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 Table of Contents  
ORIGINAL ARTICLE
Year : 2022  |  Volume : 1  |  Issue : 2  |  Page : 62-67

Addition of dexamethasone to levobupivacaine in the ultrasound-guided bilateral subcostal transversus abdominis plane block improves the quality of postoperative analgesia after laparoscopic cholecystectomy: A prospective randomized clinical study


Department of Anesthesiology and Pain Medicine, Medica Superspecialty Hospital, Kolkata, West Bengal, India

Date of Submission31-May-2022
Date of Decision20-Aug-2022
Date of Acceptance27-Aug-2022
Date of Web Publication02-Dec-2022

Correspondence Address:
Dr. Jaya Choudhary
Department of Anesthesiology and Pain Medicine, Medica Superspecialty Hospital, Kolkata - 700 099, West Bengal
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jica.jica_16_22

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  Abstract 

Background and Aims: Addition of dexamethasone to levobupivacaine in the peripheral nerve block provides improved pain scores, prolonged pain relief, and reduced postoperative opioid requirement. However, the evidence regarding its efficacy in the transversus abdominis plane (TAP) block is limited. Therefore, we conducted this study to evaluate the potential benefits of combining dexamethasone with levobupivacaine in the subcostal TAP block during the first 24 h after laparoscopic cholecystectomy. Materials and Methods: Seventy-six patients were enrolled in the study and divided into two groups to receive 20 ml of 0.25% levobupivacaine with 1 ml NS bilaterally (Group LS) or 20 ml of 0.25% levobupivacaine with 4 mg dexamethasone bilaterally (Group LD). Each patient received a standard multimodal analgesic regimen. Pain scores were recorded at rest and during coughing at 0, 2, 4, 6, 12, and 24 h postoperatively. Total opioid consumption and associated complications were recorded during the first 24 h. Results: Pain scores were lower in the LD group as compared to the LS group at all time points. Reduction in Numeric Rating Scale values was statistically significant at 4, 6, and 12 h both at rest and during coughing. Estimated P values on coughing at these time points were 0.000, 0.001, and 0.017, respectively. Postoperative opioid requirement was also significantly reduced between 2 and 24 h (P = 0.007). We did not record any complications in our study population. Conclusion: The combination of dexamethasone and levobupivacaine in the subcostal TAP block significantly improves the efficacy of multimodal analgesic regimen during the first 24 h after laparoscopic cholecystectomy.

Keywords: Levobupivacaine, multimodal analgesia, Numeric Rating Scale, perineural dexamethasone, postoperative analgesia, subcostal transversus abdominis plane block


How to cite this article:
Choudhary J, Agarwal A, Bhojwani P. Addition of dexamethasone to levobupivacaine in the ultrasound-guided bilateral subcostal transversus abdominis plane block improves the quality of postoperative analgesia after laparoscopic cholecystectomy: A prospective randomized clinical study. J Ind Coll Anesth 2022;1:62-7

How to cite this URL:
Choudhary J, Agarwal A, Bhojwani P. Addition of dexamethasone to levobupivacaine in the ultrasound-guided bilateral subcostal transversus abdominis plane block improves the quality of postoperative analgesia after laparoscopic cholecystectomy: A prospective randomized clinical study. J Ind Coll Anesth [serial online] 2022 [cited 2023 Feb 3];1:62-7. Available from: https://www.jicajournal.in//text.asp?2022/1/2/62/362609


  Introduction Top


Postoperative pain is the main reason for readmission, prolonged convalescence, and conversion to chronic pain after laparoscopic cholecystectomy.[1],[2],[3] The supraumbilical port incisions are responsible for the predominant somatic component of pain after laparoscopic cholecystectomy,[4],[5] and the dermatomes involved in these port sites can be effectively blocked by subcostal transversus abdominis plane (TAP) block.[6],[7] Dexamethasone acts as an effective adjuvant to the local anesthetics in both peripheral nerve blocks and the TAP block.[8],[9] As an adjuvant in the TAP block, it is known to provide several benefits including improved pain scores, prolonged analgesia, and reduced requirement of rescue analgesics.[10],[11],[12],[13],[14]

The volume of injection plays an important role in determining the efficacy of TAP block. Therefore, most of the previous authors have used the combination of ropivacaine and dexamethasone in the TAP block due to its higher safety margin and lower cardiac toxicity. Despite these advantages, there have been reports suggesting that plasma ropivacaine concentrations may reach potentially toxic levels after bilateral TAP injections.[15] Levobupivacaine may provide a safe and effective alternative to ropivacaine due to its lower systemic toxicity. Although the combination of levobupivacaine and dexamethasone is well studied in the peripheral nerve blocks, there is limited evidence regarding this combination in the TAP block.

Therefore, we conducted this study to evaluate the efficacy of dexamethasone as an adjuvant to 0.25% levobupivacaine in the subcostal TAP block as a component of multimodal analgesia.


  Materials and Methods Top


This prospective, double-blinded, randomized study was conducted at our tertiary care center after obtaining approval from the Institutional Ethical Committee. Seventy-six American Society of Anesthesiologists (ASA) Grade 1 and 2 patients between 18 and 60 years of age, body mass index <30 mg/kg2, scheduled for elective laparoscopic cholecystectomy were included in the study. The exclusion criteria of our study were known allergy to local anesthetics, body weight <40 kg, chronic pain conditions, opioid addiction, or local site infection. Written informed consent was obtained from each patient.

Each patient received oral premedication including 40 mg pantoprazole, 0.25 mg alprazolam, and 50 mg diclofenac on the morning of surgery. Patients were allocated into two groups using a computer-generated randomization table. An anesthesiologist not participating in the study prepared the block injectate in two separate 20 ml syringes for each side: Group LS –20 ml of 0.25% levobupivacaine and 1 ml normal saline or Group LD –20 ml of 0.25% levobupivacaine and 4 mg dexamethasone. The prepared drug solution was loaded in similar syringes and labeled as “study drug” for each patient. The patients participating in the study, the anesthesiologist performing the block, and the observer recording the data were blinded to the study drug.

Inside the operating room, after applying the standard ASA monitors, anesthesia was induced with 2–3 μg/kg fentanyl, 2.5 mg/kg propofol, and 0.6 mg/kg atracurium and maintained with 2% sevoflurane in oxygen and air mixture. After induction, an experienced anesthesiologist performed bilateral subcostal TAP block under ultrasound guidance. We performed the block at two separate injection points medial and lateral to the linea semilunaris [Figure 1]. Under aseptic precautions, a high-frequency (5–10 Hz) ultrasound probe was placed obliquely at the xiphisternum parallel to the costal margin. A 10 cm, 22G needle was introduced from the xiphisternum and advanced laterally to enter the interfascial plane at the first injection point between the rectus abdominis muscle and the transversus abdominis muscle. The correct position of the needle tip was confirmed with 0.5 ml of NS injection and half of the local anesthetic solution was injected and observed as hypoechoic expansion of the interfascial plane. For the second point injection, the ultrasound probe was shifted laterally and the remaining half of the drug was injected lateral to the linea semilunaris between the internal oblique muscle and the transversus abdominis muscle.[16] The procedure was repeated on the contralateral side.
Figure 1: Local anesthetic distribution medial and lateral to the linea semilunaris. RAM: Rectus abdominis muscle, EOM: External oblique muscle, IOM: Internal oblique muscle, TAM: Transversus abdominis muscle, LS: Linea semilunaris, LA: Local anesthetic

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Laparoscopic cholecystectomy was performed using four supraumbilical ports in each patient: two 5 mm subcostal ports and two 10 mm ports in the epigastric and the periumbilical areas, respectively. Intra-abdominal pressure was maintained ≤12 mmHg in each patient. At the end of the surgery, 4 mg ondansetron was administered to each patient and the neuromuscular block was antagonized with neostigmine and glycopyrrolate.

Postoperatively, each patient received oral diclofenac 50 mg 8 hourly and a rescue analgesic was administered if NRS ≥4. Rescue analgesics included bolus doses of 25 μg fentanyl during 0–2 h and 50 mg tramadol in 100 ml normal saline during 2–24 h (maximum dose allowed = 1.5 mg/kg/dose, not <8 h apart).

The primary outcome measure of our study was the NRS on coughing at 4 h, which was the time point of highest pain intensity based on a previous study. The secondary outcomes included the NRS at rest at 0, 2, 4, 6, 12, and 24 h, NRS on coughing at 0, 2, 6, 12, and 24 h, total postoperative opioid consumption during 24 h, levels of nausea, vomiting and sedation, local anesthetic systemic toxicity, and injection site hematoma or infection.

Thirty-six patients were required in each group to detect a difference of 2 units on the Numeric Rating Scale (NRS) between the two groups with 80% power and 5% significance level. The value of standard deviation (SD) was considered 2.8 from a previous study.[17] Thirty-eight patients were enrolled in each group to compensate for the dropouts. The categorical variables were expressed as number or percentage of patients and compared between the two groups using Pearson's Chi-square test or Fisher's exact test as appropriate. The continuous variables were expressed as mean ± SD and compared using Mann–Whitney U-test. Any P < 0.05 was considered statistically significant.


  Results Top


Seventy-six patients were enrolled in this investigation, and there were no dropouts during the study period [Figure 2]. The patients in the two groups were comparable in terms of age, sex distribution, weight, and the duration of surgery [Table 1].
Figure 2: Consort flow diagram showing the distribution of patients

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Table 1: Demographic data

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The mean postoperative pain scores recorded using NRS were lower in Group LD at all time points as compared to Group LS during coughing as well as at rest. Statistical comparison using the Mann–Whitney U-test showed that pain scores on coughing were significantly lower at 4 (P = 0.00), 6 (P = 0.00), and 12 (P = 0.02) h. Similarly, the NRS scores at rest were also significantly lower at 4 (P = 0.00), 6 (P = 0.00), and 12 (P = 0.01) h [Table 2], [Table 3] and [Figure 3], [Figure 4]. Only one patient in the LS group complained of shoulder pain, which was managed, with bolus dose of tramadol hydrochloride.
Table 2: Numeric rating scale score at rest

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Table 3: Numeric Rating Scale score on coughing

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Figure 3: NRS values at rest as mean with 95% CI in Group LS versus Group LD. NRS: Numeric Rating Scale score, CI: Confidence interval, Group LS: 0.25% levobupivacaine +1 ml NS, Group LD: 0.25% levobupivacaine +4 mg dexamethasone

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Figure 4: NRS values on coughing as mean with 95% CI in Group LS versus Group LD. NRS: Numeric rating scale score, CI: Confidence interval, Group LS: 0.25% levobupivacaine +1 ml NS, Group LD: 0.25% levobupivacaine +4 mg dexamethasone

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Although the postoperative fentanyl requirement was similar between the two groups during the first 2 h (P = 0.26), tramadol consumption was lower in Group LD and statistically significant during 2–24 h (P = 0.01) [Table 4] and [Figure 5]. We did not record any complications associated with the block such as bleeding, local anesthetic systemic toxicity, hematoma, or infection at the block site. Postoperative nausea and vomiting was recorded in 7 patients in Group LS and 4 in Group LD, and the results were statistically insignificant. Similarly, the sedation score recorded as per the Ramsay sedation score was comparable between the two groups.
Table 4: Postoperative opioid requirement

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Figure 5: Scatter plot of tramadol requirement during 2–24 h. Group LS: 0.25% levobupivacaine +1 ml NS, Group LD: 0.25% levobupivacaine +4 mg dexamethasone

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  Discussion Top


The results of our study suggest that dexamethasone as an adjuvant improves the analgesic efficacy of levobupivacaine. We observed a significant reduction in the pain scores at 4, 6, and 12 h, both at rest and on coughing. NRS on coughing at 4 h, which was not only our primary endpoint but also the time point of most severe pain, was effectively reduced to mild pain [Table 2], [Table 3] and [Figure 3], [Figure 4]. Almost all patients in Group LD experienced a better-tolerated mild pain, i.e., NRS <4. It is noteworthy that, although TAP block is effective only for somatic pain, the intensities of both NRS at rest and during coughing were significantly reduced in our study. Systemic absorption of dexamethasone may explain the visceral pain relief leading to a reduction in NRS on coughing.

Similar to our findings, past studies have demonstrated the efficacy of dexamethasone as an adjuvant to levobupivacaine in the epidural and peripheral nerve blocks.[18],[19],[20] In contrast to the neuraxial and peripheral nerve blocks, the TAP block is effective only as a component of multimodal analgesia and adjuvants have a role in providing improved pain scores and reducing the requirement of other analgesics, especially opioids. Akkaya et al. demonstrated that dexamethasone prolongs the analgesic action of levobupivacaine in the TAP block and reduces the requirement of rescue analgesics after the lower-segment cesarean section conducted under spinal anesthesia.[13] However, their findings cannot be compared with our study as spinal anesthesia itself may provide intense analgesia during the first few hours postoperatively. Furthermore, they have not described the use of any systemic analgesics for visceral pain relief apart from rescue doses of tramadol. An effective multimodal analgesic regimen must provide a systemic analgesic (opioid or nonsteroidal anti-inflammatory drugs) at regular intervals in addition to rescue analgesics. In addition, none of the previous studies have reported the effect of using this combination in the subcostal approach to TAP block. Our study is the first to investigate the potential benefits of adding dexamethasone with levobupivacaine in the subcostal TAP block as a component of multimodal analgesic regimen for patients undergoing surgery under general anesthesia.

Several studies have documented the advantages of combining dexamethasone with bupivacaine and ropivacaine in the TAP block for various open and laparoscopic abdominal procedures.[11],[12],[13],[14] However, bupivacaine due to its potential cardiac toxicity may not be the local anesthetic of choice for the volume-dependent interfascial plane blocks. At the same time, dexamethasone was not found to improve the analgesic efficacy of ropivacaine by few authors.[21],[22] Wegner et al. attributed this to the fact that ropivacaine has a lower pH than other local anesthetics, and therefore, it tends to precipitate with the alkaline dexamethasone. Furthermore, it was observed that the likelihood of the drug precipitation increased with time and higher doses of dexamethasone.[22] In contrast, levobupivacaine does not precipitate with dexamethasone and its plasma concentration also remains within the safety limits after the administration of a 100 mg dose.[23]

We recorded significantly reduced consumption of tramadol during 2–24 h in Group LD, which is consistent with the results of the previous studies.[12],[13],[14] Perineural dexamethasone potentiates the action of local anesthetics by various mechanisms such as direct inhibition of nociceptive C fibers, a local anti-inflammatory effect, and locally induced vasoconstriction.[24]

Hebbard first described the subcostal TAP block and later several modifications were described to increase the spread of the local anesthetic solution to achieve a wider segmental nerve blockade.[16] The local anesthetic can be injected using single or multiple injection points medial or lateral to the linea semilunaris.[16],[25] The multiple-point injection provides a much wider spread of local anesthetics as compared to a single-point injection.[26] Furthermore, injection lateral to the linea semilunaris is likely to achieve T9–11 block, whereas an injection medial to the linea semilunaris is likely to provide T6–8 coverage.[27] Therefore, we injected the local anesthetic mixture at two different points, medial and lateral to the linea semilunaris, to achieve the desired extent of segmental blockade.

The first limitation of our study is that we used a dose of 4 mg dexamethasone on each side, which is the ceiling dose of dexamethasone for the peripheral nerve blocks.[28] We used this dose bilaterally assuming that each side has a separate set of nerves to be blocked. However, the effective dose of dexamethasone may not be the same for the fascial plane blocks as the local anesthetic mixture spreads over a wider area in the interfascial plane block as compared to the more restricted area of spread in the peripheral nerve blocks. Therefore, further research is required to identify the ideal dose of dexamethasone for the fascial plane blocks. The second important limitation is that we did not study the time to first rescue analgesic requirement. Post laparoscopic cholecystectomy, patients have multiple components of pain and therefore longer time required to first rescue analgesic may not indicate prolongation of block effect. The third limitation is that we did not conduct a sensory assessment to confirm the success of the block in each patient.


  Conclusion Top


The result of our study suggests that the inclusion of subcostal TAP block with levobupivacaine and dexamethasone as a component of multimodal analgesic regimen provides several benefits after laparoscopic cholecystectomy. The most important advantages recorded in our study were reduction in both visceral and somatic components of pain, reduced requirement of rescue analgesics, and minimal side effects.

Acknowledgment

We would like to thank Ms. Sudarshana Biswas for her expert assistance with the statistics of this study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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