, Rajendra Institute of Medical Sciences, Ranchi, Jharkhand, India
5Department of Critical Care Medicine, Santevia Hospital, Ranchi, Jharkhand, India
6Department of Trauma Critical Care, Rajendra Institute of Medical Sciences, Ranchi, Jharkhand, India
Corresponding Author: Nitesh Sinha, Department of Cardiac Anesthesia, Rajendra Institute of Medical Sciences, Ranchi, Jharkhand, India, Phone: +91 7860337418, e-mail: dr.niteshsinha@gmail.com
Received: 10 June 2024; Accepted: 05 August 2024; Published on: 19 August 2024
ABSTRACT
Background: The supraclavicular brachial plexus block (SBPB) is a widely used approach in regional anesthesia (RA). The use of ultrasound (USG) guidance significantly reduces the complications of SBPB. Recent advancements suggest that combining lower concentrations of levobupivacaine with dexmedetomidine can maintain efficacy while minimizing adverse reactions. Levobupivacaine 0.5 and 0.25% have been used in combination with dexmedetomidine at doses of 1 µg/kg of body weight; however, the effects of concentrations of levobupivacaine (0.375 and 0.25%) on block parameters and hemodynamics in SBPB, when combined with a fixed dose of dexmedetomidine, for upper limb procedures, remain underexplored. This study investigates the efficacy of 0.375 and 0.25% levobupivacaine, combined with a fixed dose of dexmedetomidine, in USG-guided SBPB.
Materials and methods: A prospective, randomized, double-blind trial was conducted on a total of 60 patients scheduled for elective upper limb surgery from June 2021 to May 2022 at our regional medical center. Participants were divided into two groups of 30 each. Group I received 30 mL of 0.375% levobupivacaine with 1 µg/kg dexmedetomidine, and group II received 30 mL of 0.25% levobupivacaine with 1 µg/kg dexmedetomidine. The duration of analgesia was the primary outcome. The onset and duration of sensorimotor blockade, hemodynamic variables, sedation score, and adverse effects were secondary outcomes. Statistical analysis was performed using appropriate tests in Excel for Windows ver. 15, 2013, United States of America.
Results: Group I exhibited a significantly faster onset of sensory block (3.93 ± 1.70 minutes) compared to group II (6.07 ± 1.53 minutes). Additionally, group I patients experienced earlier paresthesia and paralysis of the hand and shoulder joints. The duration of analgesia was significantly longer in group I (p < 0.05). Hemodynamic evaluation 2 hours postblock showed no significant differences in mean blood pressure or heart rate between the groups (p > 0.05). Sedation scores, measured using the modified Ramsay Sedation Scale, were comparable between the groups (p > 0.05), with average scores of 2.27 ± 0.45 for group I and 2.23 ± 0.43 for group II.
Conclusion: Both concentrations of levobupivacaine, when combined with dexmedetomidine, provided effective surgical anesthesia. However, 0.375% levobupivacaine resulted in a faster onset and prolonged sensory and motor blockade duration compared to 0.25% levobupivacaine. Neither combination resulted in significant side effects or complications, highlighting their safety and efficacy for SBPB.
Keywords: Dexmedetomidine, Levobupivacaine 0.25%, Levobupivacaine 0.375%, Supraclavicular brachial plexus block
How to cite this article: Khan N, Kumar M, Akhtar N, et al. Comparison of Efficacy of Levobupivacaine 0.375% and Levobupivacaine 0.25% along with a Fixed Dose of Dexmedetomidine for Ultrasound-guided Supraclavicular Brachial Plexus Block. J Acute Care 2024;3(2):72–76.
Source of support: Nil
Conflict of interest: None
INTRODUCTION
The use of regional blocks [regional anesthesia (RA)] in contemporary anesthetic practice has grown significantly. RA is the recommended approach for upper limb surgeries on cooperative patients.1,2 For upper limb surgery, the brachial plexus block (BPB) provides dependable and flexible RA.3 The procedure most frequently performed in the world is the supraclavicular brachial plexus block (SBPB), which is less likely to cause complications since it can be done in real time with the use of ultrasound (USG)-guided SBPB. BPB employs a range of medications, including long-acting bupivacaine and short-acting lignocaine.3,4
Levobupivacaine is the S (−) enantiomer of bupivacaine and a long-acting amide local anesthetic. It causes fewer cardiovascular adverse effects and less motor nerve fiber penetration than bupivacaine.5 The effect of a single-dose brachial block generally wanes off just after surgery, leaving the surgical site prone to moderate to severe postoperative pain. Additionally, the limited therapeutic window of local anesthetic medications restricts the ability to extend the block duration by increasing the amount of local anesthetic administered.6 Studies have been conducted on several adjuvants that have been shown to modify the duration of a local anesthetic’s blockade while augmenting its effectiveness. Commonly employed adjuvants include α-2 agonists, dexamethasone, neostigmine, and opioids. The clinical application of α-2 agonists has been expanding with the use of dexmedetomidine in peripheral nerve blocks.7,8 Effectively extending the duration of nerve block has also been shown with dexmedetomidine when added as an adjuvant along with local anesthetic drugs. According to published reports,9 this phenomenon may be caused by local vasoconstriction and c-fiber blockage facilitation.10 When levobupivacaine is combined with dexmedetomidine, the duration of sensory and motor blockade is significantly extended, onset times are reduced, and analgesia is prolonged without causing additional harm to the body.9 By lowering the volume and amount of levobupivacaine and adding dexmedetomidine, we were able to lessen adverse effects while maintaining efficacy.10 The use of levobupivacaine at doses of 0.5 and 0.25% with dexmedetomidine at doses of 1 µg/kg of body weight has been studied, but the effects of levobupivacaine 0.375 and 0.25% along with dexmedetomidine on block parameters and hemodynamics in SBPB for upper limb surgeries have not been studied.7,9,11 Our hypothesis was to determine whether 0.375% is better than 0.25%. We intended to compare 0.375% with 0.25%, a lower dose than 0.5%, which is safer than 0.5% and much superior to 0.25%.
The primary objective of the study is to evaluate the effect of 0.375 and 0.25% levobupivacaine mixed with dexmedetomidine on block parameters, with secondary objectives to assess hemodynamics during upper limb procedures performed under USG guidance.
MATERIALS AND METHODS
This prospective, randomized, double-blinded study was carried out between June 2021 and May 2022 after approval from the Institutional Ethics Committee. The study was completed in accordance with the Consolidated Standards of Reporting Trials (CONSORT) guidelines. The inclusion criteria were patients between the ages of 18 and 60, regardless of gender, who were scheduled for elective upper limb surgery under SBPB guided by USG and weighed between 40 and 70 kg. Exclusion criteria included refusal, cardiovascular illness, diabetes, coagulopathy or peripheral neuropathy, severe hypotension, bradycardia, convulsions, and a history of allergic reactions to local anesthetics. The patients were randomized into two groups. In group I, a total of 30 mL of 0.375% levobupivacaine and 1 µg/kg dexmedetomidine was administered for SBPB. In group II, a total of 30 mL of 0.25% levobupivacaine and 1 µg/kg dexmedetomidine was administered for SBPB. The anesthesiologist performing the block and observing the patient was blinded to the treatment group. Data collection was done by the anesthesiologists who were unaware of the group allocation. Throughout this study, the principles outlined in the Declaration of Helsinki were followed. Hemodynamic baseline values were acquired immediately after the drug was injected for the block, followed by measurements at 5, 10, 20, and 30 minutes, and then every 15 minutes until the surgery was completed. These measurements comprised oxygen saturation (SpO2), noninvasive blood pressure (NIBP), and heart rate. The extent of motor and sensory block was documented. A blunt-tip needle test was used to detect sensory blockage between the C5 and T1 dermatomes. The term “onset of sensory blockade” refers to the period between the injection of the study drug and the absence of pinprick sensation in any dermatome.12,13 Grade 0 represented extreme pain, grade 1 represented moderate pain, and grade 2 represented no pain at all with the sensory block.11 A 0–10 numeric rating scale (NRS) was used to measure pain. On the pain scale, 0 indicated no pain, 1–3 indicated mild pain, 4–6 indicated moderate pain, 7–9 indicated severe pain, and 10 indicated the most excruciating torment.14 The patient’s status was assessed every 2 minutes, beginning with the full injection of the drug and continuing until the patient lost all ability to feel pain. The block was regarded ineffective if the required blockade was not obtained within 30 minutes. The interval of time between the study drug injection and the loss of shoulder motor function was designated as the onset of motor block. The patient’s grip strength and superior and inferior trunk functions of the brachial plexus were measured every 2 minutes. Grip strength involved elevating the arm while maintaining a straight elbow, and trunk function involved assessing the motor block at the shoulder. A motor block received a score of 0 for no weakness, 1 for paresis, or 2 for paralysis.11 The time interval between the delivery of the medication and the onset of pain that necessitated analgesia, indicated by an NRS greater than 3, was defined as the duration of analgesia. When the pain score increased above 3, an intravenous dose of one gram of paracetamol was given as rescue for postoperative pain. The amount of time that passed between the delivery of the study drug and the full restoration of motor function in the wrists and fingers was known as the motor block duration.12,13 A three-point motor block scale was also used to rate it: 1 for paresis, 2 for paralysis, and 0 for no weakness in the motor block.11 The overall block quality was assessed using the following scale: 0 for complete failure, 1 for poor block, and 2 for satisfactory block. The modified Ramsay sedation scale was utilized to evaluate the levels of sedation.11 Patients who scored 3 or above were identified and observed.
Patients were also monitored for any consequences of the BPB or drug injection-related side effects. These included tachycardia (defined as a heart rate >20% above the baseline value), hypotension (defined as a systolic blood pressure <20% below the baseline value), and bradycardia. Additionally, hypoxemia (defined as SpO2 <90%) and dysrhythmia [defined as any ventricular or supraventricular beat or rhythm other than sinus rhythm detected on electrocardiogram (ECG)] were identified. Complications included Horner’s syndrome, pleuritis, convulsions, hypersensitivity reactions, and pneumothorax.
The sample size was calculated using the observation of Nallam et al., with the duration of analgesia as the primary outcome.12 We employed a 90% power and a 95% confidence interval (α 0.05) with a 1:1 sample size ratio in each group to examine the differences between the two means. After entering the variables from the aforementioned study into the OpenEpi online calculator (version 3.03a116), it was determined that the sample size would be 25 participants in each group. With 30 participants in each group, a total of 60 participants were studied. Statistical analysis of the data was carried out using appropriate tests in Excel for Windows version 15, 2013, United States of America, which was available at the time of data production. Numbers, percentages, means ± standard deviations (SD), and standard errors of means were used to summarize the data when appropriate. The duration of analgesia, motor blockage, and hemodynamic status over various time intervals were investigated using an unpaired t-test. Significant statistical differences were defined as p < 0.05, and high statistical differences were defined as p < 0.01.
RESULTS
The present study enrolled 60 patients (30 in each group). Table 1 lists demographic information and the site of injury. The two groups did not differ statistically significantly in terms of age, weight, gender distribution, or injury location. In group I, the average age was 38.93 ± 12.46 years (range 19–60 years), while in group II, it was 36.73 ± 14.36 years (range 18–60 years). The mean weight in group I was 56.63 ± 8.34 kg (range 42–69 kg), while in group II, it was 59.00 ± 6.89 kg (range 44–69 kg). In both groups, 83.3% were male. When compared to group II, group I developed sensory blocks earlier. Table 2 shows the onset of sensory block in each dermatome. The sensory block start time at the C5 dermatome was 3.93 ± 1.70 minutes for group I and 6.07 ± 1.53 minutes for group II. Table 3 shows the onset of motor blockage at the shoulder and hand level. Patients in group I developed paresis and paralysis of the shoulder joint and hand earlier than those in group II. Table 4 demonstrates the duration of analgesia. The period of analgesia and sensory block varied significantly (p < 0.05) between the two groups, but the duration of motor block varied significantly (p < 0.001) between the two groups. Both groups I and II received a motor block quality score of 2, indicating total paralysis. The overall block quality score was 2, indicating that both groups had satisfactory blocks. Two hours following the BPB, an examination of hemodynamic parameters showed no statistically significant variations in either mean arterial pressure or heart rate (p > 0.05) (Table 5). The sedation scores (modified Ramsay Sedation Scale) did not differ significantly (p > 0.05) between groups I and II. Patients in groups I and II reported mean sedation scores of 2.27 ± 0.45 and 2.23 ± 0.43, respectively. Eight patients (26.6%) in group I and seven (23.3%) in group II had sedation scores of 3 (easily arousable). In all groups, no patients had a sedation score greater than 3. No patient in either group encountered an adverse event or consequence. None of the patients required any form of assistance.
| Group I | Group II | p-value | ||
|---|---|---|---|---|
| Age (years) | 38.93 ± 12.46 | 36.73 ± 14.36 | >0.05 | |
| Weight (kg) | 56.63 ± 8.34 | 59.00 ± 6.89 | >0.05 | |
| Male (N) | 25 | 25 | >0.05 | |
| Female (N) | 5 | 5 | >0.05 | |
| Site of injury | Arm | 12 | 10 | >0.05 |
| Forearm | 11 | 12 | >0.05 | |
| Hand | 7 | 8 | >0.05 | |
| Level | Group I (minute) | Group II (minute) | p-value |
|---|---|---|---|
| C5 | 3.93 ± 1.70 | 6.07 ± 1.53 | <0.05 |
| C6 | 4.33 ± 2.04 | 6.20 ± 1.52 | <0.05 |
| C7 | 4.80 ± 2.14 | 6.93± 1.72 | <0.05 |
| C8 | 5.33 ± 1.77 | 7.27 ± 1.53 | <0.05 |
| T1 | 5.67 ± 1.67 | 7.73 ± 1.80 | <0.05 |
| Level | Group I (minute) | Group II (minute) | p-value | |
|---|---|---|---|---|
| Shoulder | Paresis | 6.20 ± 1.85 | 8.33 ± 1.49 | <0.05 |
| Paralysis | 8.67 ± 1.92 | 11.13 ± 1.55 | <0.05 | |
| Hand | Paresis | 9.00 ± 2.51 | 10.67 ± 2.06 | <0.05 |
| Paralysis | 11.40 ± 2.74 | 13.27 ± 2.32 | <0.05 | |
| Level | Group I | Group II | p-value |
|---|---|---|---|
| Sensory block (minute) | 848.97 ± 127.20 | 776.67 ± 122.15 | <0.05 |
| Motor block (minute) | 831 ± 126.56 | 725 ± 119.85 | <0.05 |
| Quality of motor block (scale) | 2 | 2 | >0.05 |
| Overall quality of block (scale) | 2 | 2 | >0.05 |
| Mean heart rate | Mean arterial pressure | |||||
|---|---|---|---|---|---|---|
| Time | Group I | Group II | p-value | Group I | Group II | p-value |
| Baseline | 81.20 ± 10.34 | 83.40 ± 7.97 | >0.05 | 98.27 ± 9.19 | 98.40 ± 6.61 | >0.05 |
| Immediate | 80.33 ± 10.88 | 82.47 ± 7.09 | >0.05 | 96.03 ± 9.59 | 96.07 ± 6.02 | >0.05 |
| 5 minutes | 78.57 ± 11.94 | 80.57 ± 8.99 | >0.05 | 90.60 ± 9.45 | 92.03 ± 8.37 | >0.05 |
| 10 minutes | 77.90 ± 12.64 | 79.80 ± 10.09 | >0.05 | 88.43 ± 9.19 | 88.93 ± 7.57 | >0.05 |
| 20 minutes | 82.70 ± 15.24 | 82.77 ± 10.26 | >0.05 | 91.00 ± 7.72 | 94.67 ± 10.97 | >0.05 |
| 30 minutes | 78.50 ± 15.45 | 83.03 ± 11.98 | >0.05 | 91.37 ± 8.43 | 95.03 ± 12.64 | >0.05 |
| 45 minutes | 75.00 ± 14.85 | 80.40 ± 11.40 | >0.05 | 89.33 ± 7.10 | 90.70 ± 8.62 | >0.05 |
| 60 minutes | 74.80 ± 14.32 | 80.67 ± 9.37 | >0.05 | 88.80 ± 6.21 | 89.30 ± 8.76 | >0.05 |
| 75 minutes | 79.17 ± 13.31 | 74.97 ± 12.34 | >0.05 | 88.17 ± 6.84 | 89.47 ± 11.26 | >0.05 |
| 90 minutes | 78.97 ± 10.65 | 75.87 ± 11.13 | >0.05 | 86.80 ± 5.82 | 88.30 ± 8.89 | >0.05 |
| 120 minutes | 81.53 ± 9.92 | 77.77 ± 9.21 | >0.05 | 86.23 ± 6.52 | 88.60 ± 8.87 | >0.05 |
DISCUSSION
Levobupivacaine 0.25%, plus dexmedetomidine as an adjuvant, can provide adequate surgical anesthesia. Higher concentrations of levobupivacaine combined with dexmedetomidine led to a faster onset and longer duration of sensory and motor blocks. Increased concentration prolonged postoperative analgesia while shortening the onset time for the motor block. Nonetheless, motor block and total block quality were comparable across both groups. Hemodynamic parameters were steady at both doses. Reducing the dose did not compromise perioperative analgesia, resulting in significantly decreased postoperative visual analog scale (VAS) pain scores while maintaining equivalent block quality. No adverse events or complications were observed.
Our findings showed that appropriate surgical anesthesia can be attained with 0.25% levobupivacaine and dexmedetomidine as an adjuvant. We chose to employ levobupivacaine at lower concentrations (0.375 and 0.25%) to increase its safety margin. Higher concentrations of levobupivacaine (0.375%) expedite analgesia compared to lower concentrations (0.25%); however, the required outcome can also be achieved with a modest dose. Reducing high doses can help in minimizing toxicity. Kaur et al. observed a similar finding.15
In this investigation, we noted a significant difference in the onset of sensory block in all dermatomes and motor blockade at the shoulder and hand levels between the groups. When levobupivacaine was administered at a dose of 0.375% instead of 0.25% with dexmedetomidine, sensory and motor block occurred more quickly and persisted longer. Kaur et al. and Arora et al. conducted comparable studies, which corroborate our findings.15,16 Mixing levobupivacaine with dexmedetomidine can significantly lower the concentration required for surgical anesthesia.15 A lower dose can also produce similar benefits with fewer drug-related issues. Earlier studies found that higher doses were required to establish effective sensory and motor blockage in all dermatomes. The duration of postoperative analgesia and the onset time of the motor block were considerably longer in group II. When we compared our results to those of Kaur et al. and Arora et al., we observed that the onset time for the motor block was reduced for both levobupivacaine dosage levels.15,16 Our study indicated a longer duration of pain relief compared to trials conducted in both groups by Arora et al. and Kaur et al. For SBPB, a lower dose of levobupivacaine (0.25%) combined with dexmedetomidine provides an acceptable onset and duration of postoperative analgesia.
We evaluated the quality of the motor block using three metrics. Anything less than grade 2 (paralysis) at the shoulder and hand grip was judged a failure. Our findings may be consistent with Sandhu et al.’s investigation on the overall success rate of BPBs performed under USG guidance.17 The overall quality of the block was assigned a score between 0 and 2. In all cases, the block’s overall quality score was 2. This finding could be attributed to the use of USG guidance for all block procedures. When administered by a qualified anesthesiologist under USG guidance, failure rates and partial blocks are reduced.17
The hemodynamic parameters were found to be stable and did not vary significantly between the two groups with different concentrations of levobupivacaine but a fixed dose of dexmedetomidine. There was no statistically significant difference in baseline heart rates between the two groups. No patients in either group demonstrated bradycardia at any time during the perioperative period. The baseline mean blood pressure was similar in both groups, with no statistically significant differences. Throughout the operation, the patients’ hemodynamic stability was maintained, with no significant hypotension. The lower local anesthetic doses resulted in no increased perioperative analgesic demand. Bradycardia and hypotension are known side effects of dexmedetomidine-induced cardiovascular depression.18 We administered both groups a lower and consistent dose, which could have contributed to their hemodynamic stability.
The sedation scores in group I and group II were not substantially different (p > 0.05). Sedation levels averaged 2.27 ± 0.45 in group I and 2.23 ± 0.43 in group II. No patients in either group showed evidence of agitation or severe sedation, and all were easily arousable. A sedation score of 3 (easily arousable) was observed in 8 patients (26.6%) from group I and 7 patients (23.3%) from group II. No patient in either group received a sedation score greater than three. Our findings supported those of Thakur et al. and Balakrishnan et al.19,20
There were no adverse events or problems reported in either group. Although dexmedetomidine can cause bradycardia and hypotension at higher doses, these issues were not observed in our study.18 No patient in this study showed any signs of hemodynamic instability, such as bradycardia, tachycardia, dysrhythmia, hypotension, or hypoxia. The use of USG guidance likely enhanced the precision of the procedure, reducing the risk of complications such as hemorrhage, pneumothorax, Horner’s syndrome, vascular puncture, convulsion, and neuralgia.17-21 Similarly, none of the patients in either group I or group II experienced nausea or vomiting. Both concentrations of levobupivacaine, when combined with dexmedetomidine, provided adequate anesthesia and effective pain relief for upper limb surgery.
Our study’s limitations include its single-center design and relatively small sample size. Larger randomized controlled trials are needed to validate our findings. Additionally, our study focused only on otherwise healthy patients, so we cannot draw conclusions about the effects of dexmedetomidine on individuals with cardiac, hepatic, or renal impairments. Furthermore, a more standardized assessment of sedation levels, such as monitoring Bispectral Index (BIS) values, might have provided a more objective measure compared to clinical rating systems.
CONCLUSION
Lower dosages of 0.25% levobupivacaine, combined with dexmedetomidine, can still provide effective surgical anesthesia. Increasing the concentration to 0.375% levobupivacaine significantly shortens the onset period of both sensory and motor blockade, while also extending the duration of analgesia. This higher concentration enhances the overall efficacy of the block. Importantly, no severe side effects or complications were observed with either medication in our study.
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