Introduction
Various regional anesthesia techniques can be used to provide analgesia after abdominal surgery. While thoracic epidural anesthesia can be used, fascial plane blocks are favored as contemporary analgesic approaches. The thoracoabdominal nerves, also known as the T7–T12 thoracic intercostal nerves, innervate the abdominal wall muscles, parietal peritoneum, and skin [1,2]. Different fascial plane block applications targeting these nerves can be used. For instance, the transversus abdominis plane (TAP) block and subcostal TAP block can be used for analgesia in the abdominal region [3]. However, the inability of these techniques to block the lateral and anterior areas of the upper abdominal region has prompted exploration of other block methods. To provide analgesia for the abdominal region, modifications of external oblique blocks and thoracoabdominal nerve blocks using the perichondrial approach (TAPA) have been attempted. Injecting a local anesthetic into the thoracic interfascial plane beneath the external oblique muscle can block the lateral cutaneous branches of nerves supplying the abdominal wall at the T7–T11 level [4]. Additionally, a modified TAPA (M-TAPA) has been reported to provide a sensory block at the T7–T12 level for both the anterior and lateral cutaneous nerve branches from the axillary line to the mid-abdomen [4]. A different approach, utilizing two injections at the costal cartilage level, has also been implemented for anterolateral abdominal analgesia. A local anesthetic was administered beneath the external oblique and rectus muscles, providing analgesia at the T5–T9 levels [3–5]. Furthermore, application of the external oblique and rectus abdominis plane (EXORA) block at the 8th costal cartilage level, which allows local anesthetic spread beneath both the rectus abdominis and the external oblique muscles, can be used for analgesia of the lateral and anterior abdominal walls [5].
We hypothesized that M-TAPA and EXORA block application after laparoscopic cholecystectomy would provide similar levels of analgesia in the anterolateral abdomen. Therefore, in this study, we investigated M-TAPA and EXORA block effects on postoperative pain scores in patients who underwent laparoscopic cholecystectomy surgery.
Materials and Methods
This prospective, single-blind, observational study received local ethics committee approval (number 2011-KAEK-25 2023/3-1) and was registered as a clinical study. We included patients aged 18–65 years, American Society of Anesthesiologists classes I–III, who underwent laparoscopic cholecystectomy by the same surgical team. The exclusion criteria were a second surgery at the same site, uncontrolled diabetes mellitus, mental retardation, metabolic disorders, antidepressant diathesis, and body mass index (BMI) above 30 kg/m2. Written informed consent for block application was obtained from all patients. The study was conducted in accordance with the principles of the Declaration of Helsinki (2013). One hundred patients were evaluated for eligibility. Ninety patients who met the inclusion criteria were divided into three groups (n = 30 per group), as follows (Fig. 1). The control group received intravenous (IV) patient-controlled analgesia (PCA). The EXORA group received an EXORA block with 0.25% bupivacaine + IV-PCA. The M-TAPA group received an M-TAPA with 0.25% bupivacaine + IV-PCA.
Anesthetic management
Anesthesia was induced with propofol, rocuronium bromide, and opioids. Patients underwent routine anesthesia monitoring (noninvasive blood pressure, electrocardiography, heart rate, and peripheral oxygen saturation measurements). To maintain general anesthesia, sevoflurane (1%–2.5% concentration) was administered in a mixture of oxygen and air at a flow rate of 3 L/min. Intraoperative analgesia was provided with 1 μg/kg fentanyl. Tenoxicam 20 mg was administered intravenously approximately 30 min before the end of surgery.
Pain management
IV-PCA protocol
A saline solution containing 5 mg/ml tramadol was available via a PCA device (CADD-LegacyTM PCA Model 6300, Smiths Medical, Inc.) in all groups. The device was set to deliver a bolus dose of 0.3 mg/kg tramadol, had a lockout interval of 20 min, and provided a demand dose of 10 mg tramadol. The maximum daily dose was 400 mg and the allowed dose per 6 h was set to 100 mg tramadol.
Block procedure
Patients were taken to the block room before the operation, and after monitoring and sedation (premedication with intravenous midazolam at 0.03 mg/kg), the block procedures were performed bilaterally, after appropriate site hygiene, under ultrasound guidance with a linear ultrasound sonography (USG) probe (10–18 MHz, MyLab30).
EXORA block
For the EXORA block, the linear USG probe was placed sagittally in a craniocaudal direction along the parasternal line, lateral to the sternum and xiphoid process. The probe was advanced in a craniocaudal direction to identify the 6th, 7th, and 8th costal cartilages. At the 8th costal cartilage level, the probe was positioned transversely to visualize the rectus abdominis muscle and the underlying costal cartilage. A 100-mm, 22-gauge ultrasound-visible peripheral nerve block needle was directed medially and laterally, using an in-plane technique. After confirming the position of the needle beneath the rectus abdominis muscle by hydrodissection, 0.3 ml/kg bupivacaine (0.25% concentration) was injected (Fig. 2). The spread of local anesthetic was observed laterally beneath the external oblique muscle and medially beneath the rectus muscle and costal cartilage.
M-TAPA
To administer the M-TAPA, a linear USG probe was placed in the sagittal plane at the level of the 10th costal cartilage to identify the transversus abdominis, external, and internal oblique muscles. To visualize the undersurface of the 10th costal cartilage at the midline better, the probe was angled deeply and sagittally along the edge of the cartilage. A 22-gauge ultrasound-visible peripheral nerve block needle was advanced cranially using the in-plane technique, and the needle tip was directed posteriorly. After placing the needle tip on the cranial edge of the 10th costal cartilage and the lower surface of the chondrium, 0.3 ml/kg bupivacaine (0.25% concentration) was injected (Fig. 3).
For patients with a numerical rating scale (NRS) score greater than 5, in all three groups, rescue analgesia was planned with 1 g of paracetamol administered intravenously at 8-hour intervals, up to a maximum of three times per day. All block procedures were performed by the same anesthesiology and reanimation specialist (KÖ).
Outcomes
The primary outcome for this study was the NRS scores at 2, 4, 6, 12, and 24 h postoperatively.
The secondary outcomes were the tramadol consumption (12 and 24 h postoperatively), sensory block distribution level (pinprick test), side effects (nausea and vomiting), amount of opioids given during the operation (μg), the IV-PCA dose (the given and demanded doses), Ramsay Scale score, and additional analgesic requirements. Furthermore, we collected patients’ demographic characteristics (age, height, BMI, and sex) and the duration of surgery.
Pinprick test
The pinprick test was performed using a blunt 20-gauge needle. To ascertain the extent of the sensory block, the abdominal region and left shoulder were selected as reference points. The needle was initially applied to the abdominal region and the presence or absence of sensation was evaluated. The test was then conducted on the shoulder region for confirmation. The pinprick response was recorded on a two-point scale, with a value of 1 indicating the presence of a sensation and a value of 2 indicating the absence of a sensation or numbness.
Sensory block area
To ascertain the extent of analgesia provided, a pinprick test was conducted and results recorded for each dermatomal area, commencing from the 5th thoracic vertebra to the first lumbar vertebra and from the anterior abdominal wall (parasternal line) to the mid-clavicular line, anterior axillary line, and mid-axillary line, in that order. In this study, the M-TAPA and EXORA block were performed bilaterally. Thus, in each block group, 60 blocks were applied to 30 patients. Dermatomal spread in the blocked area was evaluated over the number of blocks.
Sample size calculation
In our previous study, the mean 6-h postoperative NRS score was 3 ± 1.12 in patients using tramadol [5]. For a three-group study, with a 95% confidence level, effect size of 0.378 (a 30% reduction in NRS scores by 6 h postoperatively was expected for block groups based on the reference study [5]), α = 0.05, and power (1-β) = 0.85, 81 patients was required by sample size calculation. Considering possible losses, 90 patients were included in the study, with 30 patients in each group.
Statistical analysis
The normality of data distribution of numerical variables was examined using the Shapiro–Wilk test. Mauchly's test was used to test the assumption of sphericity (P = 0.180). A repeated-measures analysis of variance (ANOVA) was employed to assess the difference among multiple numerical dependent variables. Levene's test was used to ascertain the homogeneity of variance. For non-repeated measurements, one-way ANOVA was used. When variables did not demonstrate a normal distribution, the Kruskal–Wallis test was used. When the ANOVA yielded significant differences, pairwise comparisons were conducted using the Bonferroni correction for post-hoc tests. The chi-square test was used to compare categorical parameters. Data are expressed as number (percentage), mean ± standard deviation, or median (Q1, Q3). P values less than 0.05 were considered statistically significant. Data analysis was performed using SPSS Statistics for Windows, version 22.0 (IBM Corp.).
Results
The demographic characteristics of the patients and the fentanyl amounts administered during the operation are summarized in Table 1. No statistically significant differences in these parameters were found among the groups (Table 1). The NRS scores at rest and during movement were statistically significantly different at all time points, with higher scores found in the control group than in the M-TAPA and EXORA groups (P < 0.001) (Tables 2 and 3). The tramadol consumption at 12 h and 24 h postoperatively was significantly higher in the control group than in the block groups (Table 4). The incidence of postoperative nausea and vomiting was also significantly higher in the control group (P < 0.001) (Table 4). No significant differences in terms of paracetamol consumption or operative duration were found among groups (Table 4). Sensory block distribution was evaluated in a total of 120 block areas at 30 min after block application in the 60 patients who received either the M-TAPA or the EXORA block.
A comparison of the distribution of sensory block areas after administration of the M-TAPA or EXORA block revealed that the EXORA group had a significantly higher level of sensory blockade, reaching the 11th thoracic level (Table 5). No sensory blockade was detected posterior to the mid-axillary line in any patient in the block groups. Sensory loss was detected between the T7 and T10 levels in the 60 block areas between the mid-axillary and midline regions in the M-TAPA and EXORA groups. Sensory loss at the T5 level was detected in only three block areas in the EXORA group, while sensory loss at the T11 and T12 levels was more common in the EXORA group.
Discussion
In this study, we investigated the analgesic efficacy and dermatomal distribution of the EXORA and M-TAPA blocks applied under ultrasonographic guidance in patients undergoing laparoscopic cholecystectomy. Compared with the control group, the M-TAPA and EXORA groups had significantly lower postoperative NRS scores at rest and during movement, as well as significantly lower tramadol consumption. Both blocks provided analgesia extending to the anterior abdominal wall at the T6–T11 dermatomal levels.
Postoperative pain following laparoscopic surgery can arise from various causes. Incisional pain accounts for 50%–70% of this postoperative pain, while pain is also associated with the pneumoperitoneum and the cholecystectomy area [6,7]. Multimodal analgesia methods are frequently used for the treatment of postoperative pain in different regions [8,9]. Currently, regional anesthesia techniques, particularly field blocks, are typically used as part of multimodal analgesia. Various versions of the quadratus lumborum block (QLB), erector spinae plane (ESP) block, and TAP block are used as regional anesthesia methods. While the QLB and ESP block affect the anterior and lateral cutaneous branches of the abdominal wall nerves, the patient's position and the deep application area limit the use of these blocks [3,10,11]. Therefore, different types of fascial plane blocks that can be applied more easily and that do not require patient positioning have been described in the literature. The M-TAPA, external oblique intercostal plane (EXOP) block, and EXORA block are among these techniques. These three field blocks aim to provide a wide sensory block area and analgesia to the anterior and lateral abdomen. The M-TAPA, which involves injecting a local anesthetic beneath the transversus abdominis muscle at the level of the 10th costal cartilage, has been reported to provide analgesia at the T6–T12 dermatomal levels. Its analgesic efficacy has been demonstrated in various types of surgeries [2,5,12]. It has been used for analgesia after laparoscopic cholecystectomy in two studies. Bilge et al. [13] reported lower postoperative pain scores and reduced tramadol consumption in their M-TAPA group. The high QoR-40 scores in that study also indicated better recovery quality with this block. Another study comparing the M-TAPA with local anesthetic infiltration reported similar results. Aikawa et al. [14] investigated the analgesic efficacy of the M-TAPA after laparoscopic gynecological operations and reported sensory loss at the T5–T8 levels in the anterior abdominal wall and the T7–T10 levels in the lateral wall, with sensory loss observed in the lateral wall in 5 out of 30 patients. Another study comparing the M-TAPA and wound infiltration analgesia for postoperative analgesia in patients undergoing laparoscopic gynecological surgery found that neither technique significantly reduced the postoperative analgesic needs. That study highlighted the need for sufficient visceral pain control to evaluate the effectiveness of both techniques in patients undergoing laparoscopic gynecological surgery [15]. Different opinions on application of the M-TAPA have been reported in cadaveric case series. In a study involving M-TAPA application in cadavers as well as in patients, for analgesia after open gynecological surgery, sensory blockade of the anterior branches at the T6–T12 dermatomal levels was achieved in 10 patients undergoing the surgical procedure, while dye spread was observed at the T8–T11 anterior cutaneous branches after the bilateral M-TAPA were applied in two cadavers [16]. Another cadaveric study observed dye spread, including in the internal and external oblique muscles, between the T4 and T12 levels after M-TAPA administration [17]. Ohgoshi et al. [18] reported that M-TAPA application could provide a sensory block at the T6–T12 levels, particularly at the T8–T11 levels. However, they noted that M-TAPA block application only blocked the anterior cutaneous branches. Other studies have used the EXOP block for lateral analgesia, as this block addresses the sensory innervation of the abdominal wall provided by the lateral cutaneous and anterior branches of the thoracoabdominal nerves. Additionally, these studies have suggested that a combination of the M-TAPA and EXOP block can be used to achieve complete abdominal wall analgesia [19]. Different block combinations can be used to achieve complete abdominal wall analgesia. However, the need for multiple injections is a limitation of these approaches. Injection at the level of the 8th costal cartilage, i.e., the EXORA block, can achieve spread of the local anesthetic beneath the rectus and external oblique muscles. This block, used for analgesia after laparoscopic cholecystectomy, provides a sensory block between the T6 and T11 dermatomes, which resulted in lower postoperative visual analogue scale scores and tramadol consumption in a previous study [5]. The present study compared the results of the M-TAPA and EXORA block after laparoscopic cholecystectomy and reached conclusions similar to those reported in the literature. Lower NRS scores and reduced tramadol consumption were observed in patients receiving either of those blocks as compared to those in the control group. Although both blocks consistently provided analgesia at the T7–T11 levels, the EXORA block resulted in a higher sensory block in the anterior cutaneous branches of the abdominal wall nerves.
Limitations
The variable amounts of local anesthetics used in different studies and the lack of a standardized dose limit discussions on the extent of dermatomal spread. Furthermore, clinical trials with more randomized allocation of patients to block groups are needed in future.
In conclusion, this study demonstrated that both the M-TAPA and EXORA block can be used to provide analgesia in the anterior and lateral regions of the upper abdominal wall after laparoscopic cholecystectomy.
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