Beyond the caudal: truncal blocks an alternative option for analgesia in pediatric surgical patients

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1 REVIEW C URRENT OPINION Beyond the caudal: truncal blocks an alternative option for analgesia in pediatric surgical patients Jodi-Ann Oliver and Lori-Ann Oliver Purpose of review To discuss and compare the more commonly used truncal blocks with neuraxial techniques in children undergoing a variety of thoracic, abdominal and urological procedures. Recent findings Owing to the advent of ultrasonography and its increasing use in regional anesthesia, there has been a renewed interest in implementing these techniques in children for intraoperative and postoperative pain management. Summary The use of regional anesthesia particularly with ultrasound guidance is an integral part of pain management during the intraoperative and postoperative period in children who undergo surgery. Its use is essential in improving patient pain control and overall satisfaction as well as decreasing hospital stay and reducing hospital admission after surgery. Truncal blocks serve as an excellent alternative to neuraxial blockade, in patients who have a contraindication to neuraxial blockade, patients undergoing a unilateral procedure and those in an outpatient ambulatory setting undergoing routine procedures, wherein the adverse effects of neuraxial blockade such as motor weakness, difficulty ambulating, urinary retention, increased nausea and vomiting, may delay same day discharge. Keywords neuraxial anesthesia in children, pediatric regional anesthesia, peripheral nerve blocks, truncal blocks INTRODUCTION The use of regional anesthesia is now at the forefront of management of intraoperative and postoperative pain in pediatric patients undergoing a variety of surgical procedures. This renewed interest in pediatric regional techniques is largely because of two reasons: improvement in postoperative pain scores and improvement in safety of these procedures. Firstly, regional anesthesia has been associated with a reduction in postoperative pain scores, improvement in overall patient satisfaction, decreased opioid use and associated side-effects, reduction in hospital length of stay and remission rates for uncontrolled postoperative pain [1 & ]. Secondly, the advent and use of ultrasonography has improved visualization of needle placement and vital structures, which has improved the safety profile of these invasive procedures and significantly reduced procedure-related complications [2 & ]. Despite the increased use of peripheral nerve blocks in pediatric surgical patients, the caudal, a form of neuraxial block, still remains the gold standard and is the most widely used regional technique for this patient population for a variety of abdominal, thoracic and orthopedic procedures. However, the use of neuraxial blocks has been associated with side-effects such as urinary retention, nausea, vomiting and difficulty ambulating, which can delay hospital discharge especially following routine outpatient ambulatory procedures [3]. As a result, peripheral nerve blocks particularly truncal blocks have been used more in this patient population with equivalent if not superior analgesia and minimal side-effects. The aim of this review is to compare the use of truncal blocks with the current gold standard, neuraxial blockade especially the caudal block, in pediatric patients undergoing abdominal and thoracic surgery. Department of Anesthesiology, Yale New Haven Hospital, New Haven, Connecticut, USA Correspondence to Jodi-Ann Oliver, MD, Yale-New Haven Children s Hospital, 1 Park Street, 3rd Floor, New Haven, CT 06510, USA. Tel: +1 (203) ; fax: +1 (203) ; jodi-ann.oliver@ yale.edu Curr Opin Anesthesiol 2013, 26: DOI: /ACO Volume 26 Number 6 December 2013

2 Beyond the caudal: truncal blocks an alternative option for analgesia in pediatric surgical patients Oliver and Oliver KEY POINTS In children, neuraxial anesthesia has been the main stay for intraoperative and postoperative analgesia for a variety of abdominal, thoracic and orthopedic procedures, but has been associated with significant side-effects that may delay discharge especially in the ambulatory setting. With the advent of ultrasonography, there is an increased interest and utilization of peripheral nerve block techniques in children. Truncal blocks such as transversus plane block (TAP), rectus sheath block and ilioinguinal/ iliohypogastric blocks have been shown to provide equivalent if not superior analgesia in comparison with neuraxial blockade for surgeries involving the anterior abdominal wall and urologic procedures. Paravertebral blocks (PVBs) have been used for a variety of surgical procedures because of their lower complication rates, longer duration of analgesia, decreased side-effects and reduction in opioid consumption when compared with neuraxial blocks. The truncal blocks can be divided into two categories: anterior and posterior, with the anterior division consisting of TAP, rectus sheath block, and ilioinguinal and iliohypogastric blocks (IL/IH). The posterior truncal blocks consist of paravertebral (PVB) and intercostal blocks. In this article, we will focus on the most widely used truncal blocks for intraoperative and postoperative analgesia in the pediatric surgical population: TAP block, rectus sheath block, ilioinguinal and iliohypogastric blocks and paravertebral block. posteriorly by the latissimus dorsi muscle, anteriorly by external oblique muscle and the iliac crest inferiorly [4]. The abdominal wall consists of three muscle layers: external oblique, internal oblique and transversus abdominis muscles, from superficial to deep, respectively. Sensory innervation for the anterolateral abdominal wall is provided by the anterior rami of T6 L1 and intercostal nerves (T7 11), the subcostal nerve (T12), iliohypogastric and ilioinguinal nerves (L1), which travel in this plane between the transversus abdominis and internal oblique muscles (Fig. 1) [5,6]. A blunt needle is advanced perpendicular to the skin until a single pop or tactile sensation of loss of resistance was felt, indicating proper needle placement, and local anesthetic is then injected. McDonnell et al. in 2006 ascribed the double pop technique in which loss of resistance is noted by needle penetration first through the external oblique fascia and internal oblique muscles with final entry into the plane between internal oblique and transversus abdominis muscles [7,8]. The use of ultrasound guidance using a high-frequency linear probe is now the preferred technique for TAP block placement under general anesthesia. The needle is visualized with real-time ultrasound with in-plane technique, in which the probe is placed in the axial plane of the triangle of Petit or lateral to the umbilicus following visualization of the rectus sheath [9 ]. The needle is then inserted in the plane between the internal oblique and the transversus abdominis muscles and local anesthetic is incrementally injected (Fig. 2) [10]. TRANSVERSUS ABDOMINIS PLANE BLOCK TAP block has been increasingly used to provide postoperative analgesia that is comparable with the gold standard, caudal epidural analgesia, in children undergoing abdominal procedures, with none of the side-effects such as urinary retention, limited mobility and increased opioid use often associated with neuraxial blockade. TAP block therefore serves as a viable alternative to neuraxial blockade in children who have a contraindication to the use of neuraxial blockade and it can be performed under ultrasound guidance after the induction of general anesthesia with minimal risk to the patients. ANATOMY AND TECHNIQUES The TAP block was first described as a landmark technique by Rafi in 2001 involving placement of blunt needle in the triangle of Petit, an area bounded FIGURE 1. Transversus abdominis plane block. The ultrasound image shows the anatomy of the abdominal wall with the external oblique muscle (top), internal oblique muscle (middle) and transversus abdominis muscle (bottom) above abdominal viscera ß 2013 Wolters Kluwer Health Lippincott Williams & Wilkins 645

3 Ambulatory anesthesia wound infiltration group. Though a greater volume of local anesthetic was used for patients undergoing TAP block, the results are consistent with other studies that show that TAP blocks provide a longer duration of analgesia in comparison with wound infiltration, and wound infiltration is only effective in the immediate postoperative period, whereas TAP block remains effective for up to 24 h [17 ]. FIGURE 2. Transversus abdominis plane (TAP) block. The ultrasound image shows the needle injecting locating local anesthetic between the internal oblique muscle and transversus abdominis muscle during TAP block placement. COMPLICATIONS The TAP block is associated with perforation of abdominal viscera, peritoneal puncture and intravascular injection, which is of particular concern in small infants and children [18]. These risks are significantly reduced with the use of ultrasound guidance and in fact a review of the literature indicates that these complications are relatively rare, when the block is performed under ultrasound guidance [9 ]. INDICATIONS TAP blocks have been used in children for a variety of urologic and abdominal procedures [11] and in situations, in which neuraxial procedures are contraindicated or considered too risky [12]. Visoiu et al. [13 ] showed in a small retrospective study that TAP catheters could be effectively used to provide adequate postoperative analgesia in infants with low body weight and in which neuraxial techniques were contraindicated or with difficult placement secondary to sacral-spinal abnormalities. Bielsky et al. [14] also demonstrated the efficacy of TAP block in two case reports involving two infants weighing 2.5 and 3.1 kg, respectively, in which TAP blocks were used to effectively manage pain after urgent colostomy; one patient had congenital anomalies that included imperforated anus with club feet and seventh cranial nerve paralysis, whereas the other had only anal atresia. TAP blocks can also be used in cases, in which there are relative contraindications to neuraxial blockade such as bleeding disorders, in patients after laminectomies and in patients with potential bony anatomical abnormalities such as VATER syndrome [15,16]. TAP blocks have been shown to provide postoperative analgesia in children undergoing abdominal surgeries with reduced postoperative opioid use. Sahin et al. [17 ] demonstrated, in a randomized comparative study, involving 60 patients, ages 2 8 years, that ultrasound-guided TAP blocks provided superior postoperative analgesia when compared with wound infiltration performed by the surgeons. Patients in the TAP block group had longer intervals before the need for breakthrough analgesia and a significantly lower cumulative dose of total analgesics when compared with those in the RECTUS SHEATH BLOCK Schleich [19] first described the use of the rectus sheath block in 1899 in adult patients, to provide relaxation of the anterior abdominal wall. Rectus sheath blocks have also been used for women undergoing open and laparoscopic gynecological procedures [20 22] and to augment postoperative analgesia in patients after midline laparotomy [23,24]. Ferguson et al. in 1996, then Courreges et al. in 1997 [25,26], described the use of the rectus sheath block for providing analgesia for children undergoing umbilical hernia repair. This block has been used not only for umbilical hernia repairs, but also for pyloromyotomies and procedures with midline laparoscopic incisions [27]. ANATOMY AND TECHNIQUES The umbilical area is innervated by the right and left thoracoabdominal intercostal nerves, derived from the anterior rami of spinal roots T8 T12. The nerves pass from behind the costal cartilage and travel in the plane between the transversus abdominis muscle and internal oblique muscle. The rectus sheath has an anterior and a posterior wall, with the tendons of the internal and external oblique muscles forming the anterior wall and the tendon of the transversus muscle forming the posterior wall. The nerves run between the sheath and the posterior wall of the rectus abdominis muscle, innervating the muscle and ending as the anterior cutaneous branch supplying the cutaneous area of the umbilicus. Anatomical variations have been identified, with the nerves either coursing beneath or on top of the rectus abdominis muscle before ending at the umbilicus (Fig. 3) [28 ] Volume 26 Number 6 December 2013

4 Beyond the caudal: truncal blocks an alternative option for analgesia in pediatric surgical patients Oliver and Oliver FIGURE 3. Rectus sheath block. The ultrasound image shows the abdominal wall with the rectus abdominis muscle with the linea alba at the level of the umbilicus. Traditionally, the rectus sheath block has been performed using landmarks, in which a 23-gauge needle is placed above or below the umbilicus about 0.5 cm medial to linea semilunaris. The anterior rectus sheath is identified by moving the needle back and forth until a scratching sensation or click is felt [25,26]. Because of the inaccuracy of this technique, most rectus sheath blocks are performed today using ultrasonography. Willschke et al. [29] demonstrated, using ultrasonography, that there was a poor correlation between the depth of the rectus sheath and the height, weight and body surface area of children and effectively argues the point that the use of ultrasonography is a more reliable and superior technique. A high frequency probe is placed perpendicular to the umbilicus and the linea alba is identified in the midline with the rectus muscles laterally. The needle is then inserted using the in-plane technique and local anesthetic is injected in a potential space between the rectus abdominis muscle and posterior sheath just superior to the peritoneum [30,31]. INDICATIONS Rectus sheath block has been used to provide intraoperative and postoperative analgesia in children undergoing procedures involving the midline abdominal wall and umbilical areas as well as procedures with a single incision through the umbilicus such as laparoscopic appendectomies [28,29,30, 31,32]. Rectus sheath blocks have also been used successfully in pediatric patients with chronic abdominal pain caused by abdominal cutaneous nerve entrapment, iatrogenic peripheral nerve injury, myofascial pain syndrome or of unknown cause [33]. COMPLICATIONS The rectus sheath block has been associated with bowel perforation and damage to abdominal organs because of the close proximity of the needle to the peritoneum. There have also been reports of intravascular injection involving the inferior epigastric artery and retroperitoneal hematoma [34]. These complications have significantly been reduced with the use of ultrasonography [35]. Polaner et al. conducted a multicenter study, which reviewed pediatric regional blocks and their associated complications. Based on his database, 294 rectus sheath blocks were performed in which 256 (87%) of these blocks were performed with the use of ultrasound and no adverse events or complications were noted [36 ]. ILIOINGUINAL AND ILIOHYPOGASTRIC NERVE BLOCKS The ilioinguinal/iliohypogastric block is a commonly used peripheral nerve block technique used for children undergoing groin or urologic surgeries. It has been shown to be equivalent or better than caudal block and is associated with minimal sideeffects and complications. ANATOMY AND TECHNIQUES The ilioinguinal and iliohypogastric nerves (T12 L1) travel below the internal oblique within its aponeurosis 1 3 cm medial to the anterior superior iliac spine (ASIS). This block can be performed with the use of landmarks or ultrasonography. The landmark technique involves identifying the ASIS and a mark is made 2 cm medial and 2 cm superior to the initial mark and the needle is inserted perpendicular to skin; two pops are appreciated after the needle passes first through the external oblique muscle and then the internal oblique muscle; local anesthetic is then injected [37]. Another landmark technique involves placing the needle one-third of the way between the ASIS and the umbilicus and injecting local anesthetic after feeling a pop or click when the needle passes through the internal oblique and is the space between the internal oblique and transversus abdominis muscle [38 ]. This block is more commonly performed with the use of a highfrequency linear probe placed at ASIS facing the umbilicus; the layers of the abdominal muscles are identified and the nerves are located between the internal oblique and transversus abdominis muscle; local anesthetic is injected in this potential space (Fig. 4). The use of ultrasound is associated with a higher success rate compared with landmark technique as demonstrated by Weintraud et al. [39] ß 2013 Wolters Kluwer Health Lippincott Williams & Wilkins 647

5 Ambulatory anesthesia complications especially when ultrasound is utilized. Most complications include bowel puncture or intravascular injection [43]. Other complications such as pelvic hematoma [44], femoral nerve palsy [45] and quadriceps muscle paresis [46] have occurred during ilioinguinal/iliohypogastric block placement when utilizing the conventional landmark technique. FIGURE 4. Ilioinguinal/iliohypogastric nerve block. The ultrasound image shows the muscle layers of the abdominal wall at the level of anterior superior iliac spine with nerve bundle between the internal oblique muscle and transversus abdominis muscle. INDICATIONS Ilioinguinal/iliohypogastric nerve blocks are commonly used to provide analgesia for surgery involving the inguinal region and groin area such as inguinal hernia repair, orchiopexy and hydrocelectomy. Abualhassan et al. performed a randomized prospective study in which 50 children ages 1 6 years scheduled for unilateral groin surgery were randomized into either use of a caudal or an ultrasoundguided ilioinguinal/iliohypogastric nerve block. Those in the ilioinguinal/iliohypogastric nerve block group were noted to have a longer time to first rescue analgesia min compared with min in the caudal group and more children in the caudal group required rescue medications in a day-stay unit or at home compared with the ilioinguinal/iliohypogastric nerve group [40 ]. He also noted that the use of ultrasound allowed for lower doses of local anesthetic solution compared with caudal block and significant reduction in complications. Willschke et al. clearly demonstrated in a prospective study that ultrasound-guided technique was superior to landmark technique in accuracy and had a higher success rate [41]. These findings were confirmed by Bhatpara et al. who showed that IL/IH nerve blocks provide longer postoperative analgesia and better safety margin, as lower doses of local anesthetic can be used compared with caudal block in children undergoing herniotomy [42]. COMPLICATIONS As with the other anterior trunk blocks, the ilioinguinal/iliohypogastric block has minimal PARAVERTEBRAL NERVE BLOCKS PVBs were first described in 1905 by Hugo Sellheim but were not utilized extensively until the last 15 years when the block was felt to be a viable alternative to epidural or caudal blockade in certain patient populations. PVBs have been shown to not only be safer but also to provide similar analgesic benefits for managing postoperative pain as well as delaying the recurrence of tumors and metastases when compared to epidurals [47 ]. This technique was first utilized in children undergoing surgery by Lonnqvist in 1992 and has been subsequently used to provide postoperative pain control in children undergoing thoracic, abdominal or urogenital procedures with postoperative pain control equivalent to or superior to neuraxial blockade with fewer sideeffects [48 ]. ANATOMY AND TECHNIQUES The paravertebral space is a potential space that exists lateral to the spinous process, which contains the intercostal and sympathetic nerves and is bordered anteriorly by the parietal pleura, medially by the posterolateral aspect of the vertebra and the intervertebral foramen, laterally by the parietal pleura and posteriorly by the costotransverse ligament. The paravertebral space has been estimated to be 1 cm caudal to the transverse process and 2.5 cm lateral to the spinous process in most adults and is affected by multiple factors [49 & ]. Naja et al. [50] measured the paravertebral space using nerve stimulation technique and showed that the distance from skin to the paravertebral space was influenced by BMI, which significantly affected the paravertebral space depth at upper (T1 3) and lower (T9 12) thoracic levels but had no effect at the mid (T4 8) thoracic level. Chelly et al. [51] further showed that the depth of the paravertebral space is also influenced by factors other than weight (BMI) such as age, height and thoracic level. In children, identifying the correct location and depth of the paravertebral space is of utmost importance in decreasing complications such as pneumothorax or pleural puncture, which are rare but Volume 26 Number 6 December 2013

6 Beyond the caudal: truncal blocks an alternative option for analgesia in pediatric surgical patients Oliver and Oliver often catastrophic. A variety of different techniques including 2D echocardiography, ultrasonography and computed tomography guidance have been employed to predict the location and depth of the paravertebral space by determining the lateral distance from the spinous process to the paravertebral space and the skin to paravertebral space depth of the paravertebral space. Lonnqvist and Hesser [52] first used thoracic and upper abdominal computer tomography to derive these equations for estimating the spinous process to paravertebral space (SP-PVS) depth (0.12 body weight (kg) þ 10.2) and skin to paravertebral space (S-PVS) (0.48 body weight (kg) þ 18.7) in millimeters in children and adolescents. Ponde and Desaie [53 ] used echoguidance to determine the optimal point from needle insertion as well as the depth of the paravertebral space in infants ranging in age from 2 days to 60 months of age. The paravertebral nerve block can be performed using landmark, loss of resistance, neurostimulation or ultrasound guidance. The classic or landmark technique involves identifying the spinous process and marking the skin laterally at the level of transverse process and using a Tuohy needle to contact the posterior surface of the transverse process [54 & ]. Once the transverse process is contacted, the distance from the skin to transverse process is measured and the needle is withdrawn to skin and angled at 15 to 60 degrees and advanced 1 cm caudally beyond the transverse process and local anesthetics can be injected slowly following a negative drop technique. Chelly [55 ] describes the drop technique in which a drop of fluid is injected on the top of the needle to check for respiratory variations before catheter placement. Loss of resistance technique is similar to the classic technique but employs the use of a loss of resistance syringe or pressure transducer that is filled with saline and connected to the Tuohy needle and advanced until there is a notable loss of resistance. The neurostimulation technique employs the use of an insulated Tuohy needle, which is connected to a nerve stimulator, and a motor response in the intercostal or abdominal muscles is elicited [56]. The ultrasound can also be utilized to visualize the paravertebral space using a high-frequency linear MHz probe placed perpendicular (lateral or intercostal approach) or parallel (sagittal approach) to the spinous process and has become the standard technique utilized in children undergoing surgery under general anesthesia [57 ]. In larger children and adolescents, the use of a lowfrequency curvilinear 2 5 MHz probe may offer better visualization of the paravertebral space in comparison with the high-frequency linear probe (Fig. 5). FIGURE 5. The paravertebral nerve block. The ultrasound image shows the needle during placement of T9 10 paravertebral nerve block with low-frequency curvilinear probe in a teenager undergoing thoracic surgery. INDICATIONS The PVB is a versatile technique, as it can be performed at every spinal level and has been increasingly used as an alternative to neuroaxial blockade for a variety of reasons. Koyyalamudi et al. [58] used a continuous cervical (C5) PVB with a continuous thoracic (T5) PVB to provide postoperative analgesia for a 10-year-old child undergoing a forequarter amputation for an osteosarcoma of the left humerus, where a brachial plexus block would have provided ineffective postoperative analgesia. Visoiu and Yhang [59] used ultrasound-guided bilateral thoracic paravertebral catheters to treat postoperative pain following bowel resection in an opioid tolerant and mildly coagulopathic pediatric patient, in which epidural placement was contraindicated. Berta et al. showed that a single-injection PVB at T10 12 level was as efficacious in controlling postoperative pain when compared with continuous paravertebral catheters for children undergoing major renal surgery [60]. PVBs have also been used in outpatient ambulatory settings, in which faster postoperative recovery and same-day discharges are essential. In this specific patient population, the single shot caudal has been the gold standard but has been associated with short duration of analgesia, requiring the use of supplemental analgesia in the immediate postsurgical period as well as unwanted side-effects such as urinary retention and motor weakness, which can delay patient discharge. PVBs have been associated with prolonged analgesia that exceeds the expected duration of the local anesthetics administered when compared with caudals or epidurals. Tug et al. showed in a small prospective study involving ß 2013 Wolters Kluwer Health Lippincott Williams & Wilkins 649

7 Ambulatory anesthesia 70 children from ages 3 7 that a single L2 paravertebral injection provides analgesia that is superior to caudal placement in children undergoing inguinal surgery. Patients in the paravertebral group had decreased need for supplemental analgesics (11.4 vs. 34.3%) because of increased duration of analgesia with a mean duration of 1300 min (range: min), lower block failure rates (5.7 vs. 11.4%) and higher parental satisfaction scores (74.3 vs. 40%) [61]. COMPLICATIONS PVBs are rarely associated with complications, which include pneumothorax and pleural puncture, bleeding, epidural or intrathecal spread, infection, nerve injury, hypotension and spinal headache [62 ]. Naja et al. conducted a prospective trial with 662 patients including 42 children in which PVBs were placed using neurostimulation technique. He reported a 6.1% failure rate in the adults with complications such as hypotension, inadvertent vascular puncture, epidural and intrathecal spread, pleural puncture, hematoma and pneumothorax in the adults with no failures or complications noted in the children [63]. Berta et al. also reported a complication rate of 8.3% involving two inadvertent intravascular injections in a small study group of 24 patients [60]. SUMMARY The use of regional anesthesia techniques in children has increased, largely in part because of the advent of ultrasonography, which has improved the efficacy and the safety profile of these blocks. Also peripheral nerve blocks provide excellent intraoperative and postoperative pain control, by reducing the use of opioids and its associated adverse effects. Truncal blocks offer an excellent alternative to neuraxial blockade in patients with contraindications as well as in outpatient ambulatory procedures, in which the adverse effects of neuraxial blockade such as motor weakness, difficulty ambulating and urinary retention may delay same day discharge. The use of peripheral nerve blocks in children will continue to increase and it is imperative for pediatric anesthesiologists to embrace and master these techniques, as they offer immense benefits to improving the perioperative pain management of their patients. Acknowledgements None. Conflicts of interest There are no conflicts of interest. REFERENCES AND RECOMMENDED READING Papers of particular interest, published within the annual period of review, have been highlighted as: & of special interest of outstanding interest 1. Bosenberg A. Benefits of regional anesthesia in children. 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8 Beyond the caudal: truncal blocks an alternative option for analgesia in pediatric surgical patients Oliver and Oliver 22. Alexander JI, Hull MGR. Rectus sheath and mesosalpinx block for laparoscopic sterilization. Anaesthesia 1992; 47: Collins L, Vaghadia H. Regional Anaesthesia for Laparoscopy. Anaesthesiol Clin North Am 2001; 19: Dean VS, Pitt-Miller P, Arianyagyam DC. The rectus sheath block: a medial intra-operative approach for postoperative analgesia. Anaesthesia 1997; 52: Ferguson S, Thomas V, Lewis I. The rectus sheath block in paediatric anaesthesia: new indications for an old technique? Paediatr Anesth 1996; 6: Courreges P, Poddevin F, Lecoutre D. Para-umbilical block: a new concept for regional anaesthesia in children. Paediatr Anaesth 1997; 7: Matsuda C, Tachibana K, Kinouchi K. Ultrasound guided nerve block in infants undergoing pyloromyotomy. Masui 2013; 62: Syiggum HP, Niesen AD, Sites BD, Dilger JA. 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Rectus sheath block in children. Tech Regional Anaesth Pain Manage 1999; 3: De Maria BJ, Gotzens V, Madbrok M. Ultrasound-guided umbilical nerve block in children: a brief description of a new approach. Pediatr Anesth 2007; 17: Skinner AV, Lauder GR. Rectus sheath block: successful use in the chronic pain management of pediatric abdominal wall pain. Paediatr Anaesth 2007; 17: Yuen PM, Ng PS. Retroperitoneal hematoma after a rectus sheath block. J Am Assoc Gynecol Laparosc 2004; 11: Dolan J, Lucie P, Geary T, et al. The rectus sheath block: accuracy of local anesthetic placement by trainee anesthesiologists using loss of resistance or ultrasound guidance. Reg Anesth Pain Med 2009; 34: Polaner DM, Taenzer AH, Walker BJ. Pediatric Regional Anesthesia Network (PRAN): a multiinstitutional study of the use and incidence of complications of pediatric regional anesthesia. Anesth Analg 2012; 6: The Pediatric Regional Anesthesia Network is a multicenter study, which obtained data on practice patterns and complications involving the use of regional anesthesia in infants and children. This article highlights a low rate of complications in the United States, which is comparable with the data from large multicenter European studies. 37. Hadzic A. Regional anesthesia for pediatric surgery. In: Hadzic A, editor. Textbook of Regional Anesthesia and Acute Pain Management. First edition., 1st Ed New York: McGraw Hill companies; pp Bhalla T, Sawardekar A, Dewhirst E, et al. Ultrasound guided trunk and core blocks in infants and children. J Anesth 2013; 27: This article is a review of the available literature regarding core and trunk blocks in infants and children and specifically focuses on the TAP, ilioinguinal/iliohypogastric nerve, rectus sheath, lumbar plexus, and paravertebral and intercostal nerve blockade. This article also includes the common indications, complications, anatomy and techniques for the above-stated blocks. 39. Weintraud M, Marhofer P, Bosenberg A. Ilioinguinal/iliohypogastric blocks in children: where do we administer the local anesthetic without direct visualization? Anesth Analg 2008; 106: Abualhassan AA. Ultrasound-guided ilioinguinal/iliohypogastric nerve blocks versus caudal block for postoperative analgesia in children undergoing unilateral groin surgery. Saudi J Anaesth 2012; 6: This study was designed primarily to determine whether ultrasound-guided ilioinguinal/iliohypogastric nerve blocks could provide comparable postoperative analgesia to blind technique caudal block in children undergoing unilateral groin surgery, with secondary endpoints such as analgesic consumption, parental satisfaction, and postoperative complications. They were able to show that ultrasound-guided IL/IH nerve blocks provide ideal postoperative analgesic for unilateral groin surgery in children and are as effective as caudal block, with a lower volume of local anesthetics used. 41. Willschke H, Bosenberg A, Marhofer P, et al. Ultrasonographic-guided ilioinguinal/iliohypogastric nerve block in pediatric anesthesia: what is the optimal volume? Anesth Analg 2006; 102: Bhattarai BK, Rahman TR, Sah BP, Tuladhar UR. Analgesia after inguinal herniotomy in children: combination of simplified (single puncture) ilioinguinal and iliohypogastric nerve blocks and wound infiltration vs. caudal block with 0.25% bupivacaine. Kathmandu Univ Med J (KUMJ) 2005; 11: Johnr M, Sossai R. Colonic puncture during ilioinguinal nerve block in a child. Anesth Analg 1999; 88: Vaisman J. Pelvic hematomas after an ilioinguinal nerve block for orchialgia. Anesth Analg 2001; 92: Ghani KR, McMillan R, Paterson-Brown S. Transient femoral nerve palsy following ilioinguinal nerve blockade for day case inguinal hernia repair. J R Coll Surg Edinb 2002; 47: Erez I, Buchumensky V, Shenkman Z, et al. Quadriceps paresis in pediatric groin surgery. Pediatr Surg Int 2002; 18: Chelly JE. Paravertebral blocks. Anesthesiol Clin 2012; 30:75. This article provides a comprehensive review of paravertebral nerve blocks: the anatomy, techniques, indications and complications associated with these blocks. 48. Bhalla T, Sawardekar A, Dewhirst E, et al. Ultrasound guided trunk and core blocks in infants and children. J Anesth 2013; 27: This article is a review of the available literature regarding core and trunk blocks in infants and children and specifically focuses on the TAP, ilioinguinal/iliohypogastric nerve, rectus sheath, lumbar plexus, and paravertebral and intercostal nerve blockade. This article also includes the common indications, complications, anatomy and techniques for the above-stated blocks. 49. Greengrass RA, Duclas R Jr, et al. Paravertebral blocks. Int Anesthesiol Clin & 2012; 50: This is a review article about PVB, focusing on indications as primary anesthetic, analgesia, use in acute pain associated with trauma, use in chronic pain, various block techniques, contraindications, distribution of block, choice of local anesthetics and complications of the block. 50. Naja MZ, Gustafsson AC, Ziade MF, et al. Distance between the skin and the thoracic paravertebral. Anaesthesia 2005; 60: Chelly JE, Uskova A, Merman R, et al. A multifactorial approach to the factors influencing determination of paravertebral depth. Can J Anaesth 2008; 55: Lonnqvist PA, Hesser U. Location of the paravertebral space in children and adolescents in relation to surface anatomy assessed by computed tomography. Paediatr Anaesth 1992; 2: Ponde VC, Desaie AP. Echo-guided estimation of formula for paravertebral block in neonates, infants and children till 5 years. Indian J Anaesth 2012; 56: The purpose of this study was to use echosonography to determine an equation for determining the paravertebral space in neonates, infants and children up to 5 years old. 54. & Moawad HE, Mousa SA, El-Hefnawy AS, et al. Single-dose paravertebral versus epidural blockade for pain relief after open renal surgery: a prospective randomized study. Saudi J Anaesth 2013; 7: This article compared the effectiveness of a single injection PVB to epidural blockade in patients undergoing major renal surgery and was able to show that that the single-injection PVB resulted in similar analgesia but with greater hemodynamic stability than the epidural blockade and may be recommended for patients with coexisting circulatory dysfunction. 55. Chelly JE. Paravertebral blocks. Anesthesiol Clin 2012; 30:80. This article provides a comprehensive review of paravertebral nerve blocks: the anatomy, techniques, indications and complications associated with these blocks. 56. Naja ZM, Raf M, Rajab ME, et al. Nerve stimulator-guided paravertebral blockade combined with sevoflurane sedation versus general anesthesia with systemic analgesia for postherniorrhaphy pain relief in children. Anesthesiology 2005; 103: Chelly JE. Paravertebral blocks. Anesthesiol Clin 2012; 30: This article provides a comprehensive review of paravertebral nerve blocks: the anatomy, techniques, indications and complications associated with these blocks. 58. Koyyalamudi VB, Elliot C, Gibbs CP, Boezaart AP. Perioperative analgesia for forequarter amputation in a child: a dual paravertebral approach. Anesth Analg 2010; 110: Visoiu M, Yhang Y. Ultrasound guided bilateral paravertebral continuous nerve blocks for a mildly coagulopathic patient undergoing exploratory laparotomy for bowel resection. Pediatr Anesth 2011; 21: Berta E, Spanheil J, Smakal O, et al. Single injection paravertebral block for renal surgery in children. Paediatr Anaesth 2008; 18: Tug R, Ozcengiz D, Gunes Y. Single level paravertebral versus caudal block in paediatric inguinal surgery. Anaesth Intensive Care 2011; 39: Chelly JE. Paravertebral blocks. Anesthesiol Clin 2012; 30:84. This article provides a comprehensive review of paravertebral nerve blocks: the anatomy, techniques, indications and complications associated with these blocks. 63. Naja Z, Lonnqvist PA. Somatic paravertebral nerve blockade: incidence of failed block and complications. Anesthesia 2001; 56: ß 2013 Wolters Kluwer Health Lippincott Williams & Wilkins 651