|Year : 2016 | Volume
| Issue : 3 | Page : 181-185
Randomized controlled trial to study the effect of dexamethasone as additive to ropivacaine on duration of ultrasound-guided transversus abdominis plane block in cesarean section
Jasleen Sachdeva1, Ashok Sinha2
1 Department of Anaesthesia, Adesh Institute of Medical Sciences and Research, Bathinda, Punjab, India
2 Department of Anaesthesia, Artemis Hospital, Gurgaon, Haryana, India
|Date of Web Publication||10-Jan-2017|
H. No. 387, Phase 1, Model Town, Bathinda, Punjab - 151 001
Source of Support: None, Conflict of Interest: None
Background: Transversus abdominis plane (TAP) block is a regional anesthesia technique whose efficacy has been proven for postoperative pain relief after cesarean section (CS). Dexamethasone, a glucocorticoid, is now emerging as a new adjunct to local anesthetics for prolonging the duration of action and has been studied in different brachial plexus blocks. The primary outcome was to study the effect of dexamethasone as additive to ropivacaine on the duration of TAP block as assessed by time to first analgesic (TFA) . The secondary outcome was total postoperative analgesic consumption, postoperative nausea and vomiting, and patient satisfaction. Method: This RCT was conducted on seventy American Society of Anesthesiology Grade I and II patients undergoing CS under subarachnoid block. Patients were randomly allocated to two groups comprising 35 patients each. Patients in Group I received ultrasound-guided bilateral TAP block at the end of surgery using 40 ml ropivacaine 0.2% and 2 ml saline, and patients in Group II received the block using 40 ml ropivacaine 0.2% and 2 ml (8 mg) dexamethasone. Result: TFA was significantly longer in Group II (5.92 ± 1.02 vs. 3.11 ± 0.82 h, P = 0). Group II also had decreased tramadol requirement postoperatively (100.00 ± 0.00 vs. 140.00 ± 50.26 mg, P = 0.046). The incidence of nausea and vomiting was also lower (82.86% vs. 97.14%, P = 0.02318). The patient satisfaction with regard to pain relief was more (57.14% vs. 25.71%, P = 0.038). Conclusion: Addition of dexamethasone to ropivacaine in TAP block prolonged the duration of the block. There was no complication seen with TAP block in any of the patients.
Keywords: Dexamethasone, ropivacaine, transversus abdominis plane block
|How to cite this article:|
Sachdeva J, Sinha A. Randomized controlled trial to study the effect of dexamethasone as additive to ropivacaine on duration of ultrasound-guided transversus abdominis plane block in cesarean section. Indian J Pain 2016;30:181-5
|How to cite this URL:|
Sachdeva J, Sinha A. Randomized controlled trial to study the effect of dexamethasone as additive to ropivacaine on duration of ultrasound-guided transversus abdominis plane block in cesarean section. Indian J Pain [serial online] 2016 [cited 2020 Jul 10];30:181-5. Available from: http://www.indianjpain.org/text.asp?2016/30/3/181/198056
| Introduction|| |
Cesarean section (CS) is one of the most commonly performed surgeries and commonly induces moderate-to-severe pain for up to 48 h. Adequate pain relief after CS is more compelling than any other surgery as inadequate pain relief in postoperative period leads to decreased ability of mother to breastfeed effectively and care for baby.
The transversus abdominis plane (TAP) block is a regional anesthesia technique where local anesthetics (LAs) are injected into TAP, which is an anatomic space between internal oblique and transversus abdominis muscle and spans the abdomen till these two muscles reach the rectus abdominis. It targets nerves of anterolateral abdomen wall. 
Various trials have studied the role of TAP block for postcesarean analgesia. Results showed adequate analgesia, decreased consumption of opioids, and decreased nausea and sedation in postoperative period. , However, the improved analgesia is short lived.
LAs are widely used for peripheral nerve blockade. Ropivacaine is commonly chosen instead of shorter duration agents such as mepivacaine or lidocaine in an effort to extend the duration of postoperative analgesia, and to prolong surgical block. While advantages of longer duration blocks are numerous, particularly in the postoperative setting, the possibility of both local and systemic toxicity precludes a simple increase in concentration or volume of administration as a means of increasing analgesic duration. In an effort to expand the narrow therapeutic window of LAs, several perineural adjuvants have been studied with the goal of prolonging the duration of analgesia for a given LA dose, reducing the LA dose, and minimizing other effects (e.g., motor blockade).
Dexamethasone, a glucocorticoid, is now emerging as a new adjunct to LAs for prolonging the duration of action and has been studied in different blocks such as axillary,  interscalene,  and supraclavicular blocks.  Dexamethasone acts locally on nociceptive C-fibers (through glucocorticoid receptors) to increase the activity of inhibitory potassium channels, thus decreasing their activity. 
Since there are limited studies on the use of dexamethasone as an adjuvant, this study was undertaken to study the effect of dexamethasone as an additive to ropivacaine on the duration of ultrasound-guided TAP block for lower segment CS.
| Methods|| |
This study was conducted after approval from the departmental review board and Institutional Ethics Committee. This prospective randomized study was performed on seventy American Society of Anesthesiology (ASA) Grade I and II patients undergoing lower segment CS for delivery under subarachnoid block. Written informed consent was taken from all patients. A detailed preanesthetic checkup was carried out in all patients.
The aim was to study the effect of dexamethasone as an adjunct to ropivacaine with respect to duration of TAP block (assessed as time to demand for first analgesic [TFA]), time to demand for first additional analgesic, i.e., tramadol (T1), total postoperative analgesic consumption, patient satisfaction with regard to pain relief, and postoperative nausea and vomiting.
The selection criteria were all ASA Grade I and II pregnant female patients undergoing lower segment CS under subarachnoid block. The exclusion criteria were patient refusal, known allergy to LAs/opioids/nonsteroidal anti-inflammatory drugs, infection at needle insertion site for block, recent use of glucocorticoids, patients with diabetes mellitus, patients with pregnancy-induced hypertension, and patients with morbid obesity.
Patients were randomly allocated by computer-generated random numbers to one of two groups comprising 35 patients each. The injectate in both groups was prepared by an independent anesthesiologist not involved in patient care, TAP performance, or data collection.
Group I (ropivacaine) - ultrasound-guided bilateral TAP block given at the end of surgery using 40 ml plain ropivacaine 0.2% and 2 ml saline.
Group II (ropivacaine + dexamethasone) - ultrasound-guided bilateral TAP block given at the end of surgery using 40 ml ropivacaine 0.2% and 2 ml (8 mg) dexamethasone.
The patients were explained about the whole procedure. In operation theater, monitoring for electrocardiography, pulse oximetry, and noninvasive blood pressure was started and continued till patient was out of operation room. All patients were preloaded with Ringer's Lactate amounting to 10 ml/kg body weight before the start of surgery. All patients received subarachnoid block with 10-12.5 mg of 0.5% heavy bupivacaine, and adequate sensory level was achieved.
At the end of surgery, the patients received an ultrasound-guided bilateral TAP block using the drug according to group allocation. A single-injection ultrasound-guided TAP block was performed in all patients using a linear ultrasound probe (9-12 MHz). With the patient in the supine position, the ultrasound probe was placed in the midaxillary line, in a transverse plane to the lateral abdominal wall between the lower costal margin and the iliac crest. The needle was then positioned in plane and directly under the ultrasound probe, and then advanced till it reached the plane between the internal oblique and transversus abdominis muscles (TAP) [Figure 1] and [Figure 2]. Upon reaching this plane, the LA solution was injected, which lead to expansion of the TAP that appeared as a hypoechoic space. Careful aspiration was performed before injection to exclude vascular puncture. The TAP block was then performed on the opposite side, using the same technique and the same injectate. After surgery, the patients were transferred to the postanesthesia care unit. In the ward, pain was assessed using Numerical Verbal Rating Scale (VRS) hourly for the first 4 h and then two hourly for the next 24 h. At any point of time if VRS >3, the patients received injection diclofenac 1.5 mg/kg for pain relief which was then continued 8 hourly. Since in this study, we were dealing with adult patients with weight >50 kg, a standard dose of diclofenac 75 mg intravenous was given to all patients.
|Figure 1: Position of ultrasound probe while giving transversus abdominis plane block.|
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If patient had VRS >3 even after 30 min of receiving diclofenac, injection tramadol 100 mg intravenous was given as additional analgesic for breakthrough pain relief. Duration of analgesia was defined as the time interval from completion of LA administration till first demand for analgesic.
The primary outcome was time to first demand for analgesic, i.e., diclofenac (TFA). We also measured the time to demand for additional analgesic, i.e., tramadol (T1) and total postoperative diclofenac and tramadol consumption.
Patient satisfaction regarding pain relief was assessed at the end of 24 h as either acceptable or good.
Nausea and vomiting was assessed, and patient was given score according to nausea and vomiting score described by McDonnell et al. 
0 - No nausea/vomiting in past 24 h
1 - Nausea in past interval
2 - Vomiting in past interval.
Nausea lasting for more than 10 min and vomiting was treated with ondansetron 0.1 mg/kg body weight.
At the end of 24 h, the site of block was examined for evidence of any infection, any hematoma, or signs of any other side effects related to TAP block.
Before the study, a power analysis was performed to determine the necessary number of patients in each group. With a two-sided type I error of 5% and study power at 80% and assuming the minimum detectable difference of 1 h to be significant, it was estimated that the minimum required sample size in each group was 34. Assuming attrition seventy participants were recruited in the study.
All quantitative variables have been compared using Student's unpaired t-test or Mann-Whitney U-test, and qualitative variables using Chi-square test or Fisher's exact test.
All analyses were two-tailed, and P < 0.05 was considered statistically significant.
| Results|| |
Both groups were comparable regarding the demographic data and operative characteristics [Table 1].
The time for first demand of analgesic (TFA) was significantly longer in Group II (5.92 ± 1.02 h) versus Group I (3.11 ± 0.82 h). This is statistically significant with P = 0.00. Hence, this shows that dexamethasone prolongs the duration of TAP block when added to ropivacaine [Table 2].
|Table 2: Time for demand of first and additional analgesic and total analgesic consumption|
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However, the total amount of diclofenac consumed by the patients in the two groups did not differ significantly. Total diclofenac consumption in Group I was 225.00 ± 0.00 mg, and in Group II, it was 220.71 ± 17.66 mg (P = 0.07787). This was statistically not significant.
The time for demand of additional analgesic, i.e., tramadol (T1) was also longer in Group II and was statistically significant. It was 4.88 ± 1.36 h in Group I versus 6.90 ± 0.62 h in Group II (P = 0.0020).
The total postoperative tramadol consumption was also lesser in Group II. It was 140.00 ± 50.26 mg in Group I versus 100.00 ± 0.00 mg in Group II. This was statistically significant with P = 0.04662.
In Group I, 25.71% patients described their pain satisfaction as good, whereas 74.29% patients described it as acceptable. In Group II, 57.14% patients described their pain satisfaction as good, whereas 42.86% patients described it as acceptable. This suggests that there is better patient satisfaction in Group II and it is also statistically significant [Table 3].
|Table 3: Patient satisfaction with respect to pain relief among two groups|
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In Group I, 82.86% patients did not experience any nausea or vomiting as compared to 97.14% patients in Group II (P = 0.02318), whereas 8.57% patients experienced nausea in Group I and 2.86% in Group II (P = 0.15154). The incidence of vomiting in Group I was 8.57%, whereas no patient had vomiting in Group II (P = 0.03833) [Table 4].
|Table 4: Comparison of postoperative nausea/vomiting score in two groups|
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The above data suggest that there is no statistically significant difference in the incidence of nausea in two groups, but the incidence of vomiting is significantly lower in Group II and is statistically significant.
| Discussion|| |
This study shows that the addition of 8 mg dexamethasone to 40 ml 0.2% ropivacaine for bilateral TAP block resulted in a significant reduction of pain score (VRS) over the postoperative 24 h, with prolongation of TFA, decreased requirement of postoperative opioids (Tramadol), decreased incidence of vomiting, and produced better patient satisfaction in terms of pain relief.
Various studies have demonstrated the beneficial effect of adding dexamethasone to LAs to prolong their duration of action. Addition of dexamethasone to lidocaine 1.5% solution for axillary brachial plexus block resulted in longer sensory and motor blockade duration (sensory blockade duration was 242 ± 76 vs. 98 ± 33 min for control and motor blockade duration was 310 ± 81 vs. 130 ± 31 min for control).  In another study, 40 mg methyl prednisolone was added to a mixture of LA formed of 20 mL bupivacaine + 20 mL mepivacaine + 0.2 mL epinephrine for axillary brachial plexus block. It resulted in longer analgesia (23 vs. 16 h for control) and longer motor blockade duration (19 vs. 13 h for control).  Shrestha et al.  added 8 mg of dexamethasone to a mixture of lidocaine and bupivacaine for supraclavicular brachial plexus block. This resulted in a faster onset of action and longer duration of analgesia without any adverse effects. Parrington et al.  added 8 mg of dexamethasone to 30 mL mepivacaine 1.5% during supraclavicular brachial plexus blockade. The dexamethasone group showed a longer duration of analgesia: 332 (225-448 min) versus 228 (207-263 min) min in the control group, whereas the onset times of sensory and motor blockade were similar in both groups. A study by Ammar and Mahmoud  was done to evaluate the effect of adding 8 mg dexamethasone to 0.25% bupivacaine on the quality and duration of TAP block in patients undergoing elective open abdominal hysterectomy. The pain VAS score was significantly lower at the postoperative 2 h (4.9 vs. 28.1, P = 0.01), 4 h (12.2 vs. 31.1, P = 0.01), and 12 h (15.7 vs. 25.4, P = 0.02). Furthermore, TFA was significantly longer in the dexamethasone group (459.8 vs. 325.4 min, P = 0.002), with lesser morphine requirements in the postoperative 48 h (4.9 vs. 21.2 mg, P = 0.003), and lower incidence of nausea and vomiting (6 vs. 14, P = 0.03). Cummings et al.  found that adjuvant dexamethasone with bupivacaine and ropivacaine prolongs the duration of interscalene block. They also found that there was no difference in the duration of analgesia and motor block between low-dose (4 mg) and high-dose (8 mg) dexamethasone. The effect was more potent with ropivacaine. However, the block duration was more prolonged with bupivacaine than with ropivacaine. Hence, probably, an additional group could have been added comparing the different doses of dexamethasone.
Several mechanisms have been postulated to explain the analgesic effect of corticosteroids. Stan et al.  suggested that steroids suppress the synthesis and secretion of various inflammatory mediators, which prolongs the period of analgesia up to 48 h. A direct effect on nerve membrane rather than an anti-inflammatory action has also been suggested as the corticosteroids were able to inhibit ectopic neural discharge originating in experimental neuromas.  However, it has also been reported that the steroids induce a degree of vasoconstriction, which results in reducing LA absorption, and they attach to the intracellular receptor to modulate nuclear transcription.  Attardi et al.  showed that dexamethasone acts on glucocorticoid receptors, which increase the activity of inhibitory potassium channels on nociceptive C-fibers.
Various side effects of TAP block which have been speculated are trauma to surrounding viscera, transient femoral nerve palsy, and high volume of drug used can cross the serum toxic levels. ,, No side effect of TAP block was seen in our study.
This study demonstrates that dexamethasone significantly prolongs the analgesic effect of plain ropivacaine used as a single injection for bilateral TAP block in lower segment CS patients.
This finding is generally consistent with previous studies, but direct comparisons are difficult because of the variety of LA mixtures used and different blocks that have been studied. This study is probably the first to examine the effect of dexamethasone on ropivacaine for TAP block in lower segment CS patients.
| Conslusion|| |
The addition of Dexamethasone to Ropivacaine prolongs the duration of TAP block in caesarean section.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]
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