- Email: [email protected]
Comparison of ultrasound guided Erector Spinae Plane Block and quadratus lumborum block for postoperative analgesia in laparoscopic cholecystectomy patients; a prospective randomized study
Journal of Clinical Anesthesia xxx (xxxx) xxxx
Contents lists available at ScienceDirect
Journal of Clinical Anesthesia journal homepage: www.elsevier.com/locate/jclinane
Original Contribution
Comparison of ultrasound guided Erector Spinae Plane Block and quadratus lumborum block for postoperative analgesia in laparoscopic cholecystectomy patients; a prospective randomized study Hakan Ayguna, , Nilgun Kavrutb, Aycin Sicakkan Pamukcua, Abdullah Inalc, Ilker Kizilogluc, David Terence Thomasd, Serkan Tulgare, Ahmet Nartc ⁎
a
Cigli Regional Training Hospital, Department of Anesthesiology, Izmir, Turkey Antalya Training and Research Hospital, Department of Anesthesiology, Antalya, Turkey Cigli Regional Training Hospital, Department of General surgery, Izmir, Turkey d Maltepe University Faculty of Medicine, Department of Medical Education, Istanbul, Turkey e Maltepe University Faculty of Medicine, Department of Anesthesiology, Istanbul, Turkey b c
ABSTRACT
Study objective: Erector Spinae Plane Block (ESPB) is a recently described block. Both ESPB and Quadratus Lumborum block type II (QLB-II) have been reported to provide effective postoperative analgesia in patients undergoing laparoscopic cholecystectomy (LC). In this study, we compared the postoperative analgesic effects of ESPB and QLB-II in patients undergoing LC. Design: Assessor Blinded, prospective, randomized, controlled study. Setting: Tertiary hospital, postoperative recovery room & ward. Patients: 80 patients (ASA I-II) were recruited. Patients were allocated in to two equal groups (ESB and QLB-II). All patients were included in analysis. Interventions: Standard multimodal analgesia was performed in all groups. ESPB and QLB-II were performed under ultrasound guidance. Measurements: Mean opioid consumptions and Numeric Rating Scores was measured during the first 24 postoperative hours. Main results: Demographic data was similar between groups. There was no difference between NRS scores and opioid consumption at any hour between the groups. Conclusion: While ESPB and QLB-II are not significantly different, they improve analgesia quality in patients undergoing LC.
1. Introduction The use of ultrasonographic technology in regional anesthesia practice has not only easened the application of nerve blocks and interfascial blocks but led to the definition and practical use of many new interfascial blocks [1]. Thoracoabdominal/thoracolumbar blocks - also named as truncal blocks, have gained popularity recently with the number of such defined blocks increasing substantially. When compared to conventional surgery, laparoscopic cholecystectomy (LC) is less invasive and leads to less postoperative pain. However, the postoperative pain following LC consists of both somatic and visceral components with pain originating from port entry wounds, gallbladder resection and abdominal insufflation that leads to peritoneal distention and peritoneal damage [2–4]. It is for these reasons that regional anesthesia studies have analyzed LC frequently. The recently described Quadratus Lumborum Block type II (QLB-II) has been found to be an effective interfascial plane block for LC and is used in abdominal surgeries [5]. Erector Spinae Plane Block (ESPB) is a
⁎
fairly newly defined interfascial plane block that has been used in the treatment of acute and chronic pain, with studies demonstrating its effect on all pain caused by LC [6]. The effect of ESPB on postoperative pain after LC has been published previously [7,8]. While different techniques of regional anesthesia are frequent for LC, to our knowledge no randomized controlled study exists comparing ESPB and QLB-II in LC. In this randomized study we aimed to compare the effect of ESPB and QLB-II in decreasing postoperative pain and opioid requirements in patients undergoing LC. Our null hypothesis was that there would be no difference between opioid requirement between ESPB and QLB-II groups. 2. Material & method 2.1. Study design This randomized, prospective, comparative double blinded study
Corresponding author at: Cigli Bölge Eğitim Hastanesi, 8780/1 Sokak No:18 Yeni Mahalle Ata Sanayi, Çiğli/İzmir, Turkey. E-mail address: [email protected] (H. Aygun).
https://doi.org/10.1016/j.jclinane.2019.109696 Received 27 August 2019; Received in revised form 7 November 2019; Accepted 14 December 2019 0952-8180/ © 2019 Elsevier Inc. All rights reserved.
Please cite this article as: Hakan Aygun, et al., Journal of Clinical Anesthesia, https://doi.org/10.1016/j.jclinane.2019.109696
Journal of Clinical Anesthesia xxx (xxxx) xxxx
H. Aygun, et al.
was performed between March 2019–May 2019 in accordance with the principles of the Declaration of Helsinki. The study was registered with clinicaltrials.gov (NCT03869801) following local ethical committee approval (AEAH-EK: 2019.029:08/1). American Society of Anesthesiology (ASA) class I-II patients aged 18–70 years, scheduled to undergo LC were recruited for the study. All patients gave written informed consent for inclusion in the study. Exclusion criteria were: patients not consenting, those with allergies to local anesthetics, bleeding diathesis or history of anticoagulant use, history of liver or renal pathology effecting drug elimination, psychiatric disease, use of medicines such as gabapentin-pregabalin that could effect pain perception and those unable to operate PCA. Patients were randomized in the operating room using sequentially numbered opaque sealed envelopes [9] in to ESPB and QLB-II groups. Randomization was overseen by a single author (ASP) with each patient assigned a study number. These numbers were used in postoperative data collection and analysis. Medical personnel collecting data and conducting follow-up were blinded to the group of the patient. All blocks were performed by one author (HA) who did not participate in data collection or analysis.
2.4. Standard postoperative analgesia protocol and measurements of pain Following patient transfer to RR patient controlled analgesia (PCA) that included 0.5 mg/mL of morphine with no basal infusion, 1 mg bolus and 20 min lock out time was commenced. The numeric rating scale (NRS) was used for measurement of postoperative pain at intervals (1st, 6th, 12th and 24th hours) for 24 h. NRS is a one-dimensional measure of pain intensity in adults. The NRS is a segmented numeric version of the visual analog scale in which a respondent selects a whole number (0–10 integers) that best reflects the intensity of the patient's pain. The 11-point numeric scale ranges from ‘0’ representing one pain extreme (e.g. “no pain”) to ‘10’ representing the other pain extreme (e.g. “pain as bad as you can imagine” or “worst pain imaginable”). Morphine consumptions at 1st, 6th, 12th, 18th, and 24th hours were noted. 2.5. Outcome measures First 24 h opioid consumption was the primary outcome measure while NRS scores during rest and coughing/movement were the secondary outcome measures. Also, ondansetron use for nausea/vomiting within the first 24 h was also noted.
2.2. Performance of ultrasound guided blocks All blocks were performed in a block room preoperatively under sedation using 1 mg of intravenous midazolam, in the lateral position and using ultrasound guidance with a linear or convex transducer. The same local anesthetic mixture, volume and concentration (30 mL Bupivacaine %0.5, 10 mL lidocaine %2 and 20 mL normal saline) was used for all patients. This mixture was applied bilaterally, half to each side.
2.6. Sample size and statistical analyses In a pilot study consisting of 10 patients in each group, morphine consumption was determined to be 3.5 ± −0.75 mg in the ESPB and 2.98 ± 0.85 mg in the QLB-II group. With an alpha of 0.05, beta of 0.10 and power of 0.95, the number of participants required for the study was determined to be 38 for each group. Considering possible drop-outs, we decided to include at least 40 patients per group. Statistical analysis was performed using SPSS 16.0 ((SPSS, Chicago, IL, USA). Normality of data was determined using the KolmogorovSmirnov test. Continuous variables were expressed as mean ± standard deviation, and median (25th–75th percentiles). For continuous variables with equal variance, univariate analysis was performed using a 2-sample, independent t-test. For data without normal distribution, Mann Whitney U test was used. Chi2 test was used for ratio comparison. Categorical variables (ASA, gender etc.) were compared using Fisher exact test. A p-value of < 0.05 was considered statistically significant. Bonferroni correction was used for analysis of NRS scores, statistical significance was adjusted to p < 0.01, due to measurements from 5 time points.
2.2.1. ESPB application Following skin prep using povidone iodine, a high frequency linear probe or a lower frequency convex probe for obese patients was placed 2.5-3 cm lateral to the spinous process of the 9th thoracic vertebra in the parasaggitgal plane. The skin, subcutaneous tissue, trapezius muscle, erector spinae muscles and transverse process were visualized. 30 mL of LA was applied between the erector spinae muscles in the interfascial plane. The procedure was performed bilaterally, using the out-off plane. 2.2.2. QLB-II application Patients were placed in the lateral decubitus position. Right block was performed, the patient was then repositioned for the left block. A low frequency convex probe was placed subcostally in the transverse plane. The lumbar vertebral process, vertebral body, psoas muscle, quadratus lumborum muscle, latissimus dorsi muscle and erector spinae muscles are visualized. 30 mL of LA was applied (on each side) between the posterior aspect of the quadratus lumborum muscle and the latissimus dorsi muscle in the interfascial plane, using the in-plane technique.
3. Results CONSORT diagram of the study is shown in Fig. 1. Of the 88 patients screened for inclusion in the study, 8 were excluded and 80 were recruited. There was no difference between age, gender, ASA classification or other demographics such as height and weight between groups (p < 0.05) (Table 1). The performing time of blocks were 10.65 ± 1.92 for QLB-II and 6.97 ± 2.05 for ESPB group (p < 0.001). Average morphine consumption in the first 24 h was 3.40 ± 1.42 mg for ESPB and 3.47 ± 1.57 mg for QLB-II group (p = 0.083). Morphine consumption at 1st, 6th, 12th and 18th hours were also similar (p > 0.05) (Table 2, Fig. 2). When resting and moving/coughing NRS scores were compared, NRS scores were lower in the ESPB group at 1st hour (p < 0.001). However NRS scores were similar for 6th, 12th, 18th and 24th hours (p > 0.01) (Table 3). Nausea/vomiting requiring use of ondansetron was observed in 6 patients per group. Postoperatively, 3 patients in the ESBP and 5 patients in the QLB-II groups complained of mild to moderate right shoulder pain.
2.3. Management of general anesthesia and perioperative pain Anesthesia and perioperative analgesia plan was the same for all patients. Electrocardiogram, non invasive blood pressure, peripheral oxygen saturation and end tidal carbon dioxide monitoring were performed as standard. Fentanyl 1–1.5 μg kg−1, propofol 2–3 mg kg−1 and rocuronium 0.6 mg kg−1 was used for anesthesia induction followed by 0.6–1 MAC sevoflurane for maintenance. Perioperative analgesia was obtained using 1 g paracetamol and 20 mg tenoxicam. Neuromuscular blockade was reversed with 0.04 mg kg−1 of neostigmine and 0.02 mg kg−1 of i.v. atropine and patients are extubated and transferred to the recovery room (RR) when adequate muscle strength had returned. No peritoneal (puff or injection) or surgical site anesthesia was performed. 2
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Fig. 1. Flow diagram of study.
4. Discussion
Table 1 Descriptive data for each group and statistical evaluation.
Age (year) ASA I/II Height (cm) Weight (kg) Surgical time (min) Block performance time (min)
ESPB (n = 40)
QLB-II (n = 40)
p
51.08 ± 13.30 22/18 162.25 ± 7.32 74.56 ± 8.25 65.98 ± 14.93 6.97 ± 2.05
50.55 ± 10.45 20/20 164.54 ± 9.25 72.80 ± 7.44 66,60 ± 15.99 10.65 ± 1.92
0.846 0.654 0.223 0.319 0.855 < 0.001
Previous studies have demonstrated that ultrasound guided ESPB and QLB-II are both effective on decreasing postoperative pain and analgesia requirements in patients undergoing LC. Our study has shown that when these blocks are compared, there is no difference in opioid requirement and NRS scores. LC is less invasive and painful when compared to conventional surgery. However, LC has been the subject of many regional anesthesia studies as pain caused by LC has both somatic and visceral components with multiple trocar entry points (peri and supraumbilical as well as midabdominal and lateral abdominal) [3,5,10,11]. While transversus abdominis plane block and other approaches were reported for LC, more recently studies have focused on more recently defined regional anesthesia techniques. Quadratus lumborum block is a fairly new block that aims to block the thoracoabdominal nerves and has three differing approaches. In QLB-II, LA is applied between the quadratus lumborum muscle and the latissimus dorsi/erector spinae muscles in the interfascial plane leading to widespread sensory block of both somatic and visceral fibers between Th7–8 and Th12-L1 [12]. The effect of QLB-II in LC was defined by Ökmen et al. [5]. In their study QLB-II was applied to both a block and sham group and average 24 h NRS scores were found to be lower in the block group as well as significantly less cumulative tramadol requirement at 6-12th and 24th hours. The authors also reported sensorial
p values that are written in bold represent statistical significance. Table 2 Comparison of morphine consumption (mg) between groups. Postoperative hour
ESPB (n = 40)
QLB-II (n = 40)
p
1h 6h 12 h 18 h 24 h
1 2 2 2 3
1 2 2 3 3
0.596 0.262 0.208 0.114 0.833
(1–1) (1–2) (2–3) (2–3) (2–4.25)
(1–1) (1–2) (2–3) (2–3.25) (2–5)
Data are expressed as median (percentiles 25–75), as data did not have normal distribution. p values were italicized .
3
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Fig. 2. Morphine consumption (mg) of patients at 1st, 6th, 12th, 18th and 24 h according to groups. Minimum, first quartile, median (thick line), third quartile and maximum are shown.
blocks be performed [16,17]. Although it is generally accepted that interfascial blocks performed from the anterolateral of the abdomen only affect somatic pain, blockage of the branches to the parietal peritoneum arising from the terminal portion of the anterior cutaneous branch of the intercostal nerves leads to partial effect on visceral pain [2,7]. There are studies in literature comparing peri-paravertebral blocks with abdominal interfascial blocks. The results of these studies are currently debatable. Our study is the first to compare two fairly new and recent posterior interfascial blocs. Anatomic cadaveric studies and clinical observations have demonstrated that both ESPB and QLB-II blocks effect both somatic and visceral pain [1,18–20]. Application points of ESPB and QLB-II are in close proximity and each application area is the continuation of the middle thoracolumbar fascia. However it should be considered that in both blocks, the spread of LA is unpredictable and spread to paravertebral/epidural space is not guaranteed [21]. This study was performed on patients undergoing LC. However, the comparison of ESPB and QLB-II in more painful procedures such as open surgeries is still open to study. While ESPB can be applied in the lateral, side and prone positions; QLB-II is generally performed in the lateral of prone position. Therefore QLB-II requires repositioning of the patient while ESPB does not. Regarding ease of application we believe ESPB is the easier of the two blocks. Following visualization of the transverse process, the needle is advanced towards the transverse process and LA is injected after contact with the process. In this study all blocks were performed by the same author who had adequate but not advanced experience with the two blocks. Positioning of the patient, visualization of the needle and positioning of the needle in the interfascial plane caused a nearly two fold increase in application time of QLB-II when compared to ESPB. Literature reports QLB-II in supine, prone and sitting positions however the lateral position is preferred due to better ergonomics and visualization of the relevant structures [22]. We therefore believe that ESPB is safer and should be the preferred choice of inexperienced clinicians. Our study has some limitations. Firstly, we did not perform a dermatomal analysis after block application. Although previous studies of QLB-II in LC have reported sensorial analysis, no study of ESPB has reported sensorial coverage [5,14,23]. Indeed, we believe that studies
Table 3 Average NRS scores at rest and on movement/coughing during first 24 h. ESPB (n = 40)
QLB-II (n = 40)
p
At rest 1st hour 6rd hour 12th hour 18th hour 24th hour
2 2 2 2 2
(2–2) (2–2) (1–2) (1–2) (1–2)
3 2 2 2 2
(2–3) (2–2) (2–2) (1–2) (1–1)
< 0.001 0.020 0.027 0.379 0.671
On movement 1st hour 6rd hour 12th hour 18th hour 24th hour
2 2 2 2 2
(2–3) (2–3) (2–3) (2–3) (1–3)
3 2 2 2 2
(3–3) (2–3) (2–3) (1–3) (1–3)
< 0.001 0.082 0.051 0.698 0.245
Data are expressed as median (percentiles 25–75). p values were italicized and p values that are written in bold represent statistical significance.
block between Th8–9 and L1 for a majority of patients. In a more recent study comparing QLB and oblique subcostal transversus abdominis plane block (OSTAP) in LC, no difference was found between postoperative analgesia requirements and pain scores [13]. There are no further studies of QLB-II in LC. Also, QLB-I and QLB-III have not been studied in LC. Therefore QLB-II was chosen for this study. ESPB is also a recently described block that has been reported for postoperative analgesia in many surgeries such as neck, shoulder, hip and knee [6,14,15]. There are few clinical studies regarding the use of ESPB in abdominal and laparoscopic surgeries. In the first randomized controlled study of ESPB in LC, ESPB was found to significantly decrease tramadol use in first 12 h when compared to control group [7]. Thereafter two studies where ESPB and OSTAP were compared in patients undergoing LC were published [8,16]. However there is debate regarding whether the comparison of anterior wall blocks that only block the anterior portion of the abdomen and peri/paravertebral blocks (ESPB, QLB II-III etc.) that block the whole hemiabdomen can be compared methodologically [17]. Therefore, only after the complete mechanism of action of peri/paravertabral blocks and their clinical effects are adequately defined can studies comparing these two types of 4
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analyzing the sensorial coverage including interpretations of the nerve branches that are effected will be of more value when compared to dermatomal studies. Another limitation is the lack of control or sham group. Even though the number of patients in these studies was also small, results from previous randomized controlled studies have reported adequate statistically significant data. We designed this study as a simple randomized controlled trial and calculated sample size similar to a previous study [23]. A non-inferiority/superiority or equivalence trial may have been more suited as a design. However, both ESPB and QLB-II are not gold standard techniques and their comparison has not previously been reported, this methodology was not used. Therefore, although we found no difference between the two blocks, equivalence cannot be established with our study design.
randomized controlled double blind study. J Clin Anesth 2018;49:112–7. Sep. [6] Chin KJ, Adhikary SD, Forero M. Erector spinae plane (ESP) block: a new paradigm in regional anesthesia and analgesia. Curr Anesthesiol Rep 2019:1–10. May 2. [7] Tulgar S, Kapakli MS, Senturk O, Selvi O, Serifsoy TE, Ozer Z. Evaluation of ultrasound-guided erector spinae plane block for postoperative analgesia in laparoscopic cholecystectomy: a prospective, randomized, controlled clinical trial. J Clin Anesth 2018;49:101–6. Sep. [8] Tulgar S, Kapakli MS, Kose HC, Senturk O, Selvi O, Serifsoy TE, et al. Evaluation of ultrasound-guided erector spinae plane block and oblique subcostal transversus abdominis plane block in laparoscopic cholecystectomy: randomized, controlled, prospective study. Anesth Essays Res 2019;13(1):50–6. Jan. [9] Doig GS, Simpson F. Randomization and allocation concealment: a practical guide for researchers. J Crit Care 2005;20(2):187–91. Jun. [discussion 191–3]. [10] Suseela I, Anandan K, Aravind A, Kaniyil S. Comparison of ultrasound-guided bilateral subcostal transversus abdominis plane block and port-site infiltration with bupivacaine in laparoscopic cholecystectomy. Indian J Anaesth 2018;62(7):497–501. Jul. [11] Visoiu M, Cassara A, Yang CI. Bilateral paravertebral blockade (t7-10) versus incisional local anesthetic administration for pediatric laparoscopic cholecystectomy: a prospective, randomized clinical study. Anesthesia & Analgesia 2015;120(5):1106–13. May 1. [12] Elsharkawy H, El-Boghdadly K, Barrington M. Quadratus lumborum blockanatomical concepts, mechanisms, and techniques. Anesthesiology 2019;130(2):322–35. Feb 1. [13] Baytar Ç, Yılmaz C, Karasu D, Topal S. Comparison of ultrasound-guided subcostal transversus abdominis plane block and quadratus lumborum block in laparoscopic cholecystectomy: a prospective, randomized, controlled clinical study [internet]. Pain Research and Management 2019;2019:1–6. Available from https://doi.org/10. 1155/2019/2815301. [14] De Cassai A, Bonvicini D, Correale C, Sandei L, Tulgar S, Tonetti T. Erector spinae plane block: a systematic qualitative review. Minerva Anestesiol [Internet] 2019 Jan 4. https://doi.org/10.23736/S0375-9393.18.13341-4 Available from. [15] Gürkan Y, Aksu C, Kuş A, Yörükoğlu UH, Kılıç CT. Ultrasound guided erector spinae plane block reduces postoperative opioid consumption following breast surgery: a randomized controlled study. J Clin Anesth 2018;50:65–8. Nov. [16] Altıparmak B, Toker MK, Uysal AI, Kuşçu Y, Demirbilek SG. Ultrasound-guided erector spinae plane block versus oblique subcostal transversus abdominis plane block for postoperative analgesia of adult patients undergoing laparoscopic cholecystectomy: randomized, controlled trial. J Clin Anesth 2019;57:31–6. [17] Kristensen M, Nielsen MV, Børglum J. Reply to: ultrasound-guided erector spinae plane block versus oblique subcostal transversus abdominis plane block for postoperative analgesia of adult patients undergoing laparoscopic cholecystectomy: randomized controlled trial [Internet]. J Clin Anesth 2020;60:24–5. Available from https://doi.org/10.1016/j.jclinane.2019.08.011. [18] Chin KJ, Malhas L, Perlas A. The erector Spinae plane block provides visceral abdominal analgesia in bariatric surgery: a report of 3 cases. Reg Anesth Pain Med 2017;42(3):372–6. [19] Aydin T, Balaban O, Demiṙ L. Ultrasound guided erector spinae plane block for pain management in pancreas cancer: a case report Available from https://www. journalagent.com/z4/download_fulltext.asp?pdir=agri&plng=eng&un=AGRI09815; 2019. [20] Elkoundi A, Eloukkal Z, Bensghir M, Belyamani L, Lalaoui SJ. Erector spinae plane block for hyperalgesic acute pancreatitis. Pain Med 2018. https://doi.org/10.1093/ pm/pny232 Internet. Nov 22; Available from. [21] Elsharkawy H, Bajracharya GR, El-Boghdadly K, Drake RL, Mariano ER. Comparing two posterior quadratus lumborum block approaches with low thoracic erector spinae plane block: an anatomic study. Reg Anesth Pain Med 2019. https://doi.org/ 10.1136/rapm-2018-100147 Internet. Mar 28; Available from. [22] Ultrasound-guided transversus abdominis plane and quadratus lumborum blocks NYSORA [Internet]. NYSORA; 2018 [cited 2019 Jul 12]. Available from https:// www.nysora.com/regional-anesthesia-for-specific-surgical-procedures/abdomen/ ultrasound-guided-transversus-abdominis-plane-quadratus-lumborum-blocks/. [23] Aksu C, Şen MC, Akay MA, Baydemir C, Gürkan Y. Erector spinae plane block vs quadratus lumborum block for pediatric lower abdominal surgery: a double blinded, prospective, and randomized trial. J Clin Anesth 2019;57:24–8. https:// doi.org/10.1016/j.jclinane.2019.03.006. Nov. [Epub 2019 Mar 6. PubMed PMID: 30851499].
5. Conclusion The effect of ultrasound guided bilateral QLB-II and ESPB in patients undergoing LC were found to be similar in regards to postoperative pain and opioid requirement. Further studies are required to determine the best choice between these two blocks. Ethical approval All procedures involving human participants were performed in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Informed consent Informed consent was obtained from all individual participants included in the study. Declaration of competing interest The authors declare that they have no conflict of interest. References [1] Elsharkawy H, Pawa A, Mariano ER. Interfascial plane blocks: back to basics. Reg Anesth Pain Med 2018;43(4):341–6. May. [2] Tulgar S, Selvi O, Kapakli MS. Erector spinae plane block for different laparoscopic abdominal surgeries: case series. Case rep anesthesiol [Internet]. 2018 Feb 18 [cited 2018 Apr 8];2018. Available from. https://www.hindawi.com/journals/cria/2018/ 3947281/abs/. [3] Ortiz J, Suliburk JW, Wu K, Bailard NS, Mason C, Minard CG, et al. Bilateral transversus abdominis plane block does not decrease postoperative pain after laparoscopic cholecystectomy when compared with local anesthetic infiltration of trocar insertion sites. Reg Anesth Pain Med 2012;37(2):188. [4] Shin H-J, Oh A-Y, Baik J-S, Kim J-H, Han S-H, Hwang J-W. Ultrasound-guided oblique subcostal transversus abdominis plane block for analgesia after laparoscopic cholecystectomy: a randomized, controlled, observer-blinded study. Minerva Anestesiol 2014;80(2):185–93. Feb. [5] Ökmen K, Metin Ökmen B, Topal S. Ultrasound-guided posterior quadratus lumborum block for postoperative pain after laparoscopic cholecystectomy: a
5
Contents lists available at ScienceDirect
Journal of Clinical Anesthesia journal homepage: www.elsevier.com/locate/jclinane
Original Contribution
Comparison of ultrasound guided Erector Spinae Plane Block and quadratus lumborum block for postoperative analgesia in laparoscopic cholecystectomy patients; a prospective randomized study Hakan Ayguna, , Nilgun Kavrutb, Aycin Sicakkan Pamukcua, Abdullah Inalc, Ilker Kizilogluc, David Terence Thomasd, Serkan Tulgare, Ahmet Nartc ⁎
a
Cigli Regional Training Hospital, Department of Anesthesiology, Izmir, Turkey Antalya Training and Research Hospital, Department of Anesthesiology, Antalya, Turkey Cigli Regional Training Hospital, Department of General surgery, Izmir, Turkey d Maltepe University Faculty of Medicine, Department of Medical Education, Istanbul, Turkey e Maltepe University Faculty of Medicine, Department of Anesthesiology, Istanbul, Turkey b c
ABSTRACT
Study objective: Erector Spinae Plane Block (ESPB) is a recently described block. Both ESPB and Quadratus Lumborum block type II (QLB-II) have been reported to provide effective postoperative analgesia in patients undergoing laparoscopic cholecystectomy (LC). In this study, we compared the postoperative analgesic effects of ESPB and QLB-II in patients undergoing LC. Design: Assessor Blinded, prospective, randomized, controlled study. Setting: Tertiary hospital, postoperative recovery room & ward. Patients: 80 patients (ASA I-II) were recruited. Patients were allocated in to two equal groups (ESB and QLB-II). All patients were included in analysis. Interventions: Standard multimodal analgesia was performed in all groups. ESPB and QLB-II were performed under ultrasound guidance. Measurements: Mean opioid consumptions and Numeric Rating Scores was measured during the first 24 postoperative hours. Main results: Demographic data was similar between groups. There was no difference between NRS scores and opioid consumption at any hour between the groups. Conclusion: While ESPB and QLB-II are not significantly different, they improve analgesia quality in patients undergoing LC.
1. Introduction The use of ultrasonographic technology in regional anesthesia practice has not only easened the application of nerve blocks and interfascial blocks but led to the definition and practical use of many new interfascial blocks [1]. Thoracoabdominal/thoracolumbar blocks - also named as truncal blocks, have gained popularity recently with the number of such defined blocks increasing substantially. When compared to conventional surgery, laparoscopic cholecystectomy (LC) is less invasive and leads to less postoperative pain. However, the postoperative pain following LC consists of both somatic and visceral components with pain originating from port entry wounds, gallbladder resection and abdominal insufflation that leads to peritoneal distention and peritoneal damage [2–4]. It is for these reasons that regional anesthesia studies have analyzed LC frequently. The recently described Quadratus Lumborum Block type II (QLB-II) has been found to be an effective interfascial plane block for LC and is used in abdominal surgeries [5]. Erector Spinae Plane Block (ESPB) is a
⁎
fairly newly defined interfascial plane block that has been used in the treatment of acute and chronic pain, with studies demonstrating its effect on all pain caused by LC [6]. The effect of ESPB on postoperative pain after LC has been published previously [7,8]. While different techniques of regional anesthesia are frequent for LC, to our knowledge no randomized controlled study exists comparing ESPB and QLB-II in LC. In this randomized study we aimed to compare the effect of ESPB and QLB-II in decreasing postoperative pain and opioid requirements in patients undergoing LC. Our null hypothesis was that there would be no difference between opioid requirement between ESPB and QLB-II groups. 2. Material & method 2.1. Study design This randomized, prospective, comparative double blinded study
Corresponding author at: Cigli Bölge Eğitim Hastanesi, 8780/1 Sokak No:18 Yeni Mahalle Ata Sanayi, Çiğli/İzmir, Turkey. E-mail address: [email protected] (H. Aygun).
https://doi.org/10.1016/j.jclinane.2019.109696 Received 27 August 2019; Received in revised form 7 November 2019; Accepted 14 December 2019 0952-8180/ © 2019 Elsevier Inc. All rights reserved.
Please cite this article as: Hakan Aygun, et al., Journal of Clinical Anesthesia, https://doi.org/10.1016/j.jclinane.2019.109696
Journal of Clinical Anesthesia xxx (xxxx) xxxx
H. Aygun, et al.
was performed between March 2019–May 2019 in accordance with the principles of the Declaration of Helsinki. The study was registered with clinicaltrials.gov (NCT03869801) following local ethical committee approval (AEAH-EK: 2019.029:08/1). American Society of Anesthesiology (ASA) class I-II patients aged 18–70 years, scheduled to undergo LC were recruited for the study. All patients gave written informed consent for inclusion in the study. Exclusion criteria were: patients not consenting, those with allergies to local anesthetics, bleeding diathesis or history of anticoagulant use, history of liver or renal pathology effecting drug elimination, psychiatric disease, use of medicines such as gabapentin-pregabalin that could effect pain perception and those unable to operate PCA. Patients were randomized in the operating room using sequentially numbered opaque sealed envelopes [9] in to ESPB and QLB-II groups. Randomization was overseen by a single author (ASP) with each patient assigned a study number. These numbers were used in postoperative data collection and analysis. Medical personnel collecting data and conducting follow-up were blinded to the group of the patient. All blocks were performed by one author (HA) who did not participate in data collection or analysis.
2.4. Standard postoperative analgesia protocol and measurements of pain Following patient transfer to RR patient controlled analgesia (PCA) that included 0.5 mg/mL of morphine with no basal infusion, 1 mg bolus and 20 min lock out time was commenced. The numeric rating scale (NRS) was used for measurement of postoperative pain at intervals (1st, 6th, 12th and 24th hours) for 24 h. NRS is a one-dimensional measure of pain intensity in adults. The NRS is a segmented numeric version of the visual analog scale in which a respondent selects a whole number (0–10 integers) that best reflects the intensity of the patient's pain. The 11-point numeric scale ranges from ‘0’ representing one pain extreme (e.g. “no pain”) to ‘10’ representing the other pain extreme (e.g. “pain as bad as you can imagine” or “worst pain imaginable”). Morphine consumptions at 1st, 6th, 12th, 18th, and 24th hours were noted. 2.5. Outcome measures First 24 h opioid consumption was the primary outcome measure while NRS scores during rest and coughing/movement were the secondary outcome measures. Also, ondansetron use for nausea/vomiting within the first 24 h was also noted.
2.2. Performance of ultrasound guided blocks All blocks were performed in a block room preoperatively under sedation using 1 mg of intravenous midazolam, in the lateral position and using ultrasound guidance with a linear or convex transducer. The same local anesthetic mixture, volume and concentration (30 mL Bupivacaine %0.5, 10 mL lidocaine %2 and 20 mL normal saline) was used for all patients. This mixture was applied bilaterally, half to each side.
2.6. Sample size and statistical analyses In a pilot study consisting of 10 patients in each group, morphine consumption was determined to be 3.5 ± −0.75 mg in the ESPB and 2.98 ± 0.85 mg in the QLB-II group. With an alpha of 0.05, beta of 0.10 and power of 0.95, the number of participants required for the study was determined to be 38 for each group. Considering possible drop-outs, we decided to include at least 40 patients per group. Statistical analysis was performed using SPSS 16.0 ((SPSS, Chicago, IL, USA). Normality of data was determined using the KolmogorovSmirnov test. Continuous variables were expressed as mean ± standard deviation, and median (25th–75th percentiles). For continuous variables with equal variance, univariate analysis was performed using a 2-sample, independent t-test. For data without normal distribution, Mann Whitney U test was used. Chi2 test was used for ratio comparison. Categorical variables (ASA, gender etc.) were compared using Fisher exact test. A p-value of < 0.05 was considered statistically significant. Bonferroni correction was used for analysis of NRS scores, statistical significance was adjusted to p < 0.01, due to measurements from 5 time points.
2.2.1. ESPB application Following skin prep using povidone iodine, a high frequency linear probe or a lower frequency convex probe for obese patients was placed 2.5-3 cm lateral to the spinous process of the 9th thoracic vertebra in the parasaggitgal plane. The skin, subcutaneous tissue, trapezius muscle, erector spinae muscles and transverse process were visualized. 30 mL of LA was applied between the erector spinae muscles in the interfascial plane. The procedure was performed bilaterally, using the out-off plane. 2.2.2. QLB-II application Patients were placed in the lateral decubitus position. Right block was performed, the patient was then repositioned for the left block. A low frequency convex probe was placed subcostally in the transverse plane. The lumbar vertebral process, vertebral body, psoas muscle, quadratus lumborum muscle, latissimus dorsi muscle and erector spinae muscles are visualized. 30 mL of LA was applied (on each side) between the posterior aspect of the quadratus lumborum muscle and the latissimus dorsi muscle in the interfascial plane, using the in-plane technique.
3. Results CONSORT diagram of the study is shown in Fig. 1. Of the 88 patients screened for inclusion in the study, 8 were excluded and 80 were recruited. There was no difference between age, gender, ASA classification or other demographics such as height and weight between groups (p < 0.05) (Table 1). The performing time of blocks were 10.65 ± 1.92 for QLB-II and 6.97 ± 2.05 for ESPB group (p < 0.001). Average morphine consumption in the first 24 h was 3.40 ± 1.42 mg for ESPB and 3.47 ± 1.57 mg for QLB-II group (p = 0.083). Morphine consumption at 1st, 6th, 12th and 18th hours were also similar (p > 0.05) (Table 2, Fig. 2). When resting and moving/coughing NRS scores were compared, NRS scores were lower in the ESPB group at 1st hour (p < 0.001). However NRS scores were similar for 6th, 12th, 18th and 24th hours (p > 0.01) (Table 3). Nausea/vomiting requiring use of ondansetron was observed in 6 patients per group. Postoperatively, 3 patients in the ESBP and 5 patients in the QLB-II groups complained of mild to moderate right shoulder pain.
2.3. Management of general anesthesia and perioperative pain Anesthesia and perioperative analgesia plan was the same for all patients. Electrocardiogram, non invasive blood pressure, peripheral oxygen saturation and end tidal carbon dioxide monitoring were performed as standard. Fentanyl 1–1.5 μg kg−1, propofol 2–3 mg kg−1 and rocuronium 0.6 mg kg−1 was used for anesthesia induction followed by 0.6–1 MAC sevoflurane for maintenance. Perioperative analgesia was obtained using 1 g paracetamol and 20 mg tenoxicam. Neuromuscular blockade was reversed with 0.04 mg kg−1 of neostigmine and 0.02 mg kg−1 of i.v. atropine and patients are extubated and transferred to the recovery room (RR) when adequate muscle strength had returned. No peritoneal (puff or injection) or surgical site anesthesia was performed. 2
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Fig. 1. Flow diagram of study.
4. Discussion
Table 1 Descriptive data for each group and statistical evaluation.
Age (year) ASA I/II Height (cm) Weight (kg) Surgical time (min) Block performance time (min)
ESPB (n = 40)
QLB-II (n = 40)
p
51.08 ± 13.30 22/18 162.25 ± 7.32 74.56 ± 8.25 65.98 ± 14.93 6.97 ± 2.05
50.55 ± 10.45 20/20 164.54 ± 9.25 72.80 ± 7.44 66,60 ± 15.99 10.65 ± 1.92
0.846 0.654 0.223 0.319 0.855 < 0.001
Previous studies have demonstrated that ultrasound guided ESPB and QLB-II are both effective on decreasing postoperative pain and analgesia requirements in patients undergoing LC. Our study has shown that when these blocks are compared, there is no difference in opioid requirement and NRS scores. LC is less invasive and painful when compared to conventional surgery. However, LC has been the subject of many regional anesthesia studies as pain caused by LC has both somatic and visceral components with multiple trocar entry points (peri and supraumbilical as well as midabdominal and lateral abdominal) [3,5,10,11]. While transversus abdominis plane block and other approaches were reported for LC, more recently studies have focused on more recently defined regional anesthesia techniques. Quadratus lumborum block is a fairly new block that aims to block the thoracoabdominal nerves and has three differing approaches. In QLB-II, LA is applied between the quadratus lumborum muscle and the latissimus dorsi/erector spinae muscles in the interfascial plane leading to widespread sensory block of both somatic and visceral fibers between Th7–8 and Th12-L1 [12]. The effect of QLB-II in LC was defined by Ökmen et al. [5]. In their study QLB-II was applied to both a block and sham group and average 24 h NRS scores were found to be lower in the block group as well as significantly less cumulative tramadol requirement at 6-12th and 24th hours. The authors also reported sensorial
p values that are written in bold represent statistical significance. Table 2 Comparison of morphine consumption (mg) between groups. Postoperative hour
ESPB (n = 40)
QLB-II (n = 40)
p
1h 6h 12 h 18 h 24 h
1 2 2 2 3
1 2 2 3 3
0.596 0.262 0.208 0.114 0.833
(1–1) (1–2) (2–3) (2–3) (2–4.25)
(1–1) (1–2) (2–3) (2–3.25) (2–5)
Data are expressed as median (percentiles 25–75), as data did not have normal distribution. p values were italicized .
3
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Fig. 2. Morphine consumption (mg) of patients at 1st, 6th, 12th, 18th and 24 h according to groups. Minimum, first quartile, median (thick line), third quartile and maximum are shown.
blocks be performed [16,17]. Although it is generally accepted that interfascial blocks performed from the anterolateral of the abdomen only affect somatic pain, blockage of the branches to the parietal peritoneum arising from the terminal portion of the anterior cutaneous branch of the intercostal nerves leads to partial effect on visceral pain [2,7]. There are studies in literature comparing peri-paravertebral blocks with abdominal interfascial blocks. The results of these studies are currently debatable. Our study is the first to compare two fairly new and recent posterior interfascial blocs. Anatomic cadaveric studies and clinical observations have demonstrated that both ESPB and QLB-II blocks effect both somatic and visceral pain [1,18–20]. Application points of ESPB and QLB-II are in close proximity and each application area is the continuation of the middle thoracolumbar fascia. However it should be considered that in both blocks, the spread of LA is unpredictable and spread to paravertebral/epidural space is not guaranteed [21]. This study was performed on patients undergoing LC. However, the comparison of ESPB and QLB-II in more painful procedures such as open surgeries is still open to study. While ESPB can be applied in the lateral, side and prone positions; QLB-II is generally performed in the lateral of prone position. Therefore QLB-II requires repositioning of the patient while ESPB does not. Regarding ease of application we believe ESPB is the easier of the two blocks. Following visualization of the transverse process, the needle is advanced towards the transverse process and LA is injected after contact with the process. In this study all blocks were performed by the same author who had adequate but not advanced experience with the two blocks. Positioning of the patient, visualization of the needle and positioning of the needle in the interfascial plane caused a nearly two fold increase in application time of QLB-II when compared to ESPB. Literature reports QLB-II in supine, prone and sitting positions however the lateral position is preferred due to better ergonomics and visualization of the relevant structures [22]. We therefore believe that ESPB is safer and should be the preferred choice of inexperienced clinicians. Our study has some limitations. Firstly, we did not perform a dermatomal analysis after block application. Although previous studies of QLB-II in LC have reported sensorial analysis, no study of ESPB has reported sensorial coverage [5,14,23]. Indeed, we believe that studies
Table 3 Average NRS scores at rest and on movement/coughing during first 24 h. ESPB (n = 40)
QLB-II (n = 40)
p
At rest 1st hour 6rd hour 12th hour 18th hour 24th hour
2 2 2 2 2
(2–2) (2–2) (1–2) (1–2) (1–2)
3 2 2 2 2
(2–3) (2–2) (2–2) (1–2) (1–1)
< 0.001 0.020 0.027 0.379 0.671
On movement 1st hour 6rd hour 12th hour 18th hour 24th hour
2 2 2 2 2
(2–3) (2–3) (2–3) (2–3) (1–3)
3 2 2 2 2
(3–3) (2–3) (2–3) (1–3) (1–3)
< 0.001 0.082 0.051 0.698 0.245
Data are expressed as median (percentiles 25–75). p values were italicized and p values that are written in bold represent statistical significance.
block between Th8–9 and L1 for a majority of patients. In a more recent study comparing QLB and oblique subcostal transversus abdominis plane block (OSTAP) in LC, no difference was found between postoperative analgesia requirements and pain scores [13]. There are no further studies of QLB-II in LC. Also, QLB-I and QLB-III have not been studied in LC. Therefore QLB-II was chosen for this study. ESPB is also a recently described block that has been reported for postoperative analgesia in many surgeries such as neck, shoulder, hip and knee [6,14,15]. There are few clinical studies regarding the use of ESPB in abdominal and laparoscopic surgeries. In the first randomized controlled study of ESPB in LC, ESPB was found to significantly decrease tramadol use in first 12 h when compared to control group [7]. Thereafter two studies where ESPB and OSTAP were compared in patients undergoing LC were published [8,16]. However there is debate regarding whether the comparison of anterior wall blocks that only block the anterior portion of the abdomen and peri/paravertebral blocks (ESPB, QLB II-III etc.) that block the whole hemiabdomen can be compared methodologically [17]. Therefore, only after the complete mechanism of action of peri/paravertabral blocks and their clinical effects are adequately defined can studies comparing these two types of 4
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analyzing the sensorial coverage including interpretations of the nerve branches that are effected will be of more value when compared to dermatomal studies. Another limitation is the lack of control or sham group. Even though the number of patients in these studies was also small, results from previous randomized controlled studies have reported adequate statistically significant data. We designed this study as a simple randomized controlled trial and calculated sample size similar to a previous study [23]. A non-inferiority/superiority or equivalence trial may have been more suited as a design. However, both ESPB and QLB-II are not gold standard techniques and their comparison has not previously been reported, this methodology was not used. Therefore, although we found no difference between the two blocks, equivalence cannot be established with our study design.
randomized controlled double blind study. J Clin Anesth 2018;49:112–7. Sep. [6] Chin KJ, Adhikary SD, Forero M. Erector spinae plane (ESP) block: a new paradigm in regional anesthesia and analgesia. Curr Anesthesiol Rep 2019:1–10. May 2. [7] Tulgar S, Kapakli MS, Senturk O, Selvi O, Serifsoy TE, Ozer Z. Evaluation of ultrasound-guided erector spinae plane block for postoperative analgesia in laparoscopic cholecystectomy: a prospective, randomized, controlled clinical trial. J Clin Anesth 2018;49:101–6. Sep. [8] Tulgar S, Kapakli MS, Kose HC, Senturk O, Selvi O, Serifsoy TE, et al. Evaluation of ultrasound-guided erector spinae plane block and oblique subcostal transversus abdominis plane block in laparoscopic cholecystectomy: randomized, controlled, prospective study. Anesth Essays Res 2019;13(1):50–6. Jan. [9] Doig GS, Simpson F. Randomization and allocation concealment: a practical guide for researchers. J Crit Care 2005;20(2):187–91. Jun. [discussion 191–3]. [10] Suseela I, Anandan K, Aravind A, Kaniyil S. Comparison of ultrasound-guided bilateral subcostal transversus abdominis plane block and port-site infiltration with bupivacaine in laparoscopic cholecystectomy. Indian J Anaesth 2018;62(7):497–501. Jul. [11] Visoiu M, Cassara A, Yang CI. Bilateral paravertebral blockade (t7-10) versus incisional local anesthetic administration for pediatric laparoscopic cholecystectomy: a prospective, randomized clinical study. Anesthesia & Analgesia 2015;120(5):1106–13. May 1. [12] Elsharkawy H, El-Boghdadly K, Barrington M. Quadratus lumborum blockanatomical concepts, mechanisms, and techniques. Anesthesiology 2019;130(2):322–35. Feb 1. [13] Baytar Ç, Yılmaz C, Karasu D, Topal S. Comparison of ultrasound-guided subcostal transversus abdominis plane block and quadratus lumborum block in laparoscopic cholecystectomy: a prospective, randomized, controlled clinical study [internet]. Pain Research and Management 2019;2019:1–6. Available from https://doi.org/10. 1155/2019/2815301. [14] De Cassai A, Bonvicini D, Correale C, Sandei L, Tulgar S, Tonetti T. Erector spinae plane block: a systematic qualitative review. Minerva Anestesiol [Internet] 2019 Jan 4. https://doi.org/10.23736/S0375-9393.18.13341-4 Available from. [15] Gürkan Y, Aksu C, Kuş A, Yörükoğlu UH, Kılıç CT. Ultrasound guided erector spinae plane block reduces postoperative opioid consumption following breast surgery: a randomized controlled study. J Clin Anesth 2018;50:65–8. Nov. [16] Altıparmak B, Toker MK, Uysal AI, Kuşçu Y, Demirbilek SG. Ultrasound-guided erector spinae plane block versus oblique subcostal transversus abdominis plane block for postoperative analgesia of adult patients undergoing laparoscopic cholecystectomy: randomized, controlled trial. J Clin Anesth 2019;57:31–6. [17] Kristensen M, Nielsen MV, Børglum J. Reply to: ultrasound-guided erector spinae plane block versus oblique subcostal transversus abdominis plane block for postoperative analgesia of adult patients undergoing laparoscopic cholecystectomy: randomized controlled trial [Internet]. J Clin Anesth 2020;60:24–5. Available from https://doi.org/10.1016/j.jclinane.2019.08.011. [18] Chin KJ, Malhas L, Perlas A. The erector Spinae plane block provides visceral abdominal analgesia in bariatric surgery: a report of 3 cases. Reg Anesth Pain Med 2017;42(3):372–6. [19] Aydin T, Balaban O, Demiṙ L. Ultrasound guided erector spinae plane block for pain management in pancreas cancer: a case report Available from https://www. journalagent.com/z4/download_fulltext.asp?pdir=agri&plng=eng&un=AGRI09815; 2019. [20] Elkoundi A, Eloukkal Z, Bensghir M, Belyamani L, Lalaoui SJ. Erector spinae plane block for hyperalgesic acute pancreatitis. Pain Med 2018. https://doi.org/10.1093/ pm/pny232 Internet. Nov 22; Available from. [21] Elsharkawy H, Bajracharya GR, El-Boghdadly K, Drake RL, Mariano ER. Comparing two posterior quadratus lumborum block approaches with low thoracic erector spinae plane block: an anatomic study. Reg Anesth Pain Med 2019. https://doi.org/ 10.1136/rapm-2018-100147 Internet. Mar 28; Available from. [22] Ultrasound-guided transversus abdominis plane and quadratus lumborum blocks NYSORA [Internet]. NYSORA; 2018 [cited 2019 Jul 12]. Available from https:// www.nysora.com/regional-anesthesia-for-specific-surgical-procedures/abdomen/ ultrasound-guided-transversus-abdominis-plane-quadratus-lumborum-blocks/. [23] Aksu C, Şen MC, Akay MA, Baydemir C, Gürkan Y. Erector spinae plane block vs quadratus lumborum block for pediatric lower abdominal surgery: a double blinded, prospective, and randomized trial. J Clin Anesth 2019;57:24–8. https:// doi.org/10.1016/j.jclinane.2019.03.006. Nov. [Epub 2019 Mar 6. PubMed PMID: 30851499].
5. Conclusion The effect of ultrasound guided bilateral QLB-II and ESPB in patients undergoing LC were found to be similar in regards to postoperative pain and opioid requirement. Further studies are required to determine the best choice between these two blocks. Ethical approval All procedures involving human participants were performed in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Informed consent Informed consent was obtained from all individual participants included in the study. Declaration of competing interest The authors declare that they have no conflict of interest. References [1] Elsharkawy H, Pawa A, Mariano ER. Interfascial plane blocks: back to basics. Reg Anesth Pain Med 2018;43(4):341–6. May. [2] Tulgar S, Selvi O, Kapakli MS. Erector spinae plane block for different laparoscopic abdominal surgeries: case series. Case rep anesthesiol [Internet]. 2018 Feb 18 [cited 2018 Apr 8];2018. Available from. https://www.hindawi.com/journals/cria/2018/ 3947281/abs/. [3] Ortiz J, Suliburk JW, Wu K, Bailard NS, Mason C, Minard CG, et al. Bilateral transversus abdominis plane block does not decrease postoperative pain after laparoscopic cholecystectomy when compared with local anesthetic infiltration of trocar insertion sites. Reg Anesth Pain Med 2012;37(2):188. [4] Shin H-J, Oh A-Y, Baik J-S, Kim J-H, Han S-H, Hwang J-W. Ultrasound-guided oblique subcostal transversus abdominis plane block for analgesia after laparoscopic cholecystectomy: a randomized, controlled, observer-blinded study. Minerva Anestesiol 2014;80(2):185–93. Feb. [5] Ökmen K, Metin Ökmen B, Topal S. Ultrasound-guided posterior quadratus lumborum block for postoperative pain after laparoscopic cholecystectomy: a
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