|Year : 2015 | Volume
| Issue : 4 | Page : 928-934
Effect of addition of dexamethasone to low volumes of local anaesthetics for ultrasound-guided supraclavicular brachial plexus block
Lotfy E Mamdouh, Hassan A Ghada, Zalat I Sherief, Aiad A Alaa Eldin, Elhennawy A Tarek
Department of Anaesthesiology, Faculty of Medicine, Menoufiya University, Menoufiya, Egypt
|Date of Submission||14-Sep-2014|
|Date of Acceptance||17-Nov-2014|
|Date of Web Publication||12-Jan-2016|
Elhennawy A Tarek
MSc, 9 Abobaker Elsedek St, Shebin Elkom, Menoufiya, 32512
Source of Support: None, Conflict of Interest: None
We examined the efficacy of dexamethasone as an adjuvant to low volumes of local anaesthetics in an ultrasound-guided supraclavicular brachial plexus block (SBPB).
SBPB is an effective nerve block for use during upper limb surgery as an alternative to general anaesthesia. In addition, this block has a beneficial postoperative analgesic effect for these surgeries.
Materials and methods
We compared three groups of patients; each group included 30 patients scheduled for forearm and hand orthopaedic surgeries and anaesthetized by SBPB. Group A was anaesthetized by an injection of 15 ml of bupivacaine 0.5% mixed with 8 mg (2 ml) dexamethasone, group B was anaesthetized by an injection of 20 ml of bupivacaine 0.5% mixed with 8 mg (2 ml) dexamethasone and group C was anaesthetized by an injection of 20 ml of bupivacaine 0.5% mixed with 2 ml normal saline. All groups were assessed for efficacy of the block by assessment of the onset and duration of sensory and motor block and assessment of the quality and duration of postoperative analgesia. All groups were assessed for the incidence of complications.
The addition of dexamethasone to low volumes of bupivacaine in SBPB significantly hastened the onset and prolonged the duration of sensory and motor block. Dexamethasone yielded better quality of postoperative analgesia with lower levels of the visual analogue scale; also, it led to a statistically significantly longer duration of postoperative analgesia with lower analgesic consumption, and these effects were more prominent in group B with a slightly higher volume of bupivacaine. There were very few incidences of complications among the three groups.
The addition of dexamethasone to low volumes of bupivacaine in ultrasound-guided SBPB significantly decreased the onset time and prolonged the duration of sensory and motor blockade; also, it prolonged the duration and improved the quality of postoperative analgesia, with very few incidences of complications.
Keywords: dexamethasone, local anaesthetics, supraclavicular block
|How to cite this article:|
Mamdouh LE, Ghada HA, Sherief ZI, Alaa Eldin AA, Tarek EA. Effect of addition of dexamethasone to low volumes of local anaesthetics for ultrasound-guided supraclavicular brachial plexus block. Menoufia Med J 2015;28:928-34
|How to cite this URL:|
Mamdouh LE, Ghada HA, Sherief ZI, Alaa Eldin AA, Tarek EA. Effect of addition of dexamethasone to low volumes of local anaesthetics for ultrasound-guided supraclavicular brachial plexus block. Menoufia Med J [serial online] 2015 [cited 2020 Mar 30];28:928-34. Available from: http://www.mmj.eg.net/text.asp?2015/28/4/928/173676
| Introduction|| |
The brachial plexus can be blocked using four different approaches: interscalene, supraclavicular, infraclavicular and axillary approaches. Supraclavicular brachial plexus block (SBPB) is ideal for procedures of the upper limb from the mid-humeral level down to the hand; the brachial plexus becomes most compact at the level of the trunks formed by the C5-T1 nerve roots. Thus, blockade here has the greatest likelihood of blocking all of the branches of the brachial plexus  .
Successful SBPB relies on proper techniques of nerve localization, needle placement, concentration and the volume of local anaesthetic used  . Ultrasound-guided techniques are based on direct ultrasound visualization of nerves, needle and adjacent anatomic structures, making it possible to apply the local anaesthetic precisely around nerves and to follow its dispersion in real time, achieving a more effective blockade , .
Local anaesthetics alone provide analgesia for a few hours. Increasing the duration of local anaesthetic action is often desirable because it prolongs surgical anaesthesia and analgesia. Different additives have been used to prolong the duration of blockade and thus improve the quality of anaesthesia and postoperative analgesia ,, . Steroids have a powerful anti-inflammatory as well as an analgesic property. A perineural injection of steroids is reported to influence postoperative analgesia , ; also, it prolongs regional anaesthesia as it induces a degree of vasoconstriction. Thus, one theory is that the drug acts by reducing local anaesthetic absorption. A more attractive theory holds that dexamethasone increases the activity of inhibitory potassium channels on nociceptive C-fibres (by glucocorticoid receptors), thus decreasing C-fibres activity  .
The aim of this study was to evaluate the efficacy of dexamethasone as an adjuvant to low volumes of local anaesthetic in SBPB. We hypothesized that dexamethasone may increase the analgesic effect of bupivacaine.
| Materials and methods|| |
The protocol was approved by the research ethics committee and patients provided written informed consent. Ninety adult patients in the age group of 18 to 60 years admitted during a 1.5 year period to menoufiya university hospital, ASA physical status I or II patients scheduled for forearm and hand orthopaedic surgeries received ultrasound-guided SBPB. Exclusion criteria included cardiac dysfunction or pulmonary impairment, chest or shoulder deformities, infection at the injection site, coagulopathy and allergy to local anaesthetics.
Patients were randomized by computer-generated random selection into three groups: group A received ultrasound-guided SBPB by an injection of 15 ml of bupivacaine 0.5% mixed with 8 mg (2 ml) dexamethasone, group B was anaesthetized by an injection of 20 ml of bupivacaine 0.5% mixed with 8 mg (2 ml) dexamethasone and group C was anaesthetized by an injection of 20 ml of bupivacaine 0.5% mixed with 2 ml normal saline.
After an explanation of the manoeuvre was provided to the patients and applying routine monitors including ECG, noninvasive arterial pressure and pulse oximetry, intravenous access was secured with an 18 G cannula in the contralateral arm. Patients were placed in the supine position with the face rotated to the contralateral side to facilitate performance of the block.
Patients were administered 2 mg of midazolam intravenously as a premedication immediately before beginning. After sterilization of the area by povidone iodine 10%, all patients received 3 ml lignocaine 2% at the injection site; ultrasound-guided SBPB was performed using a 22 G 1.5 inch needle inserted in-plane with the ultrasound probe in the transverse cut. A 7.5-12 MHz probe was used to visualize the brachial plexus. It was placed in the supraclavicular region in the transverse position. We used a sonoscape A5/SN1622322 Ultrasound machine manufactured in China in the present study.
Postoperative analgesia was in the form of an infusion of intravenous paracetamol 15 mg/kg when the visual analogue scale (VAS) reached more than 4 repeated every 8 h and if it reached at least 5, intravenous pethidine 0.3 mg/kg was administered according to patients' requirements.
Heart rate (HR), mean arterial blood pressure (MABP), oxygen saturation and respiratory rate were monitored every 3 min throughout the block and operation and recorded immediately before the block (baseline) and then every 15 min during the surgery.
The following parameters were recorded: the onset and depth of sensory block were evaluated by the same individual at 5, 10, 15, 20, 25 and 30 min after the block. The extent of sensory blockade was tested by pinprick in the median, radial, ulnar and musculocutaneous nerve distribution using a three-point score: 2 = normal sensation, 1 = loss of sensation to pinprick (loss of pain sensation) or 0 = loss of sensation to light touch. Sensory block onset was defined as a decrease of sensation to grade 1 or less in comparison with the contralateral limb as a reference. Sensory block duration was defined as the time from the injection of a local anaesthetic mixture to complete recovery of light touch and pain sensation as tested by a swab and pinprick, respectively.
The quality of motor block was evaluated using a three-point scale, where 2 = normal movement, 1 = paresis (weak hand grip) and 0 = absent movement. Onset of motor block was defined as the time from injection of a local anaesthetic mixture until achieving a reduction in motor power to grade 1 or less. Motor block duration was described as the time from injection of a local anaesthetic to complete recovery of motor function.
Block success was defined as loss of sensation to pinprick (sensory score 1 or less) in each of the radial, ulnar, median and musculocutaneous nerve distributions measured within 30 min after the end of a local anaesthetic injection. For patients in whom block success was not achieved after 30 min, a supplemental dose of bupivacaine was injected or general anaesthesia was induced, and the patient was excluded from data analysis.
Postoperative analgesia was evaluated by asking the patients to fill out a VAS for pain by marking a 10 cm horizontal line anchored at one end a label 'no pain' and the other end by a label the 'worst pain imaginable' every 2 h in the first 8 postoperative hours and then every 6 h from 12 up to 36 h after surgery. The duration of postoperative analgesia in all groups was assessed by the time from start of the block to the time of the first analgesic requirement, and the total analgesic requirement in the first postoperative 36 h was recorded in each group.
MABP and HR were recorded every 2 h in the first 8 h after the block and then every 6 h from 12 up to 36 h after the block.
All groups were observed and assessed for incidence of complications such as pneumothorax (assessed by chest radiography immediately postoperatively and 8 h later), haematoma or vascular injury (assessed by ultrasound), drug toxicity, hoarseness of voice, neuroaxial block and Horner's syndrome.
One-way analysis of variance (F-test) was used to collectively indicate the presence of any significant difference between several groups for a normally distributed quantitative variable. Statistical significance was assumed at P value less than 0.05.
To detect a difference of 25% in the VAS score between groups, we needed 28 patients in each group. The power of analysis in the present study for postoperative VAS was 80%.
| Results|| |
Patients in all groups were matched for age, weight and sex, with no statistically significant difference; also, there were no statistically significant differences in the duration and type of surgery ([Table 1]).
The addition of dexamethasone to low volumes of bupivacaine in SBPB significantly decreased the onset time and significantly prolonged the duration of sensory and motor block; these effects were more prominent in group B, with a slightly higher volume of bupivacaine ([Table 2]).
There were statistically significant differences among the three groups in the VAS at 12, 18, 24, 30 and 36 h, with the highest level of VAS in group C, which received plain bupivacaine ([Figure 1]).
|Figure 1 Distribution of groups in terms of their postoperative VAS. VAS, visual analogue scale|
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There was a statistically significant increase in the duration of postoperative analgesia in group B more than group A and C and in group A more than group C ([Figure 2]).
|Figure 2 Distribution of the groups in terms of their duration of analgesia|
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The total dose of intravenous paracetamol was significantly higher in the first postoperative 36 h (nearly double the dose) in group C, which received plain bupivacaine, than dexamethasone groups ([Figure 3]).
|Figure 3 Distribution of the groups in terms of their intravenous paracetamol dose|
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On comparing the three groups, there was a statistically significant increase in postoperative HR and MABP in group C more than the other two groups at 12 h, and a significant increase in HR and MABP in group A and C more than group B at 24 ([Table 3] and [Table 4]).
Correlation between VAS and haemodynamic parameters among the groups studied showed that there was a significant increase in HR and MABP in response to increased VAS in group C started at 12 h, but started in group A at 18 h and started in group B after 24 h ([Table 5] and [Table 6]).
In terms of complications, Horner syndrome developed in one patient from group A and in one patient from group C by a percent of 2.22% of all patients. Two patients in group A and one patient in group C by a percent of 3.33% of all patients failed to achieve adequate block; these patients received a supplementary dose of local anaesthetic and were excluded from data analysis and replaced by other patients with the same method of randomization.
| Discussion|| |
This study evaluated the efficacy of dexamethasone as an adjuvant to low volumes of local anaesthetics in SBPB.
The results of the present study showed that dexamethasone leads to a significant enhancement of onset of action of bupivacaine; this enhancement was greater in group B with a relatively higher volume of local anaesthetic. Also, dexamethasone improved the quality and prolonged the duration of postoperative analgesia.
In agreement with the present study, Islam et al.  used a 35 ml mixture of equal volumes of lignocaine 2% and bupivacaine 0.5% in one group and the same amount of local anaesthetics mixed with dexamethasone (8 mg) in the other group for SBPB for forearm surgeries. Their results were in agreement with those of the current study in enhancement of onset of sensory block by dexamethasone. They reported that the onset time in the dexamethasone group was 09.89 ± 1.97 min, whereas it was 11.64 ± 2.19 min in the other group that received a plain local anaesthetic mixture. The onset time in their study was slightly shorter than the current study because they mixed bupivacaine with lidocaine, which has a rapid onset of action.
Dar and Najar  injected 30 ml of 0.5% ropivacaine+2 ml saline in one group and 30 ml of 0.5% ropivacaine+2 ml dexamethasone (8 mg) in the other group. They reported that the duration of sensory block was 12.3 h when dexamethasone was added to bupivacaine, whereas it was 7.5 h when plain bupivacaine was used in the block; these results are in agreement with those of the current study.
In 2013, the Shaikh et al.  study reported that the duration of motor block was significantly longer (14.11 ± 1.70 h) in the dexamethasone group compared with 9.06 ± 0.92 h in the other group; this duration is longer than that in the current study as Shaikh et al.  used 38 ml of bubivacaine 0.25%, which is double the volume of the local anaesthetic used in the current study.
Cummings  added dexamethasone to 30 ml of ropivacaine 0.5% or 30 ml of bupivacaine 0.5% in patients who received ultrasound-guided interscalene brachial plexus blockade. Their results were in agreement with those of the present study as they showed that dexamethasone significantly prolonged the duration of analgesia and decreased the level of the mean verbal rating pain score of both ropivacaine and bupivacaine groups after an ultrasound-guided interscalene brachial plexus block.
In this study, the dose of intravenous paracetamol was significantly higher (nearly double) in the plain bupivacaine group than dexamethasone groups; it was slightly higher in group A than group B. Intravenous paracetamol was enough to yield a satisfactory level of analgesia as none of the patients in any of the groups required pethidine as a supplementary analgesic drug; thus, the present study showed that dexamethasone, when added to local anaesthetic in SBPB, led to a significant decrease in the total analgesic requirement of the patients in the first 36 h of the postoperative period.
The results of the study by Kim  and Vieira  were in agreement with those of this study as they showed that the analgesic requirement was lower in the dexamethasone group than in the plain bupivacaine group for the first 48 h.
In terms of postoperative monitoring of haemodynamic parameters, the increase in HR and MABP in the present study was directly proportional to the VAS values. They started to increase significantly when the VAS reached score 4 or more. This increase started at 12 h in group C, which received plain bupivacaine, and at 18 and 24 h in dexamethasone groups A and B, respectively.
There were no serious complications, except for the Horner syndrome. This was in agreement with other studies ,,, .
Horner syndrome occurred in 2.22% of all patients in this study; this is a very low incidence. In contrast to the present study, Islam et al.  reported a 40% incidence of Horner syndrome in the dexamethasone group and 33% in the other group.
The study of Masoud et al.  , who used the anatomical landmark technique of supraclavicular block, reported that 25% of patients of the study developed vascular injury and 8.8% of patients developed haematoma at the site of injection. This very high incidence of traumatic complication compared with the present study clearly shows the advantage of the use of ultrasound in a supraclavicular block.
| Conclusion|| |
This study found that the addition of dexamethasone to low volumes of bupivacaine in ultrasound-guided SBPB significantly decreased the onset time and prolonged the duration of sensory and motor blockade; also, it prolonged the duration and improved the quality of postoperative analgesia in patients who underwent forearm and hand surgeries, with a very low incidence of complications.
| Acknowledgements|| |
Conflicts of interest
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]