Pediatric Neuraxial Regional Anesthesia: How Much Sedation is Required?

By Werner Schmid, MD and Peter Marhofer, MD
Medical University of Vienna
Department of Anesthesia, Critical Care and Pain Medicine
Vienna, Austria

A large body of evidence indicates the neurotoxic potency of various general anesthetic drugs in neonates, infants and small children. Even not yet confirmed in large clinical and comparative studies, the use of various regional anesthetic techniques with a subsequent reduced demand of systemic sedative and analgesic drugs seem to be advantageous for these patient categories. Besides the important, but clinically unproven problem of neuroapoptosis caused by systemic anesthetic and analgesic drugs, regional anesthesia shows obvious advantages such as optimal perioperative pain therapy and minimal cardiorespiratory impairment. The use of neuraxial (caudal/epidural) regional anesthesia with or without sedation is one possibility to minimize the use of general anesthetic drugs. A large number of surgical procedures can be managed with this anesthetic concept.
Moderate to severe pain is poorly managed in approximately 30% of postoperative pediatric patients1. Opioids are first line medication for this type of pain; however, opioids are associated with significant adverse effects2.

Neuraxial regional anesthesia or multimodal pain management achieves analgesia through the effects of different classes of analgesics working through different mechanisms of action, allowing for an overall reduction or even avoidance in opioid consumption with equivalent or improved pain control3,4. With reduced opioid consumption for pain control there is a reduced incidence of opioid-related adverse effects; nausea, vomiting, sedation, pruritus, GI dysmotility, and respiratory depression, all of which can limit rapid recovery and rehabilitation5-7. Early use of non-opioid analgesia is also associated with reduced odds of serious postoperative adverse events and the need for rescue medication in pediatrics7.

The present overview discusses relevant issues in this context and describes up-to-date techniques to perform effective neuraxial regional anesthesia in sedated neonates and infants.

Caudal Blockade
Caudal blockade is one of the most popular regional anesthetic techniques in children and can be used for various indications such as uni- or bilateral inguinal hernia repair, orchidopexy, hydrocele, circumcision, hypospadia repair, rectal surgery, rectoscopy, cystoscopy, or lower extremity surgery. Most pediatric anesthesiologists perform caudal blocks under general anesthesia. Nevertheless, caudal blockade under sedation is described as a regional anesthetic method with a high success rate and low complication rates8.

The anatomical landmarks for the caudal approach to the epidural space—the sacral canal formed by the sacral cornuae and the sacrococcygeal membrane—are usually easy to palpate in neonates and small infants. The final position of the tip of the needle cannot be determined with a pure landmark-based technique, therefore ultrasound detection of the spread of local anesthetic is suggested where intravasal, interosseous, or subarachnoid administration of local anesthetic can be detected9-11. The detection of a subcutaneous position of the needle with subsequent extra-dural administration of the local anesthetic is also possible. We therefore use ultrasound in combination with the conventional landmark-based technique in the daily clinical practice. With the child in a left-lateral position, 1.0 ml kg-1 ropivacaine 3.8 mg ml-1 will be injected into the caudal space under aseptic conditions and under continuous ultrasound guidance. An ‘immobile needle technique’ will be performed using a 30 mm, 24 G Quincke needle connected with a 25 cm injection line. The patients are turned supine immediately after caudal block. Skin incision will be performed 15 min after administration of the local anesthetic in the caudal space. No additional sedation is required in neonates and infants < 1 year of age; for older children and longer procedures > 45 min, continuous propofol administration of 5 mg kg-1 h-1 is required. The same sedation management is used for lumbar or thoracic epidural anaesthesia. Some surgical procedures require endotracheal intubation, but the number of indications of neuraxial blockade plus sedation in spontaneous respiration without airway manipulation increases (see below).

The clinical observation that supraumbilical surgery cannot be reliably managed in caudal blockade is supported by the observation that the ultrasonographically observed spread of local anesthetic is higher than the sensory distribution12. We consequently manage supraumbilical surgery in lumbar or thoracic single shot or continuous epidural blockade.

Epidural Blockade (single shot and catheter technique)
Epidural blockade in children is also a well-established technique and used in the daily clinical practice for more than 60 years13. Bosenberg contributed significantly to the introduction of epidural anesthesia in children in the daily clinical practice14. The perioperative use of epidural blockade offers convincing advantages in neonates and small infants including optimal analgesia without opioid-related negative respiratory effects, and subsequently, a reduced need for postoperative ventilation, hemodynamic stability, improved gastrointestinal function, and a reduced neuro-humeral stress response4. Ultrasound guidance for epidural puncture was investigated to facilitate epidural anesthesia in infants and small children.

The advantages of direct visualization of the relevant neuraxial anatomical structures and the observation of the spread of local anesthetic inside the epidural space are convincing, but this technique requires particular hand skills, a good hand–eye coordination and an adequate caseload4. After obtaining written informed parental consent and an exact medical patients and family history (incl. blood coagulation abnormalities in the family), EMLA cream is administered at the intended regional anesthesia puncture site 30 min prior to the anesthesia induction. After standard cardiorespiratory monitoring, induction of anesthesia is performed via facemask and sevoflurane (initially 8 Vol %) or propofol (max. 4 mg kg-2), if a vascular access is preoperatively established. Spontaneous respiration should be maintained in all cases to minimize airway manipulation. Once the child is adequately sedated and a vascular access is established, we turn them to a left lateral position with flexed hips. The puncture site and the ultrasound probe are prepared in a sterile manner and a combination of loss-of-resistance and ultrasound guidance (via a paramedian, longitudinal ultrasound scan) is used for epidural catheter placement.

Following an ultrasound investigation of the relevant neuraxial structures, we perform the puncture with the conventional loss-of-resistance technique. The correct site of administration is confirmed by an ultrasound identification of anterior movement of the dura mater. After placement of the Tuohy cannula inside the epidural space, we inject 0.25 ml kg-1 ropivacaine 3.8 mg ml-1. Thereafter, the epidural catheter is introduced and another 0.15 – 0.25 ml kg-1 ropivacaine 3.8 mg ml-1 is injected through the catheter (total volume and dose of the initial bolus: max. 0.5 ml kg-1 ropivacaine 3.8 mg×ml-1 = 1.9 mg kg-1) or a single shot without catheter insertion will be administered.

If a catheter is used it will be fixed with a sterile transparent adhesive dressing and a continuous epidural infusion with 0.2 ml kg-1 ropivacaine 2 mg ml-1 is started. A ‘third hand’ observing the entire procedure by ultrasound simultaneously with the puncture can be useful. Thereafter, the child is turned back in supine position and carefully observed. We use a 20-G epidural catheter set with a 50 mm Tuohy cannula and 24 G catheter in children ≤ one year, and a 19-G epidural catheter set with a 50 mm Tuohy cannula and 22 G catheter in older children. We use exclusively ropivacaine in the above mentioned concentrations. No additives are used for neonates and ex-premature infants. Clonidine 2 µg kg-1 is used as the only additive neuraxial drug in procedures that are scheduled for >90 min in infants >3 month postgestational age (in cases where no catheter will be used). If the block is insufficient after 15 min, general anesthesia should be introduced. A well-performed neuraxial block should be sufficient after 15 min; blockade is defined as successful if the skin incision does not evoke movement of the child and if the hemodynamics remain stable. A prolonged waiting time is not recommended.

We transfer the children immediately after skin closure to the recovery room where an additional anesthesiologist and specialized nursing staff care for our patients. Ex-premature babies <60 weeks postgestational age are 24 h postoperatively monitored and observed. No ambulatory surgery is performed in this patient’s population for obvious reasons.

Risks of Neuraxial Blockades
Single-shot caudal anesthesia is exceptionally safe. A retrospective analysis where more than 158,000 patients were investigated, did not report any cases of permanent damage11. Further prospective studies examining 8,493 caudal blocks showed the same results15.

The most frequent complications (due to the technique) were vessel perforation (1.6%‑10.6%) and subcutaneous infiltration (5%-19%)15. The more serious complication was dural puncture, which has been reported in literature in 1/750 (0.13%) by Dalens et al16.

Large observational investigations demonstrate the safety of epidural anesthesia in children15,17,18. Despite this adequate safety profile, the routine use of epidural analgesia, particularly in newborns (preterm or term) is limited to a few centers. The most popular method for detecting the epidural space is the loss-of- resistance (LOR) technique, and is usually performed with the child under anesthesia. The pure LOR approach is associated with complications and adverse outcomes. This includes dural puncture or more significantly neurological deficits as a result of unintentional spinal cord trauma19-21. Since ultrasonography has been shown to improve the success rate and safety22 we use ultrasound guidance to perform epidural anesthesia. Clearly, no outcome studies in this field are published so far, which is mainly due to the large number study cases which should be included to achieve a sufficient power.

Complications of neuraxial techniques are mainly related to toxicity of the local anesthetic, but pharmacokinetics of epidural administered local anesthetic solutions are well described23,24. Nevertheless, Intralipid in the described doses should be available for the rare probability of local anesthetics intoxication25. Overall, the risks of neuraxial blockades are low, the risk-benefit ratio of these techniques of neuraxial blockades can be considered to be far on the side of the benefit due to the data which are currently available.

Conclusions
The reduction and avoidance of opioids during the entire perioperative period with all the positive implications (no cardiorespiratory depression, improved gut function, etc.) is a promising perioperative concept also in neonates and small infants. The techniques of neuraxial blockades in neonates and small infants are well described26, and a larger spectrum of indications should be considered. So far, only small case series report the use of single-shot epidural blockade in slightly sedated children for particular indications27. Nevertheless, to increase our patient’s safety and comfort, it is acceptable that techniques are investigated, which are not automatically accepted by the community of pediatric anesthetists28.

Laparoscopic surgery does not necessarily exclude neuraxial regional anesthesia under the avoidance of endotracheal intubation, despite the current standard of care indicates endotracheal intubation for laparoscopies. Single-port low-pressure laparoscopy for hypertrophic pyloric stenosis could be one possible indication for epidural anesthesia in sedation. Open and laparoscopic surgical management of vesicoureteral reflux via ureteroneocystostomy, transanal-endorectal pull-through in patients with colonic aganglionosis (Hirschprungs disease), posterior sagittal anorectoplasty (PSARP) in patients with anorectal malformations and the posterior anorectovagino-urethroplasty (PSARVUP) in patients with cloacae are further surgical procedures which could offer the opportunity to develop new anesthesia protocols by using neuraxial regional blockades under the avoidance of endotracheal intubation.

In summary, neuraxial regional anesthesia in children is safe15,17,18, but excellent hand skills and continuous training is required for a larger implementation of these techniques in the daily clinical practice of pediatric anesthesia. In modern pediatric anesthesiology it is our commitment to be competent in all combinations of anesthetic techniques for a safe and effective patient management. The ratio between regional and general anesthesia is adaptable between 0% and 100%. In modern pediatric surgery the adaption to these techniques is a permanent aim to achieve an optimal outcome.

References

1. Groenewald, C. B., Rabbitts, J. A., Schroeder, D. R. & Harrison, T. E. Prevalence of moderate-severe pain in hospitalized children. Paediatr Anesth 22, 661-668, doi:10.1111/j.1460-9592.2012.03807.x (2012).
2. Morton, N. S. & Errera, A. APA national audit of pediatric opioid infusions. Paediatr Anesth 20, 119-125, doi:10.1111/j.1460-9592.2009.03187.x (2010).
3. Kossowsky, J., Donado, C. & Berde, C. B. Immediate rescue designs in pediatric analgesic trials: a systematic review and meta-analysis. Anesthesiology 122, 150-171, doi:10.1097/ALN.0000000000000445 (2015).
4. Marhofer, P., Keplinger, M., Klug, W. & Metzelder, M. L. Awake caudals and epidurals should be used more frequently in neonates and infants. Paediatr Anesth 25, 93-99, doi:10.1111/pan.12543 (2015).
5. Walther-Larsen, S. et al. Structured intervention for management of pain following day surgery in children. Paediatr Anesth 26, 151-157, doi:10.1111/pan.12811 (2016).
6. Chalkiadis, G. A. & Berde, C. Bundled analgesia interventions for day-stay surgery. Paediatr Anesth 26, 120-121, doi:10.1111/pan.12833 (2016).
7. Voepel-Lewis, T. et al. Early adjuvant use of nonopioids associated with reduced odds of serious postoperative opioid adverse events and need for rescue in children. Paediatr Anesth 23, 162-169, doi:10.1111/pan.12026 (2013).
8. Brenner, L. et al. Caudal anesthesia under sedation: a prospective analysis of 512 infants and children. Br J Anesth 104, 751-755, doi:10.1093/bja/aeq082 (2010).
9. Brenner, L. et al. Ultrasound assessment of cranial spread during caudal blockade in children: the effect of different volumes of local anesthetics. Br J Anesth 107, 229-235, doi:10.1093/bja/aer128 (2011).
10. Raghunathan, K., Schwartz, D. & Connelly, N. R. Determining the accuracy of caudal needle placement in children: a comparison of the swoosh test and ultrasonography. Paediatr Anesth 18, 606-612, doi:10.1111/j.1460-9592.2008.02529.x (2008).
11. Triffterer, L. et al. Ultrasound assessment of cranial spread during caudal blockade in children: effect of the speed of injection of local anesthetics. Br J Anesth 108, 670-674, doi:10.1093/bja/aer502 (2012).
12. Lundblad, M., Eksborg, S. & Lonnqvist, P. A. Secondary spread of caudal block as assessed by ultrasonography. Br J Anesth 108, 675-681, doi:10.1093/bja/aer513 (2012).
13. Cox, R. G. From the Journal archives: Epidural anesthesia in young children: what have we learned in the past 60 years? Canadian journal of anesthesia = Journal canadien d'anesthesie 61, 72-75, doi:10.1007/s12630-013-0061-1 (2014).
14. Bosenberg, A. T. Epidural analgesia for major neonatal surgery. Paediatr Anesth 8, 479-483 (1998).
15. Ecoffey, C. et al. Epidemiology and morbidity of regional anesthesia in children: a follow-up one-year prospective survey of the French-Language Society of Paediatric Anesthesiologists (ADARPEF). Paediatr Anesth 20, 1061-1069, doi:10.1111/j.1460-9592.2010.03448.x (2010).
16. Dalens, B. Some open questions in pediatric regional anesthesia. Minerva anestesiologica 69, 451-456 (2003).
17. Llewellyn, N. & Moriarty, A. The national pediatric epidural audit. Paediatr Anesth 17, 520-533, doi:10.1111/j.1460-9592.2007.02230.x (2007).
18. Polaner, D. M. et al. Pediatric Regional Anesthesia Network (PRAN): a multi-institutional study of the use and incidence of complications of pediatric regional anesthesia. Anesth Analg 115, 1353-1364, doi:10.1213/ANE.0b013e31825d9f4b (2012).
19. Flandin-Blety, C. & Barrier, G. Accidents following extradural analgesia in children. The results of a retrospective study. Paediatr Anesth 5, 41-46 (1995).
20. Kasai, T., Yaegashi, K., Hirose, M. & Tanaka, Y. Spinal cord injury in a child caused by an accidental dural puncture with a single-shot thoracic epidural needle. Anesth Analg 96, 65-67, table of contents (2003).
21. Rose, J. B. Spinal cord injury in a child after single-shot epidural anesthesia. Anesth Analg 96, 3-6 (2003).
22. Willschke, H. et al. Epidural catheter placement in children: comparing a novel approach using ultrasound guidance and a standard loss-of-resistance technique. Br J Anesth 97, 200-207, doi:10.1093/bja/ael121 (2006).
23. Marhofer, P., Koinig, H. & Kapral, S. [The choice of drugs for caudal anesthesia in children. An overview]. Anesthesist 52, 55-67, doi:10.1007/s00101-002-0446-y (2003).
24. Bosenberg, A. T. et al. Plasma concentrations of ropivacaine following a single-shot caudal block of 1, 2 or 3 mg/kg in children. Acta anesthesiologica Scandinavica 45, 1276-1280 (2001).
25. Gosselin, S., et al. Evidence-based recommendations on the use of intravenous lipid emulsion therapy in poisoning. Clin Toxicol (Phila) 54, 899-923 (2016)
26. Marhofer, P. & Lonnqvist, P. A. The use of ultrasound-guided regional anesthetic techniques in neonates and young infants. Acta anesthesiologica Scandinavica 58, 1049-1060, doi:10.1111/aas.12372 (2014).
27. Willschke, H. et al. Management of hypertrophic pylorus stenosis with ultrasound guided single shot epidural anesthesia--a retrospective analysis of 20 cases. Paediatr Anesth 21, 110-115, doi:10.1111/j.1460-9592.2010.03452.x (2011).
28. Bosenberg, A. & Lonnqvist, P. A. The potential future or just a way of trespassing the safety limits of pediatric regional anesthesia? Paediatr Anesth 21, 95-97, doi:10.1111/j.1460-9592.2010.03503.x (2011).