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Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 12  |  Issue : 4  |  Page : 937-942  

Comparative evaluation of ropivacaine and ropivacaine with dexamethasone in transverse abdominis plane block for lower abdominal surgeries: a prospective, randomized, double-blinded study


Department of Anesthesiology and Critical Care, Shri Sathya Sai Medical College and Research Institute, Shri Balaji Vidyapeeth (Deemed-to-be-University), Ammapettai, Kancheepuram, Tamil Nadu, India

Date of Web Publication18-Dec-2018

Correspondence Address:
Dr. G Dilip Kumar
A 192, Casa Grand Elan, Jaganath Medows Road, Thalambur, Chennai - 600 130, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/aer.AER_162_18

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   Abstract 

Context: Dexamethasone as an adjunct to ropivacaine has shown promising results in prolonging the duration of analgesia in transverse abdominis plane (TAP) block. Only limited studies evaluated the effects of dexamethasone with ropivacaine in TAP block in specific population. Aims: The effects of adding dexamethasone to ropivacaine on the quality and duration of TAP block in lower abdominal surgeries in multiple specialties were studied. Settings and Design: This was a prospective, randomized, double-blinded study. Subjects and Methods: Seventy adult patients undergoing lower abdominal surgeries were allocated into two groups to receive general anesthesia with TAP block with 20 ml 0.25% ropivacaine with 8 mg dexamethasone (2 ml) (Group A, n = 35) or 20 mL 0.25% ropivacaine with 2 ml saline (Group B, n = 35) each side. The analgesic efficacy in terms of pain scores, morphine consumption, and occurrence of nausea and vomiting was compared between two groups. Statistical Analysis Used: Data were analyzed with SPSS 23 with independent t-test and Chi-square test as applicable. P < 0.05 was considered statistically significant. Results: The duration of analgesia was significantly prolonged in Group A (P = 0.000). The total morphine consumption was significantly lesser in Group A (P = 0.000). The pain scores (numerical pain intensity scale) were significantly lesser in Group A till the 8th postoperative hours. The occurrence of nausea and vomiting was comparable between the groups (P = 0.3821). Conclusions: Addition of dexamethasone to ropivacaine significantly improved the quality of analgesia with reduced consumption of opioids as compared to plain ropivacaine in TAP block.

Keywords: Dexamethasone, lower abdominal surgery, opioids, pain, ropivacaine


How to cite this article:
Gnanasekar N, Kumar G D, Kurhekar P, Raghuraman M S, Prasad T K. Comparative evaluation of ropivacaine and ropivacaine with dexamethasone in transverse abdominis plane block for lower abdominal surgeries: a prospective, randomized, double-blinded study. Anesth Essays Res 2018;12:937-42

How to cite this URL:
Gnanasekar N, Kumar G D, Kurhekar P, Raghuraman M S, Prasad T K. Comparative evaluation of ropivacaine and ropivacaine with dexamethasone in transverse abdominis plane block for lower abdominal surgeries: a prospective, randomized, double-blinded study. Anesth Essays Res [serial online] 2018 [cited 2019 Jun 25];12:937-42. Available from: http://www.aeronline.org/text.asp?2018/12/4/937/247656


   Introduction Top


Lower abdominal surgeries produce significant visceral, somatic, and neuropathic pain in the postoperative period. The intense neurohumoral, immunological, and catabolic changes produced by inadequate analgesia lead to physiological disturbances in organ function.[1]

Abdominal field blocks have been in the routine practice from the dawn of the century.[2],[3] Conventionally, blind blocks were limited by the accuracy in placement and side effects of the technique such as visceral injury and bleeding. This has been troubleshooted with the routine use of ultrasound which has improved the safety and success of the block.[4]

Many techniques and adjuncts were utilized to prolong the duration of analgesia produced by transverse abdominis plane (TAP) block. These included insertion of perineural catheters for continuous TAP block and use of adjuncts such as clonidine, tramadol, epinephrine, and corticosteroid.[5],[6],[7]

The use of perineural catheters was limited by techniques of placement and infection around the catheters.[8],[9]

Among the usage of adjuncts, dexamethasone has shown to be effective in prolonging the duration of analgesia produced by TAP block.[7]

Various combinations of dexamethasone and local anesthetics were studied in TAP block. Peripheral nerve blocks require minimum concentration of local anesthetics.[10] Due to the enhanced sensory blockade and less toxic profile of ropivacaine compared to bupivacaine, 0.25% ropivacaine was chosen for the study. There were also variations in the pain scores with the dose of local anesthetics and dexamethasone used in the previous studies.[11],[12],[13],[14],[15] Whether the difference in the onset of analgesia was due to increased local anesthetic concentration or dexamethasone was not evident. Moreover, for surgeries done under subarachnoid block, the early pain score assessment could also be misleading.[11],[12]

Hence, we decreased the local anesthetic concentration and used 8 mg dexamethasone to assess the quality of TAP block better under general anesthesia.

Since the pain sensation to the anterolateral abdominal wall is carried by the sensory fibers arising from the anterior primary rami of spinal nerves from T6 to L1, the postoperative pain produced by most of the lower abdominal surgeries involves these dermatomes.

Most of the studies involving dexamethasone for TAP block were done on specific surgeries.[11],[12],[13],[14],[15],[16],[17],[18]

Not much data is available which studied the analgesic quality of TAP block in lower abdominal surgeries involving multiple specialties put together.

In the current study, we evaluated the efficacy of 8 mg dexamethasone added to 0.25% ropivacaine as an adjuvant to TAP block in patients undergoing lower abdominal surgeries in multiple specialties under general anesthesia.


   Subjects and Methods Top


After obtaining the institutional ethics committee approval and informed written consent, 70 adult patients of either sex aged between 18 and 65 years of the American Society of Anesthesiologists (ASA) physical status classes I and II were enrolled for the study. The study was a prospective, single-centered, randomized, double-blinded study on patients who underwent elective lower abdominal surgeries under general anesthesia over a period of 6-month duration.

Patients who had known allergic manifestations to local anesthetics and adjuvants, those belonging to ASA III or more, patients who had acute or chronic pain ailments and those refusing the block were excluded from the study.

The patients were randomized into two groups (Group A and Group B) using computer-coded sealed envelope to receive either dexamethasone or saline as an adjunct to ropivacaine.

The patients, their anesthesiologists, and the medical staff who provided postoperative care were blinded to group assignment. The anesthesiologist who performed the block was blinded to the given mixture of drugs which was prepared by an assistant who was not otherwise involved in the study.

Following a preanesthetic evaluation, all the patients were explained about Numerical Pain Intensity Scale (NPIS) (0 – no pain and 10 – worst imaginable pain) in their own vernacular language. They were electively fasted 8 h preoperatively and were premedicated with oral ranitidine 150 mg and alprazolam 0.25 mg in the evening before and morning of the surgery.

Informed written consents were obtained from all patients, and the technique of anesthesia was explained. General anesthesia was standardized in both the groups.

All the patients were given 0.02 mg/kg of midazolam intravenous (iv) as a premedication about 20 min before induction of general anesthesia in the preoperative holding room. Standard monitors such as continuous electrocardiography, pulse oximetry, capnography, and noninvasive blood pressure were connected. Baseline vital parameters were noted down.

Patients were induced with propofol – 1.5–2 mg/kg and fentanyl – 3 μg/kg. Tracheal intubation was facilitated by administration of vecuronium 0.08 mg/kg. Anesthesia was maintained with N2O with O2 – 65%:35%, isoflurane – 1 vol %, vecuronium – 0.02 mg/kg every 30 min, and fentanyl – 1 μg/kg/hr. Patients were mechanically ventilated to keep the end-tidal CO2 concentration between 35 and 45 mmHg.

The TAP block was performed on each side at the conclusion of the surgery before extubation by the blinded anesthesiologist under ultrasound guidance using a linear array transducer of 10 MHz frequency (Mindray) using an in-plane technique.

The TAP plane was approached through the posterior technique. In supine position, the anterolateral abdominal wall on both sides were prepared with antiseptic solution and draped. The prepared mixture of drugs was handed over to the attending anesthesiologist.

The ultrasound probe was cleaned with antiseptics and a sterile transparent adhesive tape was used to cover the probe and povidone-iodine solution was used as the medium for scanning.

The scanning probe was placed transversely over the lateral abdominal wall between the iliac crest and the costal margin over the midaxillary line to identify the structures from superficial to deep as skin, subcutaneous tissue, fat, external oblique, internal oblique and transverse abdominis muscles, peritoneal cavity, and bowel loops.

A 23G Quincke Spinal Needle was advanced using an in-plane approach to the probe into the neurofascial plane between the internal oblique and transverse abdominis muscle, and 1 mL of saline was injected to open the fascial plane separating the two muscle layers. Once the needle was placed in the correct plane, 20 ml of 0.25% ropivacaine (Ropin 0.5% diluted to 0.25%, Neon Laboratories Ltd, India) +2 mL (8 mg) dexamethasone (Dexalab, Laborate Pharmaceuticals Ltd, India) was given to Group A patients (n = 35) each side and 20 ml of 0.25% ropivacaine + 2 ml saline was given to Group B patients (n = 35) each side.

After the block, residual neuromuscular blockade was reversed with neostigmine 0.05 mg/kg and glycopyrrolate 0.01 mg/kg. Patients were extubated after thorough suctioning of the oral cavity and return of the airway reflexes and transferred to the postanesthesia recovery unit where they were observed by the nursing staff who were otherwise blinded to the study group.

The NPIS scale was recorded at rest at the 1, 2, 4, 6, 8, 10, 12, 16, and 24 postoperative hours. All patients were given acetaminophen 1 g iv every 8 h during the first 24 h after surgery. Patients were given iv boluses of 1 mg morphine when NPIS scale at rest was more than 4 at any time patients complain of pain. Ondansetron 4 mg im was administered in case of reported nausea or vomiting. Any other side effects were also noted.

The primary outcome of the study was to evaluate the effects of dexamethasone on time to first request for additional analgesics in minutes after the surgery.

The pain scores (NPIS scale 0–10) at rest, total analgesic consumption (Morphine in mg), and occurrence of nausea/vomiting were chosen as secondary outcomes.

All the measured parameters were compared between the two groups.

Statistical analysis

Based on a previous study, assuming difference of 50% between the groups a minimum sample size was 35 for each group with type 1 error of 0.05, with power of the study at 80%, hence we set the sample size of 70.

The data were analyzed using the Statistical Package for the Social Sciences (SPSS) for Windows (Microsoft USA, Version 23, Armonk, NY: IBM Corporation and its licensors 2015). Continuous variables were analyzed by the independent Student t-test. NPIS scale and postoperative nausea and vomiting were analyzed with Chi-square test or Fisher's exact test as applicable, and data were expressed as the mean ± standard deviation (SD). P < 0.05 was considered statistically significant for two-sided test.


   Results Top


All the 70 patients randomized were included and analyzed for the study. The demographic data were comparable between the two groups in terms of age, sex, body mass index, and duration of surgery [Table 1]. The distribution of surgeries in various specialties among the groups is given in [Figure 1].
Table 1: Demographic data between groups (mean±standard deviation)

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Figure 1: Distribution of surgical specialties

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The time for the requirement of first rescue analgesic was significantly higher in the dexamethasone group compared to the saline group. The time interval (mean ± SD in min) elapsed before the request for the first additional analgesic was 525.8571 ± 81.30 in Group A compared to the value of 243 ± 97.36 in Group B which was statistically significant (P = 0.000 and 95% confidence interval (CI) = 240.07–325.64).

The total analgesic morphine consumption was higher in Group B compared to Group A (5.6571 ± 1.55 vs. 3.3714 ± 0.77) which was statistically significant (P = 0.000 and 95% CI = 2.87–1.70).

The mean pain scores (NPIS) at rest at various time intervals are given in [Table 2], which were statistically significant at 1st, 2nd, 4th, 6th, 8th, 10th, and 12th postoperative hours. There were no differences in the pain scores after the 16th postoperative hour, indicating the wearing off the effect of dexamethasone.
Table 2: Numerical pain intensity scale scores between groups

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The occurrence of nausea and vomiting between the groups was not statistically significant (P = 0.3821) [Table 3]. No other adverse effects were observed after the TAP block.
Table 3: Occurrence of nausea/vomiting

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   Discussion Top


The results of our study have demonstrated that addition of dexamethasone 8 mg as ropivacaine adjuvant in TAP block produces significant improvement in the quality of analgesia as evidenced by the increase in time required for the first rescue analgesic (P = 0.000) with a significant decrease in pain scores till the 8th postoperative hours. There was also significant decrease in the total morphine consumption during the first 24 h in the dexamethasone group as compared to the saline group (P = 0.000).

Regional anesthetic techniques, especially continuous epidural analgesia, have been the gold standard in providing near-complete analgesia for lower abdominal surgeries. Central neuraxial blockade may not be feasible in all situations, especially patients in coagulopathy, hypovolemia, hypotension, patient's refusal, routine use of perioperative anticoagulants, and emergence of fast tract, minimally invasive surgeries with early discharge, and hence, the routine use of epidural technique for postoperative analgesia is diminishing.[19] Parenteral analgesic drugs have been limited by their unwanted systemic effects.

The TAP block is an ideal and novel intervention in postoperative pain management for lower abdominal surgeries. As compared to the traditional epidural analgesia and parenteral analgesics, the TAP block offers innumerable advantages such as decreased hemodynamic perturbations, decreased respiratory depression, nausea, vomiting, decreased cost, and overall patient satisfaction.[20]

Ammar et al. demonstrated in their studies that addition of 8 mg dexamethasone as an adjunct to 20 ml 0.25% bupivacaine significantly prolongs the duration of analgesia of TAP block where the time to first request of analgesic was 459.8 ± 75.3 min.[14]

We found similar results with 8 mg dexamethasone added to 0.25% ropivacaine in terms of pain scores, but the time to the first analgesic request was 525.85 ± 81.3 min which could be explained by the enhanced sensory blockade of ropivacaine.[17]

Abdalla and Kartalov et al. in their prospective controlled trials have shown significant prolongation of time to first additional analgesic requirement and reduction in total morphine consumption with significant reduction in pain scores till 24 h after radical cystectomies and inguinal hernia surgeries, respectively.[7],[15]

Our study showed similar results with time to first analgesic consumption and total morphine consumption, whereas the pain scores were significantly lower in Group A only till the 8th postoperative hours probably because of surgeries involving multiple specialties leading to differences in visceral pain perception.

Deshpande et al. in their randomized double-blinded study have shown that ropivacaine 0.5% with 4 mg dexamethasone in TAP block produced significant reduction in pain scores from 4th to 12th postoperative hours with significant increase in time to first analgesic demand (13.2 ± 7.6 vs. 7.1 ± 4.6 H, P < 0.001) in abdominal hysterectomies done under subarachnoid block.[11]

Sharma et al. also found similar results with 8 mg dexamethasone added to 0.5% ropivacaine in TAP block for inguinal hernia surgeries done under spinal anesthesia. Since the above studies were done under subarachnoid block, early postoperative pain assessment could be misleading.[12]

We found a significant quicker onset of analgesia in dexamethasone group as compared to the above studies with significant reduction in pain scores from the 1st postoperative hour when 8 mg dexamethasone was used with 0.25% ropivacaine in surgeries done under general anesthesia wherein the efficacy of dexamethasone is better established.

Ropivacaine is a safe amide local anesthetic when used even at 0.25% in TAP block produced effective analgesia for abdominal surgeries as evidenced by Ahmed Zein et al. who showed that ropivacaine 0.2% produces similar analgesia compared to 0.5% in TAP block for cesarean sections done under general anesthesia.[10]

We found a significant decrease in pain scores in the saline group from the 10th to 12th postoperative hours probably due to the accumulated morphine consumption compared to the dexamethasone group. The pain scores were comparable between the groups from the 16th postoperative hours.

Various animal models have postulated the mechanism of action of dexamethasone. Barnes et al. had very well documented the anti-inflammatory effects of glucocorticoids.[21] Analgesia due to systemic absorption of peripherally injected dexamethasone-bupivacaine microcapsules in intercostal nerve blocks has also been documented in healthy volunteers.[22]

Devor et al. reported the prevention of ectopic neuronal discharge when freshly cut nerve endings were treated with corticosteroids in experimental neuromas.[23]

We did not find any significant difference in the incidence of nausea and vomiting between the two groups (P = 0.3821), and no other side effects or neurological complications were noted.

Our study was unique in a way; we evaluated the quality of TAP block with dexamethasone as an adjuvant for surgeries done under general anesthesia in multiple specialties. We postulated that lower abdominal surgeries in multiple specialties should share the same somatic pain perception pathways, and TAP block should offer equipotent analgesia in all these surgeries postoperatively. With the added advantage of dexamethasone, the quality of analgesia proved to be superior with no complications.

Although the results were similar to the previous studies, we found better quality of analgesia in terms of early onset, prolonged duration, and reduced opioid consumption which particularly delineated the effects of dexamethasone on peripheral nerves.

There were limitations of the study. First, we did not assess the pain scores on mobilization in both the groups. Since multiple specialty surgeries were studied, the influence of visceral component of pain could not be generalized which was spared by TAP block, and hence, we did not assess the pain scores on mobilization. Second, we did not use patient-controlled analgesia for postoperative morphine consumption due to technical difficulties which would have accurately delineated the opioid requirement between the groups.

Further research is required to study the role of preemptive TAP block in designing postoperative analgesia regimens compared to the postoperative TAP block in lower abdominal surgeries.


   Conclusions Top


We concluded that the addition of dexamethasone to ropivacaine in TAP block results in early, prolonged, and safe analgesia with decreased consumption of opioids and overall patient satisfaction in lower abdominal surgeries. We recommend using 8 mg dexamethasone with 0.25% ropivacaine routinely in TAP block for lower abdominal surgeries for better analgesic efficacy with no complications.

Acknowledgment

The study was registered at Clinical Trial Registry India, CTRI/2017/06/008880 on 20/06/2017.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

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Kehlet H, Holte K. Effect of postoperative analgesia on surgical outcome. Br J Anaesth 2001;87:62-72.  Back to cited text no. 1
    
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Petersen PL, Hilsted KL, Dahl JB, Mathiesen O. Bilateral transversus abdominis plane (TAP) block with 24 hours ropivacaine infusion via TAP catheters: A randomized trial in healthy volunteers. BMC Anesthesiol 2013;13:30.  Back to cited text no. 5
    
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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.  Back to cited text no. 13
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Baeriswyl M, Zeiter F, Piubellini D, Kirkham KR, Albrecht E. The analgesic efficacy of transverse abdominis plane block versus epidural analgesia: A systematic review with meta-analysis. Medicine (Baltimore) 2018;97:e11261.  Back to cited text no. 20
    
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Kopacz DJ, Lacouture PG, Wu D, Nandy P, Swanton R, Landau C, et al. The dose response and effects of dexamethasone on bupivacaine microcapsules for intercostal blockade (T9 to T11) in healthy volunteers. Anesth Analg 2003;96:576-82.  Back to cited text no. 22
    
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