regional anesthesia in pediatrics

REGIONAL ANESTHESIA 0889-8537/00 $15.00 + .OO

REGIONAL ANESTHESIA IN PEDIATRICS

Dorothea A. Markakis, MD

REGIONAL ANESTHESIA FOR PEDIATRICS

The use of regional anesthetic techniques in infants and children has become increasingly accepted as standard of care during the final decades of the twentieth century. The growing use of regional anesthetic techniques in infants and children is due in part to the increased clinical experience and training of pediatric anesthesiologists, as well as to the recognition of the benefits conferred by regional anesthesia offered in conjunction with general anesthesia. Regional anesthetic techniques can reduce the overall intraoperative requirement of both inhaled and intravenous anesthetic agents and allow a more rapid return to the conscious preoperative state while providing effective postoperative pain relief with minimal sedation. Better understanding of the pharmacologic and pharmacodynamic properties of local anesthetic agents and clinical reports of regional anesthetic-related complications in infants and children have fine-tuned our techniques and allowed us to improve patient safety.8, 58, 95

Among the most commonLy performed regional anesthesia techniques in children are caudal and lumbar approaches to the epidural space, and ilioinguinal/ iliohypogastric and penile nerve blockade. Fol- lowing is a brief review of these and other blocks, with a discussion of risks and benefits, technique, drug dosages, and local anesthetic toxicity considerations. Many of these techniques, notably the thoracic epidural, should only be performed by anesthesiologists who are well versed in regional anesthetic techniques in children. Many academic training cen-

From the Department of General Anesthesiology, Section of Pediatric Anesthesia, The Cleveland Clinic Foundation, Cleveland, Ohio

ANESTHESIOLOGY CLINICS OF NORTH AMERICA

VOLUME 18 * NUMBER 2 *JUNE 2000 355

ters caring for pediatric patients offer review courses and clinical oppor- tunities to learn or refresh regional anesthetic skills for interested anesthesiologists.

In contrast to adults, who can cooperate and remain still while undergoing a regional anesthetic procedure while awake, most of these procedures are performed under general anesthesia or deep sedation in infants and young children. The requirement of an anesthetized or heavily sedated patient eliminates the potential warning signs of neural injury, including paresthesia due to needle trauma and inadvertent intra- neural injection. In addition, detection of an intravascular or intrathecal injection after test dose may be masked by general anesthesia.3o The former issue has been examined by several investigators.3Or 31, 3a, 37, 39, 96

Suggestions for minimizing inadvertent intravascular injection of local anesthetic will be discussed later. With respect to neurologic injury, although rare, there are reports of serious permanent neurologic deficit after regional anesthetic blockade in pediatric patients.% Fortunately, as pointed out by Krane and colleagues,5* the theoretically increased risk of neurologic injury when performing epidural and peripheral nerve blocks on anesthetized children has not been borne out in the majority of case series reported in the literat~re.~, 383 94, Io1 Recent concern has been voiced by leaders in pediatric pain management in response to a report of paraplegia following placement of a thoracic epidural catheter in an anesthetized adult patient. Krane et a1 specifically examined and questioned several issues of judgment in this adult case, including patient selection, technique selected for site of surgery, insertion of an epidural needle near the site of prior spine surgery, persistence despite multiple failed attempts to perform a block, and the use of air to identify the epidural space. The authors of the case report condemned the placement of the thoracic epidural catheter after induction of general anesthesia.” This conclusion was drawn without consideration for patient age, mental status, and ability to cooperate, with obvious implications for the pediatric population, the majority of whom undergo regional anesthetic blockade after induction of general anesthesia. In an eloquent editorial, Krane and colleagues urged appropriately trained and skilled anesthesiologists not to withhold these or other valuable regional anesthesia modalities from children based on the adverse outcome reported. There are numerous surveys and reports supporting the overall safety and relatively rare serious complications of caudal, epidural, and other regional anesthetic blocks in children.15,

41, 74,

=, &, 73

Caudal Blockade

Caudal blockade is the single most popular regional anesthetic technique used in infants and children. Caudal anesthesia is useful for patients undergoing circumcision, hypospadius repair, inguinal hernia repair, orchiopexy, and minor lower extremity and perineal surgery. In surgery anticipated to be longer than 3 hours, caudal blockade can be

REGIONAL ANESTHESIA IN PEDIATRICS 357

performed before and after the surgical procedure, taking into account the maximum allowable doses of local anesthetic.

Equipment

Needles that can be used for the caudal block include a 22-gauge intravenous catheter, a 23-gauge butterfly, and a blunt 23-gauge needle connected by extension tubing to an appropriately sized syringe. Many anesthesiologists, including this author, prefer the 22-gauge, 1 inch intravenous catheter. An intravenous cannula can be advanced 1 to 2 cm over the stylette into the caudal epidural space with minimal risk of blood vessel or dural puncture. If not easily advanced, it is unlikely the catheter is in the caudal epidural space. There is a theoretical risk that use of unstyletted needles could cause an implantation d e r m ~ i d . ~ ~

Technique

The landmarks for a caudal anesthesia block are easily palpable and identified in most patients less than 30 kg. The anesthetized patient is placed in the lateral decubitus position with the legs flexed, and the sacral hiatus is identified. An equilateral triangle is formed by the two posterior iliac crests and the sacral hiatus. The large bony processes on either side of the sacral hiatus are named the sacral cornua (Fig. 1). As for all blocks, the skin should be prepared with either an iodine solution or alcohol. Iodine-containing solutions should be allowed to dry or be wiped with alcohol to avoid introducing sdution into the epidural space.

After preparation of the skin, the caudal needle is introduced with the bevel facing anteriorly (to decrease the chance of entering the anterior sacral wall) at a 45-degree angle to the dorsal surface of the sacrum. If an unstyletted needle is used, the site of needle insertion should first be punctured with a larger-bore needle. As the caudal needle is advanced, a loss of resistance is felt as the needle passes through the sacrococcygeal ligament. In larger infants and children, the angle of the caudal needle is then lowered to 15 degrees and the needle (or the intravenous catheter advanced over the stylette) is advanced 1 to 2 mm to ensure that the bevel of the needle (or intravenous catheter) lies in the caudal epidural space. In smaller infants, advancing the needle after loss of resistance may increase the risk of dural puncture.

After confirming no return of cerebrospinal fluid or blood either spontaneously or with gentle aspiration, a test dose of 1 mL (infant up to 5 kg) or 2 mL (5-20 kg) of local anesthetic containing freshly added epinephrine (1:200,000) is injected. During the 1 to 2 minutes after injection, the electrocardiogram is observed for tachycardia (heart rate increased 20%), arrhythmia, or ST or T wave changes, any of which indicate intravascular placement of the caudal needle. One should also avoid injection of air to minimize the risk of venous air embolism via

358 MAFXAKIS

Figure 1. Landmarks for caudal blockade. (From Sethna NF, Berde CB: Pediatric regional anesthesia. In Gregory GA (ed): Pediatric Anesthesia, ed 3. New York, Churchill-Living- stone, 1994, p 291; with permission.)

the vascular epidural ~pace.9~ After a negative test dose, the appropriate local anesthetic dose is slowly injected in 2 to 3 mL aliquots via the caudal needle while one or two fingers of the other hand are held over the dorsum of the sacrum cephalad to the injection site to detect inadvertent subcutaneous injection. Residual iodine-containing solution should be thoroughly removed after completion of the procedure to reduce the risk of skin irritation or burn injury.

Dosing

The duration of analgesia produced by a caudal block depends on the concentration, dose of local anesthetic, and the presence of epinephrine in the local anesthetic. Several formulas and nomograms are available to estimate the appropriate dose of local anesthetic.33, Io3 It is this author's practice to use the simple dosing scheme described by Yaster and Maxwell,"' which affords adequate analgesia levels with blood concentration levels not associated with systemic toxicity. Caudal bupivacaine 0.25% in a dose of 2.5 mg/kg, or more simply, a dose of 1 mL/kg, should block approximately 10 spinal segments (up to T7), with a maximum volume of 20 mL. Addition of epinephrine 1:200,000 not only is a useful marker for intravascular injection, but may also signifi-


cantly prolong the duration of action of b~pivacaine.~~, Io6 If a surgical procedure exceeds 3 hours, the caudal may be repeated with the same volume used in the first dose of the more dilute 0.125% bupivacaine to minimize the risk of toxicity as well as motor blockade. Medications in addition to or instead of local anesthetic have been used, including opioids, clonidine, and ketamine. These have been recently reviewed and well des~r ibed .~~

Risks, Complications, Contraindications

Risks of caudal blockade include failed block, which is most commonly caused by subcutaneous injection and intravascular or intraos- seous injection, either of which may produce systemic toxicity if peak plasma concentrations fall within the toxic range ( > 2 4 pg/mL). Slow injection of drug will result in lower peak concentrations. Local anesthetics can enter the cerebral circulation by retrograde flow via the valveless extradural veins, resulting in seizures at a lower

Dural puncture is more likely to occur in neonates, whose dura end at S3 or S4 versus S1 to S2 in children older than 1 year and adults. Dural puncture is also more likely in patients with unfused sacral vertebral laminae at a higher level than the sacral hiatus and if the caudal needle is introduced more than 2 mm into the sacral canal. A large dose of local anesthetic in the subarachnoid space will result in a "total spinal" and symptoms of apnea, unconsciousness, and dilated pupils. Young children (less than 6 years old) usually exhibit stable hemodynamics, and a total spinal typically resolves in 1 to 2 Treatment of a total spinal should include securing and supporting the airway with endotracheal intubation and ventilation and supporting the circulation in the case of unstable hernodynamics with intravenous fluid and vasoactive drugs.

Penetration of the sacrum, which is soft and cartilaginous, may result in damage to the pelvic organs or blood vessels. Urinary retention is uncommon in well-hydrated children after caudal blockade with 0.25% bupivacaine.36 Paresthesia and motor weakness occur with higher concentrations of local anesthetic and may be particularly disturbing to some children.76 Bupivacaine 0.125% offers comparable analgesia and less motor blockade.

Contraindications to caudal anesthesia and all epidural blocks include sepsis, local infection of the skin at the injection site, coagulopathy, major sacral anomalies, increased intracranial pressure, meningomyelo- cele, and uncorrected hypovolemia. Relative contraindications include active neurologic disease.

LUMBAR EPIDURAL

A catheter placed into the epidural space via the caudal, lumbar, or thoracic route offers the advantage of continuous epidural delivery of

360 MARKAKIS

local anesthetic or opioid both intraoperatively and postoperatively. In addition, placement of the epidural catheter at a level near the site of surgery allows drug delivery at the appropriate segmental level and reduced epidural drug dosage.

Many authors have successfully provided high lumbar and even thoracic levels of analgesia in infants via a caudal epidural catheter advanced to those levels.&, 84 It is logistically easier to maintain a clean, dry area at the lumbar level than at the caudal level, however. Radio- graphic examination is required to accurately determine the exact segmental level of the tip of the catheter that has been advanced cephalad from the caudal to lumbar or thoracic level, or the lumbar to thoracic level. Authors have reported different rates of success in advancing a catheter from the caudal or lumbar approach to the thoracic level. Increasing age (with accompanying increasing lumbar lordosis and increasing density of epidural fat during childhood) has been postulated to diminish the rate of successful catheter advancement when demonstrated radiographically.", 12, 85

If epidural infusion of local anesthetic is planned to provide analgesia for thoracoabdominal-level surgery, Berde recommends considering the following alternatives: (1) use of hydrophilic opioids (such as preservative-free morphine) with caudal or lumbar catheter placement, (2) advancement of caudal or lumbar catheters to the thoracic level, (3) thoracic epidural catheter placement (in skilled hands, weighing risks and benefits)?

Direct placement of an epidural catheter at the thoracic level will not be reviewed here for the reasons discussed previously. A thoracic epidural catheter should be placed only when specifically indicated because of the potentially high risk of significant injury. Only anesthesiologists with extensive expertise in pediatric and regional anesthesia techniques should attempt to place a thoracic or other epidural catheter in anesthetized children.

Epidural analgesia is useful not only for prevention and treatment of postoperative pain, but also for amelioration of symptoms and pain from chronic disorders ranging from impaired pulmonary function, as in obstructive pulmonary disease, cystic fibrosis, and trauma (flail chest), to pain refractory to conventional therapy as in sickle cell vaso-occlusive crisis and terminal cancer pain. The attendant sympathetic blockade can be beneficial to patients with reflex sympathetic dystrophy and patients status-post microvascular surgery."O

Equipment

The 18-gauge Tuohy needle is available in a shorter pediatric length of 2.0 in (5.1 cm), compared with the adult size 3.5 in (8.89 cm). The Tuohy needle has a stylette to prevent introducing skin into the epidural space and has a smooth-shaped end designed to direct the catheter along the epidural space and avoid the risk of dural puncture. If a


preassembled epidural kit is not available, the anesthesiologist should ensure that the available epidural catheter fits through the Tuohy needle and note the distance at which the catheter extends beyond the Tuohy needle.

Technique

After disinfecting the skin with an iodine-containing solution and draping the lumbar area, an 18-gauge pediatric Tuohy needle is introduced at the L3 to L4 interspace in the midline. The loss of resistance technique is used to locate the lumbar epidural space with a syringe containing preservative-free saline. The syringe should be free of air to avoid the risk of venous air embolism.95 The lumbar epidural space in children is located only 10 to 18 mm from the ~kin.2~ An epidural catheter is introduced at the lumbar epidural space and advanced 1.5 to 2 cm beyond the end of the Tuohy needle.

Epidural catheters can easily migrate or be misplaced into an epidural vein, the subarachnoid space, or a nerve root. A test dose is important in detecting intravascular or subarachnoid placement of the catheter. After confirmation of no spontaneous return of cerebrospinal fluid or blood from the catheter (held below the level of the patient), a test dose containing epinephrine (1:200,000 or 5 &mL) should be administered for the caudal test dose. A volume of 0.1 to 0.2 mL/kg of the test solution 1.5% lidocaine with 1:200,000 epinephrine is administered after aspirating for blood and cerebrospinal fluid while the electrocardiogram is observed for 2 to 3 minutes for tachycardia or T wave changes. The test dose may be repeated if necessary. A negative test dose does not rule out the possibility of an intravascular or subarachnoid catheter. As discussed previously for caudal injections, the total dose should be injected slowly and in divided doses over 5 to 10 minutes to decrease the peak plasma concentration and minimize the risk of toxicity.

Because children usually are anesthetized during epidural catheter placement, evidence of a properly placed and functioning epidural (beyond a negative test dose) includes a diminished response to surgical stimulation and a reduced requirement of anesthetic agent. During the postoperative period when the child is awake, the segmental level of blockade and adequacy of pain control can be further assessed.

Dosing

The spread of local anesthetic injected into the epidural space is less predictable at the lumbar and thoracic levels than at the caudal level. Many formulas are available to estimate the appropriate dose of local anesthetic in the lumbar epidural space. Suggested doses range from 0.5 mL/kg to 0.75 mL/kg of 0.25% bupivacaine, depending on the site of surgery and adhering to maximum allowable dosage guidelines.” 85

Epidural analgesia can be provided by continuous infusion or patient-controlled epidural analgesia (PCEA) pumps. Careful physician and nursing assessment, standardized epidural drug dosing forms with attention to maximum allowable infusion rates of local anesthetic, and adherence to systematic protocols are imperative to providing safe epidural analgesia outside the operating room.

The initial bupivacaine dose should not exceed 2.0 to 2.5 mg/ kg.* The concentration of bupivacaine for continuous epidural is most commonly 1 mg/mL at doses of 0.2 mg/kg/h (for desired sensory level below T10) and 0.3 mg/kg/h (for desired sensory level above T10). Subsequent infusion rates should not exceed 0.4 to 0.5 mg/kg/h for older infants, toddlers, and children, or 0.2 to 0.25 mg/kg/h for neonates.8 Patients with risk factors for seizures should have continuous infusion rates of bupivacaine reduced even further. Such risk factors include increased uptake into circulation, such as the presence of an arteriovenous malformation, a past history of febrile seizures, or seizures induced by hypomagnesemia or acute hyponatremia.8

Opioid can be added to the local anesthetic at doses of fentanyl 1 to 2.5 pg/mL dosed 0.5 to 1.0 pg/kg/h, or hydromorphone 10 pg/mL dosed 2 to 3 pg/kg/h, or preservative-free morphine (Duramorph) 20 to 30 Fg/mL dosed 3 to 9 pg/kg/h; lidocaine can also be used."O Epidural medication can be delivered as a continuous infusion or as patient-controlled epidural analgesia (PCEA). There must be 24-hour nursing care and standardized nursing protocols for care and monitoring specifically for pediatric patients receiving a continuous epidural infusion. Infants and children receiving a continuous epidural infusion should be monitored by continuous pulse oximetry for at least the first 24 hours of epidural analgesia with frequent and regular assessment of level of consciousness, oxygen saturation, respiratory rate, heart rate, and blood pressure. Patients at high risk for apnea or respiratory depression require even more intensive care.'l' Intravenous access should be maintained during epidural therapy.

Risks, Complications, Contraindications

When recommendations for maximum infusion rates of epidural bupivacaine are followed, taking into account individual patient risk factors for seizures, convulsions from central nervous system toxicity are rare with steady-state plasma bupivacaine concentrations less than 3 Fg/ mL.* Inadvertent injection of local anesthetic into the epidural venous circulation can cause seizures and cardiac toxicity. Injection of air into the epidural venous circulation can cause a venous or even a paradoxical arterial air embolus, as a probe-patent foramen ovale is not uncommon in children. For this reason, preservative-free saline, and not air, is used to detect loss of resistance.

Other complications of lumbar epidural blockade include dural puncture with resulting total spinal block if a large volume of local


anesthetic is inadvertently injected into the subarachnoid space. This is described in the section on caudal anesthesia. Subdural placement of the catheter will produce an unexpectedly high block of slower onset than a total spinal. Postdural puncture headache is rare in children. Symptoms include postural headache, nausea, vomiting, and photophobia. An au- tologous blood patch (using 5-10 mL) for persistent postdural puncture headache can be pe r f~ rmed .~~ Bleeding with consequent epidural hematoma is rare, as is infection resulting in meningitis or epidural abces~ .~~, 85

Contraindications for lumbar epidural blockade are the same as for caudal blockade.

Nerve trauma is another possible complication of epidural anesthesia. A catheter should never be forcibly advanced against an obstruction. In addition, one should never attempt to pull the catheter back out through the epidural needle. If the catheter does not advance, the entire unit (epidural Tuohy needle with catheter in its lumen) should be removed to avoid shearing the catheter. Reports of permanent neurologic deficit or death after epidural anesthesia in anesthetized children are rare but disturbing. One retrospective report of 24,005 regional anesthetics (67% caudal, 30% epidural, 3% spinal blocks) reported 113 accidents, 108 of which were without sequelae. Five babies who suffered major central nervous system complications were presented: three babies died, two survived-ne was left tetraplegic and one The causal link between the regional anesthesia technique and the neurologic defi- cits was not clear in all cases. Common features in these patients in- cluded age less than 3 months, predominantly black patients (4 of 5 patients), and the use of loss of resistance to air in 4 of 5 cases (technique not known in one case). All blocks were performed by an experienced pediatric anesthesiologist who routinely used that technique. More en- couraging is the prospective report by Giaufre et alM of 15,013 pediatric central regional blocks (18% caudal, 16% epidural, 3% spinal blocks) with a complication rate of 0.9 per 1000 (25 incidents). Although all complications occurred with central regional blocks and none with peripheral nerve blocks or local anesthesia infiltration cases (0 in 9396), all complications were minor and none resulted in sequelae or legal action.

Test Dose

Controversy exists regarding the effectiveness of a test dose administered to a child under anesthesia. Problems include the possibility of a false-negative test dose when using epinephrine added to local anesthetic, a wide range of parameters indicative of a positive test dose (systolic blood pressure and various electrocardiographic measurements and dysrhythmias), and even varying definitions of a positive test dose.

Fisher and colleagues37 published an observational study of all epidural anesthetics administered to pediatric patients at the Johns Hop- kins Hospital in 1 year (general anesthesia, when used, was not controlled). Of 742 pediatric epidural blocks administered (644 caudal anes-

364 MARKAKIS

thetics; 284 without catheters; 97 lumbar and 1 thoracic epidural anesthetic) with 97.7% satisfactory placement, intravascular injection was detected in 42 cases (5.6%). Detection was by aspiration of blood (6 patients), heart rate increases of more than 10 beats/& (30 patients), and heart rate decreases (5 patients). Of the 30 patients with known intravascular injection with electrocardiogram strips available, 25 (83%) had T-wave amplitude increases of more than 25%, and 29 (97%) had electrocardiographic changes in T-wave or rhythm in response to the epinephrine-containing test dose.

In children anesthetized with halothane and nitrous oxide, inadvertent intravascular injection of local anesthetic (1% lidocaine) containing added epinephrine (0.5 pg/ kg) will not reliably produce tachycardia unless preceded by atropine 10 pg/kg. This effect of atropine has been postulated to result from blocking the effect of parasympathetic tone on heart rate, thereby enhancing the sympathetic accelerator effect of epinephrine on heart rate.3O Even using the suggested criterion of an increase in heart rate of 10 beats/min as a positive test for intravascular injection does not eliminate false-negative test doses. Therefore, the total volume of local anesthetic should be administered in~rementally.~~

Sethna and colleaguesg6 demonstrated reliable detection of intravascular injection of 1% lidocaine with 0.5 pg/kg epinephrine in children anesthetized with isoflurane and nitrous oxide after atropine 10 pg/kg. No arrhythmias or electrocardiogram changes, including PR and QT intervals and ST and T wave amplitudes, were seen." Felberg and colleaguesM found systolic blood pressure a more reliable parameter than heart rate as an indication of inadvertent intravascular injection of 1.25 mg/kg bupivacaine with 5 pg/mL epinephrine in patients anesthetized with halothane in nitrous oxide after atropine 10 pg/kg. Some investigators have advocated the use of isoproterenol in epidural test doses57; however, further studies, including neurotoxicity studies, need to be performed. Freid and colleagues39 reported a series of five cases of infants who demonstrated ST-T wave changes and relative bradycardia after unintentional intravascular injection of bupivacaine with epinephrine during caudal blockade.

The conclusion drawn from most studies is that the electrocardiogram should be monitored closely and continuously during epidural test dose administration for changes in heart rate, rhythm, and T-wave amplitude. Epidural medication should be given incrementally.

SPINAL SUBARACHNOID ANESTHESIA

Many premature and ex-premature infants resent for inguinal her-

apnea, bradycardia, and hypoxemia, particularly those less than 60 weeks postconceptual age (gestational age plus extrauterine age in weeks)." 62 Several prospective studies suggest that spind subarachnoid anesthesia in these patients instead of general anesthesia will d e

nia repair. These infants are at particularly hig x risk for postoperative


crease the risk of postoperative apnea,lo7 and episodes of bradycardia and hypo~ia?~, 85 Obviating the need for general anesthesia in these patients can be beneficial in that endotracheal intubation and positive pressure ventilation can be avoided if the subarachnoid technique is successful. By decreasing the risk of respiratory complications and the need for postoperative mechanical ventilation, length of hospital stay may also be reduced.99 Supplementation of subarachnoid block with sedation may increase the premature baby's risk of developing postoperative apnea,lW although apnea after unsupplemented subarachnoid block has been reported.18, 6o Patients less than 60 weeks postconceptual age should be closely monitored for apnea and bradycardia for at least 12 hours po~toperatively.~~ If an apneic episode occurs, further episodes may occur for up to 72 hours postoperatively61 Postoperative monitors should include pulse oximetry, cardiorespiratory monitors, and nurse observati~n.~~

Technique

The spinal block can be placed with the infant in the lateral or sitting position, with the neck extended and monitoring of pulse oximetry, blood pressure (monitors are best placed on lower extremities), and electrocardiogram. The presence of an intravenous line before placing the subarachnoid block is welcomed, although an intravenous line may be easily placed in the lower extremity once the subarachnoid block has been placed. It is important that the assistant holding the infant ensure that the infant's neck be slightly extended and that the infant has a patent natural airway. In addition, emergency equipment should be prepared to intubate and resuscitate the infant in case of inadvertent intravascular injection or total spinal blockade. Appropriate patient selection is important. Infants with sufficiently large hernias may not be amenable to surgical repair under spinal anesthesia. Most difficulties under spinal anesthesia occur during traction on the peritoneum or spermatic cord or during dissection of the hernia sac.81 A failed, inadequate, or resolved block will necessitate general anesthesia.

The lumbar area is disinfected with an iodine-containing solution and draped. A 25- or 22-gauge 1 or 1.5 inch spinal needle is introduced in the midline at the L4 to L5 or L5 to S1 interspace. The infant's spinal cord may extend as far as L3, and the dura extends to S3. Thus, a lower interspace approach involves less risk of spinal cord injury."l The spinal needle is advanced slowly and the stylette is removed frequently to check for free-flowing cerebrospinal fluid.

Dosing

The commonly recommended dose of hyperbaric tetracaine is between 0.3 and 0.6 rng/kg,"' although this author has used 1 mg/kg

366

with success. Preservative-free epinephrine is drawn up into a tuberculin syringe that is then completely emptied, leaving an imperceptible coat- ing of epinephrine on the syringe’s inside. Tetracaine 1% in a dose of 1 mg/kg is drawn up in the syringe, along with an equal volume of preservative-free DloW for infants less than 10 kg.

Once the local anesthetic has been slowly injected, to avoid a high or total spinal blockade, the infant is held upright. His or her legs should soon exhibit a motor block. The infant is then placed in the supine position with his or her arms and legs gently secured to the table with gauze and tape, blow-by oxygen is administered, a pacifier put in place, and the drapes tented over the infant’s head to create a shaded, dark environment conducive to sleep. If absolutely necessary, sedation can be provided using 0.025 mg/ kg of midazolam. As discussed previously, sedation may further increase the infant’s risk of postoperative apnea.

Risks and Complications

Risks include an inadvertent intravascular injection, a high or total spinal block, and failed or inadequate block. Infants having received a subarachnoid block are still vulnerable to apnea and bradycardia. Appropriate resuscitation equipment and intensive care facilities must be immediately available should they be required.

PERIPHERAL NERVE BLOCKADE

Peripheral nerve blocks are increasingly being used in children (under general anesthesia) undergoing a wide variety of surgical procedures to provide postoperative analgesia, as well as to reduce the intraoperative requirement for anesthetic agents. These include nerve blocks for herniorrhaphy and orchiopexy (infiltration block of ilioinguinal/ iliohypogastric nerve), penile surgery (penile nerve block), tympanomastoid surgery (great auricular nerve block), hip pinning (femoral nerve block), lower extremity surgery (femoral nerve block and popliteal fossa block),24, 56 cleft lip repair (infraorbital nerve block), cleft palate repair (greater palatine nerve block), and even dermatologic procedures (digital nerve blocks, ankle In pediatric patients receiving intraoperative supplemental peripheral nerve blocks, preliminary data suggest decreased opioid requirement,’” as well as a lower incidence of nausea and vomiting and shorter postanesthesia care unit (PACU) dnd hospital stay. Although these benefits are not surprising to pediatric anesthesiologists using these techniques in their practice, randomized controlled prospective studies currently underway may allow more precise examination of these issues. (Santhanam Suresh, MD, Department of Anesthe- sia, Children’s Memorial Hospital, Northwestern University, Chicago, Illinois, personal communication, 1999).


ILIOINGUINAL AND ILIOHYPOGASTRIC NERVE BLOCK

These nerves supply the skin of the lower abdomen and inguinal region. They are formed from branches that arise from the spinal cord at the T12 and L1 level. They track laterally and forward to pierce the internal oblique muscle just below and 1 to 2 cm medial to the anterior superior iliac spine. The nerves lie between the muscle and the aponeu- rosis of the external oblique.14, 89

The ilioinguinal and iliohypogastric block provides analgesia from 2 to 8 hours postoperatively after inguinal herniorrhaphy or orchiopexy. It provides skin analgesia only; therefore, supplemental analgesic medication is required. The surgeon may also infiltrate the hernia sac and the surgical skin incision.

Several studies have shown comparable postoperative analgesia with ilioinguinal-iliohypogastric nerve block and caudal block for children undergoing orChiopexy47 and herni~rrhaphy.~~

Technique

The landmark for this block is the anterior superior iliac spine. After disinfecting the skin, identify the point one of the child’s fingerbreadths medial and just above the anterior superior iliac spine (along an imagi- nary straight line drawn between the umbilicus and the anterior superior iliac spine) (Fig. 2). It is difficult to avoid infiltrating local anesthetic into the surgical field in infants less than 1 year old. Therefore, this block is not recommended for patients younger than this age or smaller than the corresponding size. The block may be performed at the end of surgery to avoid the possibility of distorting the anatomy; however, onset of the block does take approximately 20 minutes. Using a short-beveled 20- gauge or 22-gauge block needle and staying perpendicular to the skin, the needle is advanced until a loss of resistance is felt, indicating that one has pierced the planes of the internal and external oblique muscles. If the needle hits the inner table of the iliac crest, it should be withdrawn very slightly. The needle is immobilized, and if aspiration for blood is negative, the local anesthetic is injected as the needle is withdrawn, concentrating most of the volume between the muscle and the aponeuro- sis of the external oblique, where the nerves lie. The needle is withdrawn until its tip is subcutaneous, as the remainder of the solution is injected, leaving a skin wheal that blocks the T11 and T12 innervation of the skin. Several variations of this technique have been described.65,

Dosing

The drug of choice is bupivacaine 0.25% in a dose of 1 mg/kg per side with a maximum dose of 2 mg/kg. If the calculated volume is greater than 10 mL, bupivacaine 0.5% should be used instead.

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Cut edge of apneurosis of external

oblique muscle

Internal oblique muscle

Ilioinguinal nerve \ - \

Figure 2. Landmarks and anatomy for ilioinguinal and iliohypogastric nerve block. (From Sethna NF, Berde CB: Pediatric regional anesthesia. In Gregory GA (ed): Pediatric Anesthe- sia, ed 3. New York, Churchill-Livingstone, 1994, p 305; with permission.)

Risks, Complications, and Contraindications

Although this block is relatively safe and easy to perform, even in experienced hands there may be a failure rate as high as 10%. Transient unintentional blockade of the femoral nerve after ilioinguinal / iliohypogastric nerve block has been described. This can result in transient paresis of the quadriceps muscles or numbness over the cutaneous distribution of the femoral nerve. The proposed mechanism is tracking of the local anesthetic solution along fascia1 planes to the femoral nerve.% This complication may be minimized by use of a less concentrated local anesthetic, such as 0.25% bupivacaine rather than 0.5%.

PENILE NERVE BLOCK

The penis is innervated primarily by the two dorsal nerves of the penis with a few sensory fibers from the genitofemoral (supplies skin over base of penis) and ilioinguinal (supplies base of penis) nerves.= The dorsal nerves of the penis emerge from the midline from under the symphysis pubis and run together with the dorsal arteries of the penis


along the inner aspect of Buck‘s fascia (deep fascia of the penis) at the 10:30 and 1:30 positions.

Technique of Bacon

Bacon3 has described the following midline technique. The area between the shaft of the penis and the symphysis pubis is prepared with an iodine-containing solution. Using a 22-gauge block needle, with gentle downward traction on the penis the needle is inserted midline, perpendicular to the skin, to strike the caudad border of the symphysis. The needle is removed to just below the skin and redirected to the point where it is just below the caudad border of the symphysis pubis, still perpendicular to the skin. This ”walking off the bone” is similar to the technique used in an intercostal nerve block. The needle should be midway between the symphysis and the base of the penis. After confirming negative aspiration for blood, and without moving the needle, the appropriate dose of 0.5% bupivacaine is injected.

Dosage

It is imperative that epinephrine never be used for penile blocks, as the dorsal artery of the penis is an end artery, and injection with an epinephrine-containing solution would lead to penile necrosis. Dosage of 0.5% bupivacaine for the penile nerve block is a maximum of 1 mg/ kg with 1.5 mL for ages 0 to 3 years, 2.0 mL for ages 3 to 6 years, 3.0 mL for ages 6 to 9 years, 4.0 mL for ages 9 to 12 years, 5.0 mL for ages 12 to 15 years, and 7.0 mL for ages greater than 15 years. (Mark S. Schreiner, MD, Children’s Hospital of Philadelphia, Philadelphia, Penn- sylvania, personal communication, 1991).

Technique of Dalens

DalenP refers to the area where blockade of the dorsal nerves is performed as the subpubic space (Fig. 3). This is defined above by the pubic bone and perineal membrane, below by the crura of the corpora cavernosa covered by a fibrous tissue which fuses with Buck‘s fascia, and anteriorly by skin, subcutaneous tissue, and the fatty and deep membranous layers of the superficial abdominal fascia. The subpubic space may be separated into two noncommunicating compartments by a septum at the level of the suspensory ligament. Dalens thus recommends two injections, one on either side of midline to block the dorsal nerve at this level using 0.25% to 0.5% bupivacaine in a dose of 0.1 mL/ kg for each side, up to 5 mL total per ~ ide .2~

370 MARKAKIS

Skin

Superficial fascia of the abdominal wall

Pubic bone

Deep layer of the superficial fascia of the abdominal wall

(Scarpa's Fascia) Subpubic space and fat

Dorsal nerve of the penis

Figure 3. Anatomy of retropubic space, landmarks for penile nerve block. (From Sethna NF, Berde CB: Pediatric regional anesthesia. In Gregoly GA (ed): Pediatric Anesthesia, ed 3. New York, Churchill-Livingstone, 1994, p 307; with permission.)

Technique of Yaster and Maxwell

Yaster and MaxwelP describe a technique of injecting 0.8 mL of 1% lidocaine in the newborn, and 1 to 3 mL of 0.25% bupivacaine in the older child using a 25- or 26-gauge needle at the 10:30 and 1:30 positions, just beneath Buck's fascia, approximately 3 to 5 mm below the skin surface.

Risks and Complications

Blocking the dorsal nerves of the penis at the level of the subpubic space instead of the level of the base of the penis makes damage less likely to the vascular penile structures, such as the corpus cavemosum and the paired dorsal arteries and veins. Because the subpubic space is large relative to the confined space of the penile fascia, formation of a hematoma is less likely to cause ischemic damage to the penis. Finally delivery of local anesthetic into the subpubic space minimizes the chance of nerve damage, compared with techniques where drug is delivered adjacent to the nerve.80

Reported complications of penile nerve blocks include hematoma formation from piercing the dorsalveins or arteries. Sara and L o w


reported two children who developed a complication of necrosis of the penile skin after circumcision and penile nerve block. It was unclear if this was a consequence of the surgical technique or the nerve block.

RING BLOCK OF THE PENIS

An alternative to the dorsal nerve blocks discussed previously is the ring block of the penis described by Broadman and colleague^.'^ This involves injecting a subcutaneous ring around the shaft of the penis near the base using 0.25% bupivacaine, 1.5 to 5 mL total depending on the child’s size and calculated maximum dose. This technique does not require the level of skill of the dorsal penile nerve block and avoids potential damage to dorsal blood vessels and the corpus cavernosum.

USE OF A NERVE STIMULATOR

An electrical nerve stimulator can be used to identify any peripheral nerve with a motor component. Eliciting a motor response to stimulation will ensure that the tip of the block needle is close to nerve tissue, which is particularly useful in situations of anatomic variation and if one is learning the technique.94 Use of the nerve stimulator obviates the neces- sity for patient cooperation and can be used to guide peripheral nerve blockade in patients under general anesthesia or heavy sedation. In awake patients, an insulated needle using small constant current (less than 0.5 mA)’and a lower frequency pulse (1 Hz of less than 1 ms duration) can elicit painless motor stimulation of the ner~e .9~ The block needle (insulated needle is more precise) hub is connected to the negative pole of the stimulator, and the positive pole of the stimulator is connected by an alligator clamp to a skin electrode far from the block area. The needle, connected by extension tubing to a syringe containing local anesthetic, is slowly advanced toward the nerve using standard anatomic landmarks. As the nerve is approached, the current is gradu- ally turned up to 0.5 mA until the desired motor response is elicited. Once nerve location has been confirmed, with maximal motor response to minimal current, injection of 1 to 2 mL of local anesthetic should abolish the motor contraction; otherwise, the needle should be withdrawn and the process re~eated.9~. *11

BRACHIAL PLEXUS BLOCK

Several approaches to the brachial plexus have been described. The most commonly used technique is the axillary approach. The child’s arm is abducted to 90 degrees and externally rotated. The axillary artery is palpated at the junction of the pectoralis major and coracobrachialis muscles. The axillary artery and brachial plexus are more superficial in

children than in adults. A tourniquet is placed just below the axilla to provide distal artery occlusion. The skin is disinfected with an iodine- containing solution. After draping, and with sterile technique, a blunt- tip block needle (22 or 23 gauge) is inserted perpendicular to the skin, aiming toward the upper edge of the axillary artery. Once the needle enters the axillary sheath, palpations transmitted from the axillary artery are felt. Alternatively a nerve stimulator may be used to locate the brachial plexus. Confirming negative aspiration of blood, the calculated dose of local anesthetic is injected s10wly.~ Campbell and colleagues found peak plasma concentrations below toxic levels for bupivacaine 2 mg/kg and 3 mg/kg given as 0.6 mL/kg.17, 94 Complications of this block include inadvertent intravascular injection with resulting local anesthetic toxicity. This block is useful for upper extremity procedures, excluding the shoulder. The musculocutaneous, intercostobrachial, and medial cutaneous nerves may not be reliably blocked. A catheter may be inserted to provide continuous brachial plexus nerve block via this approach?

Dalens and colleagues" have described a parascalene approach to block the brachial plexus. This approach is associated with fewer side effects than the supraclavicular approach. Other techniques of brachial plexus blockade in children are well described by Dalens.26

FEMORAL NERVE BLOCK

The femoral nerve arises from segments L2 to L4, supplying sensa- tion to the anterior and medial part of the thigh. Femoral nerve blockade can provide analgesia for examination of femoral fractures. The landmarks for this block are identical to those in adults. The femoral artery is palpated, the skin disinfected and draped, and the blunt needle is inserted approximately 1 cm lateral to the femoral artery and below the inguinal ligament. Aspiration is performed before injection of local anesthetic to confirm that the needle is not intravascular. Sethna and colleaguesg4 use 0.2 mL/kg (2 mg/kg) of lidocaine 1% without epinephrine for short procedures, such as muscle biopsy. They report onset of anesthesia within 10 minutes and duration of approximately 40 to 50 minutes. Others have used 0.2 mL/kg (1 mg/kg) of bupivacaine 0.5% up to a maximum of 10 mL, providing up to 4 hours of effective analgesia for femoral shaft fractures."

Femoral artery hematoma and femoral nerve injury are potential risks of this block.

SCIATIC NERVE BLOCK

The sciatic nerve is composed of two nerves, the tibial and the common peroneal nerves, which are enclosed in a common sheath.5 The. sciatic nerve supplies motor innervation to the hip extensor muscles and


the knee and ankle flexors. It supplies sensory innervation to the skin of the back of the thigh and leg to the dorsum of the f0ot.9~ Multiple approaches to the sciatic nerve are well de~cribed.~ Sethna and Berde94 recommend the single-position supine technique described by Raj because of the ease of patient positioning. With the hip flexed from 90 to 120 degrees, the leg is supported. The block area is disinfected. The nerve stimulator is used to locate the sciatic nerve by inserting a long 25- to 22-gauge needle perpendicular to the skin at the midpoint of a line drawn between the ischial tuberosity and the greater trochanter. Maximal flexion-extension of the ankle should be elicited. Suggested volumes of local anesthetic are 0.2 mL/kg to 0.5 mL/kg in a 12-year-old child, taking care to stay below toxic doses of the particular local anesthetic. Risks of this block include systemic toxicity from inadvertent intravascular injection or overdose of local anesthetic, and nerve inj~ry.9~

Konrad and Martin56 have recently described blockade of the sciatic nerve at the level of the popliteal fossa in 50 pediatric patients (aged 2 months to 18 years) with no failure of blockade and no complications. The patient is placed in the lateral position with the affected limb uppermost. Using as landmarks the popliteal fold and the midline, the authors used patient weight to estimate the point of insertion of the insulated stimulation cannula: distance from knee fold = 1 cm/ 10 kg of body weight. The stimulation needle is inserted just lateral to midline, with an insertion angle of 45 degrees to the skin surface aiming cephalad. Because of the paramedian approach, vascular injection is unlikely. Bu- pivacaine 0.25% dosed 0.5 mL/kg is injected at the point where successful nerve stimulation occurs (no more muscle twitch elicited with 0.3 mA at impulse width of 1.0 ms). The approach described by Konrad and Martin approaches the sciatic nerve high enough in the popliteal fossa to allow combined blockade of the tibia1 and peroneal nerves.

LOCAL ANESTHETIC TOXICITY

Local anesthetics are sodium channel blockers that exert both their therapeutic and toxic action by interrupting electrical transmission along plasma membrane. In therapeutic concentrations they will cause conduction blockade of nerves. In toxic blood concentrations they will also affect the excitable membranes of the brain and heart. The peak concentration of local anesthetic delivered to the brain and heart depend upon many factors, including the dose of local anesthetic and the speed of injection (higher dose and faster injection result in higher peak concentration). Other factors determining peak blood concentration of local anesthetic include cardiac output (higher cardiac output, lower peak concentration) and vascularity of the site of local anesthetic blockade (more vascular, higher peak c~ncentration).~~ Blood concentrations of local anesthetic after common regional blocks are listed here in decreasing order: topical anesthesia of airway mucosa>intercostal>caudal epi- durablumbar or thoracic epidural>brachial plexus>lower extremity

374 MARKAKIS

blocks (sciatic/femoral)>subcutaneous infiltrati~n.~~ Inadvertent injection of even a small amount of local anesthetic directly into the arterial or venous circulation will result in systemic toxicity at very low doses. Arterial injections will result in higher peak concentrations than venous inje~tions.~~

Patients can exhibit signs of central nervous system or cardiac toxicity. The premonitory signs of neurotoxicity not appreciated in the anesthetized patient include tinnitus, headache, circumoral numbness, irrational conversation, loss of consciousness, and apnea.” 93 The subtler of these symptoms of minor neurotoxicity may be misinterpreted in younger awake children as pain or hunger, or ascribed to a behavioral disturbance. Children receiving a continuous infusion of local anesthetic should be carefully observed for signs of local anesthetic toxicity. Be- cause they cannot communicate specific symptoms, agitation or restless- ness should be carefully evaluated.6 Arteriovenous malformations at the site of anesthesia will also increase uptake of local anesthetic into the circulation and can lead to toxicity and convulsions.*

Convulsions associated with infusion of local anesthetic are rare in children receiving infusion rates of less than 0.5 mg/kg/h unless they have risk factors predisposing them to convulsions, as discussed previously (lumbar epidural; dosing).6 If an epidural catheter does not provide adequate analgesia at the maximal recommended local anesthetic infusion rates, Berdes recommends that the following be considered: (1) adding an epidural or systemic opioid in addition to the local anesthetic infusion, (2) testing the catheter either with contrast epidurogra- phy or 2-chloroprocaine, (3) abandoning the technique in favor of systemic opioids or nonsteroidal anti-inflammatory drugs. Increasing the dose of local anesthetic to exceed the recommended limit is not accept- able. When planning the use of continuous lumbar or caudal epidural infusion of local anesthetic to provide analgesia for thoracoabdominal level surgery, the clinician should use hydrophilic opioids (such as morphine or hydromorphone). Alternatively, caudal or lumbar catheters can be advanced to the thoracic level or clinicians with appropriate skill and training may place an epidural catheter directly at the thoracic level after careful evaluation of risks versus benefits.8

Both lidocaine and bupivacaine in toxic doses impair myocardial contractility. Bupivacaine facilitates reentrant dysrhythmias and is associated with difficult to treat ventricular dysrhythmias. In contrast, lidocaine is a class I antiarrhythmic drug that does not facilitate reentrant ventricular arrhythmias in animal models except in extremely high

Investigations in animals have shown the myocardial depression ratio of bupivacaine to lidocaine is 4:1, which is the same as their anesthetic potency ratio. The electrophysiologic toxicity ratio of bupivacaine to lidocaine is much g1-eater-16:l.~~ Electrocardiographic changes with bupivacaine toxiaty include prolongation of PR and QT intervals, widening of QRS complex, development of U wave after the T wave, AV block, polymorphic ventricular tachycardia, electromechanical disso- ciation, and asystole.79 Death due to local anesthetic in most


models is not due to deprqssed myocardium, but to electrophysiologic disturbance, with progressively prolonged conduction time followed suddenly by ventricular fibrillation.”

Another postulated mechanism for bupivacaine’s cardiac toxicity in addition to its direct effects on sodium channels of myocardium is that it increases autonomic outflow via blockade of GABA (gamma- aminobutyric acid) receptors in the brainstem. Very small doses of bupivacaine given intracerebrally or intraventricularly have produced the same cardiac dysrhythmias seen with toxic doses given intravenously.“, Intravenous midazolam, a GABA agonist and hexamethonium, a peripheral autonomic ganglion blocker, have been shown capable of terminat- ing bupivacaine-induced dysrhythmias?

Most of our knowledge regarding local anesthetic toxicity and its treatment is derived from animal studies and reports of successful resuscitation of patients. Treatment of both neurotoxicity and cardiotoxicity should be immediate and aggressive, focusing on the ABCs of resuscitation, namely maintenance of airway, breathing, and circulation. Early and aggressive treatment of neuro- and cardiotoxicity has been shown to reduce mortality in the animal m0de1.3~ Maintenance of adequate oxygenation and ventilation are imperative, as local anesthetic toxicity is potentiated by hypoxia and Seizures should be treated if they have not stopped after 20 to 30 seconds with intravenous midazolam or thiopental.

Treatment of cardiotoxicity should follow advanced cardiac life sup- port (ACLS) guidelines, including cardioversion if appropriate. Animal models suggest that high-dose epinephrine during cardiopulmonary resuscitation may be necessary to treat the myocardial depressant effect of bupivacaine, although this is contr0versia1.3~ Bretylium, in the dose of 5 mg/kg repeated up to 30 mg/kg, can occasionally convert ventricular tachyarrhythmias to normal sinus rhythm, or at least facilitate electrical cardioversion, although its antifibrillatory effects may take up to 30 minutes to be effective. Bupivacaine remains in cardiac tissue much longer than lidocaine, and cardiopulmonary resuscitation must be sus- tained to account for thisn YasteP and colleagues reported successful resuscitation of two neonates with bupivacaine toxicity using phenytoin to treat broad complex tachyarrhythmias after bretylium 10 mg/kg had failed to convert to normal sinus rhythm, though cardioversion was not attempted. Phenytoin dosage is 5 mg/kg injected slowly (no more than 50 mglmin), repeated if necessary at 5-minute intervals up to 15 mg/ kg total dose.66

Neonates may be at greater risk for bupivacaine toxicity. First, infants less than two months of age have lower concentrations of albu- min and alpha-1-acid glycoproteins (alpha-1 lipoprotein), which nor- mally bind to local anesthetic, leaving a relatively larger fraction of drug free in the plasma.66 Second, neonates have low liver blood flow and immature metabolic pathways, resulting in larger fractions of unmetabo- lized amide in the plasma.66, 67 The neonate’s larger volume of distribution may be somewhat protective in reducing drug concentrations after bolus administration of local anesthetic; however, the elimination half-

376 MARKAKIS

life of lidocaine and bupivacaine are prolonged in infants less than 6 months,94 as compared with adults. Thus, accumulation of these drugs infused at the same dose or frequency as adults can lead to life-theaten- ing toxicity.

ROPIVACAINE

Ropivacaine is a new long-acting amide local anesthetic@ 69 that has fewer toxic cardiacs3 and central nervous systemx effects in adults. Ropivacaine has been demonstrated to produce less motor blockade than bupivacaine." 35 A limited but growing experience is being established in pediatric anesthesia with ropivacaine. Koining and colleagues demonstrated analgesia comparable in efficacy and duration in caudal blocks with either 0.25% bupivacaine or 0.25% ropivacaine. Although 0.5% caudal ropivacaine produced a longer duration of analgesia, it was accompanied by delayed time to voiding, standing, and produced postoperative motor blockade in one patient.55 Thus far the consensus regarding ropivacaine is that it can be used safely and effectively in children for caudal analgesia with comparablez0 or perhaps superior analgesia50 and less motor blockade.20 Ivani and col leag~es~~ also described the use of ropivacaine for epidural analgesia in infants undergoing major abdominal surgery and found onset, duration of action, and efficacy comparable to the bupivacaine group, with no major side effect noted in either

Of particular interest are the recent data of Meunier et al,71 which demonstrated low ropivacaine free fraction concentrations (unbound to alpha-1-acid glycoprotein) determined at intervals up to 48 hours after relatively high doses via lumbar epidural route in infants. Ropivacaine 0.2% was given in a dose of 1 mg/kg followed by infusion (0.4 mg/kg/ h) during 48 hours. The maximum observed free ropivacaine concentration was 0.215 pg/mL in a 2-month-old infant having the lowest alpha- 1-acid glycoprotein c~ncentration.~~ No data exist regarding the toxic threshold of ropivacaine in infants and children, although in adult volunteers no side effects were detected at venous plasma levels of 2.2 pg/ mL."

Is ropivacaine preferable to bupivacaine in children? More data and reports of its use and complications in children may provide an answer. Less motor blockade after caudal injection may be a selling point for ropivacaine's use by pediatric anesthesiologists, as a sigruhcant propor- tion of children find this symptom troubling.u, 76 The lesser toxicity of ropivacaine, however, may ultimately make it the local anesthetic of choice in pediatric regional anesthesia.

CONCLUSIONS

We have few data about how our pediatric outpatients, comfortable from their regional anesthetic on hospital discharge, fare regarding pain


after they are discharged home. The anesthesiologist and surgeon should advise parents of children undergoing outpatient procedures about the anticipated duration of local anesthetic analgesia. Parents should not only anticipate their child's increased perception of pain as the block wears off, but should be encouraged to continue to administer prescribed analgesics on schedule after discharge from the hospital to keep their child comfortable.

Local anesthetic toxicity remains a concern. With care and continued collective experience and growing pediatric anesthesia literature, the safety of regional anesthesia use in pediatrics continues to improve.

It is a general impression that infants and children who receive a pediatric regional anesthetic benefit in many ways. With reduction of intraoperative anesthetic requirement and effective postoperative analgesia, they return more rapidly to their preoperative state and are comfortable with minimal sedation. Investigators have demonstrated a decreased stress response to surgery associated with extradural anesthesia as compared to opioid analgesia al0ne.5~. Outcome studies will help further document the benefits of regional anesthesia in pediatric patients, both emotional and physical.

CAUTION

Every effort has been made to ensure the accuracy of this manu- script, particularly regarding recommended techniques and dosages. The reader is encouraged to verify above information, particularly dosage information, before using clinically.

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regional anesthesia in pediatrics

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