|Year : 2020 | Volume
| Issue : 1 | Page : 25-30
Comparative study between dexmedetomidine and fentanyl added to bupivacaine for ultrasound-guided brachial plexus block
Mamdouh E Lotfy, Nagwa M Doha, Abd-Elazeem A Elbakry, Sohila S Mohamed
Anesthesia Department, Faculty of Medicine, El Menoufia University, Al Minufya, Egypt
|Date of Submission||10-Nov-2018|
|Date of Acceptance||19-Sep-2019|
|Date of Web Publication||16-Apr-2020|
MBBCH Sohila S Mohamed
Yassine Abd El Ghafar Street, Anesthesia Department, Faculty of Medicine, Al Minufya, 32511
Source of Support: None, Conflict of Interest: None
Background Ultrasonic guided supraclavicular brachial plexus block provides complete and reliable anesthesia for upper limb surgeries. Adjuvants to regional blocks can affect the block characteristics.
Aim To evaluate supraclavicular block characteristics and adverse effects of the addition of dexmedetomidine or fentanyl to bupivacaine 0.5% in patients undergoing elective upper limb surgeries.
Patients and methods This prospective double-blind trial was conducted on 90 patients scheduled for upper limb surgeries randomized into three equal groups. The patients in group C received 30 ml 0.5% bupivacaine with 1 ml normal saline, in group F received 30 ml bupivacaine 0.5% with fentanyl 50 µg (1 ml), whereas in group D received 30 ml bupivacaine 0.5% with dexmedetomidine 75 µg (1 ml). Sensory and motor block characteristics were assessed as well as the hemodynamics, adverse effects, and complications.
Results Group D showed significantly rapid onset and longer duration of sensory and motor block, prolonged duration of anesthesia and analgesia, and higher sedation compared with C and F groups (P<0.0001). Hemodynamics (heart rate and blood pressure) were insignificant among groups, and adverse effects were minimal.
Conclusion Dexmedetomidine hastens the onset and prolongs the duration of sensory and motor blocks, as well as the duration of postoperative analgesia with minimal adverse effects compared with fentanyl when added to local anesthetic in supraclavicular brachial plexus block. We recommend further research studies for the determination of the optimum dose of dexmedetomidine used as an additive to local anesthetics.
Keywords: bupivacaine, dexmedetomidine, fentanyl, ultrasound-guided brachial block
|How to cite this article:|
Lotfy ME, Doha NM, Elbakry AEA, Mohamed SS. Comparative study between dexmedetomidine and fentanyl added to bupivacaine for ultrasound-guided brachial plexus block. Res Opin Anesth Intensive Care 2020;7:25-30
|How to cite this URL:|
Lotfy ME, Doha NM, Elbakry AEA, Mohamed SS. Comparative study between dexmedetomidine and fentanyl added to bupivacaine for ultrasound-guided brachial plexus block. Res Opin Anesth Intensive Care [serial online] 2020 [cited 2020 Jun 2];7:25-30. Available from: http://www.roaic.eg.net/text.asp?2020/7/1/25/282598
| Introduction|| |
Peripheral nerve block as an anesthetic technique plays an important role in modern regional anesthesia. Peripheral nerve blocks provide intraoperative anesthesia and postoperative analgesia without major systemic adverse effects by minimizing the stress response and using minimal doses of anesthetic drugs . Brachial plexus blocks are commonly done by an interscalene, supraclavicular, infraclavicular, or axillary approach. Supraclavicular approach for brachial plexus block achieves anesthesia of the entire upper extremity just distal to the shoulder. Ultrasound use in regional anesthesia was reported to offer many benefits including a higher success rate, shorter time to onset of blocks, possibly better quality of sensory block, and reduction of the incidence of pneumothorax and systemic toxicity .
Although local anesthetics when used alone for supraclavicular brachial plexus block provide good operative conditions , they have a shorter duration of postoperative analgesia. Hence, various adjuvants such as opioids , clonidine , neostigmine, dexamethasone , and midazolam  were added to local anesthetics in brachial plexus block to achieve quick, dense, and prolonged block, but the results are either inconclusive or associated with adverse effects.
Dexmedetomidine is a highly selective (eight times more selective than clonidine) , specific, and potent α2-adrenergic agonist with analgesic, sedative, antihypertensive, and anesthetic-sparing effects when used in systemic route . Dexmedetomidine when added to local anesthetic during peripheral nerve blockade has shown to prolong the duration of the block and the postoperative analgesia ,,,.
The primary aim of this study was to assess the sensory and motor characteristics of ultrasound-guided supraclavicular brachial plexus block using bupivacaine 0.5% alone or added with dexmedetomidine or fentanyl in patients undergoing elective upper limb surgery. The secondary aim was to evaluate the hemodynamics and adverse effects.
| Patients and methods|| |
After approval of the Ethical Committee of El Menoufia University Hospital and obtaining a written informed consent from patients, this prospective randomized double-blind clinical trial was carried out on 90 patients with American Society of Anesthesiologists I and II physical status, of both sex aged between 20 and 60 years, undergoing elective short to moderate (<90 min) orthopedic upper limb surgeries below the shoulder under supraclavicular brachial plexus block. Patients with known hypersensitivity to local anesthetics, those with diabetes mellitus, those with bleeding disorders, those with pre-existing neuropathy, those with any hepatic, renal, neurological, psychiatric, or neuromuscular diseases, or those with local skin site infection were excluded from the study. An intravenous line was secured in the unaffected limb, and Ringer lactate solution was started at a rate of 10–15 ml/kg/h. All patients were premedicated by intravenous midazolam 0.03 mg/kg. The patients were allocated by a computer-generated random number generator in a pre-prepared sealed opaque envelope. The randomization was done by a research assistant at a site remote from the study procedures. Patients were randomly assigned into three groups, with 30 patients each. After aseptic preparation of the skin, ultrasound-guided supraclavicular brachial plexus block was performed. Group C received 30 ml of 0.5% bupivacaine (5 mg/ml) with 1-ml normal saline, group F received 30 ml of 0.5% bupivacaine (5 mg/ml) with 50-µg fentanyl (1 ml), and group D received 30 ml of 0.5% bupivacaine (5 mg/ml) with 75-µg dexmedetomidine (1 ml).
Sensory blockade of each nerve was assessed by examining the affected area with a wooden stick (toothpick) and compared with the same stimulation on the contralateral arm every 5 min after drug injection till complete sensory blockade was achieved. The sensory block was graded as follows: 0=no difference from the unblocked extremity, 1=less pain sensation than the unblocked extremity, and 2=no sensation of pain. Motor block was evaluated by a modification of the Lovett rating scale  from 6 to 0: 6=normal motor function with full flexion and extension of elbow wrist and fingers, 5=slightly reduced muscular force, 4=pronounced reduction of muscular force, 3=slightly impaired mobility, 2=pronounced mobility impairment, 1=almost complete paralysis, and 0=complete paralysis. The onset time of the sensory and motor blockade was recorded as the time between the end of the last injection and the total abolition of the pinprick response and complete paralysis in all the nerve distributions. The duration of the sensory block was recorded as the time between the end of the local anesthetic injection and the total recovery of sensation. The duration of the motor block was recorded as the time between the end of the local anesthetic injection and the total recovery of motor functions. The time of the first postoperative call for analgesics was recorded. At that time the Visual analogue score (VAS) from 0 = no pain to 10= the worst pain imaginable was assessed, and the patient was given 50-mg pethidine intravenously. Since this time, the VAS was assessed every 4 h for 24 h. At any time, the VAS was at least 3, the patient received 75-mg diclofenac sodium to a maximum dose of 200 mg. If VAS was at least 5, 25-mg pethidine was given and increased by 25-mg increments up to 150 mg/bolus. The assessment was repeated after 30 min, and if the VAS was still at least 3, the patient received another 25-mg pethidine intravenously. The total dose of diclofenac sodium and pethidine consumed in the postoperative period was recorded.
Patients were observed for any adverse effects such as pruritus, pneumothorax, nausea, vomiting, respiratory depression (respiratory rate<8 breath/min), hypoxia (oxygen saturation below 90%), hypotension (mean arterial blood pressure decrease by 20% or more from the baseline), and bradycardia (heart rate<50). Hypotension was managed by ephedrine 6 mg intravenous boluses if required. Bradycardia was managed by intravenous atropine 0.5 mg to be repeated if needed. The degree of sedation was monitored after 15, 30, and 60 min after performing the block using Ramsay sedation scale as follows: (a) patient is anxious and agitated or restless, or both; (b) patient is co-operative, oriented, and tranquil; (c) patient responds to commands only; (d) patient exhibits brisk response to light glabellar tap or loud auditory stimulus; (e) patient exhibits a sluggish response to light glabellar tap or loud auditory stimulus, and (f) patient exhibits no response.
Data were analyzed by statistical package for the social sciences (SPSS) program for statistical analysis (version 20; SPSS Inc., Chicago, Illinois, USA). Quantitative data were expressed as mean±SD. Qualitative data were expressed as frequency and percent. F test (one-way analysis of variance) was used for comparison of more than two independent quantitative variables normally distributed with LSD used as a post-hoc test. K test (Kruskal–Wallis) was used for comparison of more than two independent quantitative variables not normally distributed. χ2-Test was used for comparison between two or more independent qualitative variables. P value was considered statistically significant when it is less than 0.05.
According to previous studies , the sample size was calculated with the power of study 80% and confidence interval 95% to be a total of 90 patients who were allocated into three groups, and each group included 30 patients.
| Results|| |
All groups were comparable in terms of age, sex, BMI, American Society of Anesthesiologists classification of patients and duration of surgeries (P>0.05) ([Table 1]). As shown in [Table 2], the onset of sensory block was significantly faster in group D compared with groups F and C (P<0.001), with no significant difference between groups C and F (P>0.05). The onset of motor block was significantly faster in group D compared with groups F and C (P<0.001), with no significant difference between groups C and F (P>0.05). The durations of analgesia and sensory and motor blockade were significantly longer in groups D and F compared with group C (P<0.001) and significantly longer in group D compared with group F (P<0.001), as shown in [Table 2]. Postoperative diclofenac sodium consumption (mg) was significantly lower in group D (92.5±32.3) compared with group C (160±47.2) (P<0.001) and group F (142.5±56.9) (P<0.001), with no significant difference between groups C and F (P=0.44). Postoperative rescue pethidine requirements (mg) 24 h after surgery were significantly lower in group D (76.6±29) and group F (101.2±23.6) compared with group C (118.3±35.1) (P<0.001 and 0.01, respectively), with no significant difference between groups D and F (P=0.06). The mean Ramsay sedation scale in group D at 15 and 30 min was significantly higher than groups C and F (P<0.001), with no significant difference between groups C and F (P=1), as presented in [Figure 1]. VAS pain scores in group D were significantly lower at first, second, third, fourth, and fifth reading compared with groups C and F, with significantly lower values in group F compared with group C, as shown in [Figure 2]. There were no significant differences in the heart rate and mean arterial blood pressure among groups at all times of measurement. No episodes of respiratory depression or hypoxia were observed in patients intraoperatively or 24 h postoperatively. Bradycardia was reported in four patients in group D compared with no patients in groups F and C (P<0.001). Nausea and vomiting were recorded in one patient in group D, three patients in group F, and no patients in group C. Pruritus was recorded in two patients in group F and no patients in groups C and D. Technical complications of the block such as hematoma, pneumothorax, and Horner’s syndrome were not recorded in any patient during the study ([Table 3]).
| Discussion|| |
Brachial plexus block has proven to be a better alternative to general anesthesia for upper limb surgeries. It also offers a prolonged duration of pain relief, especially with the additives or catheter. Addition of adjuvants to local anesthetics such as the α2 adrenergic receptor agonist-like clonidine, dexmedetomidine, and opioids can prolong the block to cover lengthy surgeries. This study revealed that dexmedetomidine addition to bupivacaine in supraclavicular brachial plexus block shortened the onset and prolonged the duration of sensory and motor block as well decreased the postoperative analgesic needs compared with bupivacaine used alone or with added fentanyl. Although added fentanyl to regional blocks was reported to enhance analgesia, the duration of this effect is too short to gain a useful clinical effect , which was consistent with the results of this study.
In this study, fentanyl has no effect on the onset of sensory or motor block. In contrast, Nishikawa et al.  found that addition of fentanyl to lidocaine with epinephrine for axillary block delayed the onset of the block but prolonged the duration. This effect on the onset may be explained by the differences in the pH of the solutions used.
In this study, dexmedetomidine added to bupivacaine shortened the onset time of sensory and motor block. In contrast, Lee et al.  showed that the addition of dexmedetomidine to local anesthetic in ultrasound-guided axillary brachial plexus blocks with nerve stimulation does not enhance the onset time of the sensory block. Dexmedetomidine added for regional blocks acts through inhibition of peripheral α2 receptors. The mechanism of the rapid onset of the sensory and motor block observed in this study may be attributed to the high lipophilic property of dexmedetomidine, which enhances its penetration into the nerves ,,,.
This study showed that dexmedetomidine causes a significant increase in the duration of the sensory block, motor block, and analgesia when added to bupivacaine. These results were consistent with Swastika et al.  who compared fentanyl group (group F), which received 30-ml bupivacaine and 1-ml (50 μg) fentanyl, and dexmedetomidine group (group D), which received 30-ml bupivacaine+1-ml (75 μg) dexmedetomidine in supraclavicular brachial plexus block. Charlu et al.  studied the addition of dexmedetomidine to bupivacaine in supraclavicular brachial plexus block. In the dexmedetomidine group, 40 ml of 0.25% bupivacaine+50-μg dexmedetomidine was administered, and the control group received 40 ml of 0.25% bupivacaine+2-ml normal saline. They reported no significant differences in sensory block onset between the two groups and also the durations of sensory and motor block were significantly longer in group F than group C but significantly lower than the prolongation in group D. Jinjil et al.  compared dexmedetomidine with clonidine as adjuvants to 0.25% ropivacaine for ultrasound-guided supraclavicular block. They reported that the duration of the sensory and motor block and the duration of analgesia were significantly longer in the dexmedetomidine group compared with clonidine group, which is consistent with the results of the current study. Gandhi et al.  and Ammar and Mahmoud  used dexmedetomidine along with bupivacaine for brachial plexus block, and their results were consistent with our study regarding the prolongation of the motor and sensory block durations in dexmedetomidine group. Hemodynamic parameters were similar in all groups. Hypotension was noted in two patients in group D, and bradycardia in four patients of group D and required no treatment. Abdallah and Brull , in a meta-analysis of perineural application of dexmedetomidine as a local anesthetic adjuvant, stated that dexmedetomidine produced reversible bradycardia in 7% of brachial plexus block patients, with no incidence of hypotension. Incidence of nausea and vomiting was seen in three in group F versus 1 in D group. Itching was observed in two patients receiving fentanyl as an adjuvant. It is unlikely to have systemic adverse effects with perineural administration of drugs, but the systemic absorption of the drug may have a central effect. In this study, dexmedetomidine increased the sedation score but excessive sedation was not recorded. Dixit et al.  in a study added dexmedetomidine to levobupivacaine for supraclavicular brachial plexus block and showed that dexmedetomidine increased the sedation score, which is concomitant with this study. In contrast to this result, Ammar and Mahmoud  in their study had no patient in the dexmedetomidine group who developed somnolence, whereas four patients in the control group (group I) experienced somnolence (P=0.04).
| Conclusion|| |
Dexmedetomidine hastens the onset and prolongs the duration of sensory and motor blocks, as well as the duration of postoperative analgesia, with minimal adverse effects, compared with fentanyl when added to local anesthetic in supraclavicular brachial plexus block. We recommend further research studies for the determination of the optimum dose of dexmedetomidine used as an additive to local anesthetics.
This study was supported by Faculty of Medicine, Menoufia University.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]