When Should Regional Anesthesia Be Used in Pediatric Patients?

Neuraxial Blocks

Evidence supporting the use of neuraxial regional anesthesia in children has been accumulating since the 1980s. ^, There has been particular interest in using regional anesthesia because it is associated with a lower incidence of postoperative apnea in ex-premature infants after surgery. Early reports demonstrated that using epidural analgesia (caudal approach) as a supplement to GA decreased the use of opioid medications in these infants. A Cochrane review analyzed evidence regarding improvement in perioperative apnea, bradycardia, and oxygen desaturation between a purely regional (spinal or epidural) anesthetic technique and GA. They did not find a statistically significant difference in the proportion of infants having postoperative apnea or bradycardia (relative risk [RR], 0.69; CI, 0.4, 1.21) or postoperative desaturation (RR, 0.91; CI, 0.61, 1.37). When infants sedated preoperatively were excluded from the analysis, the difference reached statistical significance (RR, 0.39; CI, 0.19, 0.81). In the conclusion, the authors noted that their review was based on analysis of only 108 patients and recommended that larger randomized controlled trials (RCTs) be performed to determine whether there was a difference between regional anesthesia and GA. The authors also noted the limitations of the spinal anesthesia technique, including its high failure rate (about 10%) and the limited time of surgical anesthesia (50–60 minutes).

A prospective randomized study using GA and a caudal block in former premature infants having inguinal hernia repair did not show any difference in outcomes between the use of sevoflurane and desflurane. The authors recommended a light GA with an inhalational agent and a caudal blockade for pain relief for ex-premature infants having inguinal hernia repair. Currently, no consensus exists regarding the use of regional anesthesia only (spinal or caudal), GA only, or a combined regional anesthesia and GA technique for this common procedure in a very vulnerable population.

Caudal block is the most commonly performed regional anesthetic technique in children because it is easily learned, reliable, and effective. Caudal block is adequate for all lower extremity and many lower abdominal surgeries. It is not recommended for surgeries above the T9 dermatome (umbilical cord). It is commonly performed in anesthetized children in the lateral decubitus position but can also be performed in the prone position. A short-bevel hypodermic needle of the smallest diameter (22- to 25-G needle) is typically used for this block. Specially designed caudal needles with a short bevel and a stylet are available. The sacral hiatus is palpated, and the needle is placed in the most proximal part of the sacral hiatus at a 45- to 60-degree angle to the skin. After the needle pierces the sacrococcygeal membrane, the needle is advanced a further 2 to 5 mm to ensure epidural location. Advancing the needle further may increase the risk for vascular puncture or intrathecal placement.

The French-Language Society of Pediatric Anesthesiologists (ADARPEF) study prospectively examined their experience with 24,409 regional anesthetics in the early 1990s. Caudal blocks accounted for about 60% of the procedures performed, all other peripheral blocks accounted for about 20%, and local infiltration accounted for 20%. They reported a complication rate for all blocks to be 0.9 per 1000, and all the complications were minor. A follow-up to this initial report found that, of the nearly 30,000 regional blocks, caudal blocks accounted for 34% of blocks, whereas PNBs accounted for the other 66%. This highlighted the increasing use of peripheral nerve techniques in children. Complications were again noted to be minor with a rate of 1.2 per 1000 blocks; central blocks had a higher complication rate. Fifteen patients developed cardiac toxicity from the local anesthetic, 10 had inadvertent spinal taps, and 5 developed temporary nerve injuries. In another audit of all 10,163 epidurals placed in the UK over a 1-year period, 56 complications were noted in this cohort, yielding an incidence of 1 in 189. Five of these were graded as serious (incidence of 1 in 2000), and one was persistent at 12 months (incidence of 1 in 10,000). Two patients developed an epidural abscess, one developed a postdural puncture headache requiring a blood patch, one developed meningism, and another one developed cauda equina syndrome secondary to an incorrectly administered dose (three times the intended bolus) of local anesthetic.

Eyres and colleagues were the first to measure blood levels of bupivacaine after caudal administration in children. Recent data show that blood levels are within safe limits when 1 mL/kg of 0.25% bupivacaine or 0.2% ropivacaine are used for caudal block placement. ^, Both 0.2% ropivacaine and 0.125% or 0.25% bupivacaine have been extensively used to perform the caudal block. Ropivacaine has a lower incidence of motor blockade and a safer profile compared with bupivacaine in case of accidental intravascular injection. ^, A dose of about 1 mL/kg to a maximum of 25 mL is adequate for most indications.

Bosenberg and colleagues were the first to describe successful placement of a thoracic epidural catheter via the caudal route. Subsequent studies showed this technique to be reliably successful when a styleted epidural catheter was used. The technique has a higher success rate when performed in children younger than 1 year of age. Bosenberg and colleagues also studied the pharmacokinetics of 0.2% ropivacaine infusion in neonates and infants and found that the plasma levels of ropivacaine were less than the suggested toxic level of 0.375 mg/L. Nevertheless, neonates did show a higher concentration than the infants for unbound ropivacaine levels. On the basis of their observation, the authors advocate the use of a dose of 0.2 mg/kg/hr for infants younger than 180 days old and 0.4 mg/kg/hr for infants older than 180 days ( Fig. 53.1 ). Meunier and colleagues evaluated the pharmacokinetics of bupivacaine during an epidural infusion in neonates and infants. They looked at an infusion rate of 0.375 mg/kg/hr for 48 hours and found two infants to have a blood level greater than 0.2 mg/L ( Fig. 53.2 ). On the basis of this observation, they recommended a dose of 0.3 mg/kg/hr for infants younger than 4 months of age and a dose of 0.375 mg/kg/hr for infants older than 4 months of age.

As demonstrated by the ADARPEF study, PNBs are gaining in popularity in the pediatric population, and increasing data are emerging to demonstrate feasibility, efficacy, and safety in this population. ^{, ,} The advantages of PNB include efficient, site-specific analgesia, a decrease in the need for opioids, and, consequently, a decrease in opioid-related side effects. Early reports of regional anesthesia in children used the fascial clicks (pops) technique to deposit the local anesthetic in the desired plane. This was followed by the use of peripheral nerve stimulators to elicit a motor response when the needle was in close proximity to the nerve. This technique is limited to the major motor nerves (e.g., femoral and sciatic) and was not applicable to blocks such as the ilioinguinal or penile block, which are commonly performed in children. The problem with anatomic and nerve stimulator–based approaches is that they do not provide any information regarding the relation of the nerve to the adjoining structures, information about the location of other important neurovascular structures in the region, or feedback regarding the spreading of local anesthetic in relation to the nerve. ^, The use of ultrasound to perform PNB has permitted the practitioner to have a clear visualization of the nerve and surrounding structures and provides visual confirmation of the spreading of local anesthetic relative to the nerve.

Head and Neck Blocks

Surgical correction for cleft lip and palate are common procedures typically performed before 1 year of age to facilitate feeding and speech development. Although these procedures are typically very effective from a surgical perspective, they can carry significant morbidity with postoperative pain requiring opioid therapy. Postoperative upper airway obstruction (palate repairs) and poorly controlled pain can increase the risk for bleeding, wound dehiscence, and other surgical complications. Regional anesthesia has traditionally been an attractive option for providing analgesia in this population. For cleft lip repair, an infraorbital nerve block can provide anesthesia of the upper lip, distal nose, and maxillary process. The infraorbital nerve, a branch of the maxillary nerve, itself the second terminal branch of the trigeminal nerve (V2), exits the skull through the infraorbital foramen, which serves as the primary landmark for the infraorbital nerve block. The infraorbital foramen lies about 2 mm between the nasospinale-to-jugale line and can be targeted via either an infraoral or extraoral approach. For cleft palate repair, a greater palatine nerve block is a well-described regional anesthetic technique that targets this branch of the V2 trigeminal distribution. Recently, the proximal suprazygomatic maxillary nerve block that targets the maxillary nerve at the level of the pterygopalatine fossa has been suggested as another effective alternative to the infraorbital and greater palatine blocks. ^, This block has been described by landmark technique, whereby the clinician identifies the frontozygomatic angle and directs the needle in a medial-inferior angle to enter the pterygopalatine fossa, anesthetizing the maxillary nerve as it exits the foramen rotundum. The advantages of entering the pterygopalatine fossa superiorly are a reduced likelihood of injecting into or damaging the maxillary artery, and intracranial injection, both of which are known complications of the infrazygomatic approach to the maxillary nerve. ^, Ultrasound guidance has also been described for the suprazygomatic approach, with adequate needle localization and local anesthetic deposition being easily visible in 96% and 98% of cases, respectively. In one RCT, bilateral suprazygomatic maxillary nerve block was shown to be more efficacious than more distal head and neck peripheral nerve blocks in both cleft lip and palate repairs. This technique is an up-and-coming alternative to traditional head and neck nerve blocks commonly used for cleft lip and palate repairs.

Abdominal Wall Blocks