|Year : 2015 | Volume
| Issue : 4 | Page : 658-663
Comparison of postoperative analgesia of ultrasound-guided ilioinguinal/iliohypogastric nerve block versus ultrasound-guided TAP block for pediatric inguinal hernia repair
Mahmoud Hassan Mohamed MD , Manal Mohamed Kamal
Department of Anesthesia, Faculty of Medicine, Ain Shams University, Cairo, Egypt
|Date of Submission||14-Sep-2014|
|Date of Acceptance||22-Jan-2015|
|Date of Web Publication||29-Dec-2015|
Mahmoud Hassan Mohamed
Department of Anesthesiology, Faculty of Medicine, Ain Shams University, Cairo
Source of Support: None, Conflict of Interest: None
Providing efficient postoperative analgesia for pediatric herinorrraphy is essential for surgical success. Different ultrasound (US)-guided techniques have been developed for pediatric nerve blocks.
This study aimed to compare US-guided ilioinguinal/iliohypogastric (II/IH) nerve block and US-guided transversus abdominis plane (TAP) block for pediatric unilateral inguinal herniorraphy with respect to postoperative analgesic efficacy by considering the time to first rescue analgesic as the primary outcome. Secondary outcomes included average pain scores, assessment of analgesic drug requirement, and incidence of postoperative vomiting.
Patient and methods
Fifty children scheduled to undergo unilateral herniorraphy were included in the study. After induction of general anesthesia patients were randomly allocated to one of two groups: group A or group B. Group A received US-guided II/IH nerve block with 0.2 ml/kg of 0.25% levobupivacaine and group B received US-guided TAP block with 0.2 ml/kg of 0.25% levobupivacaine. Fentanyl was given intravenously in case of failed block; failure was seen in one child (4%) in group A and in two children (8%) in group B and their postoperative data were not included in the statistical analysis. Time to first rescue analgesic, pain scores (FLACC score), the number of children who required postoperative analgesics, and incidence of vomiting were recorded.
Time to first rescue analgesic was longer and the duration of analgesia was more stable in group A (273 ± 41.7 min) as compared with group B (209.6 ± 98.4 min) (P < 0.001). The average FLACC pain score for group A was 2 (1-2) compared with 3 (2.25-3.5) in group B, with statistically significant difference between the two groups (P < 0.001). The total number of patients who required paracetamol as a rescue analgesic in group A was 8 (33.3%) compared with 14 (60.9%) in group B (P < 0.001). Two patients in group B required morphine and both suffered from vomiting.
US-guided II/IH nerve block provides longer and more efficient postoperative analgesia compared with TAP block for pediatric inguinal herniorraphy.
Keywords: ilioinguinal/iliohypogastric nerve block, pediatric herniorraphy, ultrasound-guided transversus abdominis plane block
|How to cite this article:|
Mohamed MH, Kamal MM. Comparison of postoperative analgesia of ultrasound-guided ilioinguinal/iliohypogastric nerve block versus ultrasound-guided TAP block for pediatric inguinal hernia repair
. Ain-Shams J Anaesthesiol 2015;8:658-63
|How to cite this URL:|
Mohamed MH, Kamal MM. Comparison of postoperative analgesia of ultrasound-guided ilioinguinal/iliohypogastric nerve block versus ultrasound-guided TAP block for pediatric inguinal hernia repair
. Ain-Shams J Anaesthesiol [serial online] 2015 [cited 2019 Jun 19];8:658-63. Available from: http://www.asja.eg.net/text.asp?2015/8/4/658/172763
| Introduction|| |
Pediatric inguinal hernia repair, a common day-surgery procedure, is associated with considerable postoperative discomfort  . Postoperative pain control for pediatric surgeries is a major issue and affects the quality of recovery, parental satisfaction, and surgical success. Opioid usage for pediatric analgesia has many disadvantages, such as postoperative vomiting, pruritus, respiratory depression, and sedation  .
The introduction of anatomy-based ultrasound (US) imaging for facilitating nerve localization is a major advancement in the field of pediatric regional anesthesia. This is because regional anesthesia techniques are challenging to perform in children as a result of:
Ilioinguinal/iliohypogastric (II/IH) nerve blocks are commonly used for anesthesia and analgesia for surgeries involving the inguinal region, including inguinal hernia repair and orchiopexy. When successfully performed, this block can be as effective as a caudal block  .
- Close proximity to critical structures,
- The need for sedation or general anesthesia masking potential warning signs (paresthesia), and
- The potential hazards of local anesthetic toxicity due to overdose  .
US-guided transversus abdominis plane (TAP) block is gaining popularity for intraoperative and postoperative analgesia in a variety of abdominal surgical procedures in adult  , pediatric, and neonatal patients  .
With the development of different US-guided approaches to various nerve blocks, researchers are focusing on which surgical procedure to follow for a particular block that would yield the most efficient outcome with the least complication rate.
The present study was designed to compare US-guided II/IH nerve block with US-guided TAP block for pediatric unilateral inguinal hernia repair with respect to postoperative analgesia.
| Patient and methods|| |
This double-blinded, randomized prospective controlled study was conducted in Ain Shams University Pediatric surgical hospital from April 2014 to August 2014. Approval from the institutional ethics committee and written informed parental consent were obtained. We enrolled 50 patients of American Society of Anesthesiologists physical status I-II aged 1-2 years scheduled for elective unilateral inguinal hernia repair.
Exclusion criteria included a history of clinically significant cardiac, hepatic, renal, or neurological conditions and known allergy to local anesthetics.
General anesthesia was induced with incremental sevoflurane in 100% oxygen. After reaching an adequate depth of anesthesia, a venous access was established, and then a disposable laryngeal mask airway was placed. Anesthesia was maintained under spontaneous ventilation with 1-1.5 MAC of isoflurane.
Standard intraoperative monitors were applied for measurement of ECG, heart rate, pulse oximetry, noninvasive blood pressure, and end-tidal carbon dioxide concentration. Baseline readings were recorded.
Patients were randomly allocated to one of two groups by means of a computer-generated program. Group A received US-guided II/IH nerve blocks with 0.2 ml/kg of 0.25% levobupivacaine and group B received US-guided TAP block with 0.2 ml/kg of 0.25% levobupivacaine. All blocks were performed by the same anesthetist who was experienced in US-guided pediatric nerve blocks. The blocks were performed using a high-resolution portable ultrasound machine (M-turbo; Fujifilm SnoSite Inc., Bothell, Washington, USA), with a 5-10 MHz linear hockey stick probe with a sterile cover and 22 G needles. All surgical procedures were performed by the same surgical team.
The probe was placed immediately medial and slightly cephalic to the upper aspect of the anterior superior iliac spine to obtain a short-axis view of the nerves situated between the two abdominal muscles (internal oblique and transversus abdominis), with the peritoneum immediately beneath the internal oblique muscle.
After aseptic preparation of the skin and probe, the needle (short beveled) was advanced using an out-of-plane technique, placing the needle tip ~1 cm caudal to the probe surface to allow for optimal needle tip visibility ~1 cm deep. Advancement of the needle continued until a characteristic 'tenting' of the interface between the internal oblique and transversus abdominis muscles was seen. The needle was then further advanced deep to this interface (usually associated with a felling of 'give⁄pop'). Subsequent manipulation of the needle was done until injectate was observed spreading between the internal oblique and transversus abdominis muscles under real-time control to view the solution surrounding the nerves.
The US probe was placed in a transverse plane to the lateral abdominal wall in the mid-axillary line immediately cephalad of the iliac crest. The needle was advanced immediately anterior to the probe using in-plane needle-probe orientation and advanced posteriorly until the needle was observed to penetrate the interface between the internal oblique and transversus abdominis muscles. Thereafter, a local anesthetic was injected incrementally, and the spread was observed within the plane.
Vital signs were recorded every 5 min after the block to ensure adequacy of the blockade especially after surgical incision. Surgical procedures were allowed to start 20 min after performance of the block. In case of patient movement at skin incision or increase in either heart rate or respiratory rate to more than 20% of the baseline, fentanyl at 50 mg/kg was administered and repeated as required every 3 min if the above parameters did not return to within 20% of the baseline values, but the postoperative data of those patients were not included in the statistical analysis.
After completion of surgery, children were transferred to the post anesthesia care unit (PACU) for continuous monitoring of vital signs and for pain assessment. Children were monitored every 15 min during the first hour in the PACU and every 30 min in the daycare unit until discharge from the hospital.
Postoperative pain assessment was done using a face, legs, activity, cry, consolability (FLACC) pain scaling system (Appendix 1). The FLACC is used to assess behavioral reactions to pain by infants and children (2 months to 7 years) who cannot express their own pain and with whom oral communication cannot be established  .
The scale has five criteria and each is assigned a score of 0, 1, or 2. It is scored between 0 and 10: 0 represents no pain, relaxed and comfortable: 1-3 represents mild discomfort; 4-6 represents moderate pain; 7-10 represents severe discomfort or pain, or both. In our study, for patients with an FLACC pain score of 4 or more, 15 mg/kg paracetamol was administered intravenously. Pain scores were re-evaluated every 5 min after administration of intravenous paracetamol to evaluate pain relief. If the pain score was still greater than 4 after 20 min from paracetamol administration, intravenous morphine 0.05 mg/kg per dose, repeated every 10 min up to a maximum of 0.2 mg/kg, was administered to bring the pain score below 4. We recorded the number of children who needed postoperative analgesics (paracetamol or morphine), the time when an analgesic was required, and incidence of vomiting.
Patients were discharged from the hospital 6 h after surgery when they were pain free and there was no other medical reason to admit them to a surgical ward.
Time to first rescue analgesic, pain scores, and the amount of rescue analgesic medication were recorded at the PACU and at the daycare unit by independent nurses blinded to both patients and procedures.
Using PASS (PASS 13 software NCSS statistical software Inc., Kaysville, Utah, USA) for sample size calculation, a sample size of 24 per group was determined to achieve 80% power to detect a difference of 60 min in time to first rescue analgesia between the two groups with a significance level (a) of 0.05 using a two-sided two-sample t-test; 25 patients were included per group to replace any dropouts.
Statistical analysis was performed using a standard SPSS software package, version 17 (SPSS Inc., Chicago, Illinois, USA). Data were expressed as mean ± SD and numbers (%). Student's t-test was used to analyze the parametric data, and discrete (categorical) variables were analyzed using the c2 -test, with P values less than 0.05 considered statistically significant.
| Results|| |
Intravenous fentanyl was required intraoperatively in one child (4%) in group A and in two children (8%) in group B (P > 0.05) because of body movement at skin incision or increased heart rate or respiratory rate more than 20% of the baseline value during the surgery. These patients were excluded from the study.
A total of 50 patients (25 in each group) were enrolled, and 47 patients (24 in group A and 23 in group B) completed the study. The two groups were equally distributed with respect to patient characteristics. There was no statistically significant difference as regards the duration of anesthesia [Table 1].
The average time to first rescue analgesia (measured from time of block performance) was longer and the duration of analgesia was more stable in group A (273 ± 41.7 min) compared with group B (209.6 ± 98.4 min) (P < 0.001).
The average FLACC pain score during hospital stay in group A was 2 (1-2) compared with 3 (2.25-3.5) [median (interquartile range)] in group B, with a statistically significant difference between the two groups (P < 0.001).
At PACU, two patients in group B required pain rescue medication (paracetamol) for pain score greater than or equal to 4, whereas no patient in group A required any rescue analgesic.
At the daycare unit, eight patients in group A and 12 patients in group B required paracetamol. The total number of patients who required paracetamol in group A was 8 (33.3%) compared with 14 (60.9%) in group B (P < 0.001).
Two patients in group B required morphine (FLACC score was still 4 or higher after 20 min of paracetamol administration) and both suffered from vomiting and required antiemetic medication (ondansetron 0.06 mg/kg). No patients in group A required morphine as analgesic and there was no statistically significant difference between the two groups (P = 0.59) [Table 2].
| Discussion|| |
This study demonstrates that for pediatric unilateral inguinal hernia repair US-guided IL/IH nerve block provides superior postoperative analgesia compared with US-guided TAP block. There was a trend toward a statistically significant difference between the two groups regarding time to first rescue analgesic administration as the primary outcome, and average pain scores and number of patients requiring analgesic medication as the secondary outcome. At the same time there is more stability in the duration of analgesia, which provides better control on the postoperative medication program.
A considerable amount of pain experienced by patients after abdominal surgery is derived from the anterior abdominal wall incision  . The use of US-guided sensory nerve block of the anterior abdominal wall for postoperative analgesia is an attractive method because of its simplicity and safety. Effective analgesia has been shown to reduce postoperative stress response and accelerate recovery from surgery  .
Ultrasonic guidance for ilioinguinal or iliohypogastric nerve block was found to be more effective, with fewer complications  and lower doses of local anesthetic drug requirement when compared with the traditional method of anatomical localization  . It provides comparable analgesia to caudal block for pediatric inguinal surgeries  . In one study, the local anesthetic was found to be inaccurately placed in the adjacent anatomical structures with unpredictable block results when traditional anatomical localization was used  .
In a study conducted on adult patients undergoing unilateral inguinal hernia repair, II/IH nerve block was found to provide longer postoperative analgesia and to facilitate earlier discharge compared with spinal anesthesia, although the time taken to perform and produce maximum effect is longer  .
In pediatric patients, the TAP block is an effective analgesic for a wide variety of surgical procedures such as laparotomy, appendectomy, Nissen fundoplication, pyloromyotomy, major abdominal wall surgery, and colostomy placement and closure  . Sixty-four pediatric patients aged 5-12 years received a TAP block for bone graft from the ilium to the alveolar cleft. In these patients analgesia was effective with a significant reduction in the amount of postoperative analgesic drugs  .
The three muscle layers of the abdominal wall (the external oblique, the internal oblique, and the transversus abdominis and their associated fascial sheaths) contain the T7-12 intercostal nerves, the ilioinguinal and iliohypogastric nerves, and the lateral cutaneous branches of the dorsal rami of L1-3. The above nerves run in the neurovascular plane between the internal oblique and transversus abdominis muscles and represent the plane of the TAP block  . Because of the individual anatomical variations, the traditional landmark-guided technique involving needle insertion at the triangle of Petit was often accompanied by a high rate of failure  . US imaging clearly visualizes the fascial plane between the transversus abdominis and the internal oblique muscle and it is possible to confirm proper administration of local anesthetics  .
One child (4%) in group A and two children (8%) in group B required intraoperative analgesia with fentanyl; these patients were excluded from the study.
The improved analgesia demonstrated with the IL/IH nerve block may be attributed to the anatomical course of the ilioinguinal and iliohypogastric nerves. Anatomical cadaveric studies showed significant variability in the anatomical course of both nerves in the TAP  (which is the plane where the local anesthetic for both the ilioinguinal block and the TAP block exert their action). In the present study, during the TAP block, the local anesthetic had to spread caudally and medially to reach both the ilioinguinal and iliohypogastric nerves as the probe was placed at the approximate level of the anterior axillary line just above the iliac crest. Moreover, at this level both nerves are 2 cm apart, requiring more spread of local anesthetic. During the ilioinguinal approach, both nerves are reliably located in the TAP and in close proximity to each other. Another factor that may play a role in the more successful IL/IH nerve block is the easier medial spread of local anesthetic to the deep inguinal ring blocking the genital branch of the genitofemoral nerve compared with the posteriorly placed TAP block, which improves the quality of analgesia further. It should be noted that in the present TAP block the local anesthetic was placed anteriorly rather than posteriorly, which was thought to be inappropriate for inguinal anesthesia.
The volume of local anesthetic used was based on the work done by Willschke et al.  . They used a modified step-up-step-down approach, with 10 children in each study group with a starting dose of 0.2 ml/kg of 0.25% levobupivacaine. They concluded that ultrasonographic guidance for IL/IH nerve block in children allowed a reduction in the volume of local anesthetic to 0.075 ml/kg with the same success rate as that the starting dose. Therefore, the used volume could be considered a high volume for the IL/IH nerve block and a relatively low volume for the TAP block compared with the volumes used traditionally (0.3-0.5 ml/kg)  .
The experience of the anesthesiologist is one of the important factors in the success of nerve blocks in pediatrics. In our study, there was no statistically significant difference between the success rates of the two techniques that could be attributed to the experience of the performing anesthesiologist.
One limitation of the study is that the assessments were limited to the first 6 h after surgery because it is a day-case surgery and the hospital policy recommends early discharge.
| Conclusion|| |
Both US-guided II/IH nerve blocks and TAP blocks provide effective intraoperative and postoperative analgesia for unilateral inguinal pediatric hernia repair. US-guided II/IH nerve blocks provide longer and more efficient postoperative analgesia compared with TAP blocks.
| Acknowledgements|| |
Conflicts of interest
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[Table 1], [Table 2]