|Year : 2022 | Volume
| Issue : 1 | Page : 29-36
A prospective randomized comparative study of dexmedetomidine versus clonidine as an adjunct to 0.75% ropivacaine in ultrasound-guided supraclavicular brachial plexus block
Gajanan Fultambkar1, Pradeepa Chavla1, Vijayanand Budi1, Rammohan Gurram1, Vinay Kukreja1, Abhijit Nair2
1 Department of Anaesthesia, Yashoda Hospitals, Secunderabad, Telangana State, India
2 Department of Anesthesiology, Ibra Hospital, North Sharqiya Governorate, Ibra, Sultanate of Oman
|Date of Submission||11-Feb-2021|
|Date of Acceptance||09-Apr-2021|
|Date of Web Publication||13-May-2022|
MD Abhijit Nair
Department of Anesthesiology, Ibra Hospital, North Sharqiya Governorate, Ibra 414
Sultanate of Oman
Source of Support: None, Conflict of Interest: None
Introduction Alpha-2 agonists are popular adjuvants used in neuraxial anesthesia like spinal, epidural, caudal anesthesia, and peripheral nerve blocks. The authors compared the efficacy of clonidine with dexmedetomidine as an adjuvant to ultrasound (US)-guided supraclavicular brachial plexus block in adult patients undergoing elective upper limb surgeries.
Materials and methods After obtaining Ethics Committee approval, 60 American Society of Anesthesiologists’- physical status (ASA-PS) I/II patients were randomized into two groups. Group Clonidine-Ropivacaine (CR) received 1 μg/kg clonidine as an adjuvant and group Dexmedetomidine-Ropivacaine (DR) received 1 μg/kg dexmedetomidine. Patients received an ipsilateral US-guided supraclavicular brachial plexus block with 0.75% ropivacaine (total volume of 20 ml). Demographic data, hemodynamics, the onset of block (sensory, motor), the duration of block (sensory, motor), duration of analgesia and surgery, total number of rescue analgesics, numerical rating scores, and Ramsay sedation score were compared between both groups using appropriate statistical tests.
Results Heart rates at 30 min, 60 min, 2 h, and 3 h were lower in group DR compared with group CR, which was statistically significant (P=0.0001, 0.0001, 0.021, and 0.026, respectively). The onset of sensory and motor block, duration of sensory and motor block, and duration of analgesia were better in group DR compared with CR, which was statistically significant (P=0.00). The number of rescue analgesics required in group CR in both groups was comparable (P=0.057). Numeric rating scale scores at 12, 18, and 24 h were significantly better in group DR compared with group CR (P=0.0001, 0.039, and 0.036, respectively).
Conclusion When added as an adjuvant to 0.75% ropivacaine in the US-guided supraclavicular brachial plexus, dexmedetomidine block produced faster onset of sensory and motor blockade, prolonged the duration of sensory and motor blockade, and also prolonged the duration of analgesia, when compared with clonidine.
Keywords: brachial plexus block, clonidine, dexmedetomidine, regional anesthesia, supraclavicular, ultrasound
|How to cite this article:|
Fultambkar G, Chavla P, Budi V, Gurram R, Kukreja V, Nair A. A prospective randomized comparative study of dexmedetomidine versus clonidine as an adjunct to 0.75% ropivacaine in ultrasound-guided supraclavicular brachial plexus block. Res Opin Anesth Intensive Care 2022;9:29-36
|How to cite this URL:|
Fultambkar G, Chavla P, Budi V, Gurram R, Kukreja V, Nair A. A prospective randomized comparative study of dexmedetomidine versus clonidine as an adjunct to 0.75% ropivacaine in ultrasound-guided supraclavicular brachial plexus block. Res Opin Anesth Intensive Care [serial online] 2022 [cited 2022 Oct 6];9:29-36. Available from: http://www.roaic.eg.net/text.asp?2022/9/1/29/345279
| Introduction|| |
A properly planned and executed brachial plexus block provides adequate surgical anesthesia and postoperative analgesia for upper limb surgeries. An anesthesiologist needs to identify whether to perform an interscalene supraclavicular, infraclavicular, or axillary block depending on the type of surgery and use of tourniquet .
The supraclavicular brachial plexus block (SCBPB) targets the trunks of brachial plexus and is considerably effective when performed under ultrasound (US) guidance. Complications like phrenic nerve involvement and Horner’s syndrome, which are possible after an interscalene block, are unlikely with SCB. However, hematoma owing to subclavian artery and pneumothorax is possible in inexperienced hands .
Adjuvants like buprenorphine, clonidine, dexamethasone, magnesium, and dexmedetomidine have been successfully used for prolonging duration of analgesia after a peripheral nerve block . Alpha-2 agonists have been quite popular among anesthesiologists owing to its several favorable properties like sedation, analgesia, sympatholysis, cardiovascular stability, and reduction in intraoperative opioid and anesthetic use . Clonidine and dexmedetomidine are alpha-2 agonists that have been used as an adjuvant for central neuraxial blocks, caudal epidural, and upper/lower limb blocks. They have been used by researchers as adjuvants successfully in upper limb blocks in varying doses. Dexmedetomidine is eight times more specific for alpha-2 receptors than clonidine. Most of the studies compared alpha-2 agonist as adjuvant with a control group where no adjuvant was used or with other group of adjuvants ,,,.
We hypothesized adding 1 μg/kg dexmedetomidine as adjuvant to SCB provides longer duration of analgesia when compared with 1 μg/kg clonidine, which was our primary outcome. Secondary outcomes which we planned to investigate were duration of sensory and motor block, degree of motor blockade by modified Bromage scale, numeric rating scale (NRS) scores for 24 h, 24 h rescue analgesic consumption, and any adverse effect or complication after block.
| Materials and methods|| |
Institutional Ethical Committee approval was obtained for this prospective, randomized, and comparative study (IEC-YAMER, DNB-65/2015, approval dated: September 4, 2015). The trial was not registered prospectively in any clinical trial registry. The study included 60 patients belonging to ASA grade I and II of either sex with age between 18 and 60 years posted for various elective upper limb surgery. Patients with American Society of Anesthesiologists’- physical status (ASA-PS) III or beyond, emergency surgeries, age beyond 60 years or less than 18 years, history of hypersensitivity to amide local anesthetics, patients with pre-existing peripheral neuropathy, incapable of providing informed consent, patients with known bleeding disorders, and infection at the site of block were excluded.
A group consisting of 60 patients were randomly divided into two groups as per computer-generated randomization. Patients in group Clonidine-Ropivacaine (CR) received 1 μ/kg clonidine+19 ml 0.75% ropivacaine, and those in group Dexmedetomidine-Ropivacaine (DR) received 1 μ/kg dexmedetomidine+19 ml 0.75% ropivacaine. Group allocation was concealed in sealed, opaque envelopes.
All patients were explained the entire procedure block and NRS, and informed consent was taken. Intravenous access was accesses on the nonoperating hand. Baseline heart rate, blood pressure, and oxygen saturation were recorded. Essential monitoring (heart rate, blood pressure (systolic, mean, and diastolic), continuous ECG monitoring, and oxygen saturation) was established. Equipment and drugs necessary for resuscitation and general anesthesia administration were kept ready. All the patients were monitored during the course with a common protocol. The standardized technique was used in both the groups.
After skin and transducer preparation, a linear-array 6–13-Hz high-frequency US transducer was placed firmly over supraclavicular fossa in the coronal oblique plane to obtain best possible view of subclavian artery and brachial plexus. Brachial plexus was identified as compact group of nerves located over first rib, lateral, and superficial to subclavian artery. Using in-plane approach and after skin infiltration with 2–3 ml of 2% lidocaine with 26 G hypodermic needle, the block was performed with 21 G 100-mm short bevel needle (Stimuplex; B-Braun, Bethlehem, Pennsylvania, USA), advanced along long axis of transducer in same plane as US beam. A negative aspiration for blood was performed before each incremental injection of 5 ml, and a total volume of 19 ml of 0.75% ropivacaine and 1 μg/kg of either adjuvants were injected so as to cause hydrodissection of planes around the plexus. A brief massage for one minute was performed for even drug distribution.
Sensory block was assessed by pin-prick method. Assessment of sensory block was done at each minute after completion of block in dermatomal areas corresponding to median, ulnar, radial, and musculocutaneous nerve. Sensory onset was considered when there was a dull sensation to pin prick along distribution of the aforementioned nerves, and complete sensory block was considered when there was complete loss of sensation to pin prick. Sensory block was graded as follows: grade 0–sharp pin felt; grade 1–analgesia, dull sensation felt; grade 2–anesthesia, and no sensation felt. Duration of sensory block was the time interval between end of local anesthetic administration and complete resolution of anesthesia.
Assessment of motor blockade was carried out each minute till complete motor blockade after drug injection using Modified Bromage scale for upper extremities on a three-point scale – grade 0: normal motor function with full flexion and extension of elbow, wrist and fingers; grade 1: decreased motor strength with ability to move fingers only; and grade 2: complete motor block with inability to move fingers. Duration of motor block was time interval from onset to recovery of complete motor function. Sedation of patients was assessed by Ramsay sedation score 1–anxious or restless or both; 2–co-operative, oriented and tranquil; 3–responding to commands; 4–brisk response to stimulus; 5–sluggish response to stimulus; and 6–no response to stimulus.
Pain was assessed using NRS. Time for first request of first analgesic was noted, that is, duration of analgesia and duration of surgery, which was the primary outcome. The NRS was recorded postoperatively first hour, 2 h, 6 h, and every hour thereafter for 24 h by a blinded investigator. Rescue analgesia planned was intravenous injection of 100 mg tramadol with rescue antiemetic injection ondansetron 0.1 mg/kg. All patients were monitored for adverse effects like nausea, dry mouth, vomiting, and complications like hematoma, pneumothorax, local anesthetic toxicity, and postblock neuropathy. The secondary outcomes were duration of sensory and motor block, degree of motor blockade by modified Bromage scale, NRS scores for 24 h, 24 h rescue analgesic consumption, and any adverse effect or complication after block.
Sample size was decided in consultation with a statistician. After observing results of similar studies (Swami and colleagues), it was considered that a clinically significant benefit of using dexmedetomidine would be a prolongation in sensory block duration by 40% compared with the clonidine group . Based on this, we calculated a sample size that would permit a type I error of α=0.05 and power of 80%. Enrollment of 27 patients in each group was required. Considering the dropouts, 30 patients were selected in each of the group.
Descriptive and inferential statistical analysis was carried out in the present study. Results on continuous measurements are presented as mean±SD, and results on categorical measurements were presented in percentage or absolute numbers. Significance was assessed at 5% level of significance (P<0.05).
Data was entered in Microsoft Excel sheet (Redmond, Washington, USA). Unpaired t-test was used to find the significance of study parameters on continuous scale between two groups on metric parameters. Fisher’s exact test was used to analyze categorical data. Statistical analysis was performed using GraphPad Prism 5 for Windows (GraphPad Software, La Jolla, California, USA).
| Results|| |
We recruited 60 patients in this study, that is, 30 patients in each group. None of the 60 patients were excluded from analysis. [Figure 1] shows Consolidated Standards of Reporting Trials (CONSORT) diagram ([Figure 1]). Demographic data between two groups were comparable and are depicted in [Table 1]. Hemodynamics (heart rate and mean arterial pressure) were compared between both groups at baseline, 15 min, 30 min, 1 h, 2 h, and 3 h. Mean heart rate in group DR was lower at 30 min, 60 min, 2 h, and 3 h than patients in group CR, which was statistically significant (P=0.0001, 0.0001, 0.021, and 0.026, respectively). However, the mean arterial pressure at all time frames was comparable in both groups and thus was not statistically significant ([Table 2]).
Onset of block (sensory and motor) was 5.233±1.569 min and 14.467±2.98 in group DR, respectively, and in group DR, it was 9.533±2.583 min and 10.233±1.755, respectively, which was statistically significant (P=0.00) ([Figure 2]a and b). Similarly, duration of block (sensory and motor) was 908.500±110.15 min and 812.5±101.623 in group DR compared with 596.533±67.03 min and 554.167±72.731 min in group CR, which was statistically significant (P=0.00) ([Figure 3]a and b). Duration of analgesia was more in group DR compared with group CR (1012.5±128.605 vs. 653.6±68.248 min), which was statistically significant (P=0.00) ([Figure 4]). Number of rescue analgesic required in group DR was lesser than in group CR (1.733±0.691 vs. 2.033±0.490), which was not significant ([Table 3]).
|Figure 2 (a) Box and whisker plot showing comparison of onset of sensory block in both groups. (b) Box and whisker plot showing comparison of onset of motor block in both groups.|
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|Figure 3 (a) Box and whisker plot showing comparison of duration of sensory block in both groups. (b) Box and whisker plot showing comparison of duration of motor block in both groups.|
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|Figure 4 Box and whisker plot showing comparison of duration of analgesia between both groups.|
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|Table 3 Comparison of various block characteristics like onset of block (sensory, motor), duration of block (sensory, motor), duration of analgesia and number of rescue analgesics required|
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Ramsay sedation score documented at 15 min, 30 min, 1, 2, and 3 h postoperatively was comparable in both groups. NRS were charted immediate postoperatively, at 60 min, and then at 3, 6, 12, 18, and 24 h postoperatively. NRS scores immediate postoperatively, at 60 min, and 3 h were similar and thus not significant. Mean NRS at 12, 18, and 24 h was better in group DR compared with group CR and was statistically significant (P=0.0001, 0.039, and 0.036, respectively) ([Table 4]).
| Discussion|| |
Based on the analysis of our results, we found that addition of 1 μ/kg dexmedetomidine as adjuvant to 0.75% ropivacaine in SCBPB produces faster onset of sensory and motor blockade, prolongs duration of sensory and motor blockade, and also prolongs duration of analgesia, when compared with 1 μ/kg clonidine.
At supraclavicular fossa, brachial plexus elements are arranged very compactly in the form of trunks. The supraclavicular approach has a high success rate as it blocks the ulnar and musculocutaneous nerve, which can be missed using interscalene and axillary approaches, respectively . Therefore, this approach is employed for various upper limb surgeries with reasonable success. However, proximity of pleura during needle placement while performing this block using landmark and neurostimulation technique has been of concern . Use of ultrasonography (USG) has not only increased the safety of this approach as pleura and vessels are visible during real time injection but has also improved the success of the block ,.
Several adjuvants are used in the local anesthetics injected during peripheral nerve block to prolong the duration of analgesia after a block. The most commonly used adjuvants are fentanyl, morphine, buprenorphine, epinephrine, clonidine, dexmedetomidine, dexamethasone, and magnesium . In this study, we compared the two alpha-2 agonists, namely, clonidine and dexmedetomidine, as adjuvants to US-guided SCBPB as sole anesthetic in patients undergoing upper limb surgeries.
Clonidine is an alpha-2 agonist which is a part of multimodal analgesia armamentarium since long. Clinicians have used clonidine in several routes like intravenously, intrathecal, epidural, as adjuvant to peripheral nerve blocks with reasonable success . Dexmedetomidine is another alpha-2 agonist approved by US-Food and Drug Administration for sedation of intubated and mechanically ventilated patients in the intensive care unit and periprocedural (or perioperative) sedation of nonintubated patients . Dexmedetomidine is approximately eight times more selective toward the α-2 adrenoreceptors when compared with clonidine .
Clonidine has been used successfully as an adjuvant to various PNBs. In a meta-analysis of randomized controlled trials, Pöpping and colleagues concluded that clonidine as an adjuvant to PNB prolonged duration of analgesia at the cost of hypotension, bradycardia, and sedation. They however mentioned that dose-responsiveness was not clear based on available data . In a qualitative systematic review by McCartney and colleagues authors concluded that when used as an adjuvant clonidine prolonged duration of analgesia and anesthesia for some peripheral nerve blocks. Adverse effects like bradycardia, hypotension, and sedation were observed when used at a dose of 150 μg . When used as an adjuvant to peripheral nerve block, dexmedetomidine has demonstrated faster onset and prolonged duration of block, reduced perioperative opioid consumption, and better quality of analgesia. This was concluded in the systematic review and meta-analysis by Abdallah and colleagues and Hussain and colleagues. They cautioned regarding monitoring for bradycardia with the use of dexmedetomidine as adjuvants ,.
Both clonidine and dexmedetomidine have been used extensively and successfully as an adjuvant to intrathecal anesthesia. In a meta-analysis of randomized controlled trials, Zhang et al.  concluded that when compared with clonidine, the use of dexmedetomidine as an adjuvant to local anesthetics was associated with earlier, prolonged sensory block characteristics, and late rescue analgesic requirements. Researchers also compared clonidine and dexmedetomidine as an adjuvant to epidural analgesia. Dexmedetomidine was found to be a superior adjuvant compared with clonidine in terms of onset of analgesia, patient comfort, and requirement of rescue analgesia for vaginal hysterectomies and lower limb surgeries ,,. However, when caudal epidural clonidine versus dexmedetomidine was compared in pediatric patients undergoing lower abdominal surgeries, there was no difference . Dexmedetomidine fared well as a component of intravenous regional anesthesia also, as it hastened onset, prolonged recovery of sensory and motor block, and also prolonged duration of analgesia when compared with clonidine . In another study, Mostafa et al.  compared dexmedetomidine with clonidine as adjuvants to levobupivacaine for US-guided transversus abdominis plane block in pediatric laparoscopic orchiopexy (three groups, 30 patients in each group: clonidine, dexmedetomidine, and saline). The authors concluded that by adding dexmedetomidine to levobupivacaine there was prolonged duration of analgesia and reduced use of postoperative analgesics with minimal sedation.
Chaudhary et al.  compared clonidine and dexmedetomidine as adjuvants to levobupivacaine in 90 patients who received US-guided femorosciatic nerve block for postoperative analgesia after below-knee orthopedic surgeries under subarachnoid block (30 in each group: saline, 0.5 μg/kg clonidine and dexmedetomidine, a total volume of 40 ml). Authors concluded that equal doses of clonidine or dexmedetomidine added to levobupivacaine prolonged the duration of analgesia and decreased requirement of rescue analgesia. However, dexmedetomidine delayed the requirement of rescue analgesics with better pain scores as compared with clonidine.
Several studies have compared dexmedetomidine and clonidine as adjuvants to upper limb blocks. Swami and colleagues compared 1 μg/kg clonidine with 1 μg/kg dexmedetomidine as an adjuvant to supraclavicular block in 60 patients undergoing elective upper limb surgeries. They concluded that as an adjuvant dexmedetomidine enhanced duration of sensory and motor block, prolonged time for rescue analgesia, and provided better quality of block. Here, authors used a total volume of 35 ml and used 0.25% bupivacaine. All blocks were performed using a nerve stimulator . In a study comparing 1 μg/kg clonidine versus dexmedetomidine as an adjuvant to supraclavicular block, Tripathi and colleagues found that there was no statistically significant difference in the onset of sensory and motor block in both the groups . However, the duration of analgesia and quality of anesthesia was better with dexmedetomidine than clonidine. However, the authors used a volume of 40 ml for the block which was performed with neurostimulation assistance. Our study was different from the aforementioned studies in various aspects. We performed the block using ultrasonography (USG); the volume used was 20 ml and the drug used was 0.75% ropivacaine instead of 0.25% bupivacaine. El-Boghdadly and colleagues performed a systematic review and meta-analysis to compare clinical efficacy of perineural clonidine versus dexmedetomidine in patients undergoing orthopedic surgery with supraclavicular block . They analyzed data of 868 patients from 14 studies. The authors concluded that perineural dexmedetomidine enhanced sensory, motor, and analgesic block characteristics compared with clonidine when used perineurally.
There were limitations to this study. Parameters like heart rate, MAP, and Ramsay sedation score were monitored and documented for first 3 h only. Thereafter, patients were shifted out to inpatient ward where we did not monitor hemodynamics or sedation due to logistics. However, pain scores were monitored and charted for the first 24 h. Clonidine and dexmedetomidine are not approved for peripheral nerve blocks, and its neurotoxic potential is not clear. We did not monitor or follow up our patients for evaluating neurotoxicity which is a major limitation. However, we conducted this study based on earlier research work and also had our Ethics Committee Approval.
To conclude, dexmedetomidine provided faster onset of sensory and motor blockade, prolonged duration of sensory and motor blockade, and also prolonged duration of analgesia when added as an adjuvant to 0.75% ropivacaine in US-guided SCBPB for upper limb surgeries when compared with clonidine.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4]