|Year : 2017 | Volume
| Issue : 3 | Page : 156-163
Prospective randomized study of interscalene brachial plexus block using 0.5% bupivacaine HCl with or without dexamethasone in shoulder surgery
Rabab S Mahrous MD , Rehab A Abd El-aziz
Department of Anesthesia and Surgical Intensive Care, Faculty of Medicine, Alexandria University, Alexandria, Egypt
|Date of Submission||30-Dec-2016|
|Date of Acceptance||08-Mar-2017|
|Date of Web Publication||5-Jul-2017|
Rabab S Mahrous
Department of Anesthesia and Surgical Intensive Care, Faculty of Medicine, Alexandria University, Alexandria, Egypt; 33 Bahaa ELDin ElGhatwary st. Smouha, Alexandria
Source of Support: None, Conflict of Interest: None
Interscalene brachial plexus block is one of the commonly performed techniques for regional anesthesia of the upper extremity. The aim of this study was to compare the analgesic efficacy and duration of 5 ml versus 10 ml of 0.5% bupivacaine HCl with and without 1 ml of dexamethasone in patients undergoing shoulder surgery.
Materials and methods
This prospective randomized blinded study was carried on 75 American Society of Anesthesiology I and II patients. Patients were assigned randomly to one of the three groups: group A received 10 ml of bupivacaine HCl 0.5%; group B received 5 ml of bupivacaine HCl 0.5%; and group C received 4 ml of bupivacaine HCl 0.5%+1 ml of dexamethasone.
There was no significant difference between the three groups in the total dose of intraoperative fentanyl dose. A statistically significantly high visual analog scale value was found in group B in comparison with groups A and C at 12 h postoperatively, and a statistically significant low visual analog scale was found in group C after 36 h. There was statistically significant earlier timing of first rescue analgesia requisite in group B and there was a significant difference between group C and the other two groups studied in the total amount of nalbuphine consumed. The incidence of block-related complications was significantly higher in group A compared with the other groups.
High volume of bupivacaine HCl 0.5% provides perioperative analgesia comparable to low volume, but low volume is safer in terms of the incidence of complications. Addition of dexamethasone to bupivacaine led to prolonged analgesic duration and was accompanied by a lower consumption of postoperative opioids.
Keywords: bupivacaine, dexamethasone, interscalene, shoulder surgery, ultrasound
|How to cite this article:|
Mahrous RS, Abd El-aziz RA. Prospective randomized study of interscalene brachial plexus block using 0.5% bupivacaine HCl with or without dexamethasone in shoulder surgery. Res Opin Anesth Intensive Care 2017;4:156-63
|How to cite this URL:|
Mahrous RS, Abd El-aziz RA. Prospective randomized study of interscalene brachial plexus block using 0.5% bupivacaine HCl with or without dexamethasone in shoulder surgery. Res Opin Anesth Intensive Care [serial online] 2017 [cited 2017 Sep 22];4:156-63. Available from: http://www.roaic.eg.net/text.asp?2017/4/3/156/209666
| Introduction|| |
Interscalene brachial plexus block (ISBPB) is one of the most commonly performed techniques for regional anesthesia of the upper extremity . It blocks the caudal part of the cervical plexus (C3, C4) and the superior (C5, C6) and middle (C7) trunks of the brachial plexus . ISBPB can be used in shoulder surgeries such as in shoulder arthroscopies, rotator cuff repairs, shoulder manipulations, procedures involving the mid to distal clavicle, and shoulder arthroplasty . It is associated with a number of complications, the most common one being phrenic nerve palsy .
Phrenic nerve block is associated with significant reductions in ventilatory function including a decrease in forced expiratory volume, decrease in forced vital capacity, and decrease in peak expiratory flow rate. Therefore, this ventilatory compromise restricts the use of this block in patients with limited pulmonary reserve such as those with obesity, asthma, and chronic obstructive pulmonary disease or in the elderly ,.
Ultrasonography is a useful tool for regional anesthesia ,. By comparison with nerve stimulation techniques, ultrasound (US) guidance has some advantages such as a direct visualization of anatomic structures, helping to minimize vascular punctures, and a dynamic vision of needle advancement and local anesthetic spread ,. Although no significant differences in the incidence and severity of postoperative neurological symptoms have been reported, US guidance has been shown to reduce the number of needle redirections and to enhance block success rate when performing an interscalene block (ISB) ,,. US-guided ISBs require lower local anesthetics (LA) doses and recent studies have shown that reducing the volume of local anesthetic for ISBPB results in significantly improved preservation of postblock diaphragmatic movement and postoperative forced vital capacity for shoulder surgery, with no decrease in the analgesic effect .
Many drugs have been studied as adjuvants for single-injection regional anesthetic techniques to prolong block duration. Epinephrine is commonly used as a marker of intravascular injection, but it has minimal effect on the duration of analgesia of long-acting LAs. Other drugs including clonidine, opioids, and ketamine have been studied for their effects on anesthesia and analgesia, and the results have been conflicting depending on the drug used and the choice of the local anesthetic ,,.
Dexamethasone is a systemic glucocorticoid used commonly to reduce postoperative nausea and vomiting, pain, and to improve the quality of recovery after surgery . Steroids induce some degree of vasoconstriction; thus, one hypothesis is that it acts in a manner similar to epinephrine by reducing local anesthetic absorption. Another hypothesis is that dexamethasone may act locally on nociceptive C-fibers (through glucocorticoid receptors) to increase the activity of inhibitory potassium channels, thus decreasing their activity .
This study was carried out to compare the efficacy of 5 ml of 0.5% bupivacaine HCl with and without dexamethasone versus10 ml of 0.5% bupivacaine HCl in an ISBPB in patients undergoing shoulder surgery as the primary objectives of our study were to determine the duration of analgesia (time to first analgesic request) after ISBs when dexamethasone was added to bupivacaine and to evaluate any difference in postoperative pain scores after performing the block because of the addition of dexamethasone; the secondary objectives were to evaluate the effect of a low volume of bupivacaine versus a high volume on postoperative pain and to determine any increase in the incidence of complications of ISBs because of high versus low volume of bupivcaine and with addition of dexamethasone.
| Materials and methods|| |
Patients and study design
This prospective randomized blinded study was carried on 75 patients of either sex undergoing shoulder surgeries (69 open shoulder surgeries and nine shoulder arthroscopy) under general anesthesia combined with an ISBPB with US guidance at the Alexandria main university hospital after obtaining informed consent from each patient and obtaining the approval of the Alexandria University Ethics Committee. The study was registered at the Pan African Clinical Trials Registry identifier PACTR201611001848252.
Inclusion criteria were age up to 18 and lower to 70 years, American Society of Anesthesiology I–II, and BMI less than 35. Exclusion criteria included patient refusal, contraindication to ISB (severe chronic obstructive pulmonary disease, infection, coagulopathy, contralateral diaphragmatic paralysis), pregnancy, neuropathy of the surgical limb, recent (<6 months) use of glucocorticoids for at least 2 weeks, and chronic pain requiring the daily use of opioid medication (>30 mg/day of oral oxycodone equivalent).
Patients were assigned randomly using a table of random numbers and sealed envelope assignment to one of three groups according to the volume of local anesthetic used for ISB:
- Group A: patients received 10 ml of bupivacaine HCl 0.5%.
- Group B: patients received 5 ml of bupivacaine HCl 0.5%.
- Group C: patients received 4 ml of bupivacaine HCl 0.5%+1 ml of dexamethasone (4 mg).
The sample size was calculated by the High Institute of Public Health, Biostatistics Department, Alexandria University using the statistical package for the social sciences program (SPSS; SPSS Inc., Chicago, Illinois, USA). According to Kawanishi et al. , a sample of 22 patients per group was required to estimate a clinically significant difference in the duration of analgesia between the group receiving a local anesthetic only versus the group receiving a local anesthetic with dexamethazone of l6.8 h, SD of 2.1 h, α error of 0.05, with a study power of 80%.
Evaluation of the patients was carried out through a proper assessment of history and clinical examination to exclude the presence of respiratory cardiovascular, neurological, and metabolic diseases. Routine laboratory investigations included complete blood count, hemostatic profile study, blood urea and blood creatinine, fasting blood glucose, liver enzymes, urine analysis, and ECG (for patients above 40 years).
Patients were informed preoperatively about the technique applied and the use of the visual analog scale (VAS) for pain assessment.
Surgical procedure and clinical observations
On arrival to the operation room, a multichannel monitor was attached to the patient for continuous ECG monitoring. Noninvasive arterial blood pressure monitoring, and arterial oxygen saturation (SpO2).
An intravenous line was secured in the contralateral limb and 0.9% saline at a maintenance rate was started. Patients were administered oxygen 6 l/min through a face mask. Patients were positioned in the semilateral position with the neck extended to facilitate the performance of US ISBPB. Patients were sedated with (3 mg) midazolam. The skin was disinfected with povidone–iodine 10%. Subcutaneous infiltration with 4 ml of 1% lidocaine was administered at the needle insertion site. A 5 cm 22 G needle was inserted in line with the US probe in the transverse plane. An Advanced Technology Laboratories 2–13 MHz probe was used to visualize the brachial plexus. The LA was injected so that spread was observed immediately posterior to or between the C5 and C6 nerve roots. Aspiration was performed to detect an unintentional intravascular needle insertion, followed by the loading dose of the local anesthetic administered incrementally .
This was done by any experienced anesthesiologist different from the one assessing the patient intraoperatively and postoperatively. Both were blinded to the treatment groups. After the performance of ISBPB and the initial assessment (30–45 min), patients were transported to the operating theater, where the standardized protocol of general anesthesia was followed, fentanyl 1 µg/kg and propofol 2 mg/kg, and tracheal intubation was facilitated with rocuronium 0.6–0.8 mg/kg and maintained with 1 minimum alveolar concentration sevoflurane.
Further intraoperative 25 µg of fentanyl was administered if heart rate or arterial pressure increased more than 25% above the preinduction baseline value. After surgery, patients were transferred to the recovery room for further assessment. Nalbuphine at 6 mg intravenous increments were administered as rescue analgesia in the postoperative period when VAS greater than 3.
Sensation of the upper extremity was reported by pinprick testing from C4 to T1 dermatomes and scored as full sensation=1 and loss of sensation to touch or pinprick=0.
The motor power assessment of the deltoid, biceps, triceps, finger flexion (median), finger extension (radial), and finger abduction (ulnar) was scored as movement present=1 and absence of movement=0 using the modified Bromage scale for upper extremities. All of the sensory and motor assessments were performed at the following time points: preoperative – baseline (preblock), 30 min after block; postoperative – 30, 60, 120, and 180 min after the completion of surgery.
The visual analog scale for pain assessment was used 30 min after transfer to the recovery room and repeated every 2 h for 6 h, and then every 6 h for 36 h.
The duration of the analgesia was measured, and the timing of first analgesia requirement and the dose of postoperative rescue analgesia were recorded.
Complications of the block were assessed: dyspnea, hoarseness of voice, Horner’s syndrome, and Bezold–Jarisch reflex. A single observer (research associate) blinded to group allocation was responsible for all the data collection.
Data were analyzed using IBM SPSS software package version 20.0 . Qualitative variables were expressed as numbers and percentage, whereas quantitative variables were described as range, mean±SD, and median. Comparison between different groups of categorical variables was performed using the χ2-test. When more than 20% of the cells had an expected count less than 5, correction for χ2-test was performed using Fisher’s exact test or Monte Carlo correction.
For the normal distributions of quantitative variables, parametric tests were used. If the data were abnormally distributed, nonparametric tests were used. For normally distributed data, a comparison between two independent populations was performed using an independent t-test. For abnormally distributed data, comparisons between two independent populations were performed using the Mann–Whitney test. Significance of the results obtained was judged at the 5% level.
| Results|| |
All the patients who participated in the study were followed up for the observational period and were included in the data analysis. There were no significant differences in age, sex, body weight, type, and duration of surgery among the three groups ([Figure 1]).
No significant difference was found in the sensory block to C4, C5, C6, C8, and T1 dermatomes at all time points of measurement, but in terms of the sensory block to C7 dermatome, there were statistically significant differences between the three groups ([Table 1] and [Figure 2]).
|Table 1 Comparison between the three groups studied according to sensory block C7 dermatome|
Click here to view
|Figure 2 Comparison between the three groups studied according to sensory block C7|
Click here to view
No statistically significant difference was found in the motor block to the deltoid muscle (C5), the biceps muscle (C5, C6), median nerve (C8), radial nerve (C7), and ulnar nerve (T1) at all time points of measurement. In terms of the motor power to elbow extension, a statistically significant lower number of patients lost the motor power to extend the elbow in group B compared with the number of patients in group A (P=0.034) and also in group C compared with group A (P=0.034). However, no statistical differences were found between group B and group C (P=1.000) ([Table 2] and [Figure 3]).
|Table 2 Comparison between the three groups studied according to elbow extension|
Click here to view
|Figure 3 Comparison between the three groups studied according to elbow extension|
Click here to view
Intraoperative fentanyl, timing first analgesia, and dose rescue analgesia
In group A, the timing of first rescue analgesia ranged between 11 and 28 h, with a mean of 19.0±5.62 h, whereas in group B, it ranged between 6 and 18 h, with a mean of 12.0±4.14 h. In group C, it ranged between 26 and 32 h, with a mean of 29.20±2.3 h. There was a statistically significant earlier timing of first rescue analgesia requisite in group B compared with groups A and C (P=0.001).
In group A, the total amount of rescue analgesia with nalbuphine ranged between 0.0 and 18, with a mean of 5.76±7.03 mg, whereas in group B, it ranged between 0.0 and 24, with a mean of 6.72±6.78 mg, and in group C, it ranged between 0.0 and 9, with a mean of 1.32±2.75 mg. There was a significant difference between group C and the other two groups studied in the total amount of nalbuphine consumed (P≤0.05) ([Table 3] and [Figure 4]).
|Table 3 Comparison between the three groups studied according to intraoperative fentanyl, timing of first analgesia, and dose rescue analgesia|
Click here to view
|Figure 4 Comparison between the three groups studied according to timing first analgesia|
Click here to view
Visual analog scale
There was a statistically significantly high VAS value in group B compared with group A and group C after 12 h (P=0.046) and there was statistically significantly low VAS in group C compared with the other two groups after 36 h ([Figure 5]).
|Figure 5 Comparison between the three groups studied according to visual analog scale. VAS, visual analog scale|
Click here to view
In group A, 32% of patients had complications, whereas in groups B and C there were no complications; three (12.0%) patients showed dyspnea secondary to diaphragmatic paralysis (postoperative chest radiography), one (4.0%) patient had hoarseness of voice, three (12.0%) patients had Horner’s syndrome, one (4.0%) patient had Bezold–Jarisch reflex. There was a significant difference between the three groups in the rate of complications ([Table 4] and [Figure 6]).
|Table 4 Comparison between the three studied groups according to complications|
Click here to view
|Figure 6 Comparison between the three groups studied according to complications|
Click here to view
| Discussion|| |
The results of this work indicate that a low-volume ISBPB under US guidance decreases the incidence of adverse effects related to an ISB and provides equivalent analgesia compared with a standard-volume US-guided technique. With the use of dexamethasone with bupivacaine for ISBPB, there was a prolongation of analgesic duration, which was accompanied by a lower consumption of postoperative opioids.
Statistically, in the present study, there was no significant difference between the three groups studied in the intraoperative fentanyl requirements. In agreement with our results, Sanjay et al.  carried out a study on 30 patients scheduled for arthroscopic shoulder surgery who were randomized to receive either 10 or 20 ml of ropivacaine 0.5% for an ISB, and there was no difference between the two groups studied in the intraoperative requirements of fentanyl.
Falcão et al. , in their study, in which the volume of the anesthetic was determined using a step-up/step-down method and was based on the outcome of the preceding block, a positive or a negative block resulted in a 1 ml reduction or increase in volume, respectively. The success of the block was defined as the presence of motor block in three muscle groups and the absence of thermal and pain sensations in three dermatomes within 30 min of the injection. Diaphragmatic paralysis and analgesia were assessed at 30 min, 4 and 6 h. No difference in the consumption of intraoperative fentanyl was found between the patients receiving the minimal effective volume (0.95 ml) and those receiving the highest volume (15 ml).
The magnitude of block prolongation that we observed is consistent with that observed by Parrington et al.  when dexamethasone was combined with mepivacaine for supraclavicular blocks. Similarly, Vieira et al.  observed that adding dexamethasone to a mixture of bupivacaine, clonidine, and epinephrine increased ISB duration from 13.9 to 24.3 h.
In the study of Kawanishi et al. , patients presenting for arthroscopic shoulder surgery with an ISB were randomized to receive ropivacaine 0.75% (group C), ropivacaine 0.75% plus perineural dexamethasone 4 mg (group D peri), or ropivacaine 0.75% plus intravenous dexamethasone 4 mg (group div). Significant differences in the duration of analgesia were observed between groups D peri and C (P=0.001).
In terms of the postoperative pain score, in the present study, there was no significant difference between the three groups studied in VAS up to 12 h after surgery, but after 36 h, there was lower VAS in group C in comparison with the other two groups. The onset of first rescue analgesia was significantly earlier in group B, with a mean of 12.0±4.14 h, and it was 19.0±5.62 h in group A, whereas in group C, it was 29.20±2.3 h. Comparison between the three groups studied using the P value showed that there was a statistically significant earlier timing of first rescue analgesia requisite of first rescue analgesia requisite in group B compared with groups A and C and in group A compared with group C.
Similarly, Lee et al.  carried out a study on 60 patients undergoing arthroscopic rotator cuff repair surgery. Patients were assigned randomly to one of two groups receiving 5 ml (group 5) or 10 ml (group 10) of 0.75% ropivacaine for ISB. It was found that the median times to first analgesic request were 12–48 h in group 5 and 12–48 h in group 10.
Riazi et al.  showed, in their study, that the use of low-volume US ISBPB is associated with no change in postoperative analgesia compared with the standard-volume technique. Pain score rating scale measured at 30, 60, 120 min, 12, and 24 h after surgery and also the total analgesic consumption in the recovery room and in the first 24 h after surgery were similar in both groups. However, in their study, the pain score was not recorded between 12 and 24 h after surgery.
Jadon et al.  carried out a study on patients scheduled for arthroscopic shoulder surgery under ISB (ISBPB); the patients were divided into group R, in which patients received 30 ml of 0.5% ropivacaine+2 ml normal saline, and group RD, in which patients received 0.5% ropivacaine 30 ml+8 mg dexamethasone.VAS scores in the first 4 h were comparable, but VAS scores were significantly higher in group R at the end of 8, 12, 16, 20, and 24 h. Patients in group RD showed excellent pain control up to 24 h and had significantly lower VAS scores (2.5–3.3) compared with group R (4.2–5.06). Also, they found that rescue analgesic consumption was significantly lower in the group RD (1.22±0.47 analgesic injections) in comparison with group R (1.9±0.73) in the first 24 h postoperatively; thus, they concluded that dexamethasone significantly prolonged the duration of analgesia of ropivacaine during ISB used for arthroscopic shoulder surgeries.
In the terms of complications, we found that patients in group A developed a significantly higher rate of complications (32% of patients) than patients in groups B and C, who developed no complications.
In agreement with our study, Falcão et al.  showed that the estimated maximum volume that did not cause diaphragmatic block was 4.29 ml. Lee et al. , in their study, found that the incidence of hemidiaphragmatic paralysis on postoperative chest radiography was 33% in group 5 and 60% in group 10 (P=0.035).
Riazi et al.  showed that the incidence of diaphragmatic paralysis was significantly lower in the low-volume group compared with the standard-volume group (45 vs. 100%). Reduction in the respiratory parameters after the block was also significantly less in the low-volume group. Also, there was a significantly greater decrease in postoperative oxygen saturation in the standard-volume group after surgery.
| Conclusion|| |
US-guided inter/scalene brachial plexus block is highly effective in providing perioperative analgesia for shoulder surgeries. A low volume of 0.5% bupivacaine HCl provides perioperative analgesia comparable to high volume. Moreover, a low volume is safer than a high volume in terms of the incidence of complications.
Perineural dexamethazone (4 mg) prolonged the analgesic duration for over 36 h when added to 0.5% bupivacaine HCl, accompanied by a lower consumption of postoperative opioids, with no observed adverse effects.
The authors acknowledge the Department of Anesthesia and Postoperative Intensive Care, Faculty of Medicine, Alexandria University, Egypt.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
McNaught A, Shastri U, Carmichael N, Awad IT, Columb M, Cheung J et al.
Ultrasound reduces the minimum effective local anaesthetic volume compared with peripheral nerve stimulation for interscalene block. Br J Anaesth 2011; 106:124–130.
Riazi S, Carmichael N, Awad I, Holtby RM, McCartney CJ. Effect of local anaesthetic volume (20 vs 5 ml) on the efficacy and respiratory consequences of ultrasound-guided interscalene brachial plexus block. Br J Anaesth 2008; 101:549–556.
Gonzales J, Auyong DB, Grant SA. Upper limb ultrasound guided regional anesthesia. In: Grant SA, Auyong DB, editors. Ultrasound guided regional anesthesia. New York: Oxford University Press; 2012. pp. 35–42.
Al-Kaisy AA, Chan VWS, Perlas A. Respiratory effects of low-dose bupivacaine interscalene block. Br J Anaesth 1999; 82:217–220.
Marhofer P, Harrop-Griffiths W, Kettner SC, Kirchmair L. Fifteen years of ultrasound guidance in regional anaesthesia: part 1. Br J Anaesth 2010; 104:538–546.
Marhofer P, Harrop-Griffiths W, Kettner SC, Kirchmair L. Fifteen years of ultrasound guidance in regional anaesthesia: Part 2-recent developments in block techniques. Br J Anaesth 2010; 104:673–683.
Baciarello M, Danelli G, Fanelli G. Real-time ultrasound visualization of intravascular injection of local anesthetic during a peripheral nerve block. Reg Anesth Pain Med 2009; 34:278–279.
Denny NM, Harrop-Griffiths W. Location, location, location! Ultrasound imaging in regional anaesthesia. Br J Anaesth 2005; 94:1–3.
Danelli G, Bonarelli S, Tognú A, Ghisi D, Fanelli A, Biondini S et al.
Prospective randomized comparison of ultrasound-guided and neuro stimulation techniques for continuous interscalene brachial plexus block in patients undergoing coraco acromial ligament repair. Br J Anaesth 2012; 108:1006–1010.
Liu SS, Zayas VM, Gordon MA, Beathe JC, Maalouf DB, Paroli L et al.
A prospective, randomized, controlled trial comparing ultrasound versus nerve stimulator guidance for interscalene block for ambulatory shoulder surgery for postoperative neurological symptoms. Anesth Analg 2009; 109:265–271.
Fredrickson MJ, Ball CM, Dalgleish AJ. A prospective randomized comparison of ultrasound guidance versus neuro stimulation for interscalene catheter placement. Reg Anesth Pain Med 2009; 34:590–594.
Neal JM, Gerancher JC, Hebl JR, Ilfeld BM, McCartney CJ, Franco CD, Hogan QH. Upper extremity regional anesthesia: essentials of our current understanding, 2008. Reg Anesth Pain Med 2010; 35:134–170.
Andan T, Elif AA, Ayşe K, Gülnaz A. Clonidine as an adjuvant for lidocaine in axillary brachial plexus block in patients with chronic renal failure. Acta Anaesthesiol Scand 2005; 49:563–568.
Duma A, Urbanek B, Sitzwohl C, Kreiger A, Zimpfer M, Kapral S. Clonidine as an adjuvant to local anesthetic axillary brachial plexus block: a randomized, controlled study. Br J Anaesth 2005; 94:112–116.
Karakaya D, Buyukgoz F, Baris S, Guldoguş F, Tur A. Addition of fentanyl to bupivacaine prolongs anesthesia and analgesia in axillary brachial plexus block. Reg Anesth Pain Med 2001; 26:434–438.
De Oliveira GS Jr, Castro Alves LJ, Nader A, Kendall MC, Rahangdale R, McCarthy RJ. Perineural dexamethasone to improve postoperative analgesia with peripheral nerve blocks: a meta-analysis of randomized controlled trials. Pain Res Treat 2014; 2014:179029.
Kopacz DJ, Lacouture PG, Wu D, Nandy P, Swanton R, Landau C. The dose response and effects of dexamethasone on bupivacaine microcapsules for intercostals blockade (T9 to T11) in healthy volunteers. Anesth Analg 2003; 96:576–582.
Kawanishi R, Yamamoto K, Tobetto Y, Nomura K, Kato M, Go R et al.
Perineural but not systemic low-dose dexamethasone prolongs the duration of interscalene block with ropivacaine: a prospective randomized trial. Local Reg Anesth 2014; 7:5–9.
Sinha SK, Abrams JH, Barnett JT, Muller JG, Lahiri B, Bernstein BA, Weller RS. Decreasing the local anesthetic volume from 20 to 10 ml for ultrasound-guided interscalene block at the cricoid level does not reduce the incidence of hemi diaphragmatic paresis. Reg Anesth Pain Med 2011; 36:17–20.
Falcão LF, Perez MV, de Castro I, Yamashita AM, Tardelli MA, Amaral JL. Minimum effective volume of 0.5% bupivacaine with epinephrine in ultrasound-guided interscalene brachial plexus block. Br J Anaesth 2013; 110:450–455.
Parrington SJ, O’Donnell D, Chan VW, Brown-Shreves D, Subramanyam R, Qu M, Brull R. Dexamethasone added to mepivacaine prolongs the duration of analgesia after supraclavicular brachial plexus blockade. Reg Anesth Pain Med 2010; 35:422–426.
Vieira PA, Pulai I, Tsao GC, Manikantan P, Keller B, Connelly NR. Dexamethasone with bupivacaine increases duration of analgesia in ultrasound-guided interscalene brachial plexus blockade. Eur J Anaesthesiol 2010; 27:285–288.
Lee JH, Cho SH, Kim SH, Chae WS, Jin HC, Lee JS, Kim YI. Ropivacaine for ultrasound-guided interscalene block: 5 ml provides similar analgesia but less phrenic nerve paralysis than 10 ml. Can J Anesth 2011; 58:1001–1006.
Jadon A, Dixit S, Kedia SK, Chakraborty S, Agrawal A, Sinha N. Interscalene brachial plexus block for shoulder arthroscopic surgery: prospective randomized controlled study of effects of 0.5% ropivacaine and 0.5% ropivacaine with dexamethasone. Indian J Anaesth 2015; 59:171–176.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3], [Table 4]