Regional anaesthetic techniques for neonatal surgery: indications and selection of techniques

Best Practice & Research Clinical Anaesthesiology Vol. 18, No. 2, pp. 357–375, 2004 doi:10.1016/j.bpa.2003.11.004 available online at http://www.sciencedirect.com

10 Regional anaesthetic techniques for neonatal surgery: indications and selection of techniques Martin Jo¨hr*

MD

Head Paediatric Anaesthesia Department of Anaesthesia, Kantonsspital, CH-6000, Luzern 16, Switzerland

Thomas M. Berger

MD

Head Neonatal and Paediatric Intensive Care Children’s Hospital, CH-6000 Luzern 16, Switzerland

The goal of neonatal care is to optimise the outcome of term and preterm infants with minimal suffering. Neonates are rare patients for the anaesthetist, therefore personal and even global experiences are limited. This chapter focuses on strategies for dealing with common clinical situations, e.g. heel lancing, obtaining vascular access, circumcision, hernia repair and pyloric stenosis, as well as major neonatal surgery. With the exception of heel lancing, regional techniques are useful in all cases. However, a careful risk –benefit analysis is mandatory, especially when considering more invasive techniques such as epidural catheters. Key words: infant; newborn; analgesia; anaesthesia; anaesthesia, caudal; anaesthesia, spinal; nerve block; brachial plexus; gastroschisis; oesophageal atresia; meningomyelocele; hernia, inguinal; circumcision.

Compared to adults, regional anaesthesia is relatively rarely done in children. According to a recent French survey1, paediatric anaesthesia represented 12% of the total anaesthesia caseload, infants represented 1% and term or preterm infants requiring anaesthesia were extremely rare. Therefore, the global experience of the anaesthesia community is limited and it may currently be difficult to determine risk –benefit ratios, especially for rarely done anaesthetic techniques in neonates. In paediatrics, nerve blocks are often performed for post-operative analgesia. Great care is necessary to avoid intraneural or unrecognised intravascular injections in the anaesthetised patient. In contrast to adult anaesthesia practice, it is considered acceptable to perform regional blocks in sleeping paediatric patients, provided the following precautions are taken: the optimal technique is chosen, there is skilled performance of the block and size-adapted material is used2. The latter is a particular problem in neonatology. Similar to the material used for venous or arterial access, epidural catheters are always relatively large compared to the size of the neonatal patient (Figure 1). * Corresponding author. Tel.: þ41-41-205-4908; Fax: þ41-41-370-5427. E-mail address: [email protected]. (M. Jo¨hr) 1521-6896/$ - see front matter Q 2003 Elsevier Ltd. All rights reserved.

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Figure 1. Material used for regional blocks is relatively large compared to the size of the patient, e.g. this figure shows a 20G epidural catheter and a preterm infant.

The maximum recommended dose of local anaesthetics (Table 1) has to be calculated for every single patient. Because of reduced protein binding in neonates3, the potential for toxicity may be higher than in older infants and children4. As a safety measure, only the exact amount needed for a specific patient should be drawn up in order to avoid accidental overdose. In general, long-acting local anaesthetics are used: bupivacaine, ropivacaine or levobupivacaine (Table 1). The use of bupivacaine5 and ropivacaine6 is well established in paediatric anaesthesia, whereas levobupivacaine has been introduced only recently. With identical dosing of levobupivacaine, reduced toxicity can be expected compared to bupivacaine. However, using levobupivacaine, the amount labelled on the ampoules relates to the free base and not to the hydrochloride, therefore, using identical Table 1. Maximum recommended doses of local anaesthetics. Drug

Single injection

Continuous infusion

Reference, remarks

Bupivacaine Levobupivacaine Ropivacaine Lidocaine Prilocaine

2.5 mg/kg 2.5 mg/kg (?) 3–4 mg/kg 7 mg/kg Not recommended in neonates

0.25 mg/kg/h 0.25 mg/kg/h (?) 0.4 mg/kg/h 2 mg/kg/h Not recommended in neonates

Berde (1992)5 Morton (2000)6 Methaemoglobinaemia

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Table 2. Common and less common surgical procedures in neonates. † Heel lancing † Circumcision † Inguinal hernia repair † Pyloromyotomy † Chest tube insertion, obtaining vascular access † Major neonatal surgery

concentrations, 13% more of the active compound would be given. Ropivacaine is well established as a caudal anaesthetic in infants7 – 9, with some limited experience in neonates10 and preterm babies.11 A word of caution is needed regarding the use of prilocaine in neonates and infants. Because of the reduced activity of methaemoglobin-reductase in this agegroup, there is an increased risk of methaemoglobinaemia, even after only moderate doses of prilocaine.12 The use of EMLAwcream (which contains prilocaine 2.5% and lidocaine 2.5%) should be problem-free as long as the dose is restricted to 1 –2 g.13,14 This review will focus on the anaesthetic strategies used to deal with common interventions in neonates (Table 2).

HEEL LANCING Clinical relevance Heel lancing for blood sampling is the most commonly performed painful procedure in neonates. Obviously, it causes significant pain. Regrettably, only limited efforts have been undertaken to prevent the pain of this often unavoidable procedure. EMLAw is not effective for heel lancing Several authors have reported on the use of topical skin anaesthesia with EMLAw cream15 – 17, 5% lidocaine ointment18 or topical amethocaine.19 No relevant side effects such as methaemoglobinaemia have occurred, but, unfortunately, all groups also reported only minimal effectiveness.17,20 A probable explanation is that heel lancing causes an injury that is too deep to be prevented by topical anaesthesia alone. In addition, skin perfusion in this area is three times higher than at the dorsum of the hand, leading to rapid clearance of the local anaesthetic drug.21 The reduction of blood flow caused by EMLAw may lead to more squeezing and therefore additional pain.16 Immobilisation, by holding the infant tightly, may also cause discomfort. Topical skin anaesthesia is useful for a variety of other procedures Except for heel lancing, EMLAw cream can be used with good success for a variety of invasive procedures in neonates and infants. Venous puncture on the dorsum of the hand is less painful following the application of EMLAwcream22, however, the peripheral

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Table 3. Relevant features of oral sucrose or dextrose as an analgesic intervention. † Oral sucrose or dextrose reduces pain behaviour in neonates † There is a dose response † Artificial sweeteners are also effective † Clinical studies exist involving circumcision and heel lancing † The oral mucosal contact is important, not the enteral resorption † The endogenous opioid system seems to be involved † A simple intervention, it only has to be done

insertion of central venous catheters may become more difficult.23 By using reasonable doses, methaemoglobinaemia is not a relevant problem.13,14 Strategies to deal with pain associated with heel lancing General anaesthesia or major regional blocks are not a suitable choice for this procedure. The oral administration of sucrose or glucose (Table 3), however, is well established as a means of reducing the pain reaction in neonates24 – 28 and infants29, and a clear dose –response relationship has been observed30. Mother’s milk31 or pacifiers alone are not as effective, whereas artificial sweeteners are.32,33 The pain relief is caused by the oral presence of these substances and not by their gastrointestinal absorption, since their administration via nasogastric tube is not effective34. The endogenous opioid system may also play a role.35 Strategies to reduce the need for heel lancing (Table 4) include the rational use of laboratory tests and the replacement of capillary blood sampling by using blood obtained from venous punctures.36,37 However, this is only feasible for a certain number of blood samples because of the limited availability of suitable veins. Umbilical artery catheters are used in many preterm babies in the first few days of life; later, an implanted central venous catheter may allow blood sampling without skin puncture in some of these patients. Not unexpectedly, systemic medication, such as paracetamol, has no demonstrable value.38

CIRCUMCISION Clinical relevance In some societies circumcision is performed in virtually all boys at a very early age for traditional or religious reasons. Other societies perform this type of surgery only for Table 4. Strategies to limit pain associated with heel lancing. † The administration of oral sucrose or dextrose during the procedure † Minimising the number of blood samples † Venous puncture instead of heel lancing † The use of arterial catheters during the initial intensive care phase † The use of implanted central venous catheters for long term care in some patients

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medical indications, such as phimosis or recurrent infections. In the past, circumcision for traditional or religious reasons has often been done in awake neonates with minimal or even no pain relief at all. Forceful immobilisation, e.g. on a circumcision board, and performance of the procedure in a crying patient has been an accepted practice until recently. Today, some type of procedural pain relief appears to be mandatory for most practitioners.39 In Western Europe, where circumcisions are largely performed for medical indications, a major regional block with a completely comfortable patient or a general anaesthetic is mandatory. Performing surgery on a crying patient would not be an acceptable standard. These two completely different attitudes might explain why for some colleagues topical anaesthesia40 – 42 or oral sucrose alone43,44 seem to be useful for procedural analgesia during circumcision,45 whereas for others, these techniques are clearly insufficient. Penile block Dorsal nerve penile block had already been proposed for neonatal circumcision by the late 1970s.46 Penile block, in Europe often combined with a general anaesthetic, provides prolonged pain relief for up to 6 – 24 h after penile surgery, much longer than a caudal block. Two paramedian injections of 0.1 ml/kg (up to 2 £ 4 ml) bupivacaine 0.5 – 0.75% into the subpubic space according to Dalens et al are preferred in our institution (Figure 2).47 Other techniques, such as one median injection48 or a subcutaneous ring block,49,50 have also been described. The latter is considered to be

Figure 2. Subpubic penile block using two paramedian injections performed in an anaesthetised child.

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less effective for post-operative analgesia than the subpubic penile block.49 However, it provides more reliable intra-operative analgesia when used as the sole anaesthetic technique in awake neonates.51 Penile block has a good safety record: in a series of 3909 penile blocks no permanent damage occurred52, while inadvertent injection of the wrong solution and urethral puncture during ring block were the important and clearly avoidable complications. For the subpubic penile block the needle penetrates the skin 0.5 – 1.5 cm lateral to the midline and is directed slightly medially and distally. The depth of needle insertion is around 2.5 cm in small infants, but much less in adolescent patients. No data exist on the type and concentration of the optimal local anaesthetic solution; however, the restricted volume mandates the use of high concentrations. For neonatal circumcision, it is our practice to combine general anaesthesia using sevoflurane and a laryngeal mask airway with a subpubic penile block with bupivacaine 0.75%. Caudal or spinal anaesthesia Single shot caudal anaesthesia can be used for neonatal circumcision. In our practice, 3 ml of a mixture at equal parts of lidocaine 1% with bupivacaine 0.25% with epinephrine were clinically effective in virtually all cases and had, apparently, the advantages of relatively rapid onset and prolonged pain relief. Nevertheless, the role of neuraxial anaesthesia for this type of intervention has to be questioned.

INGUINAL HERNIA REPAIR Clinical relevance Inguinal hernia repair is a common procedure in formerly preterm infants. Surgery is often performed before the babies are discharged home, having a body weight of between 2000 and 2500 g. Surgery in formerly preterm infants is associated with an increased incidence of post-operative complications, particularly the occurrence of post-operative apnoea. The first report on this topic was published by Steward in 198253; however, apnoea was not the only negative outcome, other side effects— potentially related to the management of general anaesthesia, such as stridor and atelectasis—also occurred. Nevertheless, the anaesthetic community have focussed on the apnoea issue and tried to avoid post-operative apnoea by avoiding general anaesthesia. Spinal and caudal anaesthesia After the revival of spinal anaesthesia by Abajian et al in 198454, numerous uncontrolled reports appeared suggesting a reduced risk for post-operative apnoea with spinal anaesthesia when compared to general anaesthesia.55 In the first prospectively randomised trial, Somri et al56 concluded that there was a significant advantage to using spinal anaesthesia56; however, critical analysis shows that 10 out of 24 patients in the spinal anaesthesia group had partial or total failure of the technique. Other studies found either no57 or a measurable, but clinically irrelevant advantage for spinal anaesthesia.58,59 Post-operative apnoea has also been reported after spinal anaesthesia.60,61 A fairly high failure rate seems to be a consistent problem.54,56,58,62 In summary, compared with skillfully performed general anaesthesia using modern anaesthetic agents, there appears to be no clear advantage of spinal anaesthesia for this

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Table 5. A critical reappraisal of the use of spinal anaesthesia in formerly preterm infants. Pros (supporting)

Cons (discouraging)

Minimally invasive Reduced incidence of post-operative respiratory abnormalities

High failure rate Post-operative apnoeas can also occur with spinal anaesthesia. Monitoring is mandatory anyway. Measurable but not clinically relevant advantage for spinal anaesthesia Potentially stressful procedure in cases of failure Stressful operation for the surgeon (time limit!) Limited duration may lead to suboptimal surgical results Limited access to the patient in case of urgent airway management Modern anaesthetic agents (sevoflurane, desflurane, remifentanil) have been introduced

Satisfaction of the anaesthetist

kind of surgery. In our institution, spinal anaesthesia in awake infants was introduced in 1986. Hyperbaric tetracaine 1 mg/kg with epinephrine, injected through a 25G-oneinch neonatal spinal needle, was the drug of choice; in more recent years, isobaric bupivacaine 1 mg/kg with epinephrine has been used. The site of injection was prepared with EMLAw-cream and vascular access was achieved routinely on a lower limb after induction of the spinal block. The use of this technique, however, has virtually been abandoned during the last few years (Table 5), since it imposes unnecessary stress on the surgeon, on the anaesthetist and, in many cases, on the patient as well. Caudal anaesthesia in the awake infant also has its proponents.63,64 Undoubtedly, caudal anaesthesia has several advantages: the technique is well known to all practitioners, it is the most commonly used regional technique in paediatric anaesthesia and has an extraordinary safety record.65,66 The rather slow onset allows a less hectic start to the surgical procedure. However, relevant disadvantages do exist: the large total dose of local anaesthetic puts the patient at serious risk in case of inadvertent intravascular injection. Measurable toxicity occurs even with a correct technique.4 In addition, the duration of the block is limited, similar to spinal anaesthesia (Table 6). In our institution, caudal anaesthesia is only used in exceptional cases for inguinal hernia repair in awake formerly preterm infants. Caudal epidural puncture is achieved in a prone (frog-like) position using a 25G needle with extension tubing. Bupivacaine 0.25% with epinephrine is injected in small increments up to a total volume of 1.2 ml/kg, resulting in a total dose of 3 mg/kg of bupivacaine. Satisfying surgical conditions are achieved after 15 –20 min. Plain ropivacaine has been used in a preliminary series, however, the duration of anaesthesia seems to be even shorter compared to Table 6. A critical reappraisal of the use of caudal anaesthesia in awake formerly preterm infants. Pros (supporting)

Cons (discouraging)

Familiar technique Slow onset

Insufficient intensity Limited duration High dose, systemic toxicity

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bupivacaine. In our institution, most formerly preterm infants presenting with inguinal hernias are successfully managed with a general anaesthetic combined with a caudal block using reduced concentrations of local anaesthetics.67 General anaesthesia combined with ilioinguinal nerve block The ilioinguinal nerve block provides pain relief after inguinal incisions, such as inguinal herniotomies or orchidopexies. The injection has to be made using a short bevel needle, e.g. a 24G Plexufixw, medial to the anterior superior iliac spine, at approximately one-quarter of the distance between the umbilicus and the anterior superior iliac spine. The needle is inclined distally and slightly medially and advanced until the perforation of the aponeurosis is felt. The local anaesthetic solution— 0.5 ml/kg of bupivacaine 0.25% or ropivacaine 0.2 – 0.375%—is injected under the fascia, followed by subcutaneous infiltration. Ilioinguinal nerve block is generally believed to be an extremely safe procedure. However, complications can occur, such as transient femoral nerve block68 – 71, even with correct technique.72 Especially in young children73, rapid absorption of the local anaesthetic solution resulting in high plasma levels74,75, has been reported. Finally, abdominal wall perforation and visceral injury can occur.76,77 In summary, compared to caudal block, ilioinguinal nerve block seems to be a more demanding technique, especially in small infants. In our institution, ilioinguinal nerve block is only used in exceptional cases in neonates. When a caudal block fails or is contraindicated, a wound infiltration is performed before skin closure by our surgical colleagues using ropivacaine 0.2% up to 1 ml/kg.

PYLORIC STENOSIS Clinical relevance Congenital hypertrophic pyloric stenosis is the commonest surgical condition in small babies, affecting 1 in 400 liveborns, usually boys. Early diagnosis with the use of abdominal ultrasound has changed the clinical presentation. The diagnosis is now made very early in life, often before 4 weeks of age, and pyloromyotomy has become a part of neonatal surgery. Severe metabolic derangement—hypochloraemic alkalosis—is now the exception. However, as a result handling of the patient has become more demanding. In our opinion, true rapid sequence induction using cricoid pressure and the avoidance of mask ventilation before intubation is of questionable value in neonates because hypoxaemia occurs regularly. Cricoid pressure often distorts the anatomy in small babies and makes intubation more difficult. It is not an established technique for airway management in neonatal intensive care. Pyloromyotomy should only be undertaken after the metabolic derangement has been corrected; a nasogastric tube is mandatory during this preparation period. Spinal and caudal anaesthesia Purely regional techniques have been described for pyloromyotomy in neonates and small infants. Somri et al78 reported that 23 out of 25 infants were successfully managed with spinal anaesthesia using 0.8 ml/kg of isobaric bupivacaine.78 Moyao-Garcia et al79 published their experience with a high dose caudal block (1.6 ml/kg of bupivacaine 0.25%) in 223 patients over three decades. The success rate was 96%, but the high total

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dose of 4 mg/kg of bupivacaine is far beyond the established dosing level and cannot be recommended for use on a routine basis. In summary, upper abdominal surgery is feasible under spinal or epidural anaesthesia in awake patients. However, as in adults, this should probably only be done in exceptional cases. Wound infiltration combined with general anaesthesia All over the world, general endotracheal anaesthesia after intravenous induction and the administration of a neuromuscular blocking agent is standard anaesthetic practice for pyloromyotomy. It is our preference to aspirate the gastric content, to induce the patient with thiopentone and to ventilate the lungs gently by mask after the administration of atracurium or mivacurium until endotracheal intubation. This practice has been supported in a recent editorial by Goudsouzian.80 Other induction techniques, such as awake intubation or true rapid sequence intubation do not seem to be advantageous.81 Post-operative analgesia is achieved by wound infiltration with up to 1 ml/kg of bupivacaine 0.25% or ropivacaine 0.2%. The infiltration is performed by the surgical colleague before wound closure with a 25G needle. Our clinical impression is that most patients can be managed without opioid medication with this procedure; however, scientific proof of the effectiveness of wound infiltration for this intervention is lacking. Sury et al82 reported no difference in pain behaviour with and without wound infiltration in a randomised trial including 20 patients. In contrast, Habre et al83 observed that only three patients needed opioid medication in a retrospective review of 72 infants who had all received wound infiltration. In summary, wound infiltration is clearly effective if surgery could be done using this technique alone. However, it is of questionable value for a laparotomy. Our recommendation is to use it for small incisions, such as those used for pyloromyotomy. Although, there are some theoretical concerns,84 no relevant side effects have been attributed to infiltration with local anaesthetics.

MISCELLANEOUS MINOR INTERVENTIONS Clinical relevance In the intensive care setting, during the first few weeks of life, neonates potentially experience a number of minor, yet uncomfortable interventions, e.g. the insertion of intravascular lines or the placement of chest tubes. Depending on the experience, skill, and involvement of the physicians who care for these patients, a wide spectrum of regional techniques can be used to minimise discomfort in these very small patients. This has been documented by some case reports in the literature; however, experience in larger series, allowing proper risk – benefit analysis, is lacking. Wound infiltration and conduction blocks Chest tubes are usually inserted in intubated and ventilated neonates. This allows the administration of systemic opioids before the procedures. Since opioids do not provide surgical anaesthesia at the doses used by neonatologists, infiltration of the skin and the chest wall with local anaesthetic is mandatory. Our practice is to use ropivacaine 0.2% up to 1 ml/kg. Theoretically, ropivacaine should provide pain relief of some duration

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with limited toxicity; however, this practice is not yet reflected in the textbooks where lidocaine is still the drug of choice. For radial artery catheterisation or the insertion of central lines, an axillary brachial plexus block can be used to immobilise the upper extremity and to provide analgesia. We have used this technique in babies weighing close to 1000 g; in earlier days lidocaine 0.5 – 1.0% was used, but nowadays ropivacaine 0.2% is injected close to the palpable pulse of the axillary artery using a short 25G butterfly needle. Messeri et al85,86 reported on the use of an axillary brachial plexus block in 35 preterm infants with a median weight of 1449 g for the insertion of small diameter central venous silicon catheters through a peripheral vein. They used 5 mg/kg of lidocaine 0.75 – 2.0%. The success rate for the insertion of the central line was higher (91%) compared with the success rate in a historical control group without a plexus block (73%). Hand surgery, such as the correction of hexadactyly, is occasionally performed in neonates on parental request (Figure 3). Ulnar nerve block at the wrist using 0.3 – 0.5 ml (0.1 ml/kg) of lidocaine 1% or, probably better ropivacaine 0.2%, provides good surgical conditions. The injection is made with a 25G or 30G needle medial to the palpable pulse of the ulnar artery. Monitoring includes pulse oximetry at most, vascular access is not obtained and the intervention should be performed immediately after feeding the patient.

Figure 3. Hexadactyly corrected on the request of the parents at the age of 5 days. Immediately after breast feeding, ulnar nerve block provided excellent surgical conditions in this patient.

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Figure 4. Skin necrosis after paravasation in a 1600 g baby. Caudal block in the awake child (1 ml/kg of bupivacaine 0.25% with epinephrine) was successfully used on four occasions for surgical debridement and finally skin grafting.

Neuraxial techniques For procedures on a lower limb, sciatic nerve block using a nerve stimulator is feasible even in very small patients. However, hip flexion and the movement of the opposite leg may interfere with delicate miniature surgery (Figure 4). Therefore, caudal anaesthesia providing reliable immobilisation of both legs is preferable. Caudal block can also be used for posterior tibial artery catherisation at the ankle or for the insertion of central venous catheters via the saphenous vein. In our experience, single shot caudal anaesthesia using up to 1 ml/kg of bupivacaine 0.25% or ropivacaine 0.2% is usually effective for providing good conditions and comfort for the baby.11 Caudal anaesthesia has been used to improve perfusion of the lower extremities after aortic thrombosis87,88 or severe vasospasm.89 However, the concomitant use of fibrinolytic agents would absolutely contraindicate caudal anaesthesia90, especially in view of its unproven effectiveness for this indication.

MAJOR NEONATAL SURGERY Clinical relevance Fortunately, major surgical interventions are relatively rare in neonates. The use of a purely regional technique in awake patients, such as spinal anaesthesia, has been

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reported for the repair of myelomeningocele91 and gastroschisis;92 however, these techniques have only a very limited value for these indications. Virtually all major surgical interventions at this age are performed in intubated and ventilated patients; many of them are already on a ventilator because of their underlying condition. The management of post-operative pain in this population remains a controversial issue. It is often difficult to obtain reliable pain relief with systemic opioids in extubated and spontaneously breathing neonates. Finding the correct dose to provide sufficient analgesia without causing respiratory depression and repeated apnoea is often impossible. A key problem is the evaluation of pain. In contrast to other authorities, it is our strong opinion that it is acceptable to temporarily ventilate a patient who requires high doses of opioids for adequate pain relief. In skilled hands, short term ventilatory support, e.g. for 24 – 48 h, is not associated with relevant morbidity. In addition, many patients are ventilated anyway because of their underlying condition (e.g. a preterm infant with necrotising enterocolitis), because of high intraabdominal pressure (e.g. following repair of gastroschisis), or by request from the surgical colleagues (e.g. following repair of oesophageal atresia). Single shot caudal anaesthesia Single shot caudal anaesthesia provides transient intense pain relief. The duration of analgesia after the epidural injection of 1 ml/kg of bupivacaine 0.125 – 0.25% with epinephrine or 1 ml/kg of ropivacaine 0.2% is unknown in neonates. The clinical impression is that it may be 120 min at most. In neonates, the addition of clonidine can result in post-operative apnoea.93 – 95 With caudal morphine also, we have not been successful in finding a safe, yet effective, dose. Respiratory depression occurs with a high incidence in this population. In our institution, single shot caudal anaesthesia is widely used to provide a smooth transition from general anaesthesia to the extubated and spontaneously breathing state, e.g. after the repair of duodenal atresia, colostomy or the removal of a sacro-coccygeal teratoma. Anaesthesia is usually maintained with sevoflurane and an infusion of remifentanil at 0.1 – 0.3 mg/kg/min; the caudal injection is made after surgery prior to extubation in order to optimise the duration of pain relief. Using modern anaesthetic agents, e.g. desflurane, sevoflurane or remifentanil, the use of a regional technique during surgery is not needed. When the caudal block is wearing off, systemic opioids are introduced, either as bolus doses of meperidine 0.5 mg/kg or as an infusion of fentanyl at 1 – 3 mg/kg/h depending on the severity and the expected duration of pain. Epidural catheter techniques Since the description of a thoracic placement of epidural catheters through a caudal access by Bo¨senberg et al in 198896 this technique has found its advocates.97,98 Direct thoracic epidural punctures have only exceptionally been performed in neonates99, and it is our belief that there is no place for this technique in neonatal surgery. Despite its rare use worldwide99,100, there have been reports of intraspinal haematomas101 and catastrophic neurological outcome while using air for loss of resistance102 in connection with attempts at lumbar insertion of epidural catheters. In skilled hands, it is undoubtedly feasible to reach a thoracic position with the catheter tip when relatively large catheters, e.g. 20G, are inserted via the sacral hiatus. This allows segmental thoracic epidural analgesia, enhances early extubation and postoperative pain relief. However, in our opinion, the enormous size of the catheters

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that are inserted into a tiny and vulnerable space, the difficulties of achieving and verifying the correct placement of the catheter tip and the potential for infectious complications raises concerns about the overall safety of caudo-thoracic anaesthesia in neonates. In addition, there is no scientific proof for some of the theoretical advantages of epidurally administered local anaesthetics, such as blocking the stress response, improving gastrointestinal function, or enhanced anastomotic healing. Even in large studies in adults, only improved pain relief could be attributed unequivocally to the epidural technique. Van Niekerk et al103 reported on the use of a 23G catheter inserted via a caudally placed 19G Tuohy needle in a series of 20 patients, weighing between 520 g (!) and 2750 g. Using epidurography in all patients, one catheter was found to be placed intrathecally, one in an epidural vessel and one was curled up in the lumbar epidural space. Furthermore, 11 out of the 20 infants were ventilated after surgery despite this invasive analgesia technique. Presacral catheter placement has also been reported.104 On rare occasions, when using thoracic epidural catheters placed via the sacral hiatus, it is our practice to measure the length of the desired insertion before placing the catheter. X-ray control105, electrocardiogram derived via the catheter106, or ultrasound107,108, are not used routinely. With regard to infections, paediatric epidural catheters have a good safety record109 – 111, but only a few neonates were included in these studies, e.g. in a series of 1620 patients no epidural abscess occurred after post-operative use.109 In another series of 210 patients, 37% of all catheters were colonised without apparent consequences.111 However, infectious complications have been observed in paediatric patients112,113 and remain a continuous threat that affects the risk – benefit analysis. Epidural abscesses can occur in neonates, even without a neuraxial catheter114,115, they are not ‘resistant’ to this complication. Optimal aseptic conditions are mandatory. An alcoholic solution is used for skin preparation since aqueous povidone is probably not optimal.116,117 In summary, epidural catheter techniques are feasible for pain relief after major neonatal surgery. Access to the epidural space is most easily obtained via the sacral hiatus. However, a careful risk – benefit assessment is needed before proceeding with this technique (Table 7). Short term ventilation, allowing effective systemic opioid medication, is often a valuable alternative.

Table 7. A critical reappraisal of the use of epidural catheters in neonates. Pros (supporting)

Cons (discouraging)

Potentially excellent analgesia Easy caudal access to the epidural space Avoidance of opioids

Restricted experience Large, potentially traumatising material has to be introduced Many patients are ventilated anyway, this allows the liberal use of opioids Surgical incision is not the only source of discomfort Catheter malpositioning is common Infectious risks and technical problems

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SUMMARY The goal of neonatal care is to optimise outcome, at the same time minimising the suffering of these small patients. This implies the liberal use of local and regional techniques, e.g. EMLAw-cream for lumbar puncture, conduction blocks for vascular access or peripheral surgery. However, a careful risk –benefit-analysis is mandatory before techniques with potentially catastrophic complications are used. Practice points † always think of using local anaesthetics to optimise the comfort of small babies. † use oral sucrose to increase their comfort during heel lancing and always try to minimise blood sampling † use a penile block with a long-acting local anaesthetic for pain relief after circumcision † restricting the anaesthetic options to the use of a purely regional technique in formerly preterm infants with inguinal hernia repair is not necessary; skilled and careful handling of these fragile patients using modern agents, local anaesthetics for post-operative pain relief and post-operative monitoring are the keys to success † use general endotracheal anaesthesia combined with wound infiltration for pyloric stenosis † use single shot caudal anaesthesia whenever possible to provide a smooth transition from the anaesthetised to the extubated and spontaneously breathing patient with major surgery † carefully evaluate the role of epidural catheters for post-operative pain relief in patients with major surgery and remember that the use of systemic opioids and short-term ventilatory support is an acceptable alternative

Research agenda † a large prospective multicentre data collection study is needed to investigate the efficacy and side effects of post-operative epidural anaesthesia in neonates † a world-wide registry for rare side effects of regional techniques in neonates is needed † the duration of analgesia after regional techniques in neonates needs to be accurately determined † the optimal concentration and dose needs to be determined for the use of local anaesthetics in neonates REFERENCES 1. Clergue F, Auroy Y, Pe´quignot F, Jougla E, Lienhart A & Laxenaire MC. French survey of anesthesia in 1996. Anesthesiology 1999; 91: 1509–1520. * 2. Krane EJ, Dalens BJ, Murat I & Murrell D. The safety of epidurals placed during general anesthesia. Regional Anesthesia and Pain Medicine 1998; 23: 433 –438. * 3. Mazoit JX, Denson DD & Samii K. Pharmacokinetics of bupivacaine following caudal anesthesia in infants. Anesthesiology 1988; 68: 387–391.

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