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Inguinal Hernia Repair in a Neonate 

Inguinal Hernia Repair in a Neonate
Inguinal Hernia Repair in a Neonate
Acute Pain Medicine

Andrew D. Franklin

, and J. Matthew Kynes


Case Scenario

A 14-week-old child presents for operative repair of bilateral inguinal hernias. The infant was born at 27 weeks postconceptual age (PCA) and spent 11 weeks in the neonatal intensive care unit (NICU) after birth. The child had an episode of acute groin pain requiring manual reduction of the hernia in the emergency room last week, and the surgeon considers it is urgent to proceed with repair of the hernias to prevent bowel incarceration. Examination of the child shows a small for stated age infant who is otherwise vigorous and well appearing.

1. Patient Factors: The Premature Infant

1.1. What are the major immediate pulmonary considerations for children born prior to adequate production of pulmonary surfactant?

Pulmonary surfactant is a phospholipoprotein that decreases surface tension of alveoli. Type II pneumocytes begin to produce surfactant between 23 and 24 weeks postconceptional age (PCA). Production may be inadequate until 36 weeks PCA, and children born without adequate surfactant experience reduced lung compliance, reduced lung volumes, ventilation-perfusion mismatch, and increased shunting leading to hypoxemia. All of these conditions may be exacerbated under general anesthesia, putting these children at increased risk for intraoperative and postoperative respiratory failure. Preterm infants are often managed initially with continuous positive airway pressure (CPAP) and supplemental oxygen, but they may require tracheal intubation, mechanical ventilation, or even extracorporeal membrane oxygenation (ECMO) in severe cases. For children who are mechanically ventilated, frequent opening and collapse of alveoli without adequate end expiratory pressure can lead to worsening pulmonary status due to mechanical lung injury. Recommendations for ventilatory management of premature infants include providing low tidal volumes (4–6 mL/kg), increased respiratory rates, minimal fraction of inspired oxygen (FiO2), sufficient positive end expiratory pressure (PEEP) to prevent alveolar collapse, and permissive hypercapnia.

Surfactant therapy was introduced clinically in 1980, and its use has increased survival and decreased long-term pulmonary complications of prematurity. Prophylactic surfactant replacement is occasionally provided to infants born at less than 26 weeks PCA at high risk of respiratory distress syndrome (RDS), but more commonly it is administered as rescue therapy after failure of CPAP ventilation. Multiple surfactant preparations are commercially available, with natural sources outperforming synthetic versions in most studies. In most settings surfactant administration requires intubation and brief mechanical ventilation, but increasingly efforts are being made to transition neonates to CPAP as quickly as possible following surfactant administration. In addition to its use for RDS, investigations into other neonatal conditions, including meconium aspiration, congenital pneumonia, pulmonary hypoplasia, pulmonary hemorrhage, and with ECMO cannulation, are underway and may expand its role in neonatal management.

Further Reading

Coté CJ, Lerman H, Anderson BJ, eds. Coté and Lerman’s A Practice of Anesthesia for Infants and Children. 5th ed. Philadelphia, PA: Elsevier; 2013:733.Find this resource:

    Sweet D, Speer CP. “Surfactant replacement: resent and future.” In: Bancalari E ed., The Newborn Lung: Neonatology Questions and Controversies. 2nd ed. Philadelphia, PA: Elsevier; 2012:283–299.Find this resource:

      1.2. Differentiate bronchopulmonary dysplasia from transient tachypnea of the newborn and respiratory distress syndrome

      Transient tachypnea of the newborn (TTN) refers to a self-limited respiratory process presenting with increased respiratory rate after birth and typically lasting 2 to 5 days. TTN may be related to decreased lung compliance from delayed lung fluid resorption and is associated with prematurity, maternal sedation, maternal asthma, and delivery by cesarean section. Respiratory distress syndrome is a pulmonary developmental disorder that is associated with preterm birth and increases in incidence and severity with prematurity, occurring in 50% of infants born between 26 and 28 weeks PCA and 20% to 30% of infants born at 30 to 31 weeks PCA. It presents at birth with increased respiratory effort and hypoxia that may resolve quickly or progress to requiring surfactant therapy, CPAP, and/or prolonged ventilatory support. Bronchopulmonary dysplasia (BPD) is a clinical diagnosis that refers to infants born at less than 32 weeks PCA whose lung disease becomes chronic, requiring supplemental oxygen treatment for at least 28 days by 36 weeks postmenstrual age or time of discharge home. In addition to prematurity and surfactant deficiency, factors that are associated with BPD include barotrauma, oxygen toxicity, inflammation, infection, nutritional status, and genetic predisposition.

      Further Reading

      MacDonald MG, Seshia MMK, Mullett MD, eds. Avery’s Neonatology: Pathophysiology and Management of the Newborn. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2015:560.Find this resource:

        Ehrenkranz RA, Walsh MC, Vohr BR, et al. Validation of the National Institutes of Health consensus definition of bronchopulmonary dysplasia. Pediatrics. 2005;116:1353–1360.Find this resource:

        1.3. Discuss the ontogeny of pain in the developing fetus

        Neurologic development of the fetus begins with early stages of brain and spinal cord formation at 3 weeks gestation followed by neural crest cell migration and neural proliferation. Spinal cord formation is complete by the beginning of the second trimester, with maximal neuronal development occurring between 8 and 18 weeks PCA. Sensory receptors begin development at 7 weeks gestation and are present throughout the skin and mucosa by 20 weeks PCA with active synaptogenesis occurring in this period. Stimulation in animals and humans in this stage produces withdrawal reflexes, hormonal stress responses (catecholamines, steroid hormones, glucagon, growth hormone), and autonomic arousal consistent with pain response at later stages of development. However, the ability to perceive painful stimuli by nociceptive pathways requires transmission of pain sensation to the cortex. The first projections from the thalamus to the cortex appear at 12 to 16 weeks gestation and do not undergo complete dendritic arborization and thalamocortical synaptogenesis until 23 weeks. Peripheral nerves undergo full maturation into the spinal cord from 23 to 25 weeks gestation, creating an intact circuit from peripheral sensation to spinothalamic transmission and cortical activation by around 26 weeks. Indeed, cortical pain response as measured by increased blood flow by near-infrared spectroscopy after heelstick has been found in neonates at 25 weeks gestation. Although the neuroanatomic system for pain perception is in place by this stage of fetal development, considerable debate and limited information exist regarding the timing of the development of a subjective and conscious pain experience in the neonate.

        Further Reading

        Coté CJ, Lerman H, Anderson BJ, eds. Coté and Lerman’s A Practice of Anesthesia for Infants and Children. 5th ed. Philadelphia, PA: Elsevier; 2013:771.Find this resource:

          Derbyshire SWG. Can fetuses feel pain? BMJ, 2006;332(7546):909–912.Find this resource:

          Slater R, et al. Cortical pain responses in human infants. J Neurosci. 2006;26(14):3663–3666.Find this resource:

          1.4. At what gestational age is it appropriate to provide analgesia to the premature neonate for painful procedures?

          Critically ill preterm neonates may experience hundreds of painful procedures during their hospitalization, and specific analgesic measures are used in less than 50% of these procedures. Assessment of pain in neonates is challenging, but multimodal tools incorporating facial expressions, physiologic measurements, and behavior (crying and consolability) have been developed (e.g., Neonatal Facial Coding System, Premature Infant Pain Profile, Neonatal Pain and Sedation Scale). Premature neonates display a lower threshold for responses to noxious stimuli compared with older infants as well as evidence of central sensitization with repeated stimuli. Given the hormonal stress response and autonomic arousal that accompany noxious stimuli as early as 20 weeks PCA and evidence that peripheral stimuli trigger cortical responses by 26 weeks PCA, efforts to reduce or relieve pain perception for neonates at any viable age are warranted. This is particularly true for neonates undergoing moderate to severely painful procedures such as circumcision, chest drain insertion and removal, and nonemergent intubations. Short-term consequences of inadequate analgesia include physiologic instability, apnea, hypoxia, and increased cortisol secretion. Central pain sensitization from noxious stimuli occurs quickly in neonates due to immaturity of descending neuroinhibitory feedback systems, which causes increased excitability of nociceptive neurons in the dorsal horn of the spinal cord and exaggerated stress responses with subsequent stimuli. In animal models there is evidence that painful stimulation at certain stages of development can produce permanent changes in basal and stress-induced hormone responses, which can last into adulthood through a process of physiologic programming. Analgesic strategies may include nonpharmacologic methods of pain control, including facilitated tucking (a soothing technique where an infant’s arms and legs are held in a flexed position), non-nutritive sucking, breastfeeding, or skin-to-skin care. Pharmacologic management of neonatal pain includes oral sucrose solutions, which can provide 4 to 5 minutes of reduction in pain scores during a mild to moderately painful procedure. Fentanyl and morphine are the most common medications used for analgesia in neonates, although infusions may carry risks for neurodevelopmental alteration and other adverse effects that outweigh benefits of pain control when used for prolonged sedation during mechanical ventilation. Topical anesthetic agents may also be used to reduce pain response to procedures in neonates.

          Further Reading

          AAP Committee on Fetus and Newborn and Section on Anesthesiology and Pain Medicine. Prevention and management of procedural pain in the neonate: an update. Pediatrics. 2016. 137(2):e20154271.Find this resource:

          Coté CJ, Lerman H, Anderson BJ, eds. Coté and Lerman’s A Practice of Anesthesia for Infants and Children. 5th ed. Philadelphia, PA: Elsevier; 2013:909.Find this resource:

            1.5. What is neonatal abstinence syndrome, and how does opioid withdrawal present in neonates?

            In neonates who have been treated with opioids for more than 7 to 10 days, physiologic tolerance develops, and increasing doses are required to provide equivalent analgesia or sedation. Rapid opioid weaning may induce withdrawal symptoms in infants, characterized by metabolic and respiratory manifestations (fever, diaphoresis, tachypnea), gastrointestinal manifestations (vomiting, loose stools, weight loss, poor feeding), and neurologic manifestations (tremors, sleep disturbance, seizures). Gradual opioid de-escalation may be facilitated by methadone, which has a longer half-life and shorter duration of weaning than morphine. Clonidine may be added for control of centrally mediated sympathetic symptoms of withdrawal. Neonatal abstinence syndrome (NAS) results when opioid-related complications occur from prenatal maternal opioid ingestion. The incidence of NAS increased fivefold from 2000 to 2012. Symptoms of opioid withdrawal usually occur within the first 24 to 48 hours after birth and do not fully resolve until 8 to 16 weeks of age. Up to 80% of infants with NAS require pharmacologic therapy, with an average hospitalization of 17 days. Standardized protocols for long-term opioid weaning often include nonpharmacologic measures (swaddling, soothing, feeding), frequent scoring for withdrawal symptoms, and gradual dose reduction. Withdrawal Assessment Tool-1 (WAT-1), a symptom assessment scale, has been validated in pediatric patients requiring opioid withdrawal in both intensive care and general ward settings. Neonates presenting for surgery with NAS or opioid tolerance will require careful titration of analgesics to attain adequate pain control in the perioperative period, and regional anesthesia options should be considered.

            Further Reading

            Franck LS, Scoppettuolo LA, Wypij D, Curley MA. Validity and generalizability of the Withdrawal Assessment Tool-1 (WAT-1) for monitoring iatrogenic withdrawal syndrome in pediatric patients. Pain. 2012 Jan;153(1):142–148.Find this resource:

            MacDonald MG, Seshia MMK, Mullett MD, eds. Avery’s Neonatology: Pathophysiology and Management of the Newborn. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2015:1577.Find this resource:

              McQueen K, Murphy-Oikonen J. Neonatal abstinence syndrome. N Engl J Med. 2016;375:2468–2479.Find this resource:

              1.6. What are the unique aspects of opioid therapy and toxicity for neonates?

              Opioids are commonly employed for painful procedures and sedation in neonates as they promote hemodynamic stability and have limited effect on myocardial function. Opioid analgesics also preserve hypoxic pulmonary vasoconstriction and control of pulmonary vascular hypertension with painful stimuli. Due to immature hepatic clearance systems, elimination half-lives for several opioids may be up to 4 times longer in neonates than in older children. Morphine clearance is particularly impaired in preterm infants. These pharmacodynamic differences, combined with a less developed blood-brain barrier and altered ventilatory response to hypoxemia and hypercapnia compared with older children, contribute to an increased risk of respiratory depression in neonates when opioids are administered. Neonates can develop rapid tolerance to opioids as demonstrated by decreased cardiovascular and sedative effect or dependence with withdrawal symptoms after therapeutic opioid administration for as little as 5 days. In the long term, there are some indications that increased morphine exposure in neonates may lead to worse neurodevelopmental outcomes, including impaired short-term memory, social problems, decreased cerebellar volume, and internalizing behavior later in childhood.

              Further Reading

              Borenstein-Levin L, et al. Narcotics and sedative use in preterm neonates. J Pediatr. 2017;180:92–98.Find this resource:

              MacDonald MG, Seshia MMK, Mullett MD, eds. Avery’s Neonatology: Pathophysiology and Management of the Newborn. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2015:1561.Find this resource:

                1.7. What are the unique aspects of local anesthetic therapy and toxicity for neonates?

                The risk of local anesthetic (LA) toxicity in neonates is elevated for several reasons. Neonates have a reduced concentration of alpha-1-acid glycoprotein (AAG) compared with older children and adults, starting around one-third of adult levels at birth and normalizing around 1 year of age. AAG, red blood cells, and albumin all play a role in binding local anesthetics, and overall serum free fraction levels of LAs are higher in neonates than in adults. In addition, amide LA metabolism by the liver is reduced in neonates due to immature development of the cytochrome P450 system. Neonates under 1 month of age have a bupivacaine clearance rate that is one-third that of adults, and bupivacaine accumulation to toxic doses after 48 hours of infusion has been found even at recommended doses of <0.2 mg/kg/h. Ropivacaine has an improved safety profile compared with bupivacaine but also displays age-dependent clearance. Because of these risks, bolus and infusion doses of LA should be reduced in neonates by at least 30% to avoid accumulation and excessive serum concentration leading to systemic toxicity. Ester local anesthetics, like 2-chloroprocaine, are rapidly metabolized by plasma cholinesterases even in premature neonates and may be considered as an alternative to amide local anesthetics.

                When local anesthetic systemic toxicity (LAST) does occur, preverbal neonates are unable to express early signs and symptoms of altered mental status and neural disturbance and are therefore more likely to present with arrhythmia, respiratory arrest, or seizures. Due to the enhanced sodium channel blocking effect of local anesthetics on nerves discharging at increased frequency, cardiac sensitivity to local anesthetic toxicity is also elevated in neonates given their higher resting heart rate. As in adults, neonates exhibiting neurologic and cardiovascular manifestations of LAST should receive supportive care and lipid emulsion administration as quickly as possible. Though lipid emulsion has a wide margin of safety when used to reverse LAST, recommendations and guidelines regarding lipid emulsion therapy in neonates have not been published.

                Further Reading

                Gregory GA, Andropoulos DB, eds. Gregory’s Pediatric Anesthesia. 5th ed. Chicester, West Sussex: Wiley-Blackwell; 2012: 419.Find this resource:

                  Mazoit JX, Dalens BJ. Pharmacokinetics of local anesthetics in infants and children. Clin Pharmacokinet. 2004;42(1):17–32.Find this resource:

                  Veneziano G, Tobias JD. Chloroprocaine for epidural anesthesia in infants and children. Paediatr Anaesth. 2017 [epub ahead of print].Find this resource:

                  1.8. Discuss the long-term manifestations of inadequately treated pain in the neonate

                  Animal data demonstrate that undertreated pain in the neonatal stage can lead to altered nociception at older ages with synaptic modulation of sensory pathways. In humans, clinical studies have shown that neonates who experience painful stimuli may have increased pain sensitivity at older ages, presumably related to increased excitability of dorsal horn nociceptive neurons to noxious and nonnoxious stimuli. In one study, infants circumcised with little or no analgesia displayed increased pain behavior during later immunizations compared with uncircumcised patients or those who received adequate analgesia for their circumcision. In other studies, low birth weight infants who were exposed to painful stimuli as neonates displayed differences in pain perception, with increased pain intensity at age 8 to 10 years compared with those who were not. In addition to pain perception, development and behavior may be affected by inadequately treated neonatal pain. Regardless of illness severity, poor cognition and motor function are associated with a greater number of painful neonatal procedures for very preterm infants. In addition, preterm infants who experience more painful stimuli in the neonatal period display less cortical thickness at age 7 as compared with preterm infants who did not. Given these findings, several pediatric societies have issued guidelines regarding pain control in this population.

                  Further Reading

                  AAP Committee on Fetus and Newborn and Section on Anesthesiology and Pain Medicine. Prevention and management of procedural pain in the neonate: an update. Pediatrics. 2016;137(2):e20154271.Find this resource:

                  Borenstein-Levin L, et al. Narcotics and sedative use in preterm neonates. J Pediatr. 2017;180:92–98.Find this resource:

                  Gregory GA, Andropoulos DB, eds. Gregory’s Pediatric Anesthesia. 5th ed. Chicester, West Sussex: Wiley-Blackwell; 2012:846.Find this resource:

                    2. Preoperative Evaluation and Preparation

                    2.1. What are the unique implications of ambulatory surgery for ex-premature infants?

                    There are several aspects the anesthesiologist must take into consideration before confirming that an ex-premature infant is appropriate for ambulatory surgery. The risk of postoperative apnea must be weighed against the benefits of ambulatory surgery in this population. Children who were born prematurely commonly experience periods of obstructive, central, and mixed apneas postoperatively. Most postoperative apneic episodes are typically managed well in the hospital with vigilant nursing, apnea monitoring, and gentle stimulation with occasional need for brief bag-mask ventilation. However, these episodes may lead to an acute life-threatening event if the child is discharged home. The risk of having postoperative apneic events is directly related to the child’s PCA, history of prior apneic events, and anemia. The risk of postoperative apnea falls to less than 1% (95% statistical confidence) when the ex-premature child reaches 56 weeks; therefore, many centers employ policies that permit ambulatory surgery for children between 56 and 60 weeks PCA. Infants younger than this age should be admitted for overnight observation and apnea monitoring. However, this suggestion is for infants without significant cardiopulmonary manifestations, anemia, or congenital syndromes. Children with additional comorbid conditions may warrant overnight apnea monitoring even if they are older than 60 weeks PCA. The appropriate timing and postsurgical disposition of such children should be discussed between the surgeon and anesthesiologist in the preoperative planning phase.

                    2.2. What specific information would you need regarding the child’s neonatal intensive care unit course?

                    Infants born preterm typically spend their first few days to first few months in the neonatal intensive care unit (NICU) based on the degree of prematurity and the associated sequelae as well as manifestations of superimposed congenital disorders. The anesthesiologist’s review of the NICU course should include each organ system, with particular emphasis placed on the cardiac and pulmonary systems. Periods of endotracheal intubation in the NICU and presence of anatomic abnormalities such as laryngomalacia, tracheomalacia, and subglottic stenosis may affect airway management and increase risk of postoperative stridor. Bronchopulmonary dysplasia is a complex entity of the premature child that is caused by extended periods on mechanical ventilation and oxygen free radical injury and may lead to the need for postoperative oxygen supplementation or CPAP, which would preclude discharge home. Pulmonary hypertension may result from a patent ductus arteriosus or severe pulmonary disease.

                    2.3. What are the regional anesthetic options for this patient? Which technique is superior?

                    For inguinal hernia repairs, the regional anesthetic options include neuraxial blockade or peripheral blockade. Neuraxial options include single-injection subarachnoid (spinal) or caudal blockade and, less commonly, lumbar epidural single injection or lumbar epidural catheters advanced from the caudal epidural space. Paravertebral, transverse abdominal plane (TAP), and ilioinguinal/iliohypogastric nerve blocks are options for peripheral blockade.

                    Caudal or spinal blocks provide similar surgical conditions; however, caudal blocks may be technically easier to place and have higher success rates. Though paravertebral nerve blocks are feasible for inguinal hernia surgery and may possibly reduce risk of nausea or urinary retention, these blocks may be more difficult to perform and require significantly more time to place. Ilioinguinal/iliohypogastric nerve blocks provide more effective analgesia than TAP blocks but have not clearly shown superiority over caudal blocks and carry the disadvantage of needing 2 injections if bilateral surgery is planned. However, the ilioinguinal/iliohypogastric nerve block technique is easily facilitated with ultrasound guidance, and less local anesthetic may be used as compared with a caudal block. Lack of clear superiority of one regional anesthetic technique over another suggests that level of comfort with the various techniques and availability of appropriate equipment should be the major considerations when choosing a regional anesthetic technique for pediatric inguinal hernia surgery.

                    Further Reading

                    Hoelzle M, Weiss M, Dillier C, Gerber A. Comparison of awake spinal with awake caudal anesthesia in preterm and ex-preterm infants for herniotomy. Paediatr Anaesth. 2010 Jul;20(7):620–624.Find this resource:

                    Law LS, Tan M, Bai Y, Miller TE, Li YJ, Gan TJ. Paravertebral block for inguinal herniorrhaphy: a systematic review and meta-analysis of randomized controlled trials. Anesth Analg. 2015 Aug;121(2):556–569.Find this resource:

                    Shanthanna H, Singh B, Guyatt G. A systematic review and meta-analysis of caudal block as compared to noncaudal regional techniques for inguinal surgeries in children. Biomed Res Int. 2014;2014:890626.Find this resource:

                    2.4. Describe the medical evidence surrounding the use of regional anesthesia to mitigate postoperative apnea for infants undergoing inguinal hernia surgery

                    A few studies have specifically studied the impact of regional anesthesia on postoperative apnea in infants undergoing inguinal hernia surgery. If general anesthesia is considered directly related to the development of postoperative apnea in this population, regional anesthesia may theoretically mitigate these risks. Two major studies have studied this topic, the General Anesthesia Compared to Spinal (GAS) study and the Cochrane Review.

                    The GAS study was a multinational randomized trial that enrolled more 700 children undergoing inguinal hernia surgery at less than 60 weeks postmenstrual age (PMA). Half of the enrolled patients were born preterm, defined as less than 37 weeks PMA. Both term and preterm infants were randomized to receive either a regional anesthetic (spinal, spinal with caudal, spinal with ilioinguinal nerve block, or caudal) or a general anesthetic (GA) with sevoflurane. Infants in the regional anesthetic (RA) arm received no sedatives, hypnotics, or opioids at any point in the perioperative period. The results of this study showed no statistically significant difference in postoperative apnea between the regional anesthetic and general anesthetic groups in the first 12 postoperative hours after inguinal hernia surgery, with both groups exhibiting an apnea risk of 3% to 4%. The researchers split the groups into early apnea (0–30 minutes after surgery) and late apnea (30 minutes to 12 hours). Late apnea was equal in both RA and GA groups (2%), but there was a statistically significant reduction in early apnea in the RA group (1%) compared with the GA group (3%). However, the clinical significance of reduction in early apnea is questionable as infants are typically highly monitored in the postanesthesia care unit during the first 30 minutes or more after surgery.

                    Like the GAS study, the goal of the Cochrane Review was to determine whether pure regional anesthesia techniques led to less postoperative apnea than GA for infants undergoing inguinal hernia surgery. Unlike the GAS study, the Cochrane Review evaluated only preterm children (born at less than 37 weeks gestational age). This meta-analysis, though perhaps inadequately powered, did suggest that regional anesthesia without additional sedative agents may reduce the incidence of postoperative apnea by up to 47% in former preterm children undergoing inguinal hernia surgery in early infancy.

                    These contradictory studies fail to provide a definitive answer on the debate. Well-aligned perioperative teams that have been well educated on the benefits and challenges of a pure regional anesthetic technique in the operating room may perhaps confer mild reductions in postoperative apnea to preterm infants undergoing inguinal hernia surgery, but the clinical impact of this apnea reduction on the overall outcome of the child has not been well elucidated.

                    Further Reading

                    Davidson AJ, Morton NS, Arnup SJ, de Graaff JC, Disma N, Withington DE, Frawley G, Hunt RW, Hardy P, Khotcholava M, von Ungern Sternberg BS, Wilton N, Tuo P, Salvo I, Ormond G, Stargatt R, Locatelli BG, McCann ME; General Anesthesia Compared to Spinal Anesthesia (GAS) Consortium. Apnea after awake regional and general anesthesia in infants: the General Anesthesia Compared to Spinal Anesthesia Study—comparing apnea and neurodevelopmental outcomes, a randomized controlled trial. Anesthesiology. 2015 Jul;123(1):38–54.Find this resource:

                    Jones LJ, Craven PD, Lakkundi A, Foster JP, Badawi N. Regional (spinal, epidural, caudal) versus general anaesthesia in preterm infants undergoing inguinal herniorrhaphy in early infancy. Cochrane Database Syst Rev. 2015 Jun 9;6:CD003669.Find this resource:

                      3. Intraoperative Management

                      3.1. During the preoperative interview, the anesthesiologist discusses placing a caudal block after induction of anesthesia. The child’s mother refuses to provide consent for the regional anesthetic technique, reporting that placement of an epidural catheter for her during labor was a very unpleasant experience. How might the anesthesiologist approach this?

                      Hesitation to provide informed consent to regional anesthesia by the parent/guardian is typically a result of misinformation about the procedure or a history of an adverse event in either the parent/guardian or other family member. The majority of these misunderstandings are easily cleared up by effective preoperative discussion with the anesthesiologist. In addition, in light of ongoing research focused on the possible long-terms effects of anesthetics in children under 3 years of age, a discussion of regional anesthesia replacing the need for general anesthesia is appropriate in this scenario. The anesthesiologist should focus on the safety of the regional anesthetic technique, explain the reasons for performing the procedure, and explain the experience he or she has had with the technique. Multiple reports provided by the Pediatric Regional Anesthesia Network (PRAN) underscore the overall safety of multiple regional anesthesia techniques, and these data may be discussed with parents during the preoperative interview. The PRAN has reported a complication risk of 1.9% for caudal blocks, after reviewing more than 18,000 patients within the PRAN database who received caudal anesthesia. Risk of complication from a caudal block is inversely related to the child’s age, and the most common reported complications were failure to achieve adequate blockade and aspiration of blood during placement. Importantly, no temporary or permanent neurologic sequelae were noted in the large group of studied patients. Most parents/guardians are sympathetic to the notion that regional anesthetics may assist with opioid reduction, earlier extubation, and fewer opioid-related side effects. Requirement for written informed consent for pediatric regional anesthesia varies across hospital systems and associated pediatric pain services. Written consent for anesthesia is occasionally obtained outside of implied anesthesia consent with the surgical consent; local policies should be followed regarding regional anesthetic techniques.

                      Further Reading

                      Andropoulos DB, Greene MF. Anesthesia and developing brains: implications of the FDA warning. N Engl J Med. 2017 Mar 9;376(10):905–907.Find this resource:

                      Lönnqvist PA, Morton NS, Ross AK. Consent issues and pediatric regional anesthesia. Paediatr Anaesth. 2009 Oct;19(10):958–960.Find this resource:

                      Suresh S, Long J, Birmingham PK, De Oliveira GS Jr. Are caudal blocks for pain control safe in children? An analysis of 18,650 caudal blocks from the Pediatric Regional Anesthesia Network (PRAN) database. Anesth Analg. 2015 Jan;120(1):151–156.Find this resource:

                      3.2. What are the absolute and relative contraindications for pediatric regional anesthesia?

                      The primary absolute contraindication for pediatric regional anesthesia is parental refusal of the technique. Obtaining assent should be considered, and risks/benefits should be discussed with the older adolescent during the preoperative interview as well. Other contraindications are similar to contraindications for regional anesthesia in adults, with few unique aspects in children. Overlying skin infection at the site, underlying coagulopathy, and anatomic abnormalities such as lumbosacral myelomeningocele are absolute contraindications. Indwelling continuous catheters should be avoided in the presence of significant systemic infection. Relative contraindications vary significantly, and the benefit of the procedure should be weighed carefully around the potential risk for each unique patient situation. These include progressive neurologic disease, risk of compartment syndrome, and volume depletion prior to neuraxial blocks. Caudal blocks in children with ventriculoperitoneal (VP) shunts are commonly performed, but strict adherence to sterile technique is indicated to reduce risk of shunt infection, and temporary increases in intracranial pressure due to the large volume (0.5–1 mL/kg) typically injected into the epidural space during this procedure must be taken into consideration. Routine administration of antibiotic prophylaxis prior to caudal blocks in children with VP shunts is a controversial topic, with limited medical evidence to either support or refute this practice.

                      Further Reading

                      Ecoffey C. Safety in pediatric regional anesthesia. Paediatr Anaesth. 2012 Jan;22(1):25–30.Find this resource:

                      Platis CM, Kachko L, Livni G, Efrat R, Katz J. Caudal anesthesia in children with shunt devices. Paediatr Anaesth. 2006 Nov;16(11):1198–1199.Find this resource:

                      Veyckemans F, Scholtes JL. Caudal block and ventricular shunt devices: beware of the consequences of increasing epidural pressure! Paediatr Anaesth. 2007 Jul;17(7):707–709.Find this resource:

                      3.3. If regional anesthesia if not possible, what perioperative analgesic strategy would you employ?

                      If regional anesthesia cannot be employed due to inability to obtain parental informed consent or due to the presence of a contraindication, an opioid-sparing perioperative analgesic regimen should be employed. These regimens reduce opioid-related side effects, particularly respiratory depression, giving the neonate the best chance of early extubation and reducing the risk of postoperative reintubation. Local anesthetic infiltration during surgical closure of the incision by the surgeon is an effective way to provide a short period of analgesia to the child and reduce overall need for postoperative opioids. Indeed, a few studies have shown equivalency of local field block to caudal block for unilateral pediatric inguinal hernia repair, and field blocks certainly require less expertise to place, utilize less total local anesthetic, and have less impact on operating room time. Oral acetaminophen (20 mg/kg load) may be given preoperatively to children, often along with oral benzodiazepine premedication if planned, or administered rectally (40 mg/kg load) after induction of anesthesia. Though the medical evidence regarding the efficacy of enteral acetaminophen is mixed, the bulk of evidence suggests that acetaminophen may play a small role in opioid reduction, particularly if paired with a nonsteroidal anti-inflammatory drug (NSAID). Intravenous (IV) acetaminophen has gained popularity due to ease of use in the perioperative period and lack of first-pass metabolism, but routine use has been tempered by the relatively high cost of the agent currently, and superiority over enteral preparations has not been established. However, if addition of IV acetaminophen leads to fewer opioid-related side effects and earlier discharge from the hospital, aggregate costs may actually be reduced. NSAIDs consistently show greater efficacy than acetaminophen in providing postoperative analgesia, with ketorolac being the most commonly prescribed IV NSAID in the perioperative period. There is considerable controversy regarding ketorolac’s role in both renal dysfunction and postoperative bleeding in infants, with inconclusive data in the medical literature. Conservative management consists of restricting the use of ketorolac to children greater than 1 year of age provided there are no coagulation or renal abnormalities.

                      Further Reading

                      Baird R, Guilbault MP, Tessier R, Ansermino JM. A systematic review and meta-analysis of caudal blockade versus alternative analgesic strategies for pediatric inguinal hernia repair. J Pediatr Surg. 2013 May;48(5):1077–1085.Find this resource:

                      Hong JY, Won Han S, Kim WO, Kil HK. Fentanyl sparing effects of combined ketorolac and acetaminophen for outpatient inguinal hernia repair in children. J Urol. 2010 Apr;183(4):1551–1555.Find this resource:

                      3.4. You plan to perform a caudal block to provide analgesia, but a sacral dimple is noted when the child is turned to the lateral position. Do you proceed with a caudal block?

                      Sacral dimples noticed during placement of a caudal injection in an infant may point toward a diagnosis of an occult spinal dysraphism. Though the majority of dimples in otherwise healthy children without an associated syndrome do not extend into the spinal canal, tethered spinal cord lesions are occasionally associated with midline soft tissue defects. If a caudal block is planned, the anesthesiologist should include an examination of the sacrococcygeal area preoperatively to evaluate for overlying skin infection or presence of midline spine lesions such as hairy patches, pits, soft tissue masses (subcutaneous lipomas), hemangiomas, drainage, or skin tags. A single midline dimple less than 5 mm in diameter, less than 2.5 cm from the anus without the above additional cutaneous findings is considered a simple sacral dimple. If a lesion is noted on preoperative examination or during placement of the caudal, the anesthesiologist should consult the medical record to see if a spinal ultrasound has been performed. In a study of nearly 4000 children with simple sacral dimples undergoing sonographic evaluation, 3.4% were found to have an abnormal finding, and only 0.13% were found to have a tethered cord requiring neurosurgical intervention. If an ultrasound has not been performed, the anesthesiologist, neonatologist, and surgeon may discuss the risks and benefits of placing the caudal block. The conservative choice is to avoid the caudal block if no spinal ultrasound has been performed, particularly if significant skin stigmata are noticed.

                      Further Reading

                      Gibson PJ, Britton J, Hall DM, Hill CR. Lumbosacral skin markers and identification of occult spinal dysraphism in neonates. Acta Paediatr. 1995 Feb;84(2):208–209.Find this resource:

                      Kucera JN, Coley I, O’Hara S, Kosnik EJ, Coley BD. The simple sacral dimple: diagnostic yield of ultrasound in neonates. Pediatr Radiol. 2015 Feb;45(2):211–216.Find this resource:

                      3.5. Discuss the unique aspects of placing a spinal block in an awake child with the goal of reducing or avoiding sedatives

                      Though the long-term manifestations of general anesthesia on the developing brain remain unclear and it is unclear if regional anesthesia can mitigate or eliminate these risks, there is concern about the routine use of general anesthesia in young children, and some anesthesiologists advocate for a pure regional anesthetic technique in this population. Placing a regional block on an awake infant and then providing no sedatives during the operation may come as a culture shock to many surgeons, nurses, and scrub technicians who are accustomed to general anesthetics for most surgical procedures in children. The anesthesiologist must take into account the viewpoints of various stakeholders on the perioperative team before planning an awake, pure regional technique in infants. Optimally, this concept is planned well in advance with the surgeon, nursing leadership, and other members of the perioperative team.

                      Infants may require a higher weight-based dose of local anesthetic than adults to achieve adequate spinal blockade but are more prone to the development of local anesthetic toxicity. The larger dosage requirement is due to larger relative volumes of cerebrospinal fluid (CSF) (4 mL/kg in infants versus 2 mL/kg in adults) and faster redistribution away from the spinal cord due to proportionally greater blood flow to vessel-rich tissue beds. Spinal blocks in infants are typically performed at the L4-L5 or L5-S1 interspace, and the anesthesiologist must remember that the spinal cord terminates at L3 in this population. A standard 25-gauge Quincke or Whitacre needle is adequate, taking care to not place the larger introducer needle (if used) through the dura. Some anesthesiologists prefer to apply eutectic preparations of lidocaine and prilocaine to the site of spinal puncture 30 minutes prior to the procedure to avoid the need for subcutaneous infiltration. There are reports of placing the IV line in the lower extremity of the infant after placement of the spinal block to avoid painful venous cannulation. Placing the blood pressure cuff on the lower extremity after spinal placement can further reduce the child’s discomfort during the procedure.

                      The benefits of a spinal block over general anesthesia are likely minimal if sedatives such as midazolam, nitrous oxide, or ketamine are used to produce a sedate child after the spinal block. Bundling the child, providing a pacifier, placing sucrose water periodically to the mouth, avoiding loud noises in the operating room, and reassuring the surgeon when the child makes minor movements of his or her upper extremities during the procedure are important facets of providing awake spinal blockade to an infant.

                      Further Reading

                      Lederhaas G. Spinal anaesthesia in paediatrics. Best Pract Res Clin Anaesthesiol. 2003 Sep;17(3):365–376.Find this resource:

                      Tobias JD. Spinal anaesthesia in infants and children. Paediatr Anaesth. 2000;10(1):5–16.Find this resource:

                      3.6. What are the local anesthetic options for a caudal block or a spinal block?

                      For single caudal epidural injections, a volume of 1 mL/kg of local anesthetic volume is sufficient to consistently attain a T10 blockade with a maximum volume of 20 mL. It is prudent to use the least amount of local anesthetic required to appropriately provide analgesia over the surgical incisions. If surgery is confined to only the penile or anal areas (sacral dermatomes), less local anesthetic volume is required (0.5–0.75 mL/kg provides blockade to L1), which significantly reduces the risk of local anesthetic toxicity. Ropivacaine 0.2%, bupivacaine 0.25%, or bupivacaine 0.125% are common agents and concentrations used for single-injection caudal blockade and will provide analgesia for about 4 to 6 hours. Chloroprocaine is a short-acting ester local anesthetic that has gained popularity due to its extremely short plasma half-life and negligible risk of local anesthetic toxicity. Given that a 20 mg/kg bolus dose of chloroprocaine confers only 1 hour of blockade, a continuous infusion of chloroprocaine is necessary to maintain intraoperative analgesia for prolonged surgical procedures or to provide postoperative analgesia for any reasonable length of time.

                      For spinal blocks, hyperbaric tetracaine 0.5% (0.4–0.6 mg/kg), hyperbaric bupivacaine 0.75% (0.3–0.6 mg/kg), or isobaric bupivacaine 0.5% (0.3–0.6 mg/kg) consistently provides 60 to 80 minutes of surgical anesthesia, with the addition of epinephrine (20–50 mcg) providing another 20 minutes. Surgical blockade with a spinal is typically limited to 90 minutes, and so the operative team must be prepared to prep, drape, and proceed with surgery in rapid fashion after spinal placement. It is advisable to have the surgeon present, scrubbed, and ready to operate, with the anesthesiologist reminding the surgeon of the time constraint, particularly if surgical trainees are present for the procedure.

                      Further Reading

                      Jöhr M. Practical pediatric regional anesthesia. Curr Opin Anaesthesiol. 2013 Jun;26(3):327–332.Find this resource:

                        Lederhaas G. Spinal anaesthesia in paediatrics. Best Pract Res Clin Anaesthesiol. 2003 Sep;17(3):365–376.Find this resource:

                        Tobias JD. Spinal anaesthesia in infants and children. Paediatr Anaesth. 2000;10(1):5–16.Find this resource:

                        Veneziano G, Iliev P, Tripi J, Martin D, Aldrink J, Bhalla T, Tobias J. Continuous chloroprocaine infusion for thoracic and caudal epidurals as a postoperative analgesia modality in neonates, infants, and children. Paediatr Anaesth. 2016 Jan;26(1):84–91.Find this resource:

                        3.7. Discuss the utility of using epinephrine in pediatric regional blocks, particularly caudal blocks

                        Negative aspiration of blood during placement of regional anesthetic blocks does not reliably eliminate the possibility of intravascular uptake. Test doses of local anesthetic are still frequently given in both adult and pediatric patients. Epinephrine within “test doses” can potentially cause tachycardia, hypertension, or T-wave changes on the electrocardiogram, alarming the anesthesiologist of the possibility of intravascular injection. An appropriate test dose method should involve injecting 0.1 mL/kg of local anesthetic solution containing 1:200,000 epinephrine and monitoring for heart rate, blood pressure, or electrocardiogram changes for 60 to 90 seconds. A 10-20-25 rule may be followed, with a positive test dose signifying intravascular injection increasing the heart rate by 10 beats per minute, increasing the systolic blood pressure by 20 mmHg, and/or altering the T-wave morphology by 25%. Electrocardiogram changes, specifically T-wave or ST segment changes, tend to be the most sensitive markers of intravascular injection. Caudal blocks are inherently high-risk blocks given the relatively large volumes needed to provide adequate analgesia, the common use in infants/neonates, and the relative vascularity of the sacral epidural space.

                        In addition to serving as an early warning sign for intravascular uptake, epinephrine is often thought to promote vasoconstriction, thereby slowing the redistribution of local anesthetic and prolonging blockade. This effect is likely minimal in the infant and becomes even more diminished in older children.

                        Further Reading

                        Tobias JD. Caudal epidural block: a review of test dosing and recognition of systemic injection in children. Anesth Analg. 2001 Nov;93(5):1156–1161.Find this resource:

                        3.8. What are appropriate opioid adjuncts that may be placed for caudal or spinal blocks? What are the associated implications for ambulatory anesthesia?

                        The most commonly utilized opioid adjuncts used in single-shot caudal blocks or spinal blocks are fentanyl, hydromorphone, and morphine.

                        Fentanyl is a lipophilic opioid that is a common adjuvant added to local anesthetic for single-shot caudal blocks. Two studies have noted that fentanyl 1 mcg/kg added to either ropivacaine 0.2% or bupivacaine 0.25% for caudal blocks resulted in no prolonged duration of blockade, reduction in time to first postoperative analgesic, or postoperative pain scores. One study comparing caudal fentanyl to caudal clonidine added to 0.25% bupivacaine noted a marginal increase in length of blockade, but also a significant increase in the incidence of postoperative vomiting. Fentanyl administered via single injection in the caudal space likely has similar efficacy as fentanyl injected intravascularly given its lipophilicity and rapid plasma uptake.

                        Vetter et al. performed a double-blind, randomized study without a nonadjuvant control arm that compared caudal clonidine, hydromorphone, and morphine in children undergoing ureteral reimplantation. Hydromorphone (10 mcg/kg) and morphine (50 mcg/kg) adjuvants in 0.2% ropivacaine provided longer periods to first postoperative morphine dose, but this effect did not reach statistical significance. Importantly, opioid adjuvants were associated with significantly greater administration of diphenhydramine for pruritus and ondansetron for nausea compared with clonidine. The anesthesiologist must exercise caution when administering hydrophilic epidural opioids, particularly to ambulatory patients, as even small doses may result in delayed respiratory depression. Somnolence, apneic episodes, upper airway obstruction, or hypoxemia may require escalation in care if the patient remains in the hospital but may result in an acute life-threatening event if the child is discharged home.

                        Further Reading

                        Karl HW, Tyler DC, Krane EJ. Respiratory depression after low-dose caudal morphine. Can J Anaesth. 1996 Oct;43(10):1065–1067.Find this resource:

                        Kawaraguchi Y, Otomo T, Ota C, Uchida N, Taniguchi A, Inoue S. A prospective, double-blind, randomized trial of caudal block using ropivacaine 0.2% with or without fentanyl 1 microg kg-1 in children. Br J Anaesth. 2006 Dec;97(6):858–861.Find this resource:

                        Vetter TR, Carvallo D, Johnson JL, Mazurek MS, Presson RG Jr. A comparison of single-dose caudal clonidine, morphine, or hydromorphone combined with ropivacaine in pediatric patients undergoing ureteral reimplantation. Anesth Analg. 2007 Jun;104(6):1356–1363.Find this resource:

                        3.9. Discuss the dosing and medical evidence for neuraxial clonidine in caudal blocks

                        Besides opioids, a variety of other additives have been utilized in caudal blocks, such as neostigmine, ketamine, and midazolam. Many of these agents cause additional problems, are ineffective in improving duration of block, or may be neurotoxic. Of all the additives historically used in single-injection caudal blocks, clonidine (1–2 mcg/kg) has emerged as the most useful and most popular additive in clinical use today. The clonidine dose of 2 mcg/kg may provide a slightly longer duration of blockade over the 1-mcg/kg dose, but there are insufficient data regarding the incidence of side effects when children are administered the higher dosage. In a meta-analysis of 20 randomized trials, addition of clonidine to local anesthetics in a single-injection caudal block was found to increase the duration of action of the block by 4 hours, corresponding to reduced need for rescue analgesics in the postoperative period. Slightly prolonged motor block is the most significant negative effect of caudal clonidine. Hypotension, bradycardia, and sedation were all mild. A few case reports of postoperative apnea in premature children administered caudal clonidine exist. Though this is a valid concern, current evidence only suggests an association, and determination of causality has not been established. The incidence and severity of apnea and respiratory depression are inversely related to the age of the child. Preterm and term neonates are perhaps more sensitive to the sedative effects of clonidine due to immature respiratory control centers in the central nervous system.

                        Further Reading

                        Ansermino M, Basu R, Vandebeek C, Montgomery C. Nonopioid additives to local anaesthetics for caudal blockade in children: a systematic review. Paediatr Anaesth. 2003 Sep;13(7):561–573.Find this resource:

                        Schnabel A, Poepping DM, Pogatzki-Zahn EM, Zahn PK. Efficacy and safety of clonidine as additive for caudal regional anesthesia: a quantitative systematic review of randomized controlled trials. Paediatr Anaesth. 2011 Dec;21(12):1219–1230.Find this resource:

                        3.10. Discuss the role of ultrasound in caudal blocks

                        Some anesthesiologists advocate for the routine use of ultrasonography in the placement of single-injection caudal blocks not only to view the passage of the needle but also to view the flow of the solution as it is injected into the caudal epidural space. A linear high-frequency ultrasound probe that has a small footprint will allow for good visualization of important structures, as well as provide adequate room to maneuver the caudal needle. The probe is held in a transverse orientation, and the sacral cornua, sacrococcygeal ligament, and sacral hiatus are typically visualized well given the shallow depth of the structures. There is no clear evidence that ultrasound-guided blocks provide superior metrics to standard, landmark-based techniques, but the ultrasound method likely takes longer to complete. In the hands of an experienced anesthesiologist, ultrasound guidance may be useful when a caudal block is desired in a child in whom surface landmarks are not readily apparent or the landmark technique has been challenging.

                        Further Reading

                        Erbüyün K, Açıkgöz B, Ok G, Yılmaz Ö, Temeltaş G, Tekin İ, Tok D. The role of ultrasound guidance in pediatric caudal block. Saudi Med J. 2016 Feb;37(2):147–150.Find this resource:

                          Tsui B, Suresh S. Ultrasound imaging for regional anesthesia in infants, children, and adolescents: a review of current literature and its application in the practice of extremity and trunk blocks. Anesthesiology. 2010 Feb;112(2):473–492.Find this resource:

                          3.11. What are the nonneuraxial regional anesthesia techniques that may be utilized to provide analgesia for children undergoing inguinal hernia repair?

                          If neuraxial techniques are not possible, unilateral or bilateral ilioinguinal/iliohypogastric (II/IH) nerve blocks are the most appropriate regional anesthetic techniques. Caudal blocks provide superior analgesia compared with II/IHnerve blocks, as quantified by need for rescue analgesia, but they carry the potential side effects of motor block and urinary retention. II/IH nerve blocks also take longer to perform, particularly if bilateral hernia surgery is planned. One study involved the placement of a caudal block at the start of surgery followed by II/IH nerve blocks at the end of surgery. This technique provided improved analgesia over II/IH nerve blocks alone. The safety and feasibility of this 2-block technique has been questioned due to concerns about local anesthetic toxicity and time constraints in the operating room.

                          Further Reading

                          Jagannathan N, Sohn L, Sawardekar A, Ambrosy A, Hagerty J, Chin A, Barsness K, Suresh S. Unilateral groin surgery in children: will the addition of an ultrasound-guided ilioinguinal nerve block enhance the duration of analgesia of a single-shot caudal block? Paediatr Anaesth. 2009 Sep;19(9):892–898.Find this resource:

                          Shanthanna H, Singh B, Guyatt G. A systematic review and meta-analysis of caudal block as compared to noncaudal regional techniques for inguinal surgeries in children. Biomed Res Int. 2014;2014:890626.Find this resource:

                          3.12. Describe the warning signs of local anesthetic toxicity during or following a regional anesthetic technique in children

                          The vast majority of children are heavily sedated or under general anesthesia when regional anesthetic procedures are performed, and so early detection of local anesthetic toxicity is challenging. In addition, preverbal or nonverbal children may not have the ability to articulate such symptoms as tinnitus, palpitations, or dizziness. Unfortunately, seizures or arrhythmias may be the first signs an anesthesiologist may observe during impending life-threatening local anesthetic toxicity. If epinephrine-containing solutions are used, an increase in heart rate, increases in blood pressure, or abnormalities in the electrocardiogram may be seen during or after injection of the local anesthetic solution. T-wave abnormalities may be the most sensitive and specific marker for toxicity, and so the anesthesiologist must place electrocardiogram leads on the child prior to injection and monitor carefully during the injection phase.

                          Further Reading

                          Lönnqvist PA. Toxicity of local anesthetic drugs: a pediatric perspective. Paediatr Anaesth. 2012 Jan;22(1):39–43.Find this resource:

                          3.13. Discuss the management of local anesthetic toxicity in an infant who just received a caudal block

                          Local anesthetic systemic toxicity must always be considered in a patient who develops any level of physiologic derangement after injection of local anesthetic, particularly with the large volumes normally injected for regional anesthetic techniques. Bupivacaine is by far the most common amide local anesthetic implicated in pediatric LAST, though reports of lidocaine and ropivacaine toxicity exist. Dysrhythmias are nearly ubiquitous in reports of amide LAST in children, with seizures, hypotension, and tachycardia also reported. As with any other catastrophic event, the anesthesiologist must immediately focus on the basic tenets set forth by Advanced Cardiac Life Support protocols, notably restoring circulation through effective chest compressions for nonperfusing rhythms, providing appropriate emergency medications like epinephrine, and ensuring adequate oxygen/ventilation. Lipid emulsions, classically used as a component of parenteral nutrition, have repeatedly shown efficacy in the treatment of acute drug toxicities. In addition to the treatment of amide local anesthetic toxicity, lipid emulsions have also been used to successfully treat amitriptyline, lamotrigine, quetiapine, olanzapine, and diltiazem toxicities. The prevailing theory regarding the mechanism of action of lipid emulsions in LAST is the “lipid sink” theory in that the lipid emulsion provides a medium by which free fraction of lipid soluble local anesthetic may reside, instead of binding to extraneural sodium channels. Other proposed theories suggest that lipid emulsions have a role in the modulation of calcium metabolism and also provide a lipid energy source for cardiac myocytes. The dosage of a 20% lipid emulsion solution in the event of local anesthetic toxicity is 1.5 mL/kg by bolus. Two bolus doses may be provided, and if a perfusing rhythm returns, an infusion of 0.25 mL/kg/min may be started. For extreme cases of local anesthetic toxicity refractory to all other therapies, ECMO may be required.

                          Further Reading

                          Presley JD, Chyka PA. Intravenous lipid emulsion to reverse acute drug toxicity in pediatric patients. Ann Pharmacother. 2013 May;47(5):735–743.Find this resource:

                          4. Postoperative Management

                          4.1. What is the role of caffeine therapy in the perioperative management of premature infants?

                          Caffeine increases central CO2 sensitivity and reduces the incidence of apneic episodes for premature neonates, which can occur more frequently following surgery and anesthesia. When used for apnea of prematurity, caffeine may reduce apneic events by 50% to 90% and decreases the need for positive pressure ventilation. A systematic review of randomized trials comparing prophylactic caffeine treatment to placebo found a 58% absolute risk reduction in apnea with bradycardia for infants treated with caffeine without any adverse effects. Typical reported doses for caffeine are 5 to 10 mg/kg IV prior to surgery. Caffeine therapy may be particularly useful for those infants with increased risk factors for apnea, including prior history of apnea or younger gestational age, or those who are at risk for pulmonary complications, such as infants with chronic lung disease. Of note, the clearance of caffeine is very slow in the neonatal period, and a single dose may last 72 hours or more.

                          Further Reading

                          Gregory GA, Andropoulos DB, eds. Gregory’s Pediatric Anesthesia. 5th ed. Chicester, West Sussex: Wiley-Blackwell; 2012:493.Find this resource:

                            Henderson-Smart DJ, Steer P. Prophylactic caffeine to prevent postoperative apnea following general anesthesia in preterm infants. Cochrane Database Syst Rev. 2001;4:CD000048.Find this resource:

                            MacDonald MG, Seshia MMK, Mullett MD, eds. Avery’s Neonatology: Pathophysiology and Management of the Newborn. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2015:542.Find this resource:

                              4.2. The child develops urinary retention postoperatively after a caudal block with bupivacaine and morphine. Discuss your management strategy

                              The rate of serious complications after caudal blockade is very small. A PRAN analysis of 18,650 caudal blocks revealed a complication rate of 1.9%, with the most commonly reported complications being block failure, blood aspiration, and intravascular injection, with no reports of temporary or permanent sequelae. The rate of urinary retention, however, is increased with neuraxial administration of opioids and may occur in up to 27% of patients receiving neuraxial morphine. Urinary retention should be suspected in children who have received adequate fluid resuscitation and have not voided; have unexplained tachycardia, discomfort, or suprapubic fullness; and have risk factors for urinary retention such as caudal blockade or opioid administration. If the patient has signs and symptoms suggestive of urinary retention, urinary catheterization should be performed. Prolonged oliguria should prompt consultation with the urology or nephrology service, depending on the suspected etiology.

                              Further Reading

                              Gregory GA, Andropoulos DB, eds. Gregory’s Pediatric Anesthesia. 5th ed. Chicester, West Sussex: Wiley-Blackwell; 2012:378.Find this resource:

                                Suresh S, et al. Are caudal blocks for pain control safe in children? An analysis of 18,650 caudal blocks from the Pediatric Regional Anesthesia (PRAN) database. Anesth Analg. 2015;120(1):151–156.Find this resource:

                                4.3. The child is unable to move his legs in the postoperative period but otherwise appears comfortable and stable. The surgeon performed bilateral ilioinguinal nerve blocks for the procedure. What is your management strategy?

                                II/IH nerve blocks are used for postoperative pain control most commonly after inguinal hernia repair or orchidopexy. Injection is performed blindly 2 to 3 cm medial to the anterior superior iliac spine between the internal oblique muscle and the external oblique aponeurosis. After intermittent aspiration and injection of 0.3 mL/kg local anesthetic in cephalad, medial, and caudad directions, the iliohypogastric nerve is commonly blocked in the subcutaneous tissue during needle withdrawal. Complications are rare, but injection into the femoral artery or around the femoral nerve is possible and occurs in up to 9% of children, which could produce lower extremity weakness. However, the use of ultrasound has been described and may decrease the incidence of such complications. In this instance, a neurologic exam would reveal sensory deficit in the femoral nerve distribution and quadriceps weakness. Observation is acceptable with follow-up for resolution of nerve blockade at the expected interval.

                                Further Reading

                                Coté CJ, Lerman H, Anderson BJ, eds. Coté and Lerman’s A Practice of Anesthesia for Infants and Children. 5th ed. Philadelphia, PA: Elsevier; 2013, 859.Find this resource:

                                  Lipp AK, Woodcock J, Hensman B, Wilkinson K. Leg weakness is a complication of ilio-inguinal nerve block in children. Br J Anaesth. 2004;92(2):273–274.Find this resource:

                                  Willschke H, Marhofer P, Bösenberg A, Johnston S, Wanzel O, Cox SG, Sitzwohl C, Kapral S. Ultrasonography for ilioinguinal/iliohypogastric nerve blocks in children. Br J Anaesth. 2005 Aug;95(2):226–230.Find this resource:

                                  4.4. A spinal block was placed for the procedure, but the procedure was difficult and required multiple attempts by multiple providers. The child is discharged home after an uneventful surgical procedure but returns to the emergency department the next day due to extreme irritability and feeding intolerance. What is your management strategy?

                                  Complications of spinal blockade may include total spinal blockade, infection, bleeding, nerve injury, and postdural puncture headache. High levels of subarachnoid injection, which may occur with excessive or rapid dosing or change in position, can cause loss of respiratory effort and respiratory failure but are usually hemodynamically stable. Nerve injury after spinal injection in children is a theoretical possibility but has not been described. Postdural puncture headache also appears to be rare, although incidence as high as 5% has been reported. The low incidence may be due to reduced CSF pressure or increased rate of CSF production in young children. When postdural puncture headache occurs in young children, it may be difficult to diagnose but typically presents 1 to 3 days following the procedure, with irritability that correlates with position, vomiting, or feeding intolerance. Presentation is generally mild and managed conservatively with acetaminophen, fluid therapy, and rest. If symptoms do not resolve within 24 to 48 hours, epidural blood patch may be considered, with recommended doses of 0.2 to 0.3 mL/kg autologous blood injected into the epidural space.

                                  Further Reading

                                  Coté CJ, Lerman H, Anderson BJ, eds. Coté and Lerman’s A Practice of Anesthesia for Infants and Children. 5th ed. Philadelphia, PA: Elsevier; 2013:847.Find this resource:

                                    Ylönen P, Kokki H. Management of postdural puncture headache with epidural blood patch in children. Paediatr Anaesth. 2002;12:526–529.Find this resource:

                                    4.5. What is an appropriate enteral analgesic regimen for the child to receive after discharge home?

                                    Recommendations for management of pain after discharge must take into account the age, comorbidities, and development of the child, as well as the type of surgery performed. For procedures with mild postoperative pain, such as inguinal hernia repair, scheduled or as-needed acetaminophen is the most common medication prescribed and is without significant gastric, renal, or hematologic side effects. Despite its safety, acetaminophen may have a narrow therapeutic index in certain children, and maximum daily dosages based on weight and age must be closely followed (75 mg/kg for children, 60 mg/kg for term infants, and 45 mg/kg for preterm infants). NSAIDs have been shown to be safe in children older than 6 months and are often prescribed in an alternating fashion with acetaminophen for mild postoperative pain. Patients who have received a regional anesthetic, such as a caudal, may not require enteral analgesics following block resolution. For moderate and severe postoperative pain, as may occur in open abdominal or orthopedic procedures, opioids are commonly required for adequate pain control. Of note, reports of death and other morbidity in young children treated with codeine for postoperative pain have severely limited its use as an analgesic. Adverse effects from codeine are related to genetic variability in metabolism to morphine and active metabolites by the CYP2D6 system, and in ultra-rapid metabolizers plasma morphine may increase to toxic levels, causing respiratory depression. If an enteral opioid analgesic must be prescribed after pediatric inguinal hernia repair, the most appropriate opioid is likely oxycodone liquid suspension 0.1 to 0.15 mg/kg every 6 hours as needed. Hydrocodone is typically formulated with acetaminophen and is less appropriate, as children may inadvertently be given additional doses of acetaminophen along with the hydrocodone/acetaminophen combination, increasing the risk of acetaminophen toxicity.

                                    Further Reading

                                    Coté CJ, Lerman H, Anderson BJ, eds. Coté and Lerman’s A Practice of Anesthesia for Infants and Children. 5th ed. Philadelphia, PA: Elsevier; 2013:919.Find this resource:

                                      Gregory GA, Andropoulos DB, eds. Gregory’s Pediatric Anesthesia. 5th ed. Chicester, West Sussex: Wiley-Blackwell; 2012:845.Find this resource:

                                        Tobias JD, Green TP, Coté CJ. Codeine: time to say “no.” Pediatrics. 2016;138(4).Find this resource:

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