Pediatric epidural analgesia (PEA)

Transcription

1 Pediatric Anesthesia ISSN REVIEW ARTICLE Pediatric epidural analgesia (PEA) Anthony Moriarty Birmingham Children s Hospital NHS Foundation Trust, Birmingham, UK Keywords acute; pain; regional; ultrasound Correspondence Dr Anthony Moriarty, Birmingham Children s Hospital NHS Foundation Trust, Steelhouse Lane, Birmingham B4 6NH, UK tony.moriarty@bch.nhs.uk The pediatric epidural is an accepted method of advanced analgesia in children. Newer techniques have now superseded pediatric epidural analgesia (PEA), being as effective and safer, especially with the advances in ultrasonography. PEA is, however, still an important technique to master and employ, and it may be that the indications for this mode of analgesia have now become more defined. Section Editor: Per-Arne Lonnqvist Accepted 3 October 2011 doi: /j x Indications The indications for continuous epidural analgesia in children have become clearer in the light of recent advances in other pain techniques. These indications would now comprise the following: l open Thoracic surgery; l major Intra-abdominal surgery, with visceral dissection; l spinal surgery (1); and l long-term pain management. All other surgeries are better managed with specific techniques such as paravertebral blockade (2), trans abdominal plexus blocks, rectus sheath blocks, and specific lower limb blocks. Benefits of PEA Medical literature concerning children is sparse when comparing PEA and morphine techniques for advanced analgesia. Wilson and Brown demonstrated a decrease in hospital stay with PEA compared with a morphine technique. In our own department, we have shown a decrease requirement for PICU stay if a child receives PEA in both esophageal atresia and gastroschisis surgery (Table 1). We are thus left to examine adult studies, Warschkow (3), and Rigg (4) in the MASTER trial demonstrated a decrease in respiratory complications in the PEA group. This MASTER study also detailed the difficulty in elucidating differences in outcome between the two groups with differences in mortality requiring enrollment of patients and differences in morbidity requiring 6000 patients. Meta-analyses have, therefore, been used, and ones by Block (5) and Guay (6) show improvements in pain control and a decreased incidence of nausea and vomiting when PEA is used. This was then neatly summarized in a Cochrane review of the subject (7). A second Cochrane review (8) demonstrated comparable pain relief but much less effect on delaying gastrointestinal recovery. Confirming studies by Taqi (9) and Zingg (10). PEA is now thus recommended as part of the NHS-enhanced recovery program tools/quality_and_service_improvement_tools/enhanced_ recovery_programme.html. Effects on mortality are much more difficult to show any benefit for PEA although the MASTER trial above showing no difference. Interestingly, recent work appears to suggest that PEA may be associated with a reduction in mortality secondary to surgery for some types of cancer (11). These studies demonstrate the advantages of PEA over morphine techniques. However, in the UK, the use of PEA is falling, and in the period , the numbers have fallen by Pediatric Anesthesia 22 (2012) ª 2011 Blackwell Publishing Ltd 51

2 Pediatric epidural analgesia A. Moriarty Factors PICU/ward PICU/ward P value Extent of Surgery Full closure 18/12 Silo 11/ Appearance of gut Abnormal 13/6 Normal 16/ Age at surgery <6 h 7/5 >6 h 9/ Gestational age Preterm 21/9 Term 8/ Anesthetic management Epidural analgesia 6/16 37% PICU Morphine analgesia 23/3 88% PICU ** Table 1 An investigation of the factors that affect requirement for Pediatric Intensive Care after major Gastroschisis surgery. (J Montgomerie, Birmingham Children s Hospital, pers. comm.) The only factor to determine the requirement for PICU was the use of pediatric epidural analgesia or morphine techniques. **signifies statistical significance. 40% (personal communication Paediatric Pain Travelling Club). This is secondary to the increase in laparoscopic surgery and the greater use and success of other local anesthetic techniques. Risks of PEA Pediatric epidural analgesia is associated with risks, and large multicenter studies have given us an idea about the extent of this risk. The UK Pediatric Epidural audit (12) showed a risk of serious complications to be 1 : 2000 and persistent complications to be 1 : epidurals. Examination of the recent medical literature has revealed two complications of epidural analgesia, one that was recovered (13) and one that resulted in persistent damage The NAP-3 (14) study in the UK looking at all complications of regional techniques in children showed one complication of PEA in c techniques performed in children. The overall incidence of complications of PEA was comparable to the Llewellyn audit above with a projected incidence of complications of c. 1 : (this is in comparison with a projected incidence of complication of caudal analgesia of 0.2 : complications). Paraplegia or death secondary to central techniques in all age patients was described as 1 : ADARPEF (15) recently described their repeat audit of all local anesthetic techniques performed over a 1-year period. There were 1500 cases of PEA. The incidence of complications was comfortingly low, but still central techniques have an incidence of complications that is seven times the regional techniques. Complications are also higher in the under 6 month age group, being four times that of the over 6 month age group. The above studies now permit much better information that may be given to parents and carers to allow a decision to be made regarding PEA. However, it is necessary to compare these with recent studies looking at the incidence of complications because of intravenous morphine techniques. Morton s (16) study was a direct comparison of the UK audit above and declared an incidence of 1 : patients, and Howard et al. (17) declared an incidence of serious complications of 0.4% (4 : 1000). Both also showed an increased risk in neonates and small children. How do we decrease the risks of PEA? 1. Correct indication for PEA in the first place, is there a better regional technique? 2. Scrupulous asepsis. 3. Understanding that attempting to repeatedly access the epidural space and inserting a catheter is associated with increased risk of damage. 4. In neonates, the caudal space is safer than lumbar spaces for insertion of an epidural catheter. 5. Neonates are at greater risk of drug-related problems, the safety margin is much lower here than in children. 6. Complications of PEA are also directly related to the duration of the infusion, and this increases greatly if the epidural is used for more than 72 h. 7. The provision of a team to monitor the PEA, both medical, nursing, and allied staff, with protocols in place for every possible side effect and complication. 8. Regular audits of efficacy and side effects. 9. A direct chain of command to senior staff for advice and decision making. Insertion of catheters Awake or asleep? Adult practice is to insert epidural catheters with the patient asleep; however, the requirement for this has been questioned (18). Many years of safe practice in the insertion of epidural catheters in children would seem to support the practice of asleep insertion. The UK audit (12) of patients had one child who developed nerve root damage; this was in a child under 6 months where it would have been impossible to have the child awake 52 Pediatric Anesthesia 22 (2012) ª 2011 Blackwell Publishing Ltd

3 A. Moriarty Pediatric epidural analgesia for the technique. It should be noted that the spinal cord has no sensory fibers, and thus no pain is elicited if the spinal cord is damaged with the tuohy needle. Ethically and practically, it is impossible to suggest that epidural placement should occur with the patient awake. Technical aspects Loss or resistance to saline is the most common technique for identifying the epidural space (19). Use of air for this technique was eradicated after the first ADA- RPEF (20) study recommended against the use of air. The problem with routine catheter insertion is that there is no control over the tip of the epidural catheter, and catheters are known to migrate to the incorrect position. The longer the catheter is introduced into the epidural space, the more likely that migration will occur. Recently other methods, namely radiology, ECG guidance (21), and ultrasonography (22), have been introduced to try and improve this situation. These techniques are useful but time consuming, and the benefit/risk ratio in older children with greater X-ray exposure is questionable. In neonates, and children up to the age of 6 months, the vertebral column remains largely cartilaginous, and epidural catheters can be visualized with ultrasonography along the length of insertion. In neonates, the caudal space is the safer and thus preferred the portal of entry resulting in the requirement for more catheters to be inserted into the epidural space, and as such, the possibility of misplacement is greater. Ultrasonography can also be used to assess neonates in whom the epidural catheter may not have been inserted with Ultrasonographic guidance; the location of the catheter tip will allow confirmation of correct or incorrect initial placement. Interestingly, ultrasonographic work in the authors department has shown in 20 consecutive children that if the epidural catheter is placed correctly in neonates, there is no further migration of the catheter over the period of the epidural infusion. Thoracic surgery It is the view of the author that for thoracic surgery, the catheter should be introduced as close to the dermatomal level of incision as is possible. In the UK audit (12), there was no increased risk with catheters inserted at the thoracic level in comparison with lumbar insertion. Thoracic surgery has results in more pain than abdominal surgery, and the epidural should be placed with the expectation of the greatest degree of success. The only proviso to this would be children under 6 months where ultrasonic evaluation of the tip of the catheter is possible. Drugs and additives The newer local anesthetic agents L-Bupivacaine and Ropivacaine are safer than Bupivacaine and have largely superseded Bupivacaine in practice. There seems to be no advantage of one drug over the other in effect (23), but Ropivacaine may have a higher therapeutic ratio when used in infusions (24). Additives Epinephrine Ropivacaine has vasoconstrictive effects, and the use of epinephrine with this solution will not improve analgesia. Ketamine Recent concerns as to the direct neurotoxic and apoptotic effects of ketamine have also removed this drug as a useful adjunct to epidural analgesia. Opioids Time and experience have verified the use of opioids as an adjunct to PEA. Longer acting (less lipid soluble) opioids such as morphine and diamorphine have central effects separate to their effect on the spinal cord and thus are more useful in generalized analgesia. The shorter acting agents such as sufentanil and fentanyl do not have a central effect but increase the intensity of the existing dermatomal spread of local anesthetic agents and thus are very useful in the presence of unilateral blocks or blocks with missed segments. Clonidine The present commercial solution is not marketed for epidural use. However, there are many papers describing its use in single-shot analgesia. Infusion analgesia with clonidine has been described (25,26). Compartment syndrome Pediatric epidural analgesia has always been questioned in orthopedic surgery where compartment syndrome is a possibility. The UK audit demonstrated that the pain from compartment syndrome would always breakthrough the analgesia provided by PEA. A recent editorial also suggested that PEA does not delay diagnosis of compartment syndrome (27). Is it Pediatric Anesthesia 22 (2012) ª 2011 Blackwell Publishing Ltd 53

4 Pediatric epidural analgesia A. Moriarty also true that morphine techniques may also mask the diagnosis of compartment syndrome if settings are not optimum (28). Future The future of PEA remains clouded. The decrease in use of PEA is concrete. It remains a technique with proven benefits, but with rare but significant risks. The benefit/risk ratio needs to be evaluated every time a catheter is placed. The decrease in use of PEA also means that: 1. staff have less opportunity to perform the technique, and a technical skill or confidence may be lost, and 2. the ward staff managing the patient has less exposure to the technique, and thus, side effects may not be noticed as quickly and managed as well. Chalkiadis in his editorial of 2003 (29) predicted the rise and fall of epidural infusions. It would appear to be prophetic. Acknowledgment This research was carried out without funding. Conflict of interest No conflicts of interest declared. References 1 Taenzer AH, Clark C. Efficacy of postoperative epidural analgesia in adolescent scoliosis surgery: a meta-analysis. Pediatr Anesth 2010; 20: Davies RG, Myles PS, Graham JM. A comparison of the analgesic efficacy and sideeffects of paravertebral vs epidural blockade for thoracotomy a systematic review and meta-analysis of randomized trials. Br J Anaesth 2006; 96: Warschkow R, Steffen T, Lu thi A et al. Epidural analgesia in open resection of colorectal cancer: is there a clinical benefit? A retrospective study on 1,470 patients. J Gastrointest Surg 2011; 15: Rigg JR, Jamrozik K, Myles PS et al. Epidural anaesthesia and analgesia and outcome of major surgery: a randomised trial. Lancet 2002; 359: Block BM, Liu SS, Rowlingson AJ et al. Efficacy of postoperative epidural analgesia: a meta-analysis. JAMA 2003; 290: Guay J. The benefits of adding epidural analgesia to general anesthesia: a metaanalysis. J Anesth 2006; 20: Nishimori M, Ballantyne JC, James HS. Epidural pain relief versus systemic opioidbased pain relief for abdominal aortic surgery. Available at: 8 Jørgensen H, Wetterslev J, Møiniche S et al. Epidural local anaesthetics versus opioidbased analgesic regimens for postoperative gastrointestinal paralysis, PONV and pain after abdominal surgery. Available at: index.html. 9 Taqi A, Hong X, Mistraletti G et al. Thoracic epidural analgesia facilitates the restoration of bowel function and dietary intake in patients undergoing laparoscopic colon resection using a traditional, nonaccelerated, perioperative care program. Surg Endosc 2007; 21: Zingg U, Miskovic D, Hamel CT et al. Influence of thoracic epidural analgesia on postoperative pain relief and ileus after laparoscopic colorectal resection: benefit with epidural analgesia. Surg Endosc 2009; 23: Gupta A, Bjo rnsson A, Fredriksson M et al. 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5 A. Moriarty Pediatric epidural analgesia undergoing the Nuss procedure. Anesth Analg 2006; 103: , table of contents. 27 Johnson DJ, Chalkiadis GA. Does epidural analgesia delay the diagnosis of lower limb compartment syndrome in children? Pediatr Anesth 2009; 19: Yang J, Cooper MG. Compartment syndrome and patient-controlled analgesia in children analgesic complication or early warning system? Anaesth Intensive Care 2010; 38: Chalkiadis G. The rise and fall of continuous epidural infusions in children. Paediatr Anaesth 2003; 13: Pediatric Anesthesia 22 (2012) ª 2011 Blackwell Publishing Ltd 55