|Year : 2019 | Volume
| Issue : 2 | Page : 156-163
Plain bupivacaine versus bupivacaine with adjuvants for ultrasound-guided supraclavicular brachial plexus block in patients undergoing below shoulder upper limb surgeries
Salwa H Waly, Yasser M Nasr
Department of Anesthesia and Surgical Intensive Care, Faculty of Medicine, Zagazig University, Zagazig, Al-Sharkia Governorate, Egypt
|Date of Submission||07-Nov-2018|
|Date of Acceptance||27-Nov-2018|
|Date of Web Publication||12-Jun-2019|
Salwa H Waly
17 El Khashab Street, Behind El Mabarra Hospital, Zagazig, Al-Sharkia Governorate, 44511
Source of Support: None, Conflict of Interest: None
Background Adding of an adjuvant to local anesthetics improves the quality of nerve block and reduces the need of postoperative analgesic intake.
Aim The aim of this study was to compare the block characteristics of bupivacaine when used alone with those characteristics after using different adjuvants in ultrasound-guided supraclavicular brachial plexus block (US-guided SCBPB) in patients undergoing below shoulder upper limb surgeries.
Patients and methods A prospective, double-blinded, randomized, controlled trial. A total of 108 patients undergoing elective upper limb surgeries under US-guided SCBPB were randomly allocated according to the studied solution into four equal groups (n=27): (i) Group C: 30 ml bupivacaine 0.5%+5 ml 0.9% saline. (ii) Group D: 30 ml bupivacaine 0.5%+100 μl dexmedetomidine diluted to 5 ml using 0.9% saline. (iii) Group N: 30 ml bupivacaine 0.5%+10 mg nalbuphine hydrochloride diluted to 5 ml using 0.9% saline. (iv) Group M: 30 ml bupivacaine 0.5%+5 ml of 10% MgSO4. We compared the onset and duration of sensory and motor blockade, hemodynamic stability, sedation, complications and postoperative analgesia.
Results There were no significant differences in the times of onset of both sensory and motor blocks between the four groups. The analgesic duration and duration of motor block were significantly longer in all adjuvant groups. The total consumption of paracetamol during the first 24 h was significantly higher in group C. Patients in groups D and M had statistically significantly higher sedation scores at different times during the study.
Conclusion Adding either dexmedetomidine, nalbuphine, or magnesium sulfate to bupivacaine in US-guided SCBPB prolongs both sensory and motor blockade. Both dexmedetomidine and magnesium sulfate produces significant sedation when added to bupivacaine.
Keywords: brachial plexus, dexmedetomidine, magnesium sulfate, nalbuphine, supraclavicular
|How to cite this article:|
Waly SH, Nasr YM. Plain bupivacaine versus bupivacaine with adjuvants for ultrasound-guided supraclavicular brachial plexus block in patients undergoing below shoulder upper limb surgeries. Res Opin Anesth Intensive Care 2019;6:156-63
|How to cite this URL:|
Waly SH, Nasr YM. Plain bupivacaine versus bupivacaine with adjuvants for ultrasound-guided supraclavicular brachial plexus block in patients undergoing below shoulder upper limb surgeries. Res Opin Anesth Intensive Care [serial online] 2019 [cited 2019 Oct 14];6:156-63. Available from: http://www.roaic.eg.net/text.asp?2019/6/2/156/260151
| Introduction|| |
The use of ultrasound technology in performing peripheral nerve block has gained wide popularity among anesthesiologists having the advantage of lower incidence of complications when compared with blind techniques ,. Brachial plexus block was found to provide excellent pain control, less side effects, and lower levels of postoperative pain when compared with general anesthesia . Nevertheless, even with the use of long-acting local anesthetics (LAs), the duration of pain relief has been found to range between 8 and 14 h . Continuous catheter-based nerve blocks can increase the duration of postoperative analgesia; however, their placement requires cost, time, and skills, with raised potentials for infection and neurological complications .
Presence of additives to LAs has the advantages of improving onset and duration of blockade, gaining patient satisfaction, maintaining proper hemodynamics, together with reducing the need to postoperative analgesics .
Seeking for an ideal adjuvant, many researches have been performed including ketamine , clonidine , dexmedetomidine , and corticosteroids , morphine , fentanyl , nalbuphine , and magnesium sulfate .
Thereby, this study aimed to evaluate the effect of adding either dexmedetomidine, magnesium sulfate, or nalbuphine to bupivacaine in ultrasound-guided supraclavicular brachial plexus blockade (US-guided SCBPB) in patients undergoing below shoulder upper limb surgeries.
The primary outcome of this study is to assess the total duration of sensory block.
Secondary outcome is to compare the onset and of sensory and motor blockade, duration of motor block, hemodynamic stability, sedation, complications, and postoperative analgesia.
| Patients and methods|| |
This randomized, prospective, double-blinded, controlled study was conducted in Zagazig University Hospitals during the time from October 2016 to September 2017, after obtaining Institutional Research Board (IRB) approval and an informed written consent from the patients after explaining the details of the technique. A total of 108 patients undergoing elective below shoulders upper limb surgeries under US-guided SCBPB were enrolled in the study. Patients between 21 and 60 years old of either sex, with a BMI of 18.5–29.9 kg/m2 and American Society of Anesthesiologists physical status of grade I or II were included. Exclusion criteria included patient refusal, pregnancy, bleeding disorders or patients on anticoagulants, presence of cardiac or respiratory disease, presence of neural deficit involving brachial plexus, local infection at the site of injection, patients receiving sedatives, patients with known allergy to any of the study drugs, and those who did not fulfill the inclusion criteria. All patients were kept fasting according to the standard guidelines (6 h for solids and 2–4 h for clear fluids preoperatively).
The patients were divided randomly into four equal groups (27 each) using the closed-envelope method. The total amount of the injected solution (both LA and the adjuvant were 35 ml). The preparation of the studied solution was performed by an anesthesiologist not involved in performing the block nor in data collection. The studied groups were:
Control group (group C) (n=27): the studied solution injected through US-guided SCBPB was 30 ml bupivacaine 0.5%+5 ml 0.9% saline.
Dexmedetomidine group (group D) (n=27): the studied solution injected through US-guided SCBPB was 30 ml bupivacaine 0.5%+100 μl dexmedetomidine diluted to 5 ml using 0.9% saline.
Nalbuphine group (group N) (n=27): the studied solution injected through US-guided SCBPB was 30 ml bupivacaine 0.5%+10 mg nalbuphine hydrochloride diluted to 5 ml using 0.9% saline.
Magnesium sulfate group (group M) (n=27): the studied solution injected through US-guided SCBPB was 30 ml bupivacaine 0.5%+5 ml of 10% magnesium sulfate.
Preoperative evaluation confirmed that the patients met the inclusion criteria and that the basal laboratory investigations were performed including ECG, complete blood picture, the coagulation profile, and liver and kidney functions.
On arrival to the operation room, standard monitors following the American Society of Anesthesiologists guidelines (noninvasive blood pressure, pulse oximetry, and ECG) were connected.
An intravenous cannula (18–20 G) was applied in the upper limb on the contralateral side of surgery and an infusion of lactated Ringer’s solution was given at a dose of 10–20 ml/kg.
The patients were positioned supine with head turned away from the limb to be operated and the arm was placed by the side of the patient. The skin was sterilized and prepared. The skin at the point of needle insertion was locally anesthetized with subcutaneous injection of 3 ml lidocaine 1%. To identify the brachial plexus in this study ultrasound (M-Turbo; Sonosite, Bothell, Washington, USA) was used. An adult linear ultrasound probe with a frequency range of 6–13 MHz was placed superior to the clavicle in the midclavicular point. Sterile water-based gel was used between the probe and skin. The brachial plexus was identified in relation to the pulsating subclavian artery and the hyperechoic first rib. The brachial plexus was seen as a collection of hypoechoic oval structures lateral and superficial to the artery ([Figure 1]). Under ultrasonographic guidance a sterile 22 G spinal needle was then advanced using an in-plane technique from the lateral to the medial direction. Once the needle tip reached the nerve sheath negative aspiration was done, then 35 ml of the prepared study solution was injected incrementally (5 ml each) around the plexus under vision at the angle between subclavian artery and first rib and also outside the nerve sheath ([Figure 2]).
|Figure 1 Ultrasound image of brachial plexus seen as a collection of hypoechoic oval structures lateral and superficial to subclavian artery. BP: Brachial plexus, SA: Subclavian artery.|
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|Figure 2 Ultrasound image showing local anesthetic spread with the needle in-plane from lateral to medial direction. BP: Brachial plexus, SA: Subclavian artery, LA: Local anesthetic.|
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If tourniquet application was anticipated, supplemental block of the intercostobrachial nerve (the lateral cutaneous branch of the ventral primary ramus of T2) was performed. The intercostobrachial nerve provides nerve supply to the skin of the axilla and the medial aspect of the proximal arm. It was anesthetized by subcutaneous infiltration of the skin of the medial aspect of the arm using a 25 G needle which was inserted at the level of the axillary fossa. The entire width of the medial aspect of the arm was infiltrated with 5 ml of 0.25% bupivacaine to raise a subcutaneous wheal of anesthesia.
The onset of sensory block was assessed via a 25 G disposable needle every 5 min till sensation is lost using a three-point scale  (0=no sensory block: a sharp prick is felt, 1=analgesia: a dull sensation is felt. 2=anesthesia, no sensation is felt). The sensory block was assessed on the palmar surface of the index finger, palmar surface of the little finger, and on the dorsum of the thumb for median, ulnar, and radial nerve, respectively . The onset of sensory blockade was defined as the time interval between the end of injection of LA and complete loss of pin prick sensation in radial, median, and ulnar dermatomes on the anesthetized upper limb.
The motor block was graded using the modified Bromage scale for upper extremities . Grade 0: normal motor function; grade 1: ability to move only fingers; grade 2: complete motor block with inability to move wrist and fingers. The onset of motor blockade was defined as the time interval from end of administration of the drug to complete motor block (motor score=2). This was assessed every 5 min till loss of finger movements. The duration of motor block was defined as the time interval between loss of movement to reappearance of the movements in the upper limb on the ipsilateral side.
The duration of analgesia was defined as the time interval between loss of pinprick sensations to the first call for analgesia. The first dose of postoperative analgesia in the form of 1 g paracetamol intravenously was given to the patient when the pain score was at least 4 according to the visual analog scale  graded from 0 to 10 (where 0=no pain, whereas 10=the worst possible pain). The total dose of paracetamol used within the first 24 h was calculated for each patient.
An unsuccessful block was defined as failure to achieve grade 1 sensory or motor block till 30 min after injection of the drug. In this case, general anesthesia was planned and the patient was excluded from the study.
Sedation was evaluated every 30 min (T0=sedation level by the end of injection of LA) for 3 h, then every 1 h for the next 6 h by a physician who is blind to the study protocol in the ward. The sedation score described by Culebras et al.  was used: 1=awake and alert, 2=sedated, responding to verbal stimulus, 3=sedated, responding to mild physical stimulus, 4=sedated, responding to moderate or severe physical stimulus, and 5=not arousable.
Heart rate (HR), mean arterial blood pressure (MAP), respiratory rate, and oxygen saturation were recorded at the following times: T0=basal readings before performing the block, T1–T3=readings obtained every 5 min after local injection for 15 min, T4–T10=readings obtained every 15 min for 2 h after injection of LA.
Hypotension was defined as a decrease in MAP of more than 20% of baseline value and was planned to be treated with crystalloid infusion and 5 mg bolus of ephedrine. Bradycardia was considered if the HR went below 50 b/min and was planned to be managed with atropine 0.2–0.5 mg. The patient was considered hypoxic if the oxygen saturation was less than 90% and was planned to be managed with supplemental oxygen through nasal cannula or face mask. Nausea and vomiting if occurred was planned to be treated with metoclopramide 10 mg intravenously.
Sample size and statistical analysis
G*POWER program, version 126.96.36.199 (Heinrich Heine; Universitat Dusseldorf; Germany) was used to calculate the number of patients. To calculate sample size, the duration of sensory block was used as the primary outcome. Twenty-seven patients were needed in each group to achieve an α error level of 0.05, with 80% power and 95% confidence limit. Allowing a 5% dropout rate, the final sample size needed was 27 patients in each of the four groups to detect a clinically significant difference of more than 20%.
Data were analyzed using IBM statistical package for the social sciences for Windows, version 24 (SPSS Inc., Chicago, Illinois, USA). Data were expressed as mean±SD, median (range), or numbers and percentages as appropriate. The data obtained from the study were examined for normal distribution using the Shapiro–Wilk test, then analyzed using one-way analysis of variance for continuous data, Mann–Whitney test to compare the significance between each pair of groups, Kruskal–Wallis test to compare between the four groups, and χ2-test for associations between categorical variables. For all the tests in the study, P value less than 0.05 was considered significant and P value less than 0.001 was considered highly significant and a P-value more than or equal to 0.05 was considered statistically nonsignificant.
| Results|| |
This study included 108 patients who divided into four equal groups (n=27). Patients’ data, duration of surgery, and the number of patients who needed intercostobrachial nerve block in the four groups of the study showed no statistically significant differences between groups. The requirement of the intercostobrachial block was found to be comparable between the four groups as shown in [Table 1].
There were no significant differences in the times of onset of both sensory and motor blocks between the four groups (P>0.05). The analgesic duration was highly significantly longer in all adjuvant groups whether dexmedetomidine (14.3±0.12 h), nalbuphine (12.8±0.73 h), or magnesium sulfate (14.1±0.68 h) when compared with the control group (8.1±0.62 h) (P<0.001), while being comparable to each other. Regarding the duration of motor block, the results obtained showed a highly significant longer duration of motor block in dexmedetomidine (9.7±0.99 h), nalbuphine (10.2±0.36 h), and magnesium sulfate (10.9±0.52 h) groups when compared with the control group (6.8±0.62 h) (P<0.001). Patients in the control group showed a highly significant increase in the total amount of paracetamol consumption during the first 24 when compared with the other studied groups (P<0.001) ([Table 2]).
|Table 2 Criteria of sensory and motor blocks and analgesic behavior of the drugs used in the four groups of the study|
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It was observed that the patients in group D (dexmedetomidine group) had statistically significant higher sedation scores at 30 min after completing the injection of the study drug and extended for 5 h as compared with other groups. In spite of that group M (the magnesium sulfate group) showed less sedation levels than group D; yet, the sedation levels in group M was significantly higher during the first 2 h than group C (control group) and group N (nalbuphine group) as shown in [Table 3].
All patients were hemodynamically stable during and after injection of the study drug. Although slower HRs ([Figure 3]) and lower MAP ([Figure 4]) were clinically observed in both groups D and M, statistical analysis showed no statistically significant differences when compared with other groups or with each other. There were no other recorded complications.
|Figure 3 Changes in heart rate (b/min) in the four groups at different times of the study.|
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| Discussion|| |
This study aimed to compare the block characteristics of bupivacaine with and without adjuvant in US-guided SBPB. The additives used were dexmedetomidine, nalbuphine, and magnesium sulfate, one at a time.
It was found that adding dexmedetomidine, nalbuphine, or magnesium sulfate to bupivacaine in US-guided SBPB prolongs the duration of both sensory and motor blockade and decreases the postoperative analgesic requirements. Besides that, addition of dexmedetomidine or magnesium sulfate produces significant sedation during intraoperative and postoperative periods.
Dexmedetomidine is an α2 adrenergic receptor agonist that has been used in many researches as an adjuvant to LAs ,,. Regarding the duration of sensory and motor block, results in this study are similar to those obtained in previous studies ,.
In respect to the onset of block, Marhofer et al.  and Esmaoglu et al.  noticed that the onset of sensory and motor blocks was more rapid when adding dexmedetomidine to the LA, which was inconsistent with the results obtained in this study. This disagreement may be attributed to the different LAs as we studied adjuvants to bupivacaine while they studied adjuvants to ropivacaine and levobupivacaine, respectively. However, this study supports the results obtained by Kaygusuz et al.  and Mathew et al. , where the onset of the block was not affected by adding dexmedetomidine to bupivacaine.
Regarding sedation, the results of this study were similar to those obtained by Mathew et al.  and Agarwal et al.  who added dexmedetomidine to LAs and observed that patients who received dexmedetomidine had higher levels of sedation.
Opioid had been studied as LAs adjuvants and it was found to improve the clinical efficacy of peripheral nerve blocks through the stimulation of opioid receptor, but they were associated with unacceptable adverse effects . Nalbuphine is a mixed κ-agonist and μ-antagonist opioid, and its affinity to κ-opioid receptors results in analgesia, sedation, together with cardiovascular stability, minimal respiratory depression and absence of pruritus, nausea, and vomiting. It may augment the action of LAs through central opioid receptor-mediated analgesia by peripheral uptake of nalbuphine to systemic circulation. It is widely studied as an additive to LAs during epidural, caudal, and intrathecal anesthesia . However, literatures studying the effect of nalbuphine as an adjuvant to LAs in the peripheral nerve blocks are few .
Abdelhaq and Elramely  as well as Gupta et al.  studied nalbuphine as an adjuvant to bupivacaine for supraclavicular brachial plexus block for upper arm surgeries. They found that nalbuphine had significantly increased in the duration of both sensory and motor block in association with prolonged postoperative analgesia which comes in agreement with the results obtained in this study.
The mechanism of analgesia produced by magnesium is not yet clear. Moreover, studies concerned with magnesium for peripheral nerve block are minimal . The surface charge theory is one hypothesis for the analgesic properties of magnesium on peripheral nerves . It was reported that a high concentration of Mg2+ ions affects Na+ channel gating, which could cause hyperpolarization and conduction block of this nerve. Antagonism of N-methyl-d-aspartate receptors is another possible mechanism .The results obtained by Fahmy et al.  and Rao et al.  comes in agreement with the results obtained in this study as regards significantly prolonged duration of the sensory and motor blocks, however, together with the decreased consumption of postoperative analgesics.
In contrast, Hung et al.  concluded that magnesium had shortened the block duration by lidocaine, bupivacaine, and ropivacaine when locally injected around the sciatic nerve. This antagonism between LAs and magnesium sulfate was not well explained and may be independent of the LA and magnesium sulfate action at the receptor.
In contrast to the results obtained in this study, bradycardia occurred with the use of dexmedetomidine was observed in the study by Esmaoglu et al. . The slower HRs in the dexmedetomidine group in our study were statistically insignificant when compared with other groups. In contrast, the hemodynamic stability found in patients included in this study came in accordance with the results obtained by other researchers ,,.
| Conclusion|| |
The inclusion of either dexmedetomidine, nalbuphine, or magnesium sulfate with bupivacaine in US-guided SBPB prolongs both sensory and motor blockade and decreases the postoperative analgesic requirement. Moreover, addition of dexmedetomidine or magnesium sulfate produces significant sedation during surgery and may extend to the postoperative period.
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Conflicts of interest
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3]