NEW CONCEPTS AND TECHNIQUES IN PEDIATRIC ANESTHESIA

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PRACTICAL PEDIATRIC REGIONAL ANESTHESIA Santhanam Suresh, MD, and Melissa Wheeler, MD

‘‘Change is never made from worse to better without inconvenience.’’ BOOKER T. WASHINGTON

Regional anesthetic techniques in children have become more popular in the past decade. This is in part because of recent research indicating biobehavioral changes associated with untreated pain in children.2, 86 Most regional techniques in children are performed under heavy sedation or general anesthesia. Concerns regarding safety and the medicolegal liability of performing regional blocks under anesthesia must be weighed against the trauma and potential danger of placing blocks in awake, uncooperative children. A large body of clinical experience supports the safety and efficacy of regional blocks placed under general anesthesia in children.49 There is evidence-based literature to show that combined regional and general anesthesia may actually improve outcome and thereby decrease hospital stay.61 The availability of better equipment and safer local anesthetic agents has also improved the safety of regional anesthetic techniques. Overall, the incidence of complications with the use of regional techniques in children is not significantly different from that in the adult population. The benefits of regional techniques include avoidance of perioperative opioids and their associated side effects,84 early ambulation, and excellent pain control. The preemptive

From the Department of Anesthesiology, Children’s Memorial Hospital, Northwestern University Medical School, Chicago, Illinois

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Table 1. DIFFERENCES BETWEEN CENTRAL NEURAXIAL AND PERIPHERAL NERVE BLOCKS Central Neuraxial Blocks

Peripheral Nerve Blocks

Epidural or intrathecal approach Cannot be used for head and neck surgery Systemic symptoms including hypotension Lower extremity weakness and delayed ambulation Duration of analgesia is limited to approximately 4 to 6 hours

Directed to the area requiring analgesia Applicable for any area that is operated on Rarely systemic effects Delay in ambulation unlikely (except lower extremity block) Analgesia may last longer than 12 hours

placement of nerve blocks may also improve postoperative recovery and decrease postoperative analgesic requirements.17 This article describes the use of regional anesthetic techniques in children. They can be divided into two major groups: (1) central neuraxial blocks; (2) peripheral nerve blocks. Differences between central neuraxial and peripheral nerve blocks are shown in Table 1. PHARMACOLOGY AND TOXICITY OF LOCAL ANESTHETICS The primary local anesthetic agents used in pediatric regional techniques are 2-chloroprocaine, lidocaine, bupivacaine, ropivacaine, mepivacaine, and tetracaine. Levobupivacine has recently been studied and may replace the racemic mixture of bupivacaine because of its decreased potential for central nervous system toxicity and cardiotoxicity.3, 23, 60 All local anesthetics block the generation and propagation of impulses in excitable tissues. This action results in effective regional blockade when these drugs are deposited near peripheral nerves, nerve roots, or the spinal cord. This also causes the adverse central nervous system and cardiac effects of local anesthetic toxicity that occur when plasma concentrations are elevated by accidental intravenous administration or increased systemic uptake secondary to relative overdose. The pharmacology of local anesthetics in children is similar to that in adults. In neonates and infants, however, the greater total body water results in a larger volume of distribution and therefore longer elimination half-life. Decreased protein binding, both qualitative and quantitative, results in greater unbound fraction of drug (particularly bupivacaine) and, therefore, increased potential for toxicity. In addition, with age, the endoneurium becomes less permeable, so both latency and duration of nerve blockade increase. Local Anesthetic Agents 2-Chloroprocaine 2% or 3% has a short time to onset of action and a short duration of action. It is useful for testing the function of caudal or

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epidural catheters. Though experience is limited, it has been recommended as a safer alternative for continuous catheter infusion in preterm and high-risk infants.37 Lidocaine 0.5% to 2% has a short time to onset and medium duration of action. It can be used for peripheral blocks or epidural anesthesia. Bupivacaine 0.1% to 0.5% has a longer onset time and duration of action than lidocaine or 2-chloroprocaine but has a greater potential for severe cardiotoxicity than other agents. It can be used for peripheral blocks, spinal anesthesia, and caudal or epidural anesthesia and analgesia. Levobupivacaine is effective for peripheral nerve block and caudal block in children.60 It has less cardiac toxicity potential and may be a more attractive alternative to bupivacaine. Ropivacaine 0.2% to 1% is supplied as the pure S-enantiomer and has an onset time and duration of action comparable with bupivacaine. It produces less motor blockade and is less toxic than bupivacaine.41 It also can be used for peripheral blocks and caudal or epidural anesthesia and analgesia. Unlike most other local anesthetic agents, onset time, duration of action, and systemic absorption are not affected by epinephrine. Tetracaine 1% is used for spinal anesthesia.77 Mepivacaine is approximately equally potent to lidocaine and can safely be used for peripheral nerve blocks.20 Mepivacaine can provide a rapid onset of block, with a shorter duration of motor block, that may allow for rapid recovery in the postoperative period.69 Central Neuraxial Blocks General Principles Patient Monitoring. Monitors should be applied and function assured before the block is performed. In particular, the electrocardiogram should be adjusted so that the P wave, QRS complex, and upright T wave can be seen clearly. Baseline systolic blood pressure and heart rates should be noted. Skin Preparation. Bacterial colonization of epidural and caudal catheters in children occurs at a rate of 6% to 35%.44, 47, 62 Gram-positive organisms are most common, though gram-negative colonization may also occur, particularly with caudal catheters.47 Children under 3 years of age are also most likely to have colonization of caudal catheters.47 Despite high rates of colonization, serious epidural infections are exceedingly rare.47, 62, 83 Chlorhexidine may be better than povidone iodine for reducing the risk of catheter colonization in children.44 Test Dose. The authors strongly recommend the use of a test dose to decrease the likelihood of intravascular injection. A test dose is not 100% reliable, however, and graded dosing with careful attention to vital signs is recommended. A test dose should be 0.1 mL/kg of a local anesthetic solution with 5 ␮g/mL of epinephrine to a maximum volume

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of 3 mL. An increase in heart rate of 10 beats per minute above baseline occurring within 1 minute of injection is a reasonable predictor of intravascular injection for children anesthetized with sevoflurane.88 This sign is less reliable in children anesthetized with halothane.88 Pretreatment with atropine may improve the accuracy of heart rate changes in detecting intravascular injection for both inhalation agents.87 An increase in systolic blood pressure of greater than 15 mm Hg within 2 minutes of injection is further confirmation of intravascular injection, although less sensitive and specific than changes in heart rate.48, 88 A 25% change in the T-wave amplitude (increase or decrease) may be the most reliable predictor of intravascular injection (Fig. 1).21, 48 All studies have evaluated this parameter by strip recording, however, and accuracy by observation of the monitor alone has not been evaluated. In addition, changes in Twave amplitude in response to epinephrine vary with age, and this test, therefore, may not be valid in children older than 92 months (7.6 years) of age.82, 89 Isoproterenol has also been evaluated as an indicator of intravascular injection.82 Studies are promising, but isoproterenol has not been extensively evaluated for neurotoxic potential; supplies of this medication in the United States are limited because of recent discontinuation of production by several manufacturers. Sympathetic Tone. A clinically significant decrease in blood pressure related to sympathectomy from central neuraxial blocks is rare in children younger than 8 years of age.65 Volume loading before such blocks, commonly practiced in adults, is unnecessary in this age group. In older patients, the sympathetic block results in a slight (20%–25%) but consistent decrease in blood pressure.65 Even in adolescents, however, fluids or vasopressors are rarely required to treat the hemodynamic effects of central neuraxial blocks. Contraindications. Contraindications are few and similar to those in adults. These include coagulopathy, infection at the insertion site, true

Figure 1. Electrocardiographic changes associated with the intravenous injection of bupivacaine and epinephrine 1:200,000. Note the marked increase in the height of the T wave. (From Freid EB, Bailey AG, Valley RD. Electrocardiographic and hemodynamic changes associated with unintentional intravascular injection of bupivacaine with epinephrine in children. Anesthesiology 1993; 79:394–398; with permission.)

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local anesthetic allergy, and abnormal superficial landmarks or lumbosacral myelomeningocele because of the risk of malposition of the cord or dural sac. Progressive neurologic disease is a relative contraindication primarily because of medico-legal concerns. The safety of central neuraxial techniques in the presence of a ventriculoperitoneal shunt has not been studied. Risks and benefits in these patients should be carefully considered on an individual basis.

‘‘Single-Shot’’ Caudal Block The single-dose or ‘‘single-shot’’ caudal technique is the most commonly used neuraxial block for children. Developmental anatomy contributes to the ease of caudal needle placement and, therefore, the popularity of the technique in young children compared with adults, for example, shows that prepubertal children have less presacral fat, making identification of the bony landmarks easier. Additionally, in children, the sacral ligament is noncalcified and the hiatus is wide, further contributing to the ease of caudal needle placement. Caudal block is a useful adjunct to general anesthesia in most procedures performed below the umbilicus. In larger volumes (1–1.25 mL/kg) and in younger children, it has been described for use in upper abdominal and lower thoracic procedures.33 It is the authors’ experience, however, that analgesia is less reliable for procedures at this higher level. It is less commonly used as the sole anesthetic technique, but has been described as an alternative to spinal or general anesthesia for herniorrhaphy in preterm infants.33, 37 Anatomy and Landmarks The posterior superior iliac spines and the sacral hiatus form an equilateral triangle, the apex of which points inferiorly. The sacral cornua are easily palpated on either side of the sacral hiatus, approximately 0.5 to 1 cm apart (Fig. 2). The sacrum is the most variable bone in the human body, hence the sacral foramina may be misidentified as the sacral hiatus. The proper location is often, but not always, at the beginning of the crease of the buttocks. Equipment A variety of needles have been used for single-shot caudal blocks, including 23-gauge to 18-gauge straight needles, 23-gauge to 19-gauge butterfly needles, 22-gauge or 20-gauge styletted block needles, 22-gauge spinal needles, and 22-gauge or 20-gauge intravenous needle catheters. Styletted needles prevent the introduction of a skin plug into the epidural space that may later develop into an epidermal inclusion cyst. Intravenous catheters offer the advantage of confirmation of correct placement if the catheter easily slides off the needle.

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Figure 2. Sacral anatomy. A, Coronal view of the sacrum showing proper needle placement for performance of a candal epidural block. The needle is advanced at a 45 angle to the skin until the bone is contacted. The angle is then decreased from 15 to 30 and the needle is advanced through the sacrococcygeal ligament into the epidural space. B, Coronal view of the sacral anatomy demonstrating potential improper needle location during a candal epidural block. (From Deshpande JK, Tobias JD, eds: The Pediatric Pain Handbook. St. Louis, Mosby; 1996: 100; with permission.)

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Technique The patient is positioned in the lateral decubitus position. After identification of the sacral hiatus and sterile skin preparation, the needle is advance at a 45 angle to the skin. A ‘‘pop’’ or ‘‘give’’ is felt as the sacrococcygeal ligament is passed. In infants under 1 year of age, the dural sac extends to the S4 level. Further needle advancement is not recommended because of the risk of dural puncture. In older children, the angle of the needle can be reduced and advanced slightly into the canal. The needle should be aspirated for blood or cerebrospinal fluid (CSF) and, if negative, a test dose is given. Injection should be easy and feel similar to injection of an epidural catheter in adults. Palpation of the skin overlying the sacrum will help rule out superficial injection. Air injection to check for crepitus is not recommended because of the risk of air embolism.31 Dosing and Duration of Block One milliliter per kilogram of bupivacaine 0.125% with epinephrine 1:200,000 reliably produces 4 to 6 hours of analgesia. Higher concentrations have been used, but motor blockade is significantly increased without improving the quality or duration of pain control. Alternatively, ropivacaine 0.2% can be used in a dose of 1 mL/kg.54 Clonidine 1 to 2 ␮g/kg appears to prolong bupivacaine block with little additional risk.40, 53 Two case reports have suggested clonidine may be responsible for apnea when used for caudal blocks in neonates, however.8, 9 The addition of opioids may increase the potency of the neuraxial block. Fentanyl 1 to 2 ␮g/kg may also prolong the block, but pruritus and nausea or vomiting are increased.13 Morphine (30 ␮g/kg) has also been used by this route, but side effects (nausea or vomiting and pruritus) often occur and the increased risk of respiratory depression precludes its use in outpatients. Timing of Block Few young children will cooperate with placement of a regional block while awake. Blocks are placed after induction of anesthesia and placement of an intravenous catheter. Prior placement of an intravenous catheter is mandatory for treatment of complications related to accidental spinal or intravascular injection. Blockade before the procedure reduces anesthetic requirements and may have a preemptive analgesic benefit.39 Complications Complications are unusual—about 1 per 1000 procedures—and usually minor.27 Most complications result from misplacement of the needle into superficial soft tissues or sacral foramina, resulting in block failure; intrathecal puncture with subsequent spinal anesthesia; or intravascular

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or intraosseous injections, leading to systemic toxicity. Using proper technique, including incremental injection, minimizes these complications. Urinary retention and motor blockade are rare with the recommended solutions. Continuous Caudal Catheter Equipment Several companies manufacture kits for caudal catheter placement. A useful component is a clear plastic drape to better identify landmarks. An 18- or 19-gauge needle (Crawford type) with a 20- or 21-gauge catheter is used in patients of all sizes. Smaller catheters tend to kink either at placement or during postoperative use. A styletted catheter has been reported to increase the successful passage of catheters to the thoracic level (discussed subsequently). After placement, care must be taken to prevent fecal contamination because of the proximity of the anus to the insertion site. Because of this risk, it is prudent to keep them in for no longer than 3 days47 and to discontinue caudal catheters if the dressing becomes soiled. Caudal-to-Thoracic Technique The caudal approach to thoracic epidural anesthesia can be used in children as old as 10 years of age. Success in this age group is related to the less densely packed epidural fat that allows for free cephalad passage of the catheter. Some authors suggest ease of removal of the stylet from a styletted-type catheter, ease of injection, and negative aspiration and test doses predict successful placement,32 whereas others suggest radiographic confirmation.12 A case report suggests that nerve stimulation through the catheter (19-gauge epidural catheter, Arrow Flextip Plus, Arrow International Inc., Reading) using a low electrical current (1– 10mA) can be used to identify correct placement.92 The level of observed intercostal muscle movement (T9–T10 level) predicted catheter tip placement at the T9–T10 interspace and this was confirmed by radiographic imaging.92 Epidural Block Anatomy and Landmarks In adults, the line drawn between the two iliac crests passes over the fourth lumbar vertebrae or the L3–L4 interspace. In children, this line may pass closer to the fifth lumbar vertebrae and in neonates it may pass over the L5–S1 interspace.10 Until 1 year of age, the spinal cord ends at a lower level than in adults (L3 versus L1), as does the dural sac (S4 versus S2). For a lumbar epidural block, it may be safer to select

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the L4–L5 or the L5–S1 interspace for infants. Thoracic spine landmarks are the roots of the scapular spines for T3 and the inferior angle of the scapula for T7. Technique and Identification of the Epidural Space Although the patient can be in the sitting position if awake, the most common position is lateral, with the surgical side down and the hips and knees flexed by 90. The spine is bent to open the interspinous space and enlarge the interlaminar space. The midline lumbar intervertebral approach is the most common technique of epidural block in children. As with adults, ‘‘loss of resistance’’ (LOR) is used in children for identification of the epidural space. The site of puncture is in the midline, midway between the spinous processes of the selected interspace. The epidural needle is inserted at right angles to the skin until it contacts the interspinous ligament. The introducer needle is then removed, and the syringe used for detecting the epidural space is connected. The epidural needle is then carefully advanced while constant pressure is exerted on the plunger of the syringe. An increased resistance is detected when the needle touches the ligamentum flavum, followed by a sudden LOR as the tip of the needle enters the epidural space. The epidural space is more superficial in children than adults. Several guidelines for determining epidural depth have been published.6, 36, 97 None is consistently accurate, though a rough estimate for children between 6 months and 10 years of age is a depth of 1 mm/kg of body weight. Other formulas are depth (cm)  1
0.15  age (years) and depth (cm)  0.8
0.05  weight (kg).36 The mean depth of epidural space in neonates has been reported as 1 cm (SD 0.2, range 0.4–1.5 cm).36 The best protection against excessive depth and resultant dural puncture is appropriately short needles and extreme care during advancement of the needle. Once the needle is in the epidural space, the absence of blood or CSF reflux is verified before insertion of the catheter. A test dose of the local anesthetic with epinephrine is administered before every bolus injection. Whether air or saline should be used to detect LOR continues to be debated.75, 80 Air has a long history of use because of its availability, simplicity, and suitability for identifying the epidural space. Several severe complications have been reported after injection of air into the epidural space, including paraplegia67 and multiradicular syndrome in adults63 and air embolism in children.31, 79, 81 These complications have led some practitioners to recommend abandoning the air-LOR technique in favor of a saline-LOR technique.30, 75 In younger patients, some practitioners believe the saline-LOR technique is not as dependable as the air-LOR technique.11 Other possible disadvantages of the saline-LOR technique are dilution of the local anesthetic and difficulty distinguishing a reflux of saline from CSF. Because of the limitations of this technique, some practitioners combine air and saline.4, 29 In general, the risk–benefit ratio seems to favor the use of saline in most circumstances.

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The most prudent course of action is to always proceed cautiously and avoid injection of large volumes of any test substrate, whether air or saline. Dosing The recommended volume of anesthetic solution depends on the upper level of analgesia necessary for completion of the surgery. Many dosing schemes have been reported. In children older than 10 years of age, a simple formula calculates the volume (V) necessary to block one spinal segment78: V (in mL)  1/10  (age in years) In younger children, the weight of the patient should be considered; 0.04 mL/kg/segment provides an initial bolus-dose estimate. Keep in mind the maximum dose recommendations (Table 2). If adequate levels are achieved, redosing after 1 to 2 hours with half the initial volume is reasonable. Alternatively, a continuous infusion can be started immediately after the bolus injection. Recommended solutions and infusion rates are available in standard pediatric anesthesia textbooks.98 Infants younger than 12 months of age are prone to accumulation with prolonged continuous bupivacaine infusions, so infusion rates should be reduced in this age group.51, 72 Lumbar-to-Thoracic Catheter In contrast to caudal-to-thoracic catheter placement, attempts to thread a catheter from the lumbar interspaces to the thoracic level are rarely successful.5 This is probably related to the more acute angulation of a catheter placed in the lumbar region. If this technique is attempted, radiographic confirmation of correct placement is recommended. Epidural Placement During General Anesthesia Krane et al49 have eloquently made the case supporting epidural placement during general anesthesia in an editorial supported by more than fifty pediatric anesthesiologists from all around the world. For children, to avoid movement during performance of a block, sedation or general anesthesia is almost always required. Two concerns regarding Table 2. LOCAL ANESTHETIC MAXIMUM DOSING GUIDELINES BY WEIGHT Bolus Dose (mg/kg) Local Anesthetic Bupivacaine Chloroprocaine Lidocaine

Infusion Rates (mg/kg/hour)

Infants ⬍ 6 Months

Child

Infants ⬍ 6 Months

Child

1.5 10 3

2.5 10 .5

0.2 18 0.8

0.4 18 1.6

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this practice are reduced reliability of test dose under anesthesia and neurologic damage secondary to the inability of the patient to report pain or paresthesia. Data on thousands of pediatric patients do not support the second concern, and careful attention to technique substantially reduces the possibility of intravascular injection.22, 27, 66 Complications The potential complications of epidural anesthesia in children are the same as those in adults. As in caudal blocks, accidental intrathecal or intravascular injection may occur. Failure or difficulties may occur because of an inappropriate insertion route, insufficient flexion of the spine, or deformities of the vertebral column. Direct trauma to the spinal cord can occur during thoracic and upper lumbar approaches and may result in the same neurologic sequelae as reported in adults. Fortunately, these sequelae are extremely unusual in children. In the French Language Society of Pediatric Anesthesiologists’ (ADARPEFs) prospective study, no complication was reported following thoracic epidurals, whereas the overall morbidity rate was 0.37% and 0.68% for lumbar and sacral epidurals, respectively.27 The morbidity rate for thoracic epidurals may have been skewed because only experienced anesthesiologists performed that block. As for adults, epidural catheters may be malpositioned, disconnected, or broken. Complete failure of the block usually results from misplacement of the needle or catheter. In a previously functional catheter, the development of new respiratory depression or increasing motor weakness may reflect migration into the subarachnoid space. Unilateral blockade is often caused by migration of the catheter through a spinal foramina. Migration of the catheter into an epidural vein may cause loss of analgesia and increased sedation if opioids are being used. The administration of epidural opioids, particularly morphine, may lead to delayed respiratory depression. All opioids have the potential to cause nausea, or pruritus. The incidence of urinary retention is difficult to determine because it is the practice of many centers to prophylactically place a urinary drainage catheter in these patients. Catheter Management for Postoperative Pain Successful use of continuous catheter techniques for postoperative pain requires physicians dedicated to their management and an educated nursing staff comfortable with monitoring and caring for these patients. Preprinted order sheets indicating infusion solutions and dosing, monitoring, patient assessment, and side-effect management increase safety and success. The article on postoperative pain management in this issue provides additional information on dosage and catheter management.

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Spinal Anesthesia In pediatric practice, spinal anesthesia is used mainly for inguinal hernia repair in former preterm infants to reduce the risk of postoperative apnea. Infants born at less than 37 weeks gestational age and less than 60 weeks postconceptional age at the time of surgery are at risk for apnea after general anesthesia. Those presenting with continuing apnea at home or anemia (hematocrit ⬍30%)14 are at even greater risk. This complication appears to be reduced, though not eliminated, following spinal anesthesia without concomitant sedation.15, 24, 25, 35, 50, 77 Of note, apnea may even be increased if regional anesthesia is combined with sedation (ketamine, midazolam).94 Spinal anesthesia is less commonly used in older children in the United States, but several European reports suggest its safety and efficacy in select cases.45, 46 Equipment Short styletted spinal needles, from 22- to 27-gauge, are available for pediatric spinal anesthesia. In former preterm infants, medications are best delivered using 1-mL syringes because of the small volumes required. Patient Positioning Lumbar puncture can be performed in the same positions as for lumbar epidural anesthesia. For the former preterm infant, it is easier when the infant is in the sitting position. In the sitting position, the assistant holds the infant so that both arms and legs are bent and the elbows and knees are brought together. This helps to keep the infant in position and maximally opens the intervertebral spaces. Attention must be paid to the position of the head, which must be extended away from the chest to avoid airway obstruction. Technique The technique does not differ from that used in adults. In infants, puncture is performed in the midline, at the L4–L5 interspace, to stay below the level of the spinal cord. Some practitioners use local anesthesia at the skin puncture site. The usual depth is several millimeters past that calculated for depth of the epidural space (discussed earlier). After reflux of CSF from the needle, the syringe is quickly attached to minimize CSF loss and the solution is injected in 10 to 20 seconds. Particularly for infants, in whom the total volume injected are very small, some practitioners advocate aspiration of spinal fluid into the syringe at the end of the block and then reinjection to assure that the complete dose is administered. Others intentionally ‘‘overfill’’ the syringe with the volume of the spinal needle. Patients should be carefully returned to the supine position, without elevating the legs, after completion of the block.96

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Dosing In general, younger and smaller children require larger doses to produce the same level of block, but the duration of the effect is shorter. Dosing recommendations for spinal anesthesia vary and are summarized in Table 3. Guidelines given are designed to reach an upper limit of block between T10 and T7. The safety of hyperbaric lidocaine has recently been questioned in adults because of the high incidence of transient neurologic symptoms (TNS) following its use.38, 42, 55 These symptoms usually consist of back and buttock pain. Cauda equina syndrome has been reported in adults.26, 55 The US Food and Drug Administration recommends diluting 5% lidocaine with an equal volume of cerebrospinal fluid before injecting the total dose, but at least one study suggests this does not influence the incidence of TNS.76 Although reducing the concentration of lidocaine to 2% has been found to provide effective analgesia,57, 71 the incidence of TNS may be unaffected.34 In general, for spinal anesthesia in preterm infants, lidocaine is unsuitable because its duration of action is too brief. Complications Few studies evaluate overall incidence of complications for spinal anesthesia in children. In the ADARPEF’s prospective study, only one complication (intravascular injection) was reported after 506 spinal anesthetics. No headaches were reported.27 In a retrospective study by the same association, the incidence of complications after spinal anesthesia (n705) was 3% and is described as ‘‘extension of the block—apnea, seizures.’’22 Recently, a report of spinal anesthesia in 100 children, age 2 to 115 months, found few complications using 0.5% isobaric or hypobaric bupivacaine. Overall, cardiovascular stability was good. A vasopressor was administered to one child to treat hypotension and atropine to another to treat bradycardia. Five children developed a mild, positiondependent headache (24–27-gauge needle).46 A report of experience with 107 spinal anesthetics in children age 7 to 18 years found that six children required vasopressor and six required atropine to treat bradycardia. Nausea (20 patients) and shivering (16 patients) were also reported. Four children had post-dural puncture headaches (27-gauge needle).45 High spinal anesthesia has been reported in infants when the legs are raised shortly after placement of the block.96 Care must be taken to avoid this scenario. A report of inguinal hernia repairs in former preterm infants found 262 of 269 spinal anesthetic placements (97.3%) were successful.24 Sixteen patients required two attempts; 56 (21.4%) required supplemental anesthesia; 34, intravenous anesthesia; six, general; 12, local; and four, other regional. One hundred fifty-three infants had histories of apnea. Thirteen episodes of apnea were noted in 13 infants (4.9%); all 13 were inpatients undergoing concomitant therapy for apnea (mean gestational age [GA] 28 weeks, postconceptional age at surgery [PCAS], 42.9 weeks). Four of these infants received supplemental

96 Table 3. RECOMMENDED DOSES AND APPROXIMATE DURATIONS OF LOCAL ANESTHETICS FOR SPINAL ANESTHESIA IN INFANTS AND CHILDREN Local Anesthetic 0.75% hyperbaric bupivacaine 0.5% hyperbaric or isobaric bupivacaine 0.5% hyperbaric tetracaine 5% hyperbaric lidocaine

0–5 kg

5–15 kg

⬎ 15 kg

Duration

0.5–0.6 mg/kg (0.06–0.08 mL/kg) 0.5–0.6 mg/kg (0.1–0.12 mL/kg) 0.5–0.6 mg/kg (0.1–0.12 mL/kg) 2.5–3 mg/kg (0.05–0.06 mL/kg)

0.4 mg/kg (0.053 mL/kg) 0.4 mg/kg (0.08 mL/kg) 0.4 mg/kg (0.08 mL/kg) 2 mg/kg (0.04 mL/kg)

0.3 mg/kg (0.04 mL/kg) 0.3 mg/kg (0.06 mL/kg) 0.3 mg/kg (0.06 mL/kg) 1.5 mg/kg (0.03 mL/kg)

⬎70 min (similar to 0.5% bupivacaine) 30–180 min (avg 80 min) 35–240 min (avg 90 min) ⬍60 min

*Adapted from Dalens BJ: Regional anesthesia in children (chapter 44). In Miller RD, (ed): Anesthesia. Philadelphia, Churchill Livingstone, 2000, p 1565; with permission.

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anesthesia. This apnea rate is significantly lower than the published rate (10%–30%) (P  .01). Thirty-nine of 103 infants who underwent inguinal hernia repair on an outpatient basis had histories of apnea. No postoperative episode of apnea was reported, though patients were not monitored for apnea at home. The mean birth weight of this group was 2091 g (weight range, 710–3693 g); mean GA, 33 weeks (GA range, 25–37 weeks); and mean PCAS, 44.3 weeks (PCAS range, 35.4–59.2 weeks).24 Unlike adults, neonates usually tolerate high thoracic spinal anesthesia with minimal changes in heart rate and arterial blood pressure. This may be because the sympatholysis from high thoracic spinal anesthesia is offset by withdrawal of cardiac vagal activity in this age group.70 Cases of aseptic meningitis after spinal anesthesia in infants have been reported, but a causative relation cannot be firmly established.1, 19

PERIPHERAL NERVE BLOCKS Peripheral nerve blocks used for surgery and postoperative pain relief are discussed by anatomic regions (Table 4). Very little equipment is needed to perform these blocks—blunt-tip needles and a nerve stimulator capable of providing low-voltage (0.01 mV) electric stimulation. Local anesthetic selection is based on the duration of the surgical procedure and the desired duration of the block. Lidocaine, mepivacaine, bupivacaine, ropivacaine and, more recently, levobupivacaine are used for peripheral nerve blocks. The addition of bicarbonate may enhance the speed of onset of the nerve block and reduce the pain on injection.

Table 4. PERIPHERAL NERVE BLOCKS Region Head and neck

Chest wall Upper extremities

Abdomen and genitals Lower extremities

Nerve to be Blocked Supraorbital and supratrochlear Infraorbital nerve Greater occipital nerve Great auricular nerve Intercostal nerve Brachial plexus Wrist blocks Elbow (radial, ulnar, and median) Digital nerve Ilioinguinal nerve, penile Femoral nerve Lateral femoral cutaneous Sciatic nerve Ankle block Digital nerve

Adapted from Polaner D, Suresh S, Cote´ CJ: Pediatric regional anesthesia. In Cote´ C, Todres ID, Ryan JF et al (eds): A Practice of Anesthesia for Infants and Children. Philadelphia, WB Saunders, 2000, pp 636–675; with permission.

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This alters the pKa of the solution, making the local anesthetic available in the active cationic form.95 Caution is required to avoid exceeding the maximum allowable dose of the local anesthetic. The total volume of local anesthetic required for a peripheral nerve block is extrapolated from adult experience.

Relative Contraindications to Peripheral Blocks Though it is rare to encounter opposition to the use of peripheral nerve blocks, certain conditions may call for a judicious avoidance of them. Relative contraindications include: Local infection Generalized sepsis Coagulopathy Predisposition to compartment syndrome Parental or child dissent

Nerve Stimulator Though not a substitute for anatomic knowledge, a nerve stimulator is useful to localize peripheral motor nerves in anesthetized children. Because paresthesias cannot be elicited in an anesthetized child, the use of a nerve stimulator may decrease the potential for nerve damage. A nerve stimulator capable of delivering low voltage is preferred. The authors prefer stimulation with an insulated needle using a voltage of 0.2 mA with a repetitive single-pole output at a 1-second interval. The area innervated by the nerve is observed for the appropriate muscle contraction. When this has been identified, 1 to 2 mL of local anesthetic agent is injected. Immediate abolishment of muscle movement indicates correct placement of the needle. Head and Neck Nerve Blocks The trigeminal nerve provides sensory innervation to the scalp and the face. The ophthalmic division of the trigeminal nerve (V1) supplies the scalp anterior to the coronal suture, and the branches of the cervical nerve (C2) supply the scalp posterior to the coronal suture. Supraorbital and Supratrochlear Nerve. Anatomy and Indication. These are the terminal branches of the first branch of the V1. The supraorbital nerve supplies the forehead and the scalp anterior to the coronal suture after it exits the supraorbital foramen. The supratrochlear nerve leaves the orbit between the trochlea and the supraorbital foramen and supplies the forehead (Fig. 3). Blockade of these nerves can be used for surgical excisions of skin lesions on the scalp84 and for neurosurgical

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Figure 3. Supraorbital and supratrochlear nerve blocks. (From Cote´ CJ, Todres ID, Goudsouzian NG, et al (eds): A Practice of Anesthesia for Infants and Children, 3rd ed. Philadelphia: WB Saunders; 2001: 644; with permission.)

procedures that involve incisions on the anterior portion of the scalp. The authors have also had success treating patients with chronic headaches with serial blockades of these nerves. Technique. Using a sterile technique, the supraorbital notch is identified, and a 27-gauge needle is inserted perpendicularly. Once resistance is obtained, the needle is drawn back a few millimeters and 1 mL of 0.25% bupivacaine with 1:200,000 epinephrine is injected to block the supraorbital nerve. The needle is then withdrawn gently and directed medially to block the supratrochlear nerve, and an additional 1 mL of 0.25% bupivacaine with 1:200,000 epinephrine is injected. Complications. Pressure is applied to the supraorbital area after the block is performed to avoid periorbital edema and ecchymosis secondary to local anesthetic solution dissecting into the surrounding loose adventitious tissue or from hematoma formation. Greater Occipital Nerve Block. Anatomy and Indications. The greater occipital nerve is a terminal branch of the superficial cervical plexus (dorsal rami of C2). The nerve becomes subcutaneous below the superior nuchal line by passing above the aponeurotic sling just medial to the occipital artery (Fig. 4). Blockade of this nerve provides ipsilateral pain relief for patients undergoing occipital incisions, including craniotomies for posterior fossa tumors and posterior ventriculo-peritoneal

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Figure 4. Greater occipital nerve block. (From Cote´ CJ, Todres ID, Goudsouzian NG, et al (eds): A Practice of Anesthesia for Infants and Children 3rd ed. Philadelphia, WB Saunders, 2001, p 644; with permission.)

shunts. Blockade can also provide anesthesia for excision of skin lesions on the scalp.84 Technique. The head is turned to the side opposite the side to be blocked. The occipital artery is palpated at the level of the superior nuchal line. Subcutaneous fanning of 2 mL 0.25% bupivacaine with 1: 200,000 epinephrine is performed. Complications. Though complications are rare, it is important to note the proximity to the spinal canal. Particular caution should be exercised in patients who have had surgery to the posterior fossa. Intravascular injection can be avoided by careful aspiration. Infraorbital Block. Anatomy and Indications. The infraorbital nerve is the terminal branch of the second division of the trigeminal nerve and is purely sensory. It leaves the skull through the foramen rotundum and enters the pterygopalatine fossa. Here it exits the infraorbital foramen, dividing into four branches—the inferior palpebral, the external nasal, the internal nasal, and the superior labial. These branches innervate the lower lid, the lateral inferior portion of the nose and its vestibule, the upper lip, the mucosa along the upper lip, and the vermilion. This block can be used to provide postoperative analgesia for procedures performed to the upper lip and vermilion (e.g., cleft lip repair).7, 74 It can also be used for nasal septal reconstruction, rhinoplasty, and in patients undergoing endoscopic sinus surgery.

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Technique. Although two approaches are described (intraoral and extraoral), the authors prefer the intraoral approach. After palpation of the infraorbital foramen, the upper lip is folded back and a 27-gauge needle is advanced to the infraorbital foramen parallel to the maxillary premolar (Fig. 5). By placing a finger at the level of the infraorbital foramen, the cephalad progression of the needle is checked. A volume of 0.5 mL to 1 mL of 0.25% bupivacaine with 1:200,000 epinephrine is injected after careful aspiration. Complications. Swelling can occur because of loose adventitious tissue around the eyelid. To prevent this, pressure is applied to the area for about 5 minutes after the block is performed. Patients and parents should be informed that the upper lip will be anesthetized after the block. Great Auricular Nerve. Anatomy and Indications. This nerve supplies the sensory innervation to the mastoid and the external ear.84 It is a branch of the superficial cervical plexus (C3). The nerve wraps around the posterior border of the belly of the clavicular head of the sternoclei-

Figure 5. Infraorbital nerve block. (From Cote´ CJ, Todres ID, Goudsouzian NG, et al (eds): A Practice of Anesthesia for Infants and Children, 3rd ed. Philadelphia: WB Saunders; 2001: 655; with permission.)

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domastoid at the level of the cricoid cartilage (C6)58 (Fig. 6). Blocking this nerve provides analgesia for patients undergoing otoplasty repair16 and tympanomastoid surgery. The authors have found that using this nerve block, can reduce the postoperative morbidity associated with the perioperative use of opioids. Technique. The belly of the clavicular head of the sternocleidomastoid is identified, and a line drawn laterally at the level of the cricoid dissecting the sternocleidomastoid is marked. This is usually about 5 to 6 cm below the bony external auditory canal. Two to 3 mL of 0.25% bupivacaine with 1:200,000 epinephrine are injected into the area. Complications. Careful attention to the location of the external jugular and carotid can prevent intravascular placement. Superficial needle placement avoids a deep cervical plexus block that can result in Horner’s syndrome. Deep injection can also affect the hemidiaphragm by blocking the phrenic nerve unilaterally or the trapezius by blocking the spinal accessory nerve.

Figure 6. Great auricular nerve block. (From Cote´ CJ, Todres ID, Goudsouzian NG, et al (eds): A Practice of Anesthesia for Infants and Children, 3rd ed. Philadelphia, WB Saunders; 2001, 655; with permission.)

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Trunk Blocks Intercostal Nerve Blocks Anatomy and Indications. The intercostal nerves are derived from the ventral rami of the first through the twelfth thoracic nerves. There are four branches for each intercostal nerve—the gray rami communicans that passes to the sympathetic ganglion; the posterior cutaneous branch, supplying the skin of the paravertebral area; the lateral cutaneous branch, supplying the lateral aspect of the lateral and anterior portions of the chest wall; and the terminal branch, providing sensory fibers to the anterior portions of the chest and abdomen. Intercostal nerve blocks can be used for isolated surgical fields. They are also used to manage the pain of postherpetic neuralgia. Technique. The authors prefer the anterior approach through the midaxillary line. A 27-gauge needle is placed into the skin over the rib at the level of the anterior axillary line. The skin is gently pulled caudad. This allows the needle to fall in the sulcus below the rib. After careful aspiration, 2 to 3 mL of 0.25% bupivacaine with epinephrine are injected. For a lesion or surgical field that covers several dermatomes, however, the authors’ choice of analgesia is the placement of a thoracic epidural catheter (see previous section on central neuraxial blockade). Complications. Intravascular injection, local anesthetic toxicity with the use of large volumes of local anesthetic, and pneumothorax from the needle puncturing the pleural cavity have been reported.64 With the posterior approach, there is a risk for subarachnoid injection because the sheath communicates directly with the subarachnoid space. Abdomen Blocks Ilioinguinal and Iliohypogastric Nerve Blocks Anatomy and Indications. The subcostal nerve (T12) and the ilioinguinal and iliohypogastric nerves (derived from L1) innervate the inguinal area. The ilioinguinal and iliohypogastric nerves pass over the anterior superior iliac spine (ASIS) and, after piercing the internal oblique aponeurosis about 2 to 3 cm medial to the ASIS, travel between the internal and external oblique aponeurosis. Here they lie in close proximity to the spermatic cord and accompany the cord structures to the genitals. This block can be used for hernia repairs and other surgeries in the groin, including orchidopexy. Recent literature contradicts the popular belief that this block, when performed preemptively, may lead to significant preemptive analgesia.28 Technique. The ASIS is palpated. A point is marked 1.5 cm below and medial to the ASIS. The cord structures are palpated and a 27-gauge needle is placed into the area. Occasionally, a ‘‘pop’’ may be felt as the sheath is entered. Five to 10 mL of 0.25% bupivacaine with 1:200,000 epinephrine are injected.

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Complications. Although rare, there is the possibility of a hematoma developing in the area after injection. Penile Blocks Anatomy and Indications. The nerve supply of the penis is from the pudendal nerve and the pelvic plexus. Two dorsal nerves of the penis separate at the level of the symphysis pubis. These are terminal branches of the pudendal nerve. This block can be used for circumcision52 and other penile procedures when caudal blocks may be contraindicated. Techniques. Two methods are commonly used—a ‘‘ring’’ block and direct blockade of the dorsal nerves of the penis. For either technique, epinephrine should be avoided in the block solution to prevent ischemia. Care should be taken to avoid intravascular placement. To place a ring block, a ring of 0.25% plain bupivacaine is injected around the base of the penis. To block the dorsal nerves of the penis, a 27-gauge needle is inserted 1 cm above the symphysis pubis. The needle is advanced 1 cm after it pierces the penile fascia. After aspiration, 2 mL of 0.25% bupivacaine without epinephrine are injected slowly. The needle is then withdrawn and directed to the 2 o’clock position. Two to 3 mL of plain bupivacaine are injected. The needle is again withdrawn and then directed to the 10 o’clock position. Two to 3 mL of local anesthetic solution are injected. Complications. There is a mild risk of compromise to organ blood flow with the ring block. Applying pressure at the base of the penis can minimize hematoma formation after the block. Upper Extremity Blocks Brachial Plexus Block Several approaches to the brachial plexus are described in adults. These include the axillary, the interscalene, the supraclavicular, and the infraclavicular approaches. The axillary approach is the most commonly used technique for brachial plexus block in children. Anatomy and Indications. The anatomy of the brachial plexus is described in detail in many standard anesthesia textbooks. It arises from the C5, C6, C7, C8, and T1 nerve roots. In children, the axillary sheath, as well as the axillary artery, are easily palpated.91 Axillary nerve blocks can be used for procedures in the hand and arm that require prolonged pain relief.69 This can increase blood flow by decreasing the sympathetic tone. It can be used for placement of an Ilizarov device for the arm as well as for reimplantation of severed fingers. Technique. The arm is abducted to a 90 angle. The artery is palpated in the axilla. The use of a nerve stimulator allows accurate placement of the needle in the neurovascular sheath without trying to elicit

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paresthesia. The axillary sheath is divided into fascial compartments for each nerve. These may limit spread of the local anesthetic in the sheath. The transarterial approach involves direct puncture of the axillary artery. The needle is then advanced further into the sheath. Once blood is no longer aspirated, half the total volume of local anesthetic is injected. The needle is then pulled back beyond the artery and the other half of the local anesthetic is injected. The total dose of local anesthetic injected is 1 mL/kg of 0.25% bupivacaine or 1 mL/kg of 0.2% ropivacaine, up to a maximum dose of 40 mL. Regardless of technique, careful aspiration should be carried out before injection to eliminate intravascular local anesthetic injection. An additional cuff of local anesthetic is injected as a subcutaneous cuff to block the intercostobrachial nerve so that tourniquet pain is not experienced. Another approach is using multiple injections with the aid of a nerve stimulator. The needle is advanced into the facial sheath at a 45 angle to the skin above the pulsation of the axillary artery. When a twitch is elicited in the appropriate muscle group with the nerve stimulator, local anesthetic solution is injected. A ring of local anesthetic should be injected around the upper aspect of the arm. This will block the intercostobrachial nerve, which will provide analgesia for tourniquetrelated pain. Complications. A hematoma may form because of puncture of the axillary artery. This is usually self contained and can be prevented by applying pressure to the area.

Lower Extremity Blocks Caudal blocks are more commonly used for lower extremity procedures, but when a caudal block is contraindicated, a peripheral block should be considered. Sciatic Nerve Block Anatomy and indications. The sciatic nerve arises from the L4, L5, and S1 roots of the sacral plexus. It passes through the pelvis and is superficial at the lower margin of the gluteus maximus muscle. It then descends in the posterior aspect of the thigh, supplying sensory innervation to the entire posterior thigh and the leg and foot below the ankle, except the medial aspect, which is supplied by the femoral nerve. This block can be used for surgery below the knee. In combination with a femoral nerve block, complete analgesia of the leg and foot can be obtained. The authors use this block for unilateral club foot repair and for triple arthrodeses of the foot. Technique. Although the posterior approach is most commonly used in adult practice, it may be difficult in the anesthetized pediatric

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patient. The authors prefer the lateral approach to the popliteal fossa to block the sciatic nerve. This has a longer duration of analgesia in adults.59 Anatomy and Indications. The popliteal fossa is a diamond-shaped area located behind the knee, bordered laterally by the biceps femoris tendon and medially by the semitendinosus and semimembranosus muscles. The sciatic nerve, in adolescents, divides approximately 5 to 6 cm above the crease of the knee into its two major branches, the tibial nerve medially and the common peroneal nerve laterally. Technique. The lower leg is elevated on a pillow. The biceps femoris tendon is palpated. After sterile preparation, an insulated needle with a nerve stimulator attached is introduced at about 5 cm above the crease of the knee. Using low-voltage (0.2 mV–0.3 mV) electrical stimulation, the needle is slowly introduced anterior to the tendon (Fig. 7). Dorsiflexion or plantar flexion of the foot is seen when the needle is in approximately the right position. On injection, this response is eliminated, suggesting correct placement of the needle. Five milliliters (in infants and toddlers) to 15 mL (in adolescents) of 0.25% bupivacaine with epinephrine 1:200,000 are injected into the space. Careful aspiration is carried out to avoid intravascular injection. Complications. Intraneural placement can be prevented by using a nerve stimulator. Though rare, intravascular placement should be prevented by careful aspiration.

Figure 7. Lateral popliteal sciatic nerve block. (From Cote´ CJ, Todres ID, Ryan JF, et al (eds): A Practice of Anesthesia for Infants and Children, 3rd ed. Philadelphia: WB Saunders; 2001: 655; with permission.)

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Femoral Nerve Block Anatomy and Indications. The femoral nerve is located immediately lateral to the femoral artery in the inguinal area. This block is useful for surgery on the shaft of the femur.18, 90 This can be performed on arrival to the hospital to prevent pain caused by transport and other manipulations. Techniques. Because this is a motor nerve, the use of a nerve stimulator is desirable. Look for movement of the knee and the adductors. In adolescents, a volume of 10 to 15 mL of 0.25% bupivacaine with epinephrine 1:200,000 are injected into the fascial sheath. Another technique is to use a blunt needle to enter the femoral sheath. After the second ‘‘pop,’’ the needle will be in the femoral sheath. Following careful aspiration, 10 to 15 mL of local are anesthetic are injected. Complications. Bleeding and hematoma formation from the femoral artery and intraneural placement are the two major complications of this block. Lateral Femoral Cutaneous Nerve Block Anatomy and Indications. This nerve arises from the L2 and L3 roots of the lumbar plexus. It traverses the lateral border of the psoas muscle and passes obliquely under the fascia iliaca to enter the lateral aspect of the thigh. It is a pure sensory nerve, providing sensory fibers to the lateral portion of the thigh. Blockade can be used to provide analgesia to the lateral aspect of the thigh for skin and bone graft procurement and muscle biopsies.43, 56 Technique. A point 2-cm caudal and medial to the ASIS is located on the side to be blocked. The authors prefer using a blunt needle that is advanced slowly into the sheath. A distinct ‘‘pop’’ is felt as the needle enters the fascia iliaca compartment. In adolescents, 10 to 15 mL of 0.25% bupivacaine with epinephrine 1:200,000 are injected after careful aspiration. Complications. It is rare to see complications from this nerve block. Intraneural injection can cause dysesthesia that can last for a few weeks, however. Ankle Block Anatomy and Indications. The nerves for the ankle are primarily derived from the lumbo-sacral plexus, L4, L5, S1, S2, and S3 roots.68 Five nerves supply the ankle—tibial, supplying the sole of the foot; deep peroneal, supplying the web between the great toe and the middle toe; superficial peroneal, supplying the dorsum of the foot; saphenous, a branch of the femoral nerve supplying the medial aspect of the foot; and sural, supplying the lateral aspect of the foot. Technique. Because it is not necessary to elicit paresthesias while these nerves are located, an ankle block can be performed in the sedated

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patient without the use of a nerve stimulator. A 25-gauge needle is usually used to inject the local anesthetic. In adolescents, a volume of 5 to 10 mL for each of the nerves to be blocked may be necessary. • Tibial nerve: A 27-gauge needle is inserted at the posterior angle of the tibia lateral to the pulsation of the tibial artery until bony contact is made. The needle is then pulled back a few millimeters and 5 to 10 mL of 0.25% plain bupivacaine are injected. • Deep peroneal nerve: This nerve continues midway between the malleoli onto the dorsum of the feet. A 27-gauge needle is inserted between the anterior tibial and the extensor hallucis longus tendons. This is usually lateral to the pulsation of the dorsalis pedis artery. The needle is advanced until the bony surface of the tibia is felt. It is then withdrawn a few millimeters and 3 to 5 mL of 0.25% bupivacaine are injected. • Superficial peroneal nerve: This nerve perforates the deep fascia and runs along the anterior aspect of the dorsum of the foot. A subcutaneous infiltration of 3 to 4 mL of local anesthetic solution between the medial and lateral malleolus can block this nerve. • Sural nerve: This is a cutaneous nerve that arises from the union of a branch of the tibial and the common peroneal nerves. It runs below and lateral to the lateral malleolus. A 27-gauge needle is inserted below the lateral malleolus toward the fibula. Three to 5 mL of plain 0.25% bupivacaine are injected. • Saphenous nerve: This is the terminal sensory branch of the femoral nerve. A skin wheal placed above and medial to the medial malleolus will block the saphenous nerve. Digital Nerve Blocks Anatomy and Indications. Digital nerves supply all fingers and toes. In the hand, the common digital nerves are derived from the median and ulnar nerves and divide in the palm to volar digital nerves that supply the fingers. All digital nerves have accompanying digital arteries. The digital nerves of the foot are derived from the plantar cutaneous branches of the tibial nerve. Digital blocks can be used for providing analgesia for ingrown toenails, laser treatment of warts,93 traumatic injuries of the nailbed, and for ischemia secondary to Raynaud’s phenomenon related to collagen vascular disease. Techniques. Thumb. With the thumb extended, a 27-gauge needle is inserted into the palmar surface of the hand between the index finger and thumb. The needle is advanced to the junction of the web space and the palmar skin of the hand. One mL of local anesthesia without epinephrine is injected after careful aspiration to prevent intravascular placement. Other fingers. Digital nerves for the other fingers can be blocked by placing a 27-gauge needle into the web about 3 mm proximal to the

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junction between the web and the palmar skin; 1 mL of 0.25% bupivacaine without epinephrine is injected into each web space. Toes. These techniques can be difficult to perform because of the thickness of the overlying skin. A dorsolateral approach is preferred, in which the web space is accessed from the dorsum of the foot; 1 mL of local anesthetic without epinephrine is injected into each web space. Complications. Large volumes can cause ischemia through pressure. Vasoconstrictors should be avoided because they may lead to ischemia and necrosis of the digit. SUMMARY In children, regional anesthetic techniques are safe and effective adjuncts to general anesthesia and for postoperative pain relief. Application of the techniques described in this article will contribute to improved care for pediatric patients undergoing surgical procedures. The judicious choice of local anesthetics, along with the blockades of targeted nerves, decrease the need for supplemental analgesics in the recovery phase. References 1. Abouleish A, Nguyen NC, Mayhew JF: Aseptic meningitis after spinal anesthesia in an infant. Anesthesiology 92:1200–1201, 2000 2. Anand KJ: Pain, plasticity, and premature birth: A prescription for permanent suffering? Nat Med 6:971–973, 2000 3. Bardsley H, Gristwood R, Baker H, et al: A comparison of the cardiovascular effects of levobupivacaine and rac- bupivacaine following intravenous administration to healthy volunteers. Br J Clin Pharmacol 46:245–249, 1998 4. Barros S: Loss-of-resistance technique using both air and saline. Reg Anesth 20: 462–463, 1995 5. Blanco D, Llamazares J, Rincon R, et al: Thoracic epidural anesthesia via the lumbar approach in infants and children. Anesthesiology 84:1312–1316, 1996 6. Bosenberg AT, Gouws E: Skin–epidural distance in children. Anaesthesia 50:895–897, 1995 7. Bosenberg AT, Kimble FW: Infraorbital nerve block in neonates for cleft lip repair: Anatomical study and clinical application. Br J Anaesth 74:506–508, 1995 8. Bouchut JC, Dubois R, Godard J: Clonidine in preterm-infant caudal anesthesia may be responsible for postoperative apnea. Reg Anesth Pain Med 26:83–85, 2001 9. Breschan C, Krumpholz R, Likar R, et al: Can a dose of 2 microg.kg(1) caudal clonidine cause respiratory depression in neonates? Paediatr Anaesth 9:81–83, 1999 10. Busoni P, Messeri A: Spinal anesthesia in children: Surface anatomy. Anesth Analg 68: 418–419, 1989 11. Busoni P, Messeri A: Loss of resistance technique to air for identifying the epidural space in infants and children. Use an appropriate technique! Paediatr Anaesth 5: 397, 1995 12. Casta A: Attempted placement of a thoracic epidural catheter via the caudal route in a newborn. Anesthesiology 91:1965–1966, 1999 13. Constant I, Gall O, Gouyet L, et al: Addition of clonidine or fentanyl to local anaesthetics prolongs the duration of surgical analgesia after single-shot caudal block in children. Br J Anaesth 80:294–298, 1998

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14. Cote´ CJ, Zaslavsky A, Downes JJ, et al: Postoperative apnea in former preterm infants after inguinal herniorrhaphy. A combined analysis. Anesthesiology 82:809–822, 1995 15. Cox RG, Goresky GV: Life-threatening apnea following spinal anesthesia in former premature infants. Anesthesiology 73:345–347, 1990 16. Cregg N, Conway F, Casey W: Analgesia after otoplasty: Regional nerve blockade vs local anaesthetic infiltration of the ear. Can J Anaesth 43:141–147, 1996 17. Dahl JB, Kehlet H: The value of pre-emptive analgesia in the treatment of postoperative pain. Br J Anaesth 70:434–439, 1993 18. Denton JS, Manning MP: Femoral nerve block for femoral shaft fractures in children: Brief report. J Bone Joint Surg Br 70:84, 1988 19. Easley RB, George R, Connors D, et al: Aseptic meningitis after spinal anesthesia in an infant. Anesthesiology 91:305–307, 1999 20. Fanelli G, Casati A, Beccaria P, et al: A double-blind comparison of ropivacaine, bupivacaine, and mepivacaine during sciatic and femoral nerve blockade. Anesth Analg 87:597–600, 1998 21. Fisher QA, Shaffner DH, Yaster M: Detection of intravascular injection of regional anaesthetics in children. Can J Anaesth 44:592–598, 1997 22. Flandin-Blety C, Barrier G: Accidents following extradural analgesia in children. The results of a retrospective study. Paediatr Anaesth 5:41–46, 1995 23. Foster RH, Markham A: Levobupivacaine: A review of its pharmacology and use as a local anaesthetic. Drugs 59:551–579, 2000 24. Frumiento C, Abajian JC, Vane DW: Spinal anesthesia for preterm infants undergoing inguinal hernia repair. Arch Surg 135:445–451, 2000 25. Gallagher TM, Crean PM: Spinal anaesthesia in infants born prematurely. Anaesthesia 44:434–436, 1989 26. Gerancher JC: Cauda equina syndrome following a single spinal administration of 5% hyperbaric lidocaine through a 25-gauge Whitacre needle. Anesthesiology 87: 687–689, 1997 27. Giaufre E, Dalens B, Gombert A: Epidemiology and morbidity of regional anesthesia in children: A 1-year prospective survey of the French-Language Society of Pediatric Anesthesiologists. Anesth Analg 83:904–912, 1996 28. Gill P, Kiani S, Victoria BA, et al: Pre-emptive analgesia with local anaesthetic for herniorrhaphy. Anaesthesia 56:414–417, 2001 29. Glantz L, Gozal Y, Gertel M: A loss-of-resistance technique using both air and saline. Reg Anesth Pain Med 19:294, 1994 30. Goldman LJ: Complications in regional anaesthesia. Paediatr Anaesth 5:3–9, 1995 31. Guinard JP, Borboen M: Probable venous air embolism during caudal anesthesia in a child. Anesth Analg 76:1134–1135, 1993 32. Gunter JB, Eng C: Thoracic epidural anesthesia via the caudal approach in children. Anesthesiology 76:935–938, 1992 33. Gunter JB, Watcha MF, Forestner JE, et al: Caudal epidural anesthesia in conscious premature and high-risk infants. J Pediatr Surg 26:9–14, 1991 34. Hampl KF, Schneider MC, Pargger H, et al: A similar incidence of transient neurologic symptoms after spinal anesthesia with 2% and 5% lidocaine. Anesth Analg 83:1051– 1054, 1996 35. Harnik EV, Hoy GR, Potolicchio S, et al: Spinal anesthesia in premature infants recovering from respiratory distress syndrome. Anesthesiology 64:95–99, 1986 36. Hasan MA, Howard RF, Lloyd-Thomas AR: Depth of epidural space in children. Anaesthesia 49:1085–1087, 1994 37. Henderson K, Sethna NF, Berde CB: Continuous caudal anesthesia for inguinal hernia repair in former preterm infants. J Clin Anesth 5:129–133, 1993 38. Hiller A, Karjalainen K, Balk M: Transient neurological symptoms after spinal anaesthesia with hyperbaric 5% lidocaine or general anaesthesia. Br J Anaesth 82:575–579, 1999 39. Holthusen H, Eichwede F, Stevens M, et al: Pre-emptive analgesia: Comparison of preoperative with postoperative caudal block on postoperative pain in children. Br J Anaesth 73:440–442, 1994 40. Ivani G, De Negri P, Conio A, et al: Ropivacaine–clonidine combination for caudal blockade in children. Acta Anaesthesiol Scand 44:446–449, 2000

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41. Ivani G, Mereto N, Lampugnani E, et al: Ropivacaine in paediatric surgery: Preliminary results. Paediatr Anaesth 8:127–129, 1998 42. Keld DB, Hein L, Dalgaard M, et al: The incidence of transient neurologic symptoms (TNS) after spinal anaesthesia in patients undergoing surgery in the supine position. Hyperbaric lidocaine 5% versus hyperbaric bupivacaine 0.5%. Acta Anaesthesiol Scand 44:285–290, 2000 43. Khan ML, Hossain MM, Chowdhury AY, et al: Lateral femoral cutaneous nerve block for split skin grafting. Bangladesh Med Res Counc Bull 24:32–34, 1998 44. Kinirons B, Mimoz O, Lafendi L, et al: Chlorhexidine versus povidone iodine in preventing colonization of continuous epidural catheters in children: A randomized, controlled trial. Anesthesiology 94:239–244, 2001 45. Kokki H, Hendolin H: Hyperbaric bupivacaine for spinal anaesthesia in 7–18 year old children: Comparison of bupivacaine 5 mg mL1 in 0.9% and 8% glucose solutions. Br J Anaesth 84:59–62, 2000 46. Kokki H, Tuovinen K, Hendolin H: Spinal anaesthesia for paediatric day-case surgery: A double-blind, randomized, parallel-group, prospective comparison of isobaric and hyperbaric bupivacaine. Br J Anaesth 81:502–506, 1998 47. Kost-Byerly S, Tobin JR, Greenberg RS, et al: Bacterial colonization and infection rate of continuous epidural catheters in children. Anesth Analg 86:712–716, 1998 48. Kozek-Langenecker SA, Marhofer P, Jonas K, et al: Cardiovascular criteria for epidural test dosing in sevofluvane and halathane anesthetized in children. Anesth Analg 90: 579–583, 2000 49. Krane EJ, Dalens BJ, Murat I, et al: The safety of epidurals placed during general anesthesia. Reg Anesth Pain Med 23:433–438, 1998 50. Krane EJ, Haberkern CM, Jacobson LE: Postoperative apnea, bradycardia, and oxygen desaturation in formerly premature infants: Prospective comparison of spinal and general anesthesia. Anesth Analg 80:7–13, 1995 51. Larsson BA, Lonnqvist PA, Olsson GL: Plasma concentrations of bupivacaine in neonates after continuous epidural infusion. Anesth Analg 84:501–505, 1997 52. Lau JT: Penile block for pain relief after circumcision in children. A randomized, prospective trial. Am J Surg 147:797–799, 1984 53. Lee JJ, Rubin AP: Comparison of a bupivacaine–clonidine mixture with plain bupivacaine for caudal analgesia in children. Br J Anaesth 72:258–262, 1994 54. Lonnqvist PA, Westrin P, Larsson BA, et al: Ropivacaine pharmacokinetics after caudal block in 1–8 year old children. Br J Anaesth 85:506–511, 2000 55. Loo CC, Irestedt L: Cauda equina syndrome after spinal anaesthesia with hyperbaric 5% lignocaine: A review of six cases of cauda equina syndrome reported to the Swedish Pharmaceutical Insurance, 1993–1997. Acta Anaesthesiol Scand 43:371–379, 1999 56. Maccani RM, Wedel DJ, Melton A, et al: Femoral and lateral femoral cutaneous nerve block for muscle biopsies in children. Paediatr Anaesth 5:223–227, 1995 57. Markey JR, Montiague R, Winnie AP: A comparative efficacy study of hyperbaric 5% lidocaine and 1.5% lidocaine for spinal anesthesia. Anesth Analg 85:1105–1107, 1997 58. McKinney P, Gottlieb J: The relationship of the great auricular nerve to the superficial musculoaponeurotic system. Ann Plast Surg 14:310–314, 1985 59. McLeod DH, Wong DH, Vaghadia H, et al: Lateral popliteal sciatic nerve block compared with ankle block for analgesia following foot surgery. Can J Anaesth 42: 765–769, 1995 60. McLeod GA, Burke D: Levobupivacaine. Anaesthesia 56:331–341, 2001 61. McNeely JK, Farber NE, Rusy LM, et al: Epidural analgesia improves outcome following pediatric fundoplication. A retrospective analysis. Reg Anesth Pain Med 22:16–23, 1997 62. McNeely JK, Trentadue NC, Rusy LM, et al: Culture of bacteria from lumbar and caudal epidural catheters used for postoperative analgesia in children. Reg Anesth Pain Med 22:428–431, 1997 63. Miguel R, Morse S, Murtagh R: Epidural air associated with multiradicular syndrome. Anesth Analg 73:92–94, 1991 64. Moore DC, Bridenbaugh PO: Pneumothorax: Its incidence following intercostal nerve block. JAMA 174:842, 1960

112

SURESH & WHEELER

65. Murat I, Delleur MM, Esteve C, et al: Continuous extradural anaesthesia in children. Clinical and haemodynamic implications. Br J Anaesth 59:1441–1450, 1987 66. Murrell D, Gibson PR, Cohen RC: Continuous epidural analgesia in newborn infants undergoing major surgery. J Pediatr Surg 28:548–552, 1993 67. Nay PG, Milaszkiewicz R, Jothilingam S: Extradural air as a cause of paraplegia following lumbar analgesia. Anaesthesia 48:402–404, 1993 68. Needoff M, Radford P, Costigan P: Local anesthesia for postoperative pain relief after foot surgery: A prospective clinical trial. Foot Ankle Int 16:11–13, 1995 69. Neill RS: Postoperative analgesia following brachial plexus block. Br J Anaesth 50: 379–382, 1978 70. Oberlander TF, Berde CB, Lam KH, et al: Infants tolerate spinal anesthesia with minimal overall autonomic changes: Analysis of heart rate variability in former premature infants undergoing hernia repair. Anesth Analg 80:20–27, 1995 71. Peng PW, Chan VW, Perlas A: Minimum effective anaesthetic concentration of hyperbaric lidocaine for spinal anaesthesia. Can J Anaesth 45:122–129, 1998 72. Peutrell JM, Hughes DG: A grand mal convulsion in a child in association with a continuous epidural infusion of bupivacaine. Anaesthesia 50:563–564, 1995 73. Polaner D, Suresh S, Cote´ CJ: Pediatric regional anesthesia. In Cote´ C, Todres ID, Ryan JF, et al (eds): Pediatric Regional Anesthesia: A Practice Of Anesthesia for Infants and Children. Philadelphia, WB Saunders, 2000, pp 636–675 74. Prabhu KP, Wig J, Grewal S: Bilateral infraorbital nerve block is superior to periincisional infiltration for analgesia after repair of cleft lip. Scand J Plast Reconstr Surg Hand Surg 33:83–87, 1999 75. Saberski LR, Kondamuri S, Osinubi OY: Identification of the epidural space: Is loss of resistance to air a safe technique? A review of the complications related to the use of air. Reg Anesth Pain Med 22:3–15, 1997 76. Salmela L, Aromaa U: Transient radicular irritation after spinal anesthesia induced with hyperbaric solutions of cerebrospinal fluid-diluted lidocaine 50 mg/mL or mepivacaine 40 mg/mL or bupivacaine 5 mg/mL. Acta Anaesthesiol Scand 42:765–769, 1998 77. Sartorelli KH, Abajian JC, Kreutz JM, et al: Improved outcome utilizing spinal anesthesia in high-risk infants. J Pediatr Surg 27:1022–1025, 1992 78. Schulte-Steinberg O: Regional anaesthesia for children. Ann Chir Gynaecol 73:158– 165, 1984 79. Schwartz N, Eisenkraft JB: Probable venous air embolism during epidural placement in an infant. Anesth Analg 76:1136–1138, 1993 80. Scott DB: Identification of the epidural space: Loss of resistance to air or saline? Reg Anesth Pain Med 22:1–2, 1997 81. Sethna NF, Berde CB: Venous air embolism during identification of the epidural space in children. Anesth Analg 76:925–927, 1993 82. Shiga M, Nishina K, Mikawa K, et al: Oral clonidine premedication does not change efficacy of simulated epidural test dose in sevoflurane-anesthetized children. Anesthesiology 93:954–958, 2000 83. Strafford MA, Wilder RT, Berde CB: The risk of infection from epidural analgesia in children: A review of 1620 cases. Anesth Analg 80:234–238, 1995 84. Suresh S, Barcelona S, Young N, et al: Postoperative pain management in children undergoing tympanomastoid surgery: Is a local block better than intravenous opioids? Anesthesiology 91:A1281, 1999 85. Suresh S, Wagner AM: Scalp excisions: Getting ‘‘ahead’’ of pain. Pediatr Dermatol 18: 74–76, 2001 86. Taddio A, Katz J, Ilersich AL, et al: Effect of neonatal circumcision on pain response during subsequent routine vaccination. Lancet 349:599–603, 1997 87. Tanaka M, Nishikawa T: Simulation of an epidural test dose with intravenous epinephrine in sevoflurane-anesthetized children. Anesth Analg 86:952–957, 1998 88. Tanaka M, Nishikawa T: The efficacy of a simulated intravascular test dose in sevoflurane-anesthetized children: A dose-response study. Anesth Analg 89:632–637, 1999 89. Tanaka M, Kimura T, Goyagi T, et al: Evaluating hemodynamic and T wave criteria of simulated intravascular test doses using bupivacaine or isoproterenol in anesthetized children. Anesth Analg 91:567–572, 2000

PRACTICAL PEDIATRIC REGIONAL ANESTHESIA

113

90. Tobias JD: Continuous femoral nerve block to provide analgesia following femur fracture in a paediatric ICU population. Anaesth Intensive Care 22:616–618, 1994 91. Tobias JD: Brachial plexus anaesthesia in children. Paediatr Anaesth 11:265–275, 2001 92. Tsui BC, Seal R, Entwistle L: Thoracic epidural analgesia via the caudal approach using nerve stimulation in an infant with CATCH22. Can J Anaesth 46:1138–1142, 1999 93. Wagner AM, Suresh S: Peripheral nerve blocks for warts: Taking the cry out of cryotherapy and laser. Pediatr Dermatol 15:238–241, 1998 94. Welborn LG, Rice LJ, Hannallah RS, et al: Postoperative apnea in former preterm infants: Prospective comparison of spinal and general anesthesia. Anesthesiology 72: 838–842, 1990 95. Wong K, Strichartz GR, Raymond SA: On the mechanisms of potentiation of local anesthetics by bicarbonate buffer: Drug structure-activity studies on isolated peripheral nerve. Anesth Analg 76:131–143, 1993 96. Wright TE, Orr RJ, Haberkern CM, et al: Complications during spinal anesthesia in infants: High spinal blockade. Anesthesiology 73:1290–1292, 1990 97. Yamashita M: Mathematical formula for assessing the depth of the epidural space in children. Anaesthesia 52:94–95, 1997 98. Cote´ CJ, Todres ID, Goudsouzian NG, et al (eds): A Practice of Anesthesia for Infants and Children, 3rd ed. Philadelphia, WB Saunders, 2001, p 655 Address reprint requests to Santhanam Suresh, MD Department of Anesthesiology, Box #19 Children’s Memorial Hospital Northwestern University Medical School Chicago, IL 60614 e-mail: [email protected].