|Year : 2018 | Volume
| Issue : 2 | Page : 475-479
Dexmedetomidine and fentanyl as an adjunct to bupivacaine 0.5% in supraclavicular nerve block: A randomized controlled study
Mohamed Ahmed Hamed, Saffa Ghaber, Ahmed Reda
Department of Anesthesiology, Faculty of Medicine, Fayoum University, Fayoum, Egypt
|Date of Web Publication||14-Jun-2018|
Dr. Mohamed Ahmed Hamed
20, Batl Salam, Fayoum
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Brachial plexus block is gaining popularity day by day for upper limb surgery. The supraclavicular brachial plexus block may be used for surgical anesthesia alone or in conjunction with general anesthesia. Aims: We intended to compare the effect of dexmedetomidine and fentanyl as adjuvant to bupivacaine on onset and duration of block and postoperative analgesia during ultrasonic guided supraclavicular nerve block for upper limb surgeries. Settings and Design: This study design was a prospective randomized controlled double-blinded clinical study. Patients and Methods: Sixty patients with American Society of Anesthesiologists physical status Classes I and II, aged 18–50 years, scheduled for upper limb surgery were randomly divided into three study groups each group contains 20 patients: C Group: receive 0.5 mL/kg up to a maximum of 40 mL volume. The dose of bupivacaine was 1.5 mg/kg. D Group: Bupivacaine as control group + 1 mg/kg dexmedetomidine. F Group: Bupivacaine as control group + 1 mg/kg fentanyl. Patients were observed for onset and duration of sensory and motor blockade, duration of analgesia, postoperative pain, and adverse effects. Statistical Analysis Used: One-way ANOVA test and Chi-square test were used. Results: The onset time of sensory and motor blockade was shortened. and the duration of the block was significantly prolonged in the D Group (P < 0.001) and F Group (P < 0.001). The duration of postoperative analgesia was also longer in the D Group 13.5 h compared with the F Group 8.3 h and C Group 7.5 h. Hypotension and bradycardia were recorded in 2 patients in D Group, and nausea and vomiting were recorded in F Group. Conclusions: Addition of dexmedetomidine was better in prolongation of the duration of supraclavicular brachial plexus block and improvement of postoperative analgesia than fentanyl and bupivacaine alone without significant adverse effects in patients undergoing upper limb surgeries.
Keywords: Bupivacaine, dexmedetomidine, fentanyl, postoperative analgesia, supraclavicular brachial plexus block
|How to cite this article:|
Hamed MA, Ghaber S, Reda A. Dexmedetomidine and fentanyl as an adjunct to bupivacaine 0.5% in supraclavicular nerve block: A randomized controlled study. Anesth Essays Res 2018;12:475-9
|How to cite this URL:|
Hamed MA, Ghaber S, Reda A. Dexmedetomidine and fentanyl as an adjunct to bupivacaine 0.5% in supraclavicular nerve block: A randomized controlled study. Anesth Essays Res [serial online] 2018 [cited 2019 May 19];12:475-9. Available from: http://www.aeronline.org/text.asp?2018/12/2/475/230461
| Introduction|| |
In general, regional nerve blockade avoids the unwanted effects of anesthetic drugs used during general anesthesia and beneficial for the patients with various cardiorespiratory comorbidities. In supraclavicular approach, the plexus is blocked where it is most compactly arranged at the level of the nerve trunks; as a result, a block with rapid onset can be achieved. Various adjuvants, including opioids, midazolam, magnesium sulfate, dexamethasone, and neostigmine, have been added to local anesthetics in an attempt to increase the duration of block and postoperative analgesia.
Dexmedetomidine (α2 adrenoceptor agonist) is being used for intravenous (IV) sedation and analgesia for intubated and mechanically ventilated patients in Intensive Care Units.
Its use in peripheral nerve blocks has recently been described. It has been reported to have a rapid onset time, to prolong the duration of local anesthetics, and it is approximately 8 times more potent than clonidine and is also reportedly safe and effective in peripheral nerve blocks.
Opiates are widely known to have an analgesic effect at the central and spinal cord level. However, opioid analgesia can be initiated by activation of peripheral opioid receptors. Opioids such as fentanyl have been used for regional nerve plexus blocks to improve the block duration and quality. The peripheral administration of opioids provides stronger and longer lasting analgesia without central side effect. Studies have shown better block duration and success rate of brachial plexus block on addition of fentanyl.
Various clinical trials have found that administration of dexmedetomidine and fentanyl with local anesthetics in neuraxial and peripheral nerve blocks prolonged the duration of sensory and motor blockade.
However, there are limited data available on comparing of dexmedetomidine and fentanyl as addition to local anesthetic in brachial plexus block.
| Patients and Methods|| |
The Ethical Committee of our institute approved this randomized prospective double-blinded controlled study to be executed in Fayoum University Hospital for 1 year (from October 2016 to October 2017) on sixty patients scheduled for upper limb surgeries not exceeding 2 hours as fractures and plastic surgeries. After obtaining a written informed consent for anesthesia from each patient after explaining to them the nature of study and complications.
Inclusion criteria included patients aged 18–60 years, weighted 55–85 kg, and with American Society of Anesthesiologists physical status Classes I and II scheduled for upper limb surgeries not exceeding 2 h as fractures and plastic surgeries.
Exclusion criteria included local infection at the site of puncture, patients having any neurologic deficit in the upper limb, patients having history of hematological disorders, including coagulation abnormality, patients with severe hepatic impairment, and patient had a known allergy to study drug or additions.
The patients were randomly divided into three study groups as simple randomization by computer-generated random numbers. Each group contains 20 patients:
- Group C (control group): Bupivacaine + saline
- Group D (dexmedetomidine group): Bupivacaine + dexmedetomidine
- Group F (fentanyl group): Bupivacaine + fentanyl.
Routine preoperative investigations including electrocardiogram (ECG), complete blood picture, renal function tests, liver function tests, and coagulation profile were done. All patients were fast 8 h preoperatively. IV access obtained (one peripheral venous cannula 18 g) in the nonoperative arm. The patient received cefotaxime 1 g IV drip. Standard monitoring devices including ECG, finger tip pulse oximetry, and noninvasive blood pressure used to measure the hemodynamic variability.
The patient lied supine with 45° head elevation with a bellow below shoulder and with the head turned 45° to the contralateral side. After skin sterilization, an ultrasound (Phillips-Saronno Italy) with (linear) probe placed in the coronal plane in the supraclavicular fossa to visualize the brachial plexus. After anesthetizing the skin and the subcutaneous tissue with 2–4 ml 2% lidocaine, a 22-gauge Short bevel needle (Spinocan, B. Braun Melsungen AG, Germany) was placed at the outer end of the probe and advanced along the long axis of the probe until the tip of the needle was located lateral to round pulsating hypoechoic subclavian artery on the top of hyperechoic first rib. The drug solution was prepared and administered as a single injection of 0.5 mL/kg up to a maximum of 40 mL (the dose of bupivacaine was 1.5 mg/kg). Group C received anesthetic dose of isobaric bupivacaine 0.5%. Group D received 1 mg/kg of dexmedetomidine along with equal volumes of 0.5% isobaric bupivacaine. Group F received 1 mg/kg of fentanyl along with equal volumes of 0.5% isobaric bupivacaine.
A blinded assistant, who was unaware of local anesthetic mixture, was asked to assess the nerve blocks.
A successful block was defined as complete sensory and motor blockade in all regions of median, ulnar, redial, and musculocutaneous nerve distribution. Anesthetic failure in the surgical area was defined if the patient experienced pain during surgery and this was controlled by IV fentanyl 1–2 mg/g or recourse to general anesthesia. Surgical effectiveness was defined as surgery ended without patient discomfort and the need for supplementation of the block. Sensory and motor blocks assessed every 1 h after the surgery until block resolution. Duration of sensory block was defined as the time interval between the success of the block and the complete resolution of anesthesia on all nerves area and it was recorded. Duration of motor block was defined as the time interval between the success of the block and the recovery of complete motor function of the hand and forearm and it was recorded too. Postoperative pain was assessed by using visual analog scale (VAS) scoring from 0 to 10: Score 0: no pain. Score 10: maximum imaginable pain. Injection diclofenac 1 mg/kg intramuscular was given if VAS >4. Sensory block. Assessed by a pin prick test using a three-point scale: 0: normal sensation, 1: decreased pain sensation to pinprick, 2: loss of pain sensation to pinprick in the median, ulnar, radial, and musculocutaneous nerve. Onset of sensory block was defined as the time interval between injection and complete loss of sensation. Onset of motor block was defined as the time interval between injection and complete loss of motor power. Duration of motor block: Assessed by using modified Bromage three-point scale: 0: normal motor function, 1: decreased motor strength with ability to move the fingers only, 2: complete motor block. Moreover, tested every 5 min for 30 min. On arrival to the operating theater, the vital signs parameters including mean arterial blood pressure (MAP), heart rate (HR), respiration rate, and SpO2 were recorded at base line, 15, 30, 45, 60, 75, 90, 120 min. After completion of surgery, the patients were monitored in the postanesthesia care unit. HR and blood pressure was recorded every hour for 6 h. The following side effects were observed: nausea, vomiting, episode of hypotension (20% decrease in MAP in relation to baseline values), bradycardia (HR <50 beats/min), and hypoxemia (SpO2<90%). If systolic blood pressure is <20% from base line or MAP <60 mmHg, IV ephedrine 5 mg was given incrementally. If the HR is <50 beats/min, 0.5 mg atropine sulfate was administrated. Any complications including vascular puncture, Horner's syndrome, pneumothorax, and phrenic nerve palsy were recorded. Furthermore, any side effects of dexmedetomidine such as dry mouth, hypotension, bradycardia, or sedation were recorded.
The primary outcome of this prospective, randomized, and observer blinded study was to compare duration of sensory block between groups. The secondary outcomes of this study were to compare the onset of sensory block, the onset of motor block, and the duration of motor block between groups.
Sample size was calculated using G power program 3.1.7 (Universitat Kiel, Germany) based on a pilot study of the first 5 patients. Assuming that the power is 80% and α- error was 0.05, the calculated effect size was 0.968. We calculate 18 patients on each group. A total of 60 patients were recruited in the study to compensate for possible dropouts. Statistical presentation and analysis of the present study were conducted, using SPSS software version 21.0 (IBM Corporation, Armonk, NY, USA) statistics. Quantitative variables were presented as mean and standard deviation and were analyzed by one-way ANOVA test. Significant ANOVA test was further analyzed by post hoc test to determine the significant group. Qualitative variables were presented as numbers and percentages and were analyzed by Chi-square test. P < 0.05 was considered significant and <0.01 was considered highly significant.
| Results|| |
The current study included sixty patients in Fayoum university hospital, randomly divided into three study groups. Each group contains twenty patients: Group C (control group): bupivacaine and saline. Group D (dexmedetomidine group): bupivacaine and dexmedetomidine. Group F (fentanyl group): bupivacaine and fentanyl. [Table 1] illustrates that there is no statistically significance difference with P > 0.05 between study groups as regards the age and anthropometric measures, which indicated proper matching between groups in age and anthropometric measures.
|Table 1: Comparisons of age and anthropometric measures in different study groups|
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[Table 2] illustrates that there is statistically significance difference with P < 0.05 between study groups as regards total sensory and motor duration, with high mean among Group D sensory 819 ± 76.6 and motor 777 ± 74.6, low mean among Group C sensory 473.9 ± 36.8 and motor 420.5 ± 44.4, and Group F between the two groups with sensory 500.2 ± 37.2 and motor 465.5 ± 46.8.
|Table 2: Comparison of onset and duration of sensory and motor block in different study groups|
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Moreover, there is statistically significance difference with P < 0.05 between study groups as regards onset of sensory and motor duration, with low mean among Group D sensory 5.75 ± 2.2 and motor 6.85 ± 2.4, high mean among Group C sensory 16.3 ± 4.8 and motor 18.4 ± 5.2, and Group F between the two groups with sensory 11.8 ± 3.4 and motor 13.7 ± 3.3.
[Table 3] illustrates that there is no statistically significance difference with P > 0.05 between study groups as regards the intraoperative HR follow-up in the 1st h, which indicated all groups of drugs had same effect on intraoperative HR. On the other hand, there is statistically significance difference with P < 0.05 between Group F 76 ± 6 and C 95 ± 7as regards to intraoperative HR after 2 h with low HR among Group F.
Moreover, there is no statistically significance difference with P > 0.05 between study groups as regards the postoperative HR follow-up in the first 2 h, and after 4 h which indicated all groups of drugs had same effect on HR. On the other hand, there is statistically significance difference between Group F and each of D and C groups as regards to postoperative HR after 3 h; also between Group F and C as regards postoperative HR after 5, and 6 h with decrease HR among Group F.
[Table 4] illustrates that there is no statistically significance difference with P > 0.05 between study groups as regards the Mean arterial blood pressure (MBP) follow-up after 45 min of operation. On the other hand, there is statistically significance difference with P < 0.05 between Group F 93 ± 7 and Group C 88 ± 7 with high MBP among Group F, also between Group F and D, as regards to MBP after 10, 20, and 30 min with low MBP among Group D 80 ± 3. Moreover, there is no statistically significance difference with P > 0.05 between study groups as regards the postoperative MBP follow-up after 1 and 3 h of operation. On the other hand, there is statistically significance difference with P < 0.05 between Group D and Group F with low MBP among Group D at 2 and 6 h after operation, also between Group D and C, as regards to postoperative MBP after 4, 5, and 6 h with low MBP among Group D.
|Table 4: Comparisons of intraoperative mean blood pressure in different study groups|
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| Discussion|| |
The current study shows that addition of dexmedetomidine to bupivacaine for ultrasound-guided supraclavicular nerve block significantly leads to earlier onset of sensory and motor block as well as increased duration of analgesia than addition of fentanyl or bupivacaine alone while fentanyl was better than bupivacaine alone in the same outcomes.
Murphy et al. and Brummett et al. in their studies on administration of dexmedetomidine as an adjuvant to local anesthetics reported that the mechanism of the analgesic effect of dexmedetomidine is still not clear and may be multifactorial.,
Possible mechanisms explained by Lee et al., Talke et al., and Yoshitomi et al. were that dexmedetomidine induces vasoconstriction through an action on α2 adrenoceptors or it produces analgesia peripherally by reducing norepinephrine release and increasing the potassium conduction in C and A-delta neurons responsible for passage of pain stimulus, whereas it produces analgesia and sedation centrally by inhibition of substance P release in the nociceptive pathway at the level of the dorsal root ganglia and locus coeruleus.,,
On the other hand, there were studies that had used fentanyl as adjuvant to local anesthetics during regional or peripheral nerve blocks and resulted in significant prolongation of duration of analgesia.
Rajkhowa et al. mentioned in their study on fentanyl as adjuvant in brachial plexus nerve block that the mechanism of fentanyl in prolongation of analgesia may be due to the existence of peripheral functional opioid receptors, but this existence in peripheral tissue is still doubtful. Furthermore, Rajkhowa et al. mentioned in their study that fentanyl used with ropivacaine prolonged the duration of sensory and motor blockade, probably by directly binding with opioid binding sites on the dorsal nerve roots aided with these axonal transports or by diffusing into surrounding tissues and subsequently into the epidural and subarachnoid spaces; it may also have been central opioid receptor mediated after systemic absorption of fentanyl. Regarding, MBP changes;results showed statistically significance in our study for dexmedetomidine This came in agreement with Rashmi and Komala. Regarding onset of sensory and motor anesthesia, results showed statistically significance in our study for dexmedetomidine as adjuvant which has earlier onset of anesthesia than fentanyl group and control group while fentanyl has earlier onset than control group which came in agreement with Bharti et al. and Rajkhowa et al., Regarding, total block duration, results showed statistically significance in our study for dexmedetomidine in prolongation of anesthetic duration by 5 h and total analgesic duration by 6 h compared to the patient receiving only bupivacaine that was stated by Bharti et al. found in their study on dexmedetomidine as adjuvant with local anesthetic in supraclavicular nerve block that it prolonged anesthetic duration by 3 h and total analgesic duration by 4 h compared to control group. Concerning addition of fentanyl, we found that it prolongs anesthesia and enhances postoperative analgesia by 1 h when compared with the control group, and this is consistent with Rajkhowa et al. which found in their study that fentanyl prolongs sensory and motor duration by 3 h. On the other hand, Farooq et al. in their study showed that addition of fentanyl and dexmedetomidine were nearly equal effective in extending the duration of ropivacaine in ultrasound-guided brachial plexus block. This may be due to the use of ropivacaine rather than bupivacaine as ropivacaine has a longer duration of action, and the effect of adjuvants may not appear. Furthermore, our results shows that there is statistically difference between fentanyl group, dexmedetomidine group, and bupivacaine group as regards to intraoperative HR with low HR among fentanyl group which can be explained by association of fentanyl with a vagus nerve-mediated bradycardia. This differs from Manohar and Prakash that shows lower HRs with dexmedetomidine group than fentanyl, and this difference may be due to larger number of patients in their study with use of smaller doses of fentanyl (50 mg only).
Technical complications of supraclavicular brachial Plexus block such as hematoma and pneumothorax were not observed in our study. No respiratory depression was observed in any patient of the study. Hypotension was noted in two patients of dexmedetomidine group and in one patient of control group. Bradycardia occurred in one patient of dexmedetomidine group. Incidence of nausea and vomiting was recorded in fentanyl group in two patients only.
Quality of anesthesia was excellent in three groups of the study with no incidence of block failure necessitating induction of general anesthesia. Sedation of score 2 was observed in one patient receiving dexmedetomidine and resolved spontaneously with time without any interference on recession of block. Achievement of sedation with the lack of the hemodynamic or any other side effect can make dose of 1 mg/kg of dexmedetomidine an attractive choice as adjuvant for supraclavicular brachial plexus block.
A limitation of our study was small sample size; more studies with larger sample sizes will be needed to confirm our results. The second was expense and unavailability of dexmedetomidine vials.
We recommend using dexmedetomidine as adjuvant with supraclavicular nerve block to provide earlier onset of the block and longer period of postoperative analgesia.
| Conclusions|| |
Addition of dexmedetomidine was better in prolongation of the duration of supraclavicular brachial plexus block and improvement of postoperative analgesia than fentanyl and bupivacaine alone without significant adverse effects in patients undergoing upper limb surgeries.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]