The supraclavicular block is used extensively and effectively for the distal upper extremity surgical operation [
2Using additive drugs in local anesthetic can reduce the dosage of local anesthetic drugs for nerve block and reduce the probable side effects of these drugs, and increasing the benefits of adjuvant drugs can be used. The new drugs have been used in this field, including buprenorphine [
Bupivacaine is a potent local anesthetic with unique characteristics from the amide group of local anesthetics, which was first discovered in 1957 and widely used for prolonged local and regional anesthesia. [
The dexmedetomidine is an active D-isomer of medetomidine and is similarly related to clonidine. Dexmedetomidine is a specific Alpha2 agonist with an
Some studies have been conducted on the use of local anesthetics with additive agents [
This randomized, double-blind prospective clinical trial study was approved by the Research and Ethics Committee of the Urmia University of Medical Sciences (IR.UMSU.REC.1397.181) and registered in the Iranian Registry of Clinical Trials (IRCTID:
All patients were visited by an anesthesiologist the day before the surgery. All patients were adequately explained and educated about the visual analog scale (VAS) (zero: no pain and ten: the worst pain ever experienced). In this study, patients were excluded from the study with the following criteria: the history of central nervous system disease or neuromuscular disorders; psychiatric; renal dysfunction; respiratory disease; cardiovascular disease; hepatic disease; pregnant women, lactating mothers; a history of allergy to any drugs, diabetics; patients who were contraindicated for performing a supraclavicular block such as coagulopathy; local infection; and patients’ dissatisfaction of technique.
Intervention group: patients in the dexmedetomidine group (intervention group) received 39 ml of bupivacaine (0.25%) + 0.75
Control group: patients in the control group, received 39 ml of 0.25% bupivacaine + 1 ml normal saline (total volume 40 ml).
Patients were kept fasting for at least 8 hours before surgery. The patients, surgeons, and anesthesiologists were blinded to the division of the groups.
A standard pulse oximetry monitor, a noninvasive blood pressure measurement system, and an electrocardiogram were attached to patients in the operating room. Baseline heart rate, blood pressure, and oxygen saturation were recorded. After inserting an 18 cm venous catheter on the nonoperative arm before performing supraclavicular block, all patients premedicated with midazolam 0.04 mg/kg and received oxygen 5 L/min. They were placed in the supine position and slightly turned 45° their heads to the contralateral side. The upper arm was abducted at 90°. All aseptic precautions were conducted before performing the procedure. The supraclavicular plexus site was determined using a nerve stimulator (Stimuplex; B. Braun Melsungen, Melsungen, Germany) attached to a 22-gauge, 55 mm long stimulating needle (Stimuplex D; B. Braun Melsungen, Melsungen, Germany) under ultrasonic apparatus. The needle’s location was considered acceptable when the output current of 0.5 mA still produced a suitable motor response in the distal of the limb.
The solution was injected under the guidance of the ultrasonic apparatus. Sensory and motor blocks were assessed every 3 min to the first 30 minutes after full drug injection. The surgery was allowed when the block was determined to be sufficient.
All vital parameters, including HR, NIBP, RR, and SPO2, were recorded in the checklist every 5 min to the first 30 min and then every 10 min to the end of surgery.
Sensory and motor block and vital signs were measured instantly after surgery in the recovery room (where the block was done). Sensory blockade of each nerve evaluated by pinprick method in sensory dermatomes related to the sensory areas and graded as score 0 = no sensation score 1 = dull sensation score 2 = sharp pain felt [
Based on the Tripathi et al. study in 2016 [
The patient’s demographics data in the two groups are presented in Table
Studied patients' demographic data and surgical characteristics.
Intervention group | Control group | ||||
---|---|---|---|---|---|
Gender (F/M) | Female | Male | Female | Male | 0.133 |
12 | 18 | 7 | 23 | ||
Age (year) | 39.5 ± 14.9 | 34.7 ± 10.8 | 0.165 | ||
Kind of surgery | Soft tissue | Bone tissue | Soft tissue | Bone tissue | 0.398 |
14 | 16 | 16 | 14 | ||
Weight (kg) | 76.72 ± 18.9 | 73.75 ± 24.9 | 0.9 |
Values are mean ± SD or number of patients and kind of surgery. There are no significant differences between the two groups. Intervention group = dexmedetomidine + bupivacaine and control group = bupivacaine alone.
The onset time of the upper extremity sensory block in the intervention group was shorter than the control group, and this difference was significant (
According to the nonnormal distribution of data in the Mann–Whitney test, the mean score of the sensory block in the control group was 31.25 with a total of 937.5 and in the intervention group, the mean score and the total score were respectively 29.75 and 892.5. This difference was not significant (
Patients’ supraclavicular block characteristics in two groups.
Control group | Intervention group | ||
---|---|---|---|
Onset time of motor block | 24.66 ± 9.2 min | 15.93 ± 6.36 min | |
Onset time of sensory block | 31.03 ± 9.65 min | 21.36 ± 8.34 min | |
Duration time of motor block | 317 ± 10.52 min | 488 ± 157.5 min | |
Duration time of sensory block | 333.5 ± 94.35 min | 475 ± 137.5 min | |
First analgesia request | 308 ± 109. 14 min | 458 ± 205/43 min | |
Score of sensory block | 31.25 | 29.75 | |
Score of motor block | 35.58 | 25.42 |
Values are mean ± SD or mean of sensory and motor block score. Intervention group = dexmedetomidine + bupivacaine and control group = bupivacaine alone.
The mean score of the motor block (Bromage score) in the control group was 35.58 with a total score of 10.567, and in the intervention group, the mean score was 25.42 with a total score of 765.5. This difference was statistically significant (
In the bupivacaine group, the duration time of sensory block in the upper extremity was 333.5 ± 94.35 min, and in the intervention group, it was 475 ± 137.5 minutes. In the intervention group, the duration time of anesthesia was longer than the control group, and this difference was statistically significant (
In the control group, the duration time of motor block was 317 ± 10.52 minutes, and in the intervention group, it was 488 ± 157.5 minutes, and this difference was significant (
The first analgesia request in the control group was 308 ± 109.14 minutes, and in the intervention group, it was 458 ± 205/43 minutes. The first analgesic request in the intervention group was more than the control group, and this difference was significant (
Study flow diagram.
The mean of heart rate variations at the outset and the end of the surgical procedure was reduced in both groups: in the intervention group, it was 72.45 ± 8.05 beats and in the control group, it was 76.3 ± 14.4 beats. In the conducted independent
The mean of heart rate variations in both groups during the study period. ∗
The mean arterial pressure changes during surgery in the intervention group were 83.24 ± 11.36 mm Hg. The control group was 76.93 ± 10.06 mm Hg, which in conducted independent
Mean arterial pressure during surgery in both groups during the study period. ∗
Mean pain score based on VAS after surgery; at recovery; and 6 hours, 12 hours, and 24 hours after surgery in the control group (receiving bupivacaine alone) were 0.633, 2.633, 3.313, 6.017, and 5.11, respectively and in the intervention group (bupivacaine + dexmedetomidine), they were 0.47, 1.14, 3.23, 5.12, and 3.92, respectively (Figure
Comparison of visual analog scale (VAS) of pain in patients' groups within 24 hours after surgery. The VAS score in all hours of study in the intervention group was lesser than the control group and it was significant
Hypotension occurred in 3 patients in both intervention and control groups that were not statically significant (
Frequency of complications in two groups. The difference in all of the side effects frequency was not significant (
Rapid onset time and prolonged analgesia and motor block without adverse effects highlighted an ideal local block. Hence, many various drugs have been added to topical anesthetic drugs as an adjuvant. Clonidine has been used as an
The activation of the presynaptic receptor in the central nervous system prevents the norepinephrine release and pain signals [
In the Gandhi et al. study in 2012 conducted on 70 patients, the sensory block’s onset time was shorter in the bupivacaine group than bupivacaine with dexmedetomidine. Also, in the control group, the motor block’s onset time was faster than the dexmedetomidine group. In the dexmedetomidine group, the duration time of sensory and motor block was prolonged. Mean arterial pressure and heart rate variations were similar between the two groups, and the duration time of analgesia in the control group was shorter than the intervention group (dexmedetomidine) [
In this study, the reason for the earlier onset of the motor block than a sensory block is motor fibers’ presence in the nerves’ outer layers in front of the central sensory fibers. Winnie and Nader explained the study [
Bharti et al. conducted a study on 60 patients in two groups: control group (ropivacaine and lidocaine with adrenaline) and intervention groups (dexmedetomidine 1
In a recent meta-analysis conducted by Abdallah and Brull, adding dexmedetomidine to other drugs has been reported to prolong the brachial plexus’ motor block and prolonged the postoperative analgesia [
In separate studies conducted by Kathuria et al., dexmedetomidine with ropivacaine had improved the onset time of sensory and motor block. It increased the duration time sensory block and motor block compared with ropivacaine [
In our study, dexmedetomidine reduced sensory and motor blocks’ onset time and increased sensory and motor blocks’ duration time. This finding was similar to previous studies. The decrease of the onset time of sensory and motor block in the present study and the inconsistent results of previous studies due to the use of multiple drugs at the same time and the difference in the definition of the onset time of sensory and motor block, however, in Gandhi’s study did not provide a precise definition of the onset time of sensory and motor block [
In explaining dexmedetomidine’s mechanism in previous studies on rats, cationic hyperpolarization blocks and maintenance of nerve stimulation have been attributed to prolonged sensory and motor blocks [
In another study conducted by Fritsch et al. in 2014, they have reported the use of dexmedetomidine with ropivacaine in interscalene block, decreasing postoperative pain and prolonged block time [
Postoperative pain score in all hours of the present study in the intervention group was lesser than the control group. In Bharti et al.’s study, pain score was comparable among groups except at 8 and 10 hours, and pain scores were lower in the dexmedetomidine group versus the control group [
Hypotension and bradycardia are the most common side effect observed with
In our study, bradycardia was observed in 4 of the 30 patients in the intervention group, which seems to be due to the low dose of dexmedetomidine. Hypotension in 3 patients has occurred in both groups, and this difference was not statistically significant. However, in previously conducted studies, the use of dexmedetomidine was not associated with hypotension and bradycardia [
Dexmedetomidine with bupivacaine in the supraclavicular block effectively reduced the onset time of sensory and motor blocks. It increased sensory and motor blocks’ duration time without considerable side effects such as hypotension and bradycardia. Besides, dexmedetomidine significantly reduced postoperative pain in the dexmedetomidine with the bupivacaine group.
Our study’s limitations were the no measurement of dexmedetomidine serum dose during surgery that would make the evaluation of this drug’s systemic effect unpredictable after local absorption and evaluation of another group of patients with receiving intravenous dexmedetomidine in future studies will resolve this restriction.
Increased surgery duration and general anesthesia needs were other limitations of the present study, leading to the exclusion of these cases.
All relevant data are included in the article. Additional information is available from the corresponding author on reasonable request.
Ethical approval was obtained from the Research and Ethics Committee (IR.UMSU.REC.1397.181) of the Urmia University of Medical Sciences, Urmia, Iran. The trial was registered in the Iranian Registry of Clinical Trials (IRCTID:
Before the trial was started, all participating patients signed an informed consent form.
The authors have no conflicts of interest.
The study concept was designed by Shahryar Sane, Shahram Shokouhi, and Behzad Kazemi Haki. Shahryar Sane, Parang Golabi, Mona Rezaeian, and Behzad Kazemi Haki participated in the study design. Shahram Shokouhi, Parang Golabi, Mona Rezaeian, and Behzad Kazemi Haki drafted the manuscript. Shahryar Sane, Shahram Shokouhi, Parang Golabi, and Behzad Kazemi Haki performed the manuscript’s critical revision. All authors read and approved the final manuscript.
The authors thank the Urmia University of Medical Sciences and all the colleagues who helped them with the project.