Analgesic efficacy of ultrasound-guided modified thoracoabdominal nerve block in paediatric upper abdominal surgery: A randomised controlled trial

Abstract

Background and Aims:

Adequate pain management is crucial for postoperative recovery in paediatric patients. This study aimed to evaluate the analgesic efficacy of ultrasound (US)-guided modified thoracoabdominal nerve block through perichondrial approach (mTAPA) block in paediatric patients undergoing upper abdominal surgeries.

Methods:

This randomised controlled trial included 40 paediatric patients aged between 2 and 8 years scheduled for unilateral upper abdominal surgeries. Patients were randomised into two groups: Group I received general anaesthesia (GA) with US-guided mTAPA block (0.5 mL/kg of 0.2% ropivacaine), while Group II received GA only. Intravenous fentanyl 0.5 µg/kg was utilised for perioperative pain management. The primary outcome was to assess intraoperative opioid consumption, whereas secondary outcomes were postoperative pain scores, 24-h opioid consumption, and adverse effects such as nausea and vomiting. The independent Student t-test compared quantitative, normally distributed data, while the Mann-Whitney U test compared quantitative, discrete data. A P value of <0.05 was considered statistically significant.

Results:

Patients in Group I had a statistically lower intraoperative median fentanyl consumption of 10.0 µg [range: 0–20, interquartile range (IQR): 0–10] versus 20 µg (range: 5–48, IQR: 20–27) in Group II (P = 0.001). There was a significant reduction in the number of patients requiring rescue opioid top-ups (32.5% vs 50%) and postoperative pain scores (till 16 hours) in Group I. The median time to rescue analgesia was significantly higher in Group I than Group II (P = 0.001). No significant side effects were observed in either group.

Conclusion:

Ultrasound-guided modified thoracoabdominal nerve block through perichondrial approach as an adjunct to general anaesthesia provides effective analgesia by significantly reducing opioid consumption in paediatric patients undergoing upper abdominal surgeries through a unilateral subcostal incision.

INTRODUCTION

Pain management during the perioperative period is vital for postoperative outcomes in paediatric patients undergoing upper abdominal surgeries. Opioids are known to cause side effects such as nausea, vomiting, and respiratory depression.[1,2] The effort to find an effective regional analgesia technique that offers adequate postoperative pain relief in these surgeries continues.[3] Recently, various interfascial plane block methods, including the erector spinae plane (ESP) block, oblique subcostal transversus abdominis plane (OSTAP) block, and serratus intercostal plane block (SIPB), have been introduced as part of multimodal analgesic approaches for upper abdominal (supra-umbilical) surgeries.[4,5,6] These blocks have limitations, such as the inability to be administered in a supine position (ESP block) and insufficient coverage of the anterior and lateral abdominal wall (OSTAP and SIPB).[6,7,8]

In modified thoracoabdominal nerve block through perichondrial approach (mTAPA), local anaesthetic (LA) is deposited only on the lower aspect of the costochondrium at the 9^th costal cartilage, thus targeting T4/T5-T12/L1 thoracoabdominal nerves.[9] Studies have established its efficacy in adult surgeries such as sleeve gastrectomy and laparoscopic gynaecological surgery/cholecystectomy. Evidence is limited regarding its use in paediatric patients.[2]

We aimed to evaluate the analgesic effect of ultrasound (US)-guided unilateral mTAPA block in paediatric patients. The primary objective was to assess the intraoperative fentanyl consumption in paediatric patients (age 2–8 years) undergoing abdominal surgery through a unilateral upper quadrant incision, who received a unilateral mTAPA block. The secondary objectives were pain scores at 1, 4, 8, 16, and 24 h at rest; time to first rescue analgesia administration; postoperative analgesic consumption; and adverse reactions such as nausea, vomiting, sedation, and LA systemic toxicity (LAST) in these patients. We hypothesised that administration of US-guided unilateral mTAPA would decrease intraoperative opioid consumption and postoperative pain scores in paediatric patients (aged 2–8 years) undergoing upper abdominal surgeries when compared to patients not receiving this block.

METHODS

After receiving approval from the Institutional Ethics Committee (vide approval number AIIMS/Pat/IEC/PGTh/July 21/29; dated 11 November 2022), this trial was registered at Clinical Trials Registry-India (vide registration number CTRI/2022/12/048639; https://ctri.nic.in/). This double-blinded, randomised controlled trial was conducted in a tertiary care centre between December 2022 and June 2024. Forty American Society of Anesthesiologists (ASA) physical status I/II paediatric patients between the ages of 2 and 8 years, scheduled to undergo upper abdominal surgeries through a unilateral upper quadrant approach, were recruited for the study. This study was conducted in accordance with the principles of the Declaration of Helsinki (2013) and the Good Clinical Practice guidelines. After explaining the study procedure in detail, written and informed consent for the study and publication was obtained from the parents, allowing for their participation in the study and the use of patient data for research and educational purposes. Exclusion criteria included patients with coagulation abnormalities, developmental or mental delays, skin lesions or infections at the planned needle insertion site, and parents who did not give consent to participate in the study.

Block randomisation was performed using online software (Open Epi software version 3.01, Atlanta, GA, USA). Patients were randomised into two groups of 20, each using blocks of 4. Patients in Group I received a US-guided mTAPA block with 0.5 mL/kg of 0.2% ropivacaine, along with general anaesthesia (GA), whereas those in Group II received GA only. Allocation concealment was achieved by using sequentially numbered, opaque, and sealed envelopes that were opened by the technician on the morning of the surgery. All the blocks were given by an anaesthesiologist with more than 5 years of experience in paediatric regional anaesthesia. Intraoperative assessments were done by a resident blinded to the intervention. Pain nurses, blinded to the group allocations and interventions, collected the postoperative data [Figure 1].

Figure 1.

Consolidated standards of reporting trials (CONSORT) flow diagram. GA = general anaesthesia; mTAPA = modified thoracoabdominal nerve block through perichondrial approach; n = number of patients

All patients were enroled in the study 1 day before surgery, and a routine pre-anaesthetic assessment was done. After the patients were transferred to the operating room, standard ASA monitors were attached. GA was initiated using intravenous (IV) fentanyl 2 μg/kg, propofol 2 mg/kg, and atracurium 0.5 mg/kg. The anaesthesia was maintained with sevoflurane in an oxygen and air mixture (1:1) with a target minimum alveolar concentration (MAC) of 1. Intraoperatively, mean arterial pressure (MAP) and heart rate (HR) were recorded every 5 minutes after skin incision till the end of surgery.

Following tracheal intubation with a suitably sized tube, a US-guided mTAPA block was administered at the level of the 9^th costal cartilage in the supine position to all patients in Group I. Under aseptic precautions, a high-frequency (6–13 MHz) linear probe (footprint size: 4 cm) (M-Turbo, Fujifilm Sonosite, Inc., Bothell, WA, USA) was placed longitudinally (sagittal plane) on the costochondral angle of the operating side. The angle of the probe was deepened to view the lower aspect of the chondrium in the midline. A 22-gauge 5-cm echogenic needle (Pajunk, Germany) was inserted in-plane to the probe in a caudal to cephalad direction to target the lower aspect of the chondrium. After confirmation of the injection point (into the plane between the transversus abdominis muscle and the lower aspect of the costal cartilage) by hydro-dissection with normal saline, 0.5 mL/kg 0.2% ropivacaine was administered [Figure 2]. IV paracetamol 15 mg/kg, dexamethasone 0.1 mg/kg and ondansetron 0.1 mg/kg were given to all patients.

Figure 2.

Modified thoracoabdominal nerve block through perichondrial approach: panel a: needle probe position; panel b: sonoanatomy; panel c: injected drug spread. CC: costal cartilage; IOM: internal oblique muscle; TAM: transversus abdominis muscle

Skin incision was allowed 20 minutes after intervention in Group I patients. Intraoperatively, any increase in HR/MAP of more than 20% was treated with additional IV fentanyl doses of 0.5 µg/kg. Total fentanyl consumption during the intraoperative period was noted in both groups. No LA was used by the surgeon for infiltration in either group. For postoperative analgesia, diclofenac suppository 25 mg 8^th hourly was given to the patients.

A pain nurse blinded to the group allocation assessed the pain score using the Children’s Hospital of Eastern Ontario Pain Scale (CHEOPS) in the postoperative period.[10] IV paracetamol 15 mg/kg IV was administered as rescue analgesia to patients with a CHEOPS score greater than 6, and the time to the first rescue analgesic requirement was recorded. An IV fentanyl top-up (0.5 µg/kg) was also given if the CHEOPS score failed to decrease 20 minutes after paracetamol use. Thereafter, IV paracetamol was given every 8^th hours to the patients. Any adverse effects such as nausea, vomiting, sedation, or respiratory depression [peripheral oxygen saturation (SpO₂0 < 90%] were documented. Block-related complications, such as vascular puncture or LAST, were also noted.

The sample size was calculated using an online calculator (www.clincalc.com, CCL Health Care, North America) based on the study by Mostafa et al.[6] According to that study, the mean IV intraoperative opioid consumption was 37.87 [standard deviation (SD):8.2] µg of fentanyl in paediatric patients undergoing splenectomy. Anticipating a 20% reduction in consumption, with a power of 80% and an alpha error of 5%, the sample size was calculated to be 18. To accommodate dropouts, we took a sample size of 20 in each group.

Data were analysed using Jamovi 2.3.28 software (Jamovi Project, Sydney, New South Wales). Continuous quantitative normally distributed data (height, weight, and duration of surgery) were expressed as mean and SD and analysed using an independent Student t-test. Quantitative discrete data (age, heart rate, mean arterial blood pressure, SpO₂, intraoperative fentanyl consumption, CHEOPS score, time to rescue analgesia, and paracetamol consumption) were expressed as median and interquartile range and were analysed using the Mann-Whitney U test. Qualitative nominal data (gender, types of surgery, and frequency of complications) were expressed as percentages and analysed using Chi-square or Fisher’s exact tests. A P value of <0.05 was considered statistically significant.

RESULTS

Forty-three patients were enroled in this study, out of which three did not meet the inclusion criteria (cancellation of surgery in one, and refusal to give consent in two patients) [Figure 1]. There was no difference in demographic parameters or the type of surgery between the two groups [Table 1].

Table 1.

Patient demographics and surgical characteristics

Variables	Group I (n=20)	Group II (n=20)
Age (years) Median [range (IQR)]	5.75 [2–8 (3.75–8.00)]	5 [2–8 (3.38–3.7.25)]
Height (cm) Mean (SD) [95% CI]	105 (16.6) [97.4, 113]	104 (18) (95.9, 113)
Weight (kg) Mean (SD) [95% CI]	17.4 (5.84) [14.7, 20.2]	17.1 (5.99) (14.3, 19.9)
Gender (Male/Female) (n)	15/5	12/8
ASA (I/II) (n)	17/3	18/2
Duration of surgery (minutes) Mean (SD) [95% CI]	119 (37.0) [101, 136]	122 (34.3) [106, 138]
Type of surgery: choledochal cyst excision/pyeloplasty/splenectomy (n)	3/12/5	3/13/4

Data expressed as median [range (IQR)] or mean (SD) [95% CI]. CI=confidence interval; IQR=interquartile range; n=number of patients; SD=standard deviation; Group I=group that received GA with mTAPA; Group II=group that received only GA; ASA=American Society of Anesthesiologists physical status

We found a statistically significant reduction in intraoperative fentanyl requirements in patients in Group I (P = 0.001) [Table 2]. We also observed that the number of patients requiring fentanyl and the mean number of fentanyl top-ups were significantly lower in patients in Group I (P = 0.004 and P = 0.001, respectively) [Table 2]. Postoperative pain scores were significantly lower up to 16 hours [Table 3]. The median rescue analgesia time was significantly higher in Group I than in Group II (P = 0.001) [Table 3].

Table 2.

Perioperative fentanyl consumption in the two groups

Variables	Group I (n=20)	Group II (n=20)	Effect Size (95% CI)	P
Intraoperative fentanyl consumption (μg) Median [range (IQR)]	10 [0–20 (0–10)]	20.0 [5–48 (20–27)]	−1.81 (−2.64, −0.95)	0.001
Number of patients requiring postoperative fentanyl Frequency (%)	13 (32.5%)	20 (50%)	-	0.004
Number of times fentanyl top-up Mean (SD)	1.10 (1.07)	2.95 (1.15)	−1.740 (−2.56, −0.901)	0.001

Data expressed as median [range (IQR)] or frequency (%) or mean (SD). CI=confidence interval; IQR=interquartile range; n=number of patients; SD=standard deviation; Group I=group that received GA with mTAPA; Group II=group that received only GA

Table 3.

Postoperative pain scores at various time points and time to rescue analgesia in the two groups

Time interval	Group I (n=20)	Group II (n=20)	Effect Size (95% CI)	P
1 h	5 [5–9 (5–6)]	8 [5–10 (5–10)]	−1.096 (−1.79, −0.37)	0.001
4 h	5 [ 4–6 (5–5)]	6 [5–9 (5–9)]	−1.057 (−1.75, −0.34)	0.001
8 h	5 [4–8 (4–8)]	5.5 [5–8 (5–7)]	−0.915 (−1.59, −0.22)	0.003
16 h	5 [4–8 (5–5)]	5 [5–9 (5–5)]	−0.565 (−1.20, 0.08)	0.038
24 h	5 [4–7 (5–5)]	5 [5–9 (5–5)]	−0.454 (−1.08, 0.18)	0.102
Time to rescue analgesia (minutes)	1440 [5–1440 (240–1440)]	60 [5–1440 (5–480)]	1.11 (0.437, 1.77)	0.001

Data expressed as median [range (IQR)]. CI=confidence interval; n=number of patients; Group I=group that received GA with mTAPA; Group II=group that received only GA; IQR=interquartile range

There were no significant differences in haemodynamic parameters, such as mean HR, mean MAP, and SpO₂, between the groups (P > 0.05) during the intraoperative and postoperative periods [Figure 3]. The incidence of nausea and vomiting was lower in Group I (5%) compared to Group II (20%); however, the difference between the two groups was statistically insignificant. Block-related complications were not noted.

Figure 3.

Postoperative median CHEOPS score variation with time. CHEOPS = Children’s Hospital of Eastern Ontario Pain Scale. * statistically significant

DISCUSSION

This study demonstrates that patients receiving mTAPA blocks have better pain scores and reduced perioperative analgesic consumption, without any increase in adverse effects, in paediatric patients undergoing upper abdominal surgeries. The median time to first rescue analgesia was significantly longer in the mTAPA group than in those receiving GA only.

Hideki Matsuura et al.[11] conducted a retrospective study on mTAPA block in adult laparoscopic cholecystectomy surgeries, where there was a notable reduction in the consumption of intraoperative remifentanil in patients who received mTAPA than in those who received LA infiltration (P < 0.001). The LA deposited in mTAPA tends to cross the linea semilunaris to block both anterior and lateral cutaneous branches of the thoracoabdominal nerve, providing wide coverage from T4 to L1 of the anterior wall and T3-T12 of the lateral abdominal wall.[12] This coverage is more extensive than that of the subcostal TAP block, where the LA is deposited in the transversus abdominis plane below the subcostal margin. Though it covers the dermatomes T7-T10, the lateral cutaneous branches of segmental nerves are not blocked.[7]

Both postoperative pain scores and opioid consumption were significantly lower in patients in our study who received the block. These results are similar to those of Bilge et al.,[12] who used bilateral mTAPA for laparoscopic cholecystectomy. The perioperative tramadol consumption and pain scores were lower post-surgery.

Tulgar et al.[13] reported effective analgesia of bilateral mTAPA (volume: 50 mL) block up to 24 h in a case posted for laparotomy for ovarian cancer. No additional analgesia was required other than standard paracetamol. Similar to their study, we found that the duration of analgesia was prolonged up to 24 h, despite administering a dose of 0.5 mL/kg.[14]

Erturk and Ersoy[3] compared the mTAPA and TAPA blocks in 56 adult patients undergoing laparoscopic cholecystectomy. Patients who received TAPA block had statistically lower postoperative pain scores at the 1^st and 12^th h. This could be due to the larger volume of LA used in two-point injection in the TAPA block (35 mL of 0.25% bupivacaine) compared to the mTAPA block (20 mL of 0.25% bupivacaine).

In our study, the incidence of nausea and vomiting was higher in the control group. This is expected considering the higher opioid consumption in the control group. A study by Onur Avci et al.[15] assessed the effects of mTAPA block in 42 patients undergoing laparoscopic cholecystectomy. There was a significantly decreased frequency of nausea in patients who received a block, due to lower total tramadol consumption.

Most of these studies have been done in adult patients. We have limited literature on paediatric patients, most of which are case reports. Pain management in children has been a challenge due to different drug pharmacology, assessment tools, and various non-pharmacological approaches.[16]

mTAPA can be incorporated as a component of multimodal analgesic strategies in paediatric patients undergoing upper abdominal surgery. This block has the added advantage of ease of performance in supine position, adequate coverage, and needle insertion away from the incision site.

This study has a few limitations. We did not find significance in outcomes such as time to rescue analgesia, which could be due to the small sample size. Studies using adjuvants and continuous catheter techniques can be formulated in the future. In this study, we have not measured intraoperative inhalational agent requirements. Comparison with other interfascial blocks providing visceral analgesia would provide more information. Studies with a larger sample size are needed to confirm our findings.

CONCLUSION

Ultrasound-guided modified thoracoabdominal nerve block through perichondrial approach as an adjunct to general anaesthesia provides effective analgesia by significantly reducing intraoperative opioid consumption in paediatric patients undergoing upper abdominal surgeries through a unilateral subcostal incision. It also reduces postoperative opioid consumption and pain scores.

Conflicts of interest

There are no conflicts of interest.

Presentation at conferences/CMEs and abstract publication

NONE.

Study data availability

De-identified data may be requested with reasonable justification from the authors (email to the corresponding author) and shall be shared after approval as per the authors’ Institution policy.

Disclosure of use of artificial intelligence (AI)-assistive or generative tools

The AI tools or language models (LLM) have not been utilised in the manuscript, except that software has been used for grammar corrections and references.

Declaration of Use of Permitted Tools

The scales, scores, figures, not copyrighted.

Author contributions

AJ: writing-original draft, data curation. AK: conceptualization, writing-review and editing. CS: writing-review and editing, supervision. AK: writing-review and editing. PK: writing-review and editing. AKS: writing-review and editing, data curation.

Funding Statement

Nil.