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ORIGINAL ARTICLE
Year : 2020  |  Volume : 21  |  Issue : 2  |  Page : 109-113
 

Comparative study of bupivacaine with dexmedetomidine as an adjuvant versus bupivacaine alone in ultrasound-guided supraclavicular brachial plexus block


1 Department of Anaesthesiology, ESIC Medical College, Bengaluru, Karnataka, India
2 Department of Anaesthesiology, Rajarajeshwari Medical College, Bengaluru, Karnataka, India

Date of Submission06-Mar-2020
Date of Decision15-Apr-2020
Date of Acceptance02-May-2020
Date of Web Publication19-Sep-2020

Correspondence Address:
Dr. Rashmi
No. 14, 15 Main, J C Nagar, Kurubarahalli, Bengaluru - 560 086, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/TheIAForum.TheIAForum_23_20

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  Abstract 

Background: Skillful usage of adjuvants in peripheral nerve blocks can resolve the key issue of postoperative pain. This study was conducted to compare the effects of dexmedetomidine as an adjuvant with bupivacaine in terms of the duration of analgesia (DOA), onset and duration of sensory and motor block.
Materials and Methods: This prospective, randomized, double-blind trial consists of total 72 patients undergoing elective upper limb elective procedures, divided into two groups, 36 in each. Group-C received ultrasound-guided (USG) supraclavicular brachial plexus block using injection 0.25% bupivacaine 20 ml + 0.9% normal saline diluted to total 22 ml and Group D received USG supraclavicular brachial plexus block using injection 0.25% bupivacaine 20 ml + dexmedetomidine 1 μg/kg diluted to total of 22 ml with 0.9% normal saline. The parameters recorded were onset and duration of sensory and motor block, DOA, and side effects.
Results: In both the groups, demographic data were similar. Sensory and motor block onset was significantly shorter (P < 0.05) in Group D than Group C, while the duration of blocks and DOA was prolonged in Group D (P < 0.05). Intraoperative hemodynamics were significantly lower in Group D except in two patients, who had bradycardia and were treated.
Conclusion: Dexmedetomidine as an adjuvant to bupivacaine in USG supraclavicular plexus block shortens the onset and prolongs the duration of sensory and motor block and DOA.


Keywords: Bupivacaine, dexmedetomidine, supraclavicular brachial plexus block, ultrasound guided


How to cite this article:
Manjunatha C, Srinivas Prasad CG, Rashmi. Comparative study of bupivacaine with dexmedetomidine as an adjuvant versus bupivacaine alone in ultrasound-guided supraclavicular brachial plexus block. Indian Anaesth Forum 2020;21:109-13

How to cite this URL:
Manjunatha C, Srinivas Prasad CG, Rashmi. Comparative study of bupivacaine with dexmedetomidine as an adjuvant versus bupivacaine alone in ultrasound-guided supraclavicular brachial plexus block. Indian Anaesth Forum [serial online] 2020 [cited 2020 Oct 20];21:109-13. Available from: http://www.theiaforum.org/text.asp?2020/21/2/109/295394



  Introduction Top


Ultrasound-guided (USG) nerve blocks play an important role in modern regional anesthesia. These not only provides intraoperative anaesthesia and also postoperative analgesia without major systemic side effects.[1]

Local anesthetics when used alone for supraclavicular brachial plexus block provide good operative conditions, but have shorter duration of postoperative analgesia. Hence, various adjuvants such as opioids,[2] clonidine,[3] dexamethasone, midazolam, and fentanyl[4],[5],[6] are added to local anesthetics in brachial plexus block to achieve quick, dense, and prolonged block.

Dexmedetomidine, an α2 adrenergic receptor agonist with α2:α1 selectivity ratio of 1600:1, has been used as a safe adjuvant in diverse clinical applications.[7] This increased selectivity results in more predictable and effective analgesia with fewer side effects. It is increasingly being used nowadays for regional anesthesia, intravenous aesthesia (Bier's block), sedation and analgesia for mechanically ventilated patients in intensive care units.[8] Recently, its use in peripheral nerve blocks has been described. The present study has been undertaken to evaluate the effect of dexmedetomidine as an adjuvant with bupivacaine for USG supraclavicular brachial plexus block.


  Materials and Methods Top


This prospective, randomized, double-blind, comparative study was undertaken after approval of institutional research and ethics committee. Following a detailed pre-anesthetic checkup, informed written consent was obtained from patients fulfilling the inclusion criteria: the American Society of Anesthesiologists (ASA) physical Status I or II, age 18–60 years of either gender, elective orthopedic or plastic surgery procedures on the right upper limb. Patients with ASA physical Status III and IV with a history of significant neurological, psychiatric, neuromuscular, cardiovascular, renal and hepatic disease, alcoholism, drug abuse, on adrenergic receptor agonist or antagonist therapy, with known hypersensitivity to local anesthetic drugs, bleeding disorders, uncontrolled diabetes mellitus, and pregnant women were excluded.

Randomization was done by computer-generated randomized number table. Random number was enclosed in a sealed opaque envelope and opened by one of the investigators to know the study drug/combination to be administered just before the block. Observer anesthesiologist was blind to the test drug/combination.

A total of 72 patients were randomly allocated into two groups 36 in each namely, Group C received injection bupivacaine (0.25%) 20 ml + 0.9% normal saline diluted to total 22 ml, and Group D received injection bupivacaine (0.25%) 20 ml + dexmedetomidine 1 μg/kg, diluted to total of 22 ml with 0.9% normal saline.

Before performing the procedure venous cannula 18 gauze was secured in opposite hand and routine monitors such as pulse oximetry, noninvasive blood pressure, and electrocardiogram were attached and baseline readings were noted. Injection midazolam, intravenous (i.v) one mg was given to all patients. Procedure was done in supine position with arms adducted. USG supraclavicular brachial plexus block was performed under all aseptic precautions with 22 G echogenic needle using linear probe 8–12 Hz of ultrasound machine (MINDRAY M7). Time of drug injection was recorded.

Sensory block was assessed by pinprick method in the dermatomal areas corresponding to median nerve, radial nerve, ulnar nerve, and musculocutaneous nerve. Onset of sensory block was considered when there is a loss of sensation to pin prick (analgesia) in any of the segment supplied by the nerves. Sensory block is graded as: Grade 0 – normal sensation, Grade 1 – loss of sensation to pin prick (analgesia), and Grade 2 – loss of sensation to touch (anesthesia).

Onset of motor blockade was considered when there was Grade 1 motor blockade. Motor blockade was determined according to modified “Bromage scale”[9] for upper extremities on a 3-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 the fingers only
  • Grade 2 – Complete motor block with inability to move the fingers.


The block was considered failed, when there was no analgesia even after 30 min of drug injection in any of the segments supplied by the four nerves and these patients received general anesthesia. The block was considered incomplete, when there was no analgesia even after 30 min of drug injection in any one of the segments supplied by the four nerves. These patients were either supplemented with additional dose of injection fentanyl 1 μgm/kg and injection midazolam 0.02 mg/kg or general anesthesia was given.

The duration of sensory block was defined as the time interval between the end of local anesthetic administration and complete resolution of sensory block of all nerves. The duration of motor block was defined as the time interval between the end of local anesthetic administration and the recovery of complete motor function of the hand and forearm.

The patient's hemodynamic variables such as heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and oxygen saturation (SPO2) were monitored every 5 min after administration of supraclavicular block for 30 min, then at 45, 60, 90, and 120 min interval. HR of <60 considered as bradycardia and treated with atropine 0.2 mg i.v. Blood pressure of <20% of baseline considered as hypotention and treated with mephentermine 6 mg i.v. bolus along with intravenous fluids.

Postoperatively, pain was assessed by visual analog scale (VAS) from 0 to 10 (0 = No pain, 10 = Worst pain), at every 15 min interval up to 120 min after administration of supraclavicular block. Injection paracetamol one gram i.v. was given when VAS ≥3 (rescue analgesia). The time between the complete sensory block and the first rescue analgesia is considered as DOA.

Patients were observed for any side effects such as nausea, vomiting, dryness of the mouth and complications as pneumothorax, hematoma, local anesthetic toxicity, and postblock neuropathy in the intraoperative and postoperative period.

Statistical analysis

The sample size was calculated based on the DOA obtained by Agarwal et al.,[10] to detect a difference of 15%, with power as 80% and confidence interval [CI] as 95%. The sample size obtained was 34. To allow dropouts, 36 patients were enrolled in each group.

All data were analyzed with SPSS version 21.0 software (IBM Corp., Released 2015. IBM SPSS Statistics for Windows, Version 23.0; Armonk, NY, USA). Continuous variables were presented as mean, for parametric data and median if data are nonparametric or skewed. Student's t-test or Mann–Whitney test was applied for the calculation of statistical significance when the data followed normative or nonnormative distribution, respectively. Categorical variables were expressed as frequencies and percentages. Nominal categorical data between the groups were compared using Chi-square test or Fisher's exact test as appropriate. P < 0.05 was considered statistically significant.


  Results Top


The demographic data were comparable in both the groups [Table 1]. The results regarding the characteristics of sensory block and motor block are summarized in [Table 2]. Both onset and duration of sensory and motor blocks in Group D was statistically significant (P <0.05). DOA in Group D (1094 ± 132.8 min) was prolonged compared to Group C (711 ± 108.7 min), which is found to be significant statistically [Table 2]. HR in Group D was significantly lower than in Group C, except at 0, 5, 10, and 15 min after administration of block [Figure 1]. SBP and DBP were significantly lower in Group D after 5 min of block administration than in Group C [Figure 2]. Only two patients in Group D had bradycardia, treated with injection atropine i.v. and there was no sequelae. No other side effects were found in either group. There was one failure in Group C and two in Group D.
Table 1: Demographic data in both the groups

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Table 2: Characteristic of blocks in both the groups


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Figure 1: Comparison of mean heart rate in both groups

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Figure 2: Comparison of mean SBP and DBP in both groups

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  Discussion Top


Supraclavicular blocks are performed at the level of the brachial plexus trunks. Here, almost the entire sensory, motor and sympathetic innervations of the upper extremity are carried in just three nerve structures (trunks). Local anesthetics alone for supraclavicular brachial plexus block provide good operative conditions but have a shorter duration of postoperative analgesia. Different authors have used various local anesthetic agents (bupivacaine, levobupivacaine, ropivacaine, lignocaine) with varying volume and concentration. Chakraborty et al.[11] observed the effect of clonidine as an adjuvant in 0.5% 25 ml of bupivacaine-induced supraclavicular brachial plexus block. Esmaoglu et al.[8] studied the effect of mixing dexmedetomidine to 0.5% 45 ml of levobupivacaine for axillary brachial plexus blockade.

Additives such as opioids, benzodiazepines, dexamethasone, dexmedetomidine, and clonidine are used to prolong the analgesia.[4],[5],[6] Dexmedetomidine has been used as an additive to improve the effect of local anesthetics for brachial plexus block with dose varying from 1-μg/kg to fixed dose of 100 μg in adults.[10],[12],[13] Different doses have been recommended for intravenous, intrathecal, epidural, and peripheral nerve block.[14] As our study involved USG supraclavicular approach to brachial plexus block, we used 1 μg/kg of dexmedetomidine as an adjuvant with 20 ml of 0.25% of bupivacaine.

The procedure was done by same anesthesiologist to overcome various access approaches, patient position, technique, and individual expertise. The demographic profiles were comparable in both the group.

In our study, the onset time of sensory and motor block was shorter in Group D than in Group C, which was significant (P <0.05). Our results concur with study of Agarwal et al.,[10] and Ammar and Mahmoud.[12] However, there is wide variation in the onset time in different studies. These variations must be interpreted in the light of differences in the nature of local anesthetics, their concentration and volumes, dose of dexmedetomidine, and nature of blocks. Agarwal et al.[10] used dexmedetomidine 100 μg or 1 ml saline with 30 ml of 0.325% bupivacaine for supraclavicular block. Ammar and Mahmoud[12] compared bupivacaine 0.33% with dexmedetomidine 0.75 μg/kg for infraclavicular brachial plexus block against plain bupivacaine.

The duration of sensory and motor block was prolonged (863.8 ± 106.8 min and 758. 5 ± 121.6 min) in Group D compared to (335.6 ± 58.6 min and 308.4 ± 71.8 min) Group C, respectively, which was significant statistically (P <0.05). Our results coincides with the study of Agarwal et al.,[10] and Esmaoglu et al.,[8] This increased duration of motor block could be because of direct impairment of excitatory amino acid release from spinal interneurons.[15] Abdallah and Brull[16] conducted a systematic review and meta-analysis to determine the facilitatory effects of perineural dexmedetomidine as a local anesthetic adjuvant for neuraxial and peripheral nerve block. A total of 516 patients were analyzed from 9 randomized control trials. Out of 9, 5 trials were for spinal anaesthesia and 4 trials for brachial plexus block. Sensory block and motor block duration was prolonged for both intrathecal and brachial plexus block. They concluded that dexmedetomidine is a potential local anesthetic adjuvant that can exhibit a facilitatory effect on intrathecal and brachial plexus block.

DOA in our study was statistically significant. Group D DOA was 1094 ± 132.8 min, which was much longer when compared to Group C, i.e. 711 ± 108.7 min there by reducing the requirement of analgesic drugs in postoperative period. The increased duration may be due to peripheral alpha 2 agonist action releasing norepinephrine resulting in alpha 2 receptor independent inhibitory effect on nerve fiber action potential. The analgesic action is dose dependent.[11] Abdallah and Brull[16] in their meta-analysis review also concluded longer DOA in dexmedetomidine group. Tripathi et al.,[17] in their study of clonidine and dexmedetomidine as an adjunct to bupivacaine in supraclavicular brachial plexus block found DOA was 349.33 ± 42.91 min in clonidine with local anesthetic group and 525.33 ± 42.89 min in dexmedetomidine with local anesthetic group, respectively. Several studies have found dexmedetomidine to extend the DOA but there is wide variation in the DOA ranging from 403 min to 1279 min.[8],[12],[13] This may be attributed to variations in the dosage and concentration of local anesthetic drug and dose of dexmedetomidine used.

Only two patients in our study had bradycardia in Group D, were treated with injection atropine-i.v. HR and blood pressure were lower in Group D compared to Group C, except for initial few minutes, but not more than 20% of baseline value and this gave a good surgical field by reducing blood loss. The decrease in blood pressure is due to the inhibition of central sympathetic outflow. The presynaptic alpha-2 receptors are also stimulated by dexmedetomidine, thereby decreasing norepinephrine release and causing a fall in blood pressure and HR.[18],[19] Esmaoglu et al.,[8] reported 7 incidence of bradycardia. In the study of Aggarwal et al.,[10] and Kaygusuz et al.,[20] dexmedetomidine provided better hemodynamic stability.

No other side effects such as nausea, vomiting, local anesthetic toxicity, hematoma, and respiratory depression were found in either of the groups. In our study, one patient in Group C and two patients in Group D received general anaesthesia because of block failure.


  Conclusion Top


USG supraclavicular block using dexmedetomidine with bupivacaine improves the effect of block by reducing onset of sensory and motor block, prolonging duration of sensory and motor block and DOA with hemodynamic stability and minimal side effects.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflict of interest.

 
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Kaygusuz K, Kol IO, Duger C, Gursoy S, Ozturk H, Kayacan U, et al. Effects of adding dexmedetomidine to levobupivacaine in axillary brachial plexus block. Curr Ther Res Clin Exp 2012;73:103-11.  Back to cited text no. 20
    


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