Comment on "Feasibility and efficacy of erector spinae plane block versus transversus abdominis plane block in laparoscopic bariatric surgery: a randomized comparative trial"

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Korean J Anesthesiol. 2023;76(1):79-80
Publication date (electronic) : 2022 August 23
doi :
Department of Anesthesiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
Corresponding author: Fu-Shan Xue, M.D. Department of Anesthesiology, Beijing Friendship Hospital, Capital Medical University, NO. 95 Yong-An Road, Xi-Cheng District, Beijing100050, China Tel: +86-13911177655 Fax: +86-10-63138362 Email:
Received 2022 July 14; Accepted 2022 August 22.

In a randomized controlled trial that included 60 obese patients undergoing elective laparoscopic bariatric surgery, Elshazly et al. [1] compared the postoperative analgesic efficacy of the erector spinae plane block (ESPB) with the transversus abdominis plane block (TAPB). They showed that the bilateral ESPB was more effective than the TAPB for intraoperative and postoperative analgesia. Given that the use of a multimodal strategy (including a nerve or fascial plane block) to improve perioperative analgesia, enhance postoperative recovery, and decrease opioid requirements is highly desirable for patients undergoing bariatric surgery [2], this study has considerably potential implications. Other than the limitations described by the authors in the discussion, several issues with this study need further clarification and discussion.

First, postoperative pain was determined using a visual analog scale (VAS). However, the status of the patients during pain level assessment was not provided. The available literature indicates that pain intensity following bariatric surgery is higher during movement than at rest [3]. We are thus concerned that this unknown factor could have affected the postoperative pain assessment results in this study.

Second, the mean VAS score in the first 24 h postoperatively was higher in patients receiving the TAPB than in those receiving the ESPB. However, we noted that the mean VAS scores during the first 24 h postoperatively in the two groups were < 3, with small standard deviations (2.78 ± 0.34 vs. 2.32 ± 0.12). This indicates that most patients experienced only mild postoperative pain. Furthermore, the maximal between-group difference in the mean VAS scores during the first 24 h postoperatively appeared 20 min after extubation and was < 1. Most importantly, this study did not assess and compare patient satisfaction with postoperative pain control for the TAPB and ESPB. On this basis, we cannot determine whether the greater postoperative pain control reported with the ESPB compared to the TAPB should be considered clinically important.

Third, the authors reported that intravenous nalbuphine was used as the first rescue analgesic and intravenous ketorolac as the second rescue analgesic in cases where the postoperative pain VAS score was ≥ 4, as needed. In the results, the authors only provided total nalbuphine consumption during the first 24 h postoperatively and not ketorolac consumption. We were thus very interested to know whether any of the patients received intravenous ketorolac as a second rescue analgesic. Moreover, when between-group difference in postoperative analgesic consumption has been compared in previous studies assessing the efficacy of different analgesia modalities in patients undergoing bariatric surgery, the dosages of all the analgesics used for postoperative pain control were converted into morphine milligram equivalents in the oral or intravenous form [2]. As the equianalgesic conversion factor of morphine and nalbuphine for postoperative analgesia is approximately 1 : 1.5, the net between-group difference in mean nalbuphine consumption within the first 24 h postoperatively in this study were only equivalent to 2.94 mg intravenous morphine. The available literature recommends that the minimal clinically important difference in morphine milligram equivalents for postoperative pain control be an absolute reduction of 10 mg of intravenous morphine within 24 h [4]. Thus, the clinical significance of postoperative opioid sparing with the ESPB compared to the TAPB is not clearly evident.

Finally, this study assessed the time to first flatus or stool but no other outcome variables of enhanced recovery after surgical protocols for bariatric surgery, such as the incidence of postoperative nausea and vomiting, time to early mobilization, time to hospital discharge, and quality of postoperative recovery [5]. Because of this design limitation, an important question that this study cannot answer is whether the improved postoperative pain control and decreased opioid consumption reported for the ESPB compared to the TAPB can be translated into early postoperative benefits in obese patients undergoing bariatric surgery.




Conflicts of Interest

No potential conflict of interest relevant to this article was reported.

Author Contributions

Xue Gao (Conceptualization; Formal analysis; Writing – original draft; Writing – review & editing)

Tian Tian (Conceptualization; Formal analysis; Methodology; Writing – review & editing)

Fu-Shan Xue (Conceptualization; Formal analysis; Methodology; Supervision; Writing – review & editing)


1. Elshazly M, El-Halafawy YM, Mohamed DZ, Wahab KA, Mohamed TM. Feasibility and efficacy of erector spinae plane block versus transversus abdominis plane block in laparoscopic bariatric surgery: a randomized comparative trial. Korean J Anesthesiol 2022;75:502–9.
2. Cralley AL, Hopman J, Leasia K, Robinson C, Morton A, Pieracci FM. Earlier liposomal bupivacaine blocks improve analgesia and decrease opioid requirements for bariatric surgery patients. Am J Surg 2022;224:75–9.
3. Albrecht E, Kirkham KR, Endersby RV, Chan VW, Jackson T, Okrainec A, et al. Ultrasound-guided transversus abdominis plane (TAP) block for laparoscopic gastric-bypass surgery: a prospective randomized controlled double-blinded trial. Obes Surg 2013;23:1309–14.
4. Laigaard J, Pedersen C, Rønsbo TN, Mathiesen O, Karlsen AP. Minimal clinically important differences in randomised clinical trials on pain management after total hip and knee arthroplasty: a systematic review. Br J Anaesth 2021;126:1029–37.
5. Jarrar A, Eipe N, Wu R, Neville A, Yelle JD, Mamazza J. Effect of intraperitoneal local anesthesia on enhanced recovery outcomes after bariatric surgery: a randomized controlled pilot study. Can J Surg 2021;64:E603–8.

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