|Year : 2016 | Volume
| Issue : 2 | Page : 284-289
Ultrasound-guided transversus abdominis plane block versus caudal block for postoperative analgesia in children undergoing unilateral open inguinal herniotomy: A comparative study
Ashraf A Ahmed MD 1, Ayman A Rayan2
1 Department of Anesthesia, Ain Shams University, Menoufia, Egypt
2 Department of Anesthesia, Menoufia University, Menoufia, Egypt
|Date of Submission||20-Aug-2014|
|Date of Acceptance||17-Nov-2014|
|Date of Web Publication||11-May-2016|
Ashraf A Ahmed
Prince Sultan Armed Forces Hospital, Madinah 15616
Source of Support: None, Conflict of Interest: None
Ultrasound (US)-guided transversus abdominis plane (TAP) block is an effective technique in providing analgesia for abdominal surgery. This study was designed to evaluate the efficacy of a US-guided TAP block and to compare it with a caudal block in unilateral day-case open inguinal hernia repair in children.
Patients and Methods
Forty ASA I-II, 1-5-year-old children scheduled for elective unilateral open inguinal herniotomy were studied. All patients received general anesthesia; sevoflurane was used for induction and maintenance of anesthesia and laryngeal mask airway (LMA) was used to secure the airway. After securing an intravenous cannula, patients were randomized to a US-guided TAP block (n = 20) (group T) using 0.5 ml/kg 0.25% bupivacaine, injected on the same side of surgery, and group C received a caudal block using 1 ml/kg 0.2% bupivacaine (n = 20). Surgery was allowed 15 min after administration the block. Block failure was considered in case of gross movement or more than 20% change in heart rate and/or ABP persisting more than 1 min after skin incision. Any adverse events were recorded. After surgery, patients remained for 4 h in the recovery room. Postoperative analgesia was evaluated using Children and Infants Postoperative Pain Scale (CHIPPS). An anesthesiologist, who was not part of the study team, evaluated the need for rescue analgesia in the intraoperative and postoperative period and a recovery nurse collected the data. If the CHIPPS score was greater than 4, a rescue analgesia of 20 mg/kg acetaminophen was administered.
No difference was found in hemodynamics in both groups. Also, intraoperative fentanyl consumption was not different and no rescue analgesia was required in the postanesthesia care unit.
A US-guided TAP block is as effective as a caudal block in providing immediate postoperative analgesia in inguinal hernia repair.
Keywords: caudal block, inguinal herniotomy, ultrasound-guided transversus abdominal plane block
|How to cite this article:|
Ahmed AA, Rayan AA. Ultrasound-guided transversus abdominis plane block versus caudal block for postoperative analgesia in children undergoing unilateral open inguinal herniotomy: A comparative study. Ain-Shams J Anaesthesiol 2016;9:284-9
|How to cite this URL:|
Ahmed AA, Rayan AA. Ultrasound-guided transversus abdominis plane block versus caudal block for postoperative analgesia in children undergoing unilateral open inguinal herniotomy: A comparative study. Ain-Shams J Anaesthesiol [serial online] 2016 [cited 2021 Oct 26];9:284-9. Available from: http://www.asja.eg.net/text.asp?2016/9/2/284/182270
| Introduction|| |
Caudal epidural analgesia is the most common regional technique performed in children. It has been used for many years as a sole anesthetic, adjuvant to a general anesthesia, and to provide postoperative analgesia for subumbilical procedures; it is the preferred technique in groin surgery .
The caudal approach to the epidural space is preferred in children because of the ease of access through the sacrococcygeal ligament and the potential decreased risk of injury to neural structures at this level compared with access at the lumbar and thoracic levels .
The transversus abdominis plane (TAP) block is a new regional anesthesia technique that provides analgesia after abdominal surgery . It can be performed using a landmark technique through the lumbar triangle or with ultrasound (US) guidance.
As safe and effective regional anesthesia requires local anesthetics to be placed in close proximity to target nerves without injury to target nerves or adjacent structures, the use of US in regional anesthesia in children was shown to improve sensory and motor block, and might reduce the risk of complications .
Few studies have described the use of a TAP block for hernia repair in children [5-7]; however, it has not been compared with the most commonly used technique, caudal block, as yet.
The aim of this study was to evaluate the analgesic efficacy of a US-guided TAP block and to compare it with a caudal block in children undergoing day-surgery unilateral opening unilateral herniotomy.
| Patients and Methods|| |
After obtaining approval of the Hospital Research and Ethics Committee (King Abdul-Aziz air base hospital], Dhahran, KSA, 40 ASA I-II patients aged 1-5 years scheduled for elective outpatient unilateral open inguinal herniotomy were enrolled. A written informed consent was obtained from the father or the legal guardian of the patient.
Patients were excluded if there was parental refusal, any contraindication to a caudal block, for example, bleeding disorders, local site infection, and a history of relevant drug allergy.
All patients received general anesthesia; sevoflurane was used for the induction and maintenance of anesthesia (together with NO 2 60% in O 2 ) and LMA was used to secure the airway. Standard monitoring (ECG, ABP, SPO 2 , and end-tidal CO 2 ) was applied to all patients and the monitoring results were recorded every 5 min. After securing an intravenous cannula, patients were randomized, by computer-generated random tables and the sealed-envelope technique, to receive either a US-guided TAP block (group T) or a caudal block (group C).
In group T, patients were placed in a supine position and a high-frequency 6-13 MHz, hockey-stick transducer, connected to a SonoSite M-Turbo portable US machine (SonoSite, Bothell, Washington, USA), was used. The probe was initially positioned perpendicular to the anterior abdominal wall to visualize the rectus abdominis muscle at the level of the umbilicus. The ultrasound probe was moved laterally at the same level to scan the anterolateral part of the abdominal wall to obtain a transverse view of the abdominal layers: external oblique abdominal muscle, internal oblique abdominal muscle, transversus abdominis muscle, and most deeply, peritoneal cavity, from superficial downward [Figure 1].
|Figure 1: Transverse ultrasound view of the external oblique abdominal muscle, internal oblique abdominal muscle, and transversus abdominis muscle|
Click here to view
After skin disinfection, a 22-G 50-mm needle with an injection line (Stimuplex A; B/Braun Melsungen AG, Berlin, Germany) was used. Once the tip of the needle was placed in the space between the internal oblique abdominal muscle and transversus abdominis muscle in the same operative site, using an 'in-plane' technique to visualize the entire needle, and after negative aspiration, bupivacaine 0.5 ml/kg 0.25% was injected. An injection was considered successful when an echolucent lens shape appeared between the two muscles.
In group C, patients were placed in the left lateral position and a caudal block was administered under aseptic conditions using 1 ml/kg 0.2% bupivacaine. The maximum dose of 2 mg/kg bupivacaine was not exceeded in both groups.
Both TAP and caudal techniques were performed by the same anesthetist (first author) who was not involved in patient management after performing the block. Patients were managed by another anesthetist who was unaware of the technique used.
Successful blockade was defined by the absence of gross movement or a significant (>20%) change in heart rate (HR) and/or ABP on application of skin incision, which was allowed 15 min after performing the technique. Signs of inadequate analgesia (gross movement or >20% change in HR and/or ABP) persisting more than 1 min after skin incision were managed by increasing the sevoflurane concentration and fentanyl 1 mg/kg and the block was considered a failure (those patients were administered paracetamol 20 mg/kg per rectum immediately after the completion of surgery). Fentanyl was repeated as clinically indicated and the total number of intraoperative fentanyl doses administered was recorded.
After surgery, patients were observed for 4 h in the postanesthesia recovery unit by recovery room nurses who were blinded to the technique used. Postoperative analgesia was evaluated using the Children and Infants Postoperative Pain Scale (CHIPPS) . CHIPPS is a well-validated and reliable scale in determining postoperative analgesia demand in children [Table 1]. It consists of five items (crying, facial expression, posture of the trunk, posture of the legs, and motor restless) with a score of 0-2 for each item. Values between 0 and 3 indicate a pain-free state and 4 points or more identify the increasing need for supplemental analgesia. Motor weakness was determined using a simple three-point scale (0, no movements; 1, possible to move the legs; and 2, able to stand) .
CHIPPS and motor weakness were measured every 30 min for 4 h. If the CHIPPS score was greater than 4, rescue analgesia of 20 mg/kg rectal acetaminophen was administered.
The duration of analgesia, defined as the time from termination of anesthesia to the first analgesic administration, was also recorded. If no rectal acetaminophen was necessary within 4 h, the duration of analgesia was counted as 4 h. The sites of injection of the TAP block and the caudal area were inspected to detect complications such as hematomas. Any adverse events were also recorded.
Patients were discharged home 4 h postoperatively according to the study protocol. Full instructions were provided together with the postoperative medications. Home analgesia was administered in the form of a suppository of paracetamol 15 mg/kg 4-6 h; the total dose should not exceed 60 mg/kg in 24 h.
The primary outcome was the proportion of patients who required rescue analgesia in the recovery room. The secondary outcomes included pain score in the recovery room, time to rescue analgesia, and number of unplanned admissions.
Sample size and statistical methods
Group sample sizes of 18 per group will achieve an 80% power to detect a difference between the group proportions of 0.08. The proportion in the TAP group is assumed to be 0.9000 under the null hypothesis and 0.9800 under the alternative hypothesis. The proportion in caudal blocks is 0.9000. The statistical test used was the two-sided Z-test with pooled variance. The significance level of the test was set at 0.05. Twenty patients per group were included to replace any dropouts. The collected data were coded, tabulated, and statistically analyzed using the SPSS program (Statistical Package for Social Sciences) software version 17.0 (SPSS Inc., Chicago, Illinois, USA).
Data were expressed as mean values ± SD for numerical parametric data, median (range) for nonparametric data, and n (%) for categorical data. An independent t-test was used in cases of two independent groups with parametric data and a paired t-test was used in cases of two dependent groups with parametric data. The Mann - Whitney U-test was used for nonparametric data and the c2 -test for discrete (categorical) variables, with P values less than 0.05 considered statistically significant.
| Results|| |
Forty patients who underwent elective outpatient unilateral open inguinal herniotomy were included in this study. Abdominal muscles, the needle, and the spread of the local anesthetic could be observed clearly in all patients in group T and the caudal block was performed successfully in all patients in group C.
No case of blood aspiration was recorded during the technique in group T. However, one patient in group C received blood aspiration and the trial was repeated twice until the caudal injection was administered satisfactorily. No other local or systemic complications related to the technique of regional anesthesia or surgeries were reported.
The groups did not differ with respect to age, weight, sex, duration of surgery, and duration of anesthesia [Table 2].
One patient in group T showed signs of block failure (HR and/or ABP >20% of the baseline for more than 1 min) and was excluded from the study. The block was considered successful for the rest of the patients and no intraoperative fentanyl was used. [Table 3] shows the hemodynamic variables in both groups.
No rescue analgesia was required in the postanesthesia recovery unit for both groups. The CHIPPS score showed a tendency to be higher in group T compared with group C; however, the difference was not statistically significant [Table 4].
|Table 4 Children and Infants Postoperative Pain Scale score in the first 4 h postoperatively|
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No signs of motor blockade could be observed after the first postoperative hour in any of the patients. During the first postoperative hour, one patient in group C had a motor blockade score of 1, whereas none of the patients in group T had any sign of motor blockade.
All patients were discharged home 4 h postoperatively according to the study protocol and nonrequirement of hospital admission.
No adverse events were noted during the observation period in the postanesthesia recovery unit.
| Discussion|| |
Regional anesthesia attenuates the stress response to surgery and produces excellent postoperative analgesia in infants and children. Caudal anesthesia is the oldest and still most commonly used technique in children. It is recommended mainly for surgical procedures below the umbilicus, including inguinal hernia repair, urinary, and digestive tract surgeries, and orthopedic procedures on the lower extremities .
The TAP block is an anatomical compartment block. The nerve endings originate from T7 to L1 and, including the ilioinguinal and iliohypogastric nerves, are the target nerves. TAP block can be performed blindly on the basis of the click perceived when the needle passes through the fascia of the external and internal oblique and again between the internal oblique and transversus abdominis muscles; however, the use of US guidance is likely to improve the reliability of the block . US allows the precisely visualization of the blocking needle (the entire needle or its tip depending on the use of the inplane or the out-of-plane technique), the anatomy (the three abdominal muscle layers, the peritoneum, and intraperitoneal visceral structures), and also the real-time assessment of the local anesthetic distribution characterized by an anechoic image between the internal oblique and the transversus abdominis muscles .
Although the preliminary literature in infants and children suggests that the TAP block provides effective analgesia following various umbilical and lower abdominal procedures, including laparoscopy , few studies have been carried out showing its analgesia efficacy in hernia repair surgery [5-7], and none has compared it with the most commonly used regional technique in children: the caudal block.
The results of this study show that a US-guided TAP block is as effective as a caudal block in providing intraoperative and postoperative analgesia for unilateral day-surgery hernia repair in children. Both techniques (TAP block and caudal block) were successful in providing effective intraoperative and postoperative analgesia for the study patients (except for one patient in group T). No intraoperative fentanyl was used and no postoperative rescue analgesia was required during the study period (4 h postoperatively).
In agreement with our results, TAP block provided effective analgesia in a prospective study of eight children undergoing unilateral inguinal hernia repair . All patients recorded postoperative pain scores of 0-2 and seven patients required no postoperative opiates; one patient received intravenous morphine for the treatment of emergence agitation. Three patients showed signs of intraoperative incomplete analgesia and were treated with fentanyl (<0.5 mg/kg). The short time between the block and the skin incision, 5 min, may explain the incomplete intraoperative analgesia. In our study, skin incision was allowed 15 min after the block.
In a prospective randomized comparative study, Sahin et al.  evaluated the analgesic efficacy of a TAP block (US-guided) using 0.5 ml/kg levobupivacaine 0.25% in comparison with wound infiltration with 0.2 ml/kg levobupivacaine 0.25% during the first 24 h after surgery in 57 children (2-8 years) undergoing inguinal hernia repair. The mean time to first analgesic was significantly longer in the TAP group than in the infiltration group (17 ± 6.8 vs. 4.7 ± 1.6 h, respectively; P < 0.001) and 45% of the patients in the TAP group did not require any analgesic within the first 24 h.
However, Fredrickson et al.  under US guidance, compared TAP blocks with ilioinguinal blocks in children undergoing elective inguinal surgery. No difference was found in the intraoperative fentanyl requirements; however, more children in the TAP group reported pain in the recovery unit and required more analgesia in comparison with the ilioinguinal group. The discrepancy in the results of the TAP group with ours can be explained partially by the type of surgery; only hernia repair was explored in our study versus groin surgery (inguinal herniotomy, hydrocelectomy, orchidopexy) in the Fredrickson study .
Also, Stewart et al.  in an interesting study, found that after inguinal hernia repair, children experience mild pain that can be treated with paracetamol and only a few required analgesia 24 h postoperatively, whereas orchidopexy was associated with greater and more prolonged pain requiring a multimodal analgesia approach (paracetamol and ibuprofen) for a longer time. The authors (Fredrickson and colleagues) acknowledged the limitations of their study, which include the possible observer bias in the data collected by the principal investigator/operator, who was not blinded to the treatment group, and midazolam premedication was not controlled, which may have confounded recovery room and day-stay pain assessment .
Variable doses were used in US-guided TAP blocks in neonates, infants, and children for different surgeries; 0.2, 0.3, 0.5, and 1 ml/kg were all tried [6, 7, 15, 16]. We chose 0.5 ml/kg for use in this study as the TAP block was unilateral and the total dose was limited to 2 mg/kg, which is less than the 3 mg/kg upper dose limit suggested by Suresh and Chan  for a TAP block in children.
Femoral nerve block (partial or complete) is a potential complication of a TAP block that may not be avoided completely even with US guidance. The transversalis fascia includes the fascial plane deep to the rectus abdominis muscles. This fascial plane is continuous with the fascia iliaca. An injection of local anesthetic into the TAP can potentially spread along the transversalis fascia to the fascia iliaca, thereby blocking the femoral nerve . In this study, no signs of motor blockade could be observed in group T, whereas one patient in group C had a motor blockade score of 1 during the first postoperative hour. However, this did not affect patients discharge from hospital admission was required.
Although one patient had bloody aspiration in group C, no patient had symptoms or signs of systemic local anesthetic toxicity, and no other local or systemic complications related to the technique of regional anesthesia or surgeries were reported in both groups; no adverse events were noted during the observation period in the postanesthesia recovery unit.
We found a TAP block under US guidance in children to be a safe and easy to perform technique with effective intraoperative and postoperative analgesic effects in unilateral day surgery hernia repair. However, as different surgeries produce different levels of pain , the results of this study cannot be generalized to other groin or abdominal surgeries and further studies are still required to show the comparative effectiveness of TAP blocks among the various other analgesic techniques in different abdominal surgeries.
The short postoperative pain assessment time, 4 h, is a limitation in this study and should have been followed by telephone calls; however, because of cultural reasons, this could not be done.
| Conclusion|| |
A US-guided TAP block is as effective as a caudal block in providing intraoperative and postoperative analgesia in day-case open inguinal hernia repair in children.
| Acknowledgements|| |
Conflicts of interest
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[Table 1], [Table 2], [Table 3], [Table 4]
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