In recent years, advances in regional anesthesia techniques have revolutionized perioperative multimodal analgesia (Anesthesiology 2018;129:721-32). Although, the utilization of regional anesthesia in the adult patient population is widespread, clinical practice of pediatric regional anesthesia (PRA) is still suboptimal. With increasing health care costs and the current opioid epidemic, PRA has an exceptional role in impacting quality and safety outcomes in this population (Br J Anaesth 2014;113:375-90).
Is regional anesthesia in children safe?
According to the Pediatric Regional Anesthesia Network (PRAN) database, complications associated with PRA are very rare (Anesthesiology 2018;129:721-32). In a prospective cohort of more than 100,000 regional blocks in children, the rate of transient neurologic deficit was low (2.4 per 10,000), and no cases of permanent neurologic deficits were found. Incidence of local anesthesia systemic toxicity (LAST) was also low at 0.76 per 10,000 blocks (Anesthesiology 2018;129:721-32; Curr Pain Headache Rep 2017;21:11). Comparable safety results were also noted from the French-Language Society of Pediatric Anesthesiologists' (ADARPEF) large prospective trials (Paediatr Anaesth 2010;20:1061-9). No cases of cutaneous infections were noted with a single-shot injection, but the incidence rate was 53 per 10,000 with peripheral nerve catheters (PNC) and an even higher rate was present with neuraxial catheters (Anesthesiology 2018;129:721-32; Curr Pain Headache Rep 2017;21:11). Despite the demonstrated overall safety of regional anesthesia in children, utilization was not as prevalent until the last two decades (Smith's Anesthesia for Infants and Children. 8th ed, 2011). “Reluctance to regional” in children was mainly contributed to the false assumption of higher complication rates in anesthetized patients. It is now well established that an anesthetized child aids the precision of block placement and decreases the likelihood of injury caused by unexpected movements (Curr Pain Headache Rep 2017;21:11; Best Pract Res Clin Anaesthesiol 2019;33:447-63). Therefore, contrary to common belief, regional anesthesia in children is safe in the hands of an experienced practitioner and use of the correct equipment.
Children are not small adults, and knowing the difference is the key:
Several anatomical differences, especially in neuraxial anatomy, are present between children and adults. Lower levels of conus medullaris (L3) and dural sac (S2-S4) makes younger individuals susceptible to inadvertent damage during neuraxial block placement. Epidural space content in children has a higher amount of fat lobules, facilitating faster spread of anesthetic agents. Epidural space is also accessible easily via sacral hiatus/caudal space until 7 to 8 years of age. The higher turnover rate of CSF and higher volume on per weight basis result in increased requirement of local anesthetic (LA) volume and shorter duration of spinal blocks (A Practice of Anesthesia for Infants and Children. 5th ed, 2013).
Children lack prominent hemodynamic responses to test dose epinephrine due to immature cardiac fibers, higher basal heart rate, and presence of I.V. and/or inhalational agents. Therefore, a negative test dose may not be a reliable indicator of ruling out an intravascular injection in neonates and young children (Reg Anesth Pain Med 2015;40:526-32).
Neonates and infants have a higher predilection of developing local anesthetic systemic toxicity (LAST) (Best Pract Res Clin Anaesthesiol 2019;33:447-63; A Practice of Anesthesia for Infants and Children. 5th ed, 2013). Lower levels of a-1 glycoprotein (AGP) and P-450 enzymes at birth leads to a higher free-fraction of LA, whereas increased levels of AGP (also an acute phase protein) during the perioperative period decreases the rate of clearance (A Practice of Anesthesia for Infants and Children. 5th ed, 2013; Paediatr Anaesth 2012;22:39-43; Paediatr Anaesth 2012;22:31-8). Hence, adherence to maximum recommended doses of LA should be practiced at all times to minimize the incidence of LAST (Table 1) (Reg Anesth Pain Med 2018;43:211-6).
The misconception regarding presence of a regional block masking the onset of ischemia pain and acute compartment syndrome (ACS) has been a major barrier in utilization of PRA. In fact, clinical evidence suggests that the delay in detection of ACS and ischemic pain is mostly secondary to the communication difficulties in younger children. Therefore, it is recommended to use diluted and lower volumes of LA in cases where risk of developing ACS is higher (Reg Anesth Pain Med 2018;43:211-6).
Common pediatric regional blocks
Due to the limitations of this overview article, descriptions of common pediatric regional blocks are listed in Table 2.
Head and neck blocks
Head and neck blocks have provided a new facet to multimodal analgesia for ambulatory ENT and ophthalmologic surgeries in pediatric patients. They are relatively low risk and easy to place. Despite no observed complications and/or adverse events in over 500 head and neck blocks reviewed, these remain one of the most underutilized blocks in the pediatric population (Paediatr Anaesth 2012;22:81-7; Anesth Analg 2012;115:1353-64).
The upper-extremity (UE) blocks are the least-performed single-shot nerve blocks in children per the PRAN database, with an overall complication rate of 2% (Anesth Analg 2012;115:1353-64). These mainly include interscalene, supraclavicular, infraclavicular, axillary, and musculocutaneous nerve blocks. Interscalene block remains one the most controversial UE blocks in pediatrics after a practice advisory from the European Society of Regional Anesthesia & Pain Therapy (ESRA) and American Society of Regional Anesthesia and Pain Medicine (ASRA) recommended avoiding this block in children under sedation due to potential neurologic complications (Curr Opin Anaesthesiol 2019;32:649-52). Later, this recommendation was changed when Taenzer et al. showed no significant difference in complications for interscalene blocks with or without sedation and/or general anesthesia (Reg Anesth Pain Med 2015;40:526-32; Reg Anesth Pain Med 2014;39:502-5).
Better visualization of anatomical structures and lack of respiratory complications make lower extremity (LE) blocks more prevalent in children (Curr Pain Headache Rep 2017;21:11). Commonly performed LE blocks include lumbar plexus, fascia iliaca, femoral, lateral femoral cutaneous, sciatic (subgluteal, popliteal fossa), adductor canal, and ankle blocks. Though earlier studies comparing the safety and efficacy of LE blocks were insufficient, PRAN review of over 2,300 blocks indicate overall safety with a complication rate of only 1% (Anesth Analg 2012;115:1353-64).
Truncal blocks are becoming an integral part of multimodal analgesic regimes for abdominal surgeries (Best Pract Res Clin Anaesthesiol 2019;33:447-63). Transversus abdominis plane, ilioinguinal/iliohypogastric, and rectus sheath blocks are the most commonly performed truncal blocks, with an overall complication rate of 0.3% (Anesth Analg 2012;115:1353-64). On the other hand, utilization of paravertebral blocks is declining due to the higher complication rate (7%) (Anesth Analg 2012;115:1353-64) and availability of novel blocks like erector spinae plane blocks (Paediatr Anaesth 2020;30:96-107).
A single-shot caudal epidural injection is the most common block performed in the pediatric population for sub-umbilical procedures (Anesth Analg 2015;120:151-6). Even though ultrasound-guided caudal blocks are gaining popularity, landmark-based caudal injections are performed more frequently (Anesth Analg 2012;115:1353-64). Data analysis of more than 6,000 single-shot caudal blocks have shown an overall complication rate of 1.9%, given the recommended dose of LA is used (Anesth Analg 2012;115:1353-64; Anesth Analg 2015;120:151-6). Although safety of single-shot spinal blockade became more prominent after the publication of the GAS study (Lancet 2016;387:239-50), clinical implementation is not common. In premature neonates and infants with risk of postoperative apnea, it is a safe and cost-effective alternative to general anesthesia, but limitations like lack of trained personnel and shorter duration of block with almost 10% failure rate are barriers for this technique (Lancet 2016;387:239-50; Anesthesiology 2015;123:38-54).
Epidural catheters can be placed in the thoracic, lumbar, and caudal regions for a controlled, longer duration of blockade. They can be placed in respective anatomical regions or advanced to the desired level using a caudal approach. According to Polaner et al., a prospective analysis of >2,900 epidural catheters demonstrated an overall complication rate of 0.7%, with a cumulative failure rate of 2%. Thoracic epidurals were associated with more catheter-related adverse events (8%) than lumbar (5%) and caudal (2%) catheters. Accidental dural puncture was present in 0.9% with a much higher incidence in lumbar followed by thoracic and caudal epidural catheters. Transient neurological complications were only found in cases with lumbar and thoracic epidural catheters (0.2%), whereas cutaneous infections were more prevalent in thoracic (0.17%) compared to caudal (0.15%) and lumbar (0.6%) epidural catheters. Although the complication rate of continuous neuraxial catheters is slightly higher than a single-shot, benefits like longer duration of block, decrease opioid requirements, and patient satisfaction should be considered to outweigh the risks (Anesth Analg 2012;115:1353-64).
“With increasing health care costs and the current opioid epidemic, PRA has an exceptional role in impacting quality and safety outcomes in this population.”
Peripheral nerve catheters
Though the safety of peripheral nerve catheters (PNCs) has been established in adult literature, studies are limited in children. Delayed diagnosis of ACS was considered as one of the contraindications of PNC in children, but recent practice advisories from ESRA/ASRA do not support the above, given that PNC is used in an appropriate clinical setting (Reg Anesth Pain Med 2018;43:211-6). Lower-extremity nerve catheters are the most commonly placed PNC in children, with an overall complication rate of 12.1%. Most of these included catheter-related complications like dislodgement, kinking or failure of block, whereas, only 0.04% resulted in serious outcomes. This was not applicable to children younger than 3 years of age due to lower representation in the cohort. Also, use of lower concertation of LA (0.1%) was recommended when indicated to prevent motor blockage and risk of falls (Anesth Analg 2012;115:1353-64; Curr Opin Anaesthesiol 2016;29:691-5).
Adjuncts for pediatric regional blocks
Clonidine is the most studied regional anesthesia adjunct in children, showing an increase in analgesia duration when used for neuraxial blockade (Pain Manag 2012;2:479-86). Dexmedetomidine appears to be similar in prolonging the blockade duration (Paediatr Anaesth 2014;24:1224-30). Although ketamine seems more potent than clonidine when used in neuraxial blocks, concerns regarding neurotoxicity in animal models has resulted in restricted use (Br J Anaesth 2011;107:601-11). Preservative-free morphine up to 50 mcg/kg can also be used safely in caudal blocks (Anesthesiology 1989;71:48-52).
While clonidine, dexmedetomidine, and dexamethasone have all been used as adjuncts in peripheral nerve blocks in children, use of dexmedetomidine is supported by the recent ASRA/ESRA guidelines (Reg Anesth Pain Med 2018;43:211-6).
Due to the paucity of data from prospective trials and lack of specialized training, many care providers shy away from PRA in perioperative settings. Databases like PRAN and ADARPEF continue to support the use of ultrasound-guided regional anesthesia in children with proven safety, improved clinical outcomes, and overall satisfaction by families. With the momentum in advocacy for multimodal analgesia, further prospective studies are warranted to enable practitioners to deliver cost-effective and quality perioperative care.