Response to editorial by Davidson

Paediatric Anaesthesia 2003

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Baclofen pumps: comment on Anderson et al. SIR—We read with interest the report of Anderson et al. (1) concerning the use of baclofen pumps and reversible coma in children. We would like to report three children who experienced similar reversible coma following placement of baclofen pumps under general anaesthesia. All three were alert and responding when discharged from the PACU to the ward. However, 1.5 h later, we were asked to reevaluate the patients because of coma, hypotension, and bradycardia. Since the patients had received morphine in the PACU, a trial of Narcan was used with no improvement. All patients were given oxygen, fluid boluses and atropine. The baclofen infusion was stopped, and we continued to monitor our patients with other interventions. All of our patients responded slowly to our therapeutic measures and made an uneventful recovery. We thank Anderson et al. for their report and excellent discussion of the issues relating to starting the baclofen infusion in the immediate postoperative period and the concerns and confusion in treatment decisions. Timothy W. Martin James F. Mayhew Arkansas Children’s Hospital Little Rock, AR, USA

Reference 1 Anderson MJ, Farmer JS, Brown K. Reversible coma in children after improper baclofen pump insertion. Paediatr Anaesth 2002; 12: 454–460.

Baclofen pumps: comment on Anderson et al. SIR—We read with interest the report of Dr Anderson and colleagues who experienced unexpected coma in five patients postoperatively (1). Although some influence of the anaesthetic technique and analgesic medication could be related to this occurrence, the delay strongly suggests a relation with an accidental high dose of baclofen. Based on our early experiences of overdosing (2), we focused mainly on the intrathecal baclofen procedures. In hundreds of implantations involving adults and children, we have used another procedure for purging the pump, without any problem of postoperative coma or even sedation. In our procedure, the pump function testing in vitro is not carried

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out with sterile water but with baclofen solution. This includes emptying the pump reservoir followed by filling it with baclofen solution, usually 2000 lgÆml)1, before starting purging. By using a sterile video camera drape for covering the Medtronic programming head, the pump can be programmed for purging during the operation. After surgery, the implanted catheter dead space is calculated as mentioned in the article. The pump is then programmed for a bolus of 75% of the catheter dead space and in addition for the desired continuous daily infusion dose (2 · the effective test bolus dose during the screening phase). The 75% filling is an additional safety procedure, preventing overdose in cases of error in measurement of catheter length or calculation. The consequence is that postoperatively, the patient will not immediately have intrathecal medication, but will gradually receive the therapeutic continuous baclofen infusion. In this way the anaesthetic and analgesic influences are negligible. An additional advantage is that 0.3–0.4 ml water, which would influence the cerebrospinal fluid (CSF)-pH, is not injected into the intrathecal space. The need for immediate purging of the complete tubing ‘allowing the neurosurgeon to titrate the rate of the infusion prior to discharge from the hospital’ is not clear to us. E. Delhaas S. Goslinga Department of Anaesthesiology and Pain Treatment Groene Hilledijk, Rotterdam, the Netherlands (Email: [email protected])

References 1 Anderson KJ, Farmer JP, Brown K. Reversible coma in children after improper baclofen pump insertion. Paediatr Anaesth 2002; 12: 454–460. 2 Delhaas EM, Brouwers JRBJ. Intrathecal overdose: report of 7 events in 5 patients and review of the literature. Int J Clin Pharmacol Ther Toxicol 1991; 29: 274–280.

Authors’ reply SIR—We thank the authors for their letter concerning our article (1). We agree with them, and this was the message of our analysis that the coma in these children was more likely due to inadequate latency between the pump purge and the implantation. We addressed the problem by allowing the sterile water purge to fully take place prior to filling the baclofen reservoir. We have alerted the company supplying the pumps to that effect and a warning has been sent to  2003 Blackwell Publishing Ltd

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all the centres implanting pumps. The cost of these pumps at malfunction is elevated and we have preferred not to alter the company’s protocol to ensure the pump malfunction rate is kept to a minimum. With respect to the bolus, we have preferred to use more dilute concentration initially and calculate the bolus at 100% instead of 75%. I think the author’s suggestion of using 75% of this amount is an interesting one for safety issues, especially if a 2000 lgÆml)1 concentration is used. Our analysis suggested inadequate latency between the sterile water purge and baclofen bolus was the problem rather than the bolus. Patients are kept in the postanaesthesia care unit for 6 h and despite our calculation of the bolus at 100%, no respiratory depression or comatose state has recurred following the change in our latency policy. These spastic children more likely benefit from having baclofen, which starts its effect usually within 30 min following cessation of intraoperative conditions, because the postoperative pain exacerbates their spasticity. In young children requiring low doses, a shortfall of 25% in the bolus dose could mean that the baclofen effect would only start 24–48 h after implanation. K.J. Anderson J.-P. Farmer K. Brown Department of Anaesthesia, Montreal Children’s Hospital Montreal, Quebec, Canada (Email: [email protected])

Reference 1 Anderson KJ, Farmer JP, Brown K. Reversible coma in children after improper baclofen pump insertion. Paediatr Anaesth 2002; 12: 454–460.

Postanaesthetic excitation and agitation SIR—I read the Editorial on postanaesthetic excitation (1) with a little bit of agitation. The author suggested that excitation was not reported at the time of the initial introduction of sevoflurane in Japan. Although not too much emphasized, excitation or agitation at emergence was described not only in the Japanese literature (2–4) but also in a European journal in 1991 (5) and this journal in 1993 (6). In 1991, Naito et al. (5) reported a greater incidence of postoperative restlessness and agitation after sevoflurane (60%) than after halothane (20%). and in 1993, Muto et al. (6) reported a greater incidence of excitement and agitation in the recovery room in comparison with halothane anaesthesia.  2003 Blackwell Publishing Ltd, Paediatric Anaesthesia, 13, 640–648

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It remains unclear why our Swiss colleague did not cite these last two articles from the journals of the Western world. It may be that in 1993 Paediatric Anaesthesia was not yet indexed in Index Medicus or MEDLINE. Masao Yamashita Ibaraki Children’s Hospital Mito Ibaraki Japan

References 1 Jo¨hr M. Postanaesthesia excitation. (Editorial). Paediatr Anaesth 2002; 12: 293–295. 2 Iwai S, Hoshina H, Murata H et al. Clinical experiences of sevoflurane in pediatric anesthesia. (in Japanese). Masui 1987; 36: 1796–1801. 3 Furuya Y, Tachibana C, Kobayashi N et al. Comparison of sevoflurane and halothane in pediatric anesthesia. (in Japanese). Masui 1993; 42: 46–51. 4 Yamamoto I, Yukioka H, Fujimori M. Clinical study of postoperative sedation in pediatric patients- Effects of inhalation anesthetics and postoperative analgesics. (in Japanese). Masui 1994; 43: 1191–1195. 5 Naito Y, Tamai S, Shingu K et al. Comparison between sevoflurane and halothane for paediatric ambulatory anaesthesia. Br J Anaesth 1991; 67: 387–389. 6 Muto R, Miyasaka K, Takata M et al. Initial experience of complete switchover to sevoflurane in 1550 children. Paediatr Anaesth 1993; 3: 229–233.

Comment on editorial by M Jo¨hr SIR—I was rather astonished to read the editorial by Dr Jo¨hr on postanaesthesia excitation, in particular, regarding the description of sevoflurane. I felt obligated to respond to his dubious assumptions such as ‘It remains unclear why our Japanese colleagues did not report this striking phenomenon’ and ‘It may be their cultural background accepted crying after surgery, probably associated with insufficient pain relief in the early 1990s, to be normal behaviour for children.’ (1)., Sevoflurane was approved in Japan in January or 1990, rather than 1992, as Dr Jo¨hr stated, and has been the principal inhalation agent of all ages in Japan since then, Sevoflurane has been the sole inhalation agent in our institution from July 1990 to today. We reported our initial experience in Paediatric Anaesthesia in 1993 (2). In this paper, we discussed agitation during emergence from sevoflurane anaesthesia, as we experienced occasional agitation during our initial period of experience with the agent. We were not used to such a rapid recovery from sevoflurane then, but it became obvious that common sense in paediatric anaesthesia could easily overcome the situation., We soon found and reported that appropriate adjustment of the anaesthesia level at the end of surgery (not lightening anaesthesia

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prematurely), minimum stimulation during transfer to and time in the recovery room, and anticipatory administration of analgesics (regional anaesthesia and ⁄ or narcotics) substantially decreased such episodes of excitation (2). We felt then that sevoflurane and halothane produced a similar incidence of postanaesthetic excitement, as reported by others later (3)., We have been following the above policy on sevoflurane administration for the past 12 years and we have not found anything particularly disturbing about postanaesthesia excitement. This is not to say that we do not care about crying children. We were providing active care management as early as the 1980s in Japan (4). We are not saying that sevoflurane is a perfect agent, rather that it is similar to other inhalation agents and demands sensitivity to the patient. Katsuyuki Miyasaka Director, Department of Anaesthesia and ICU National Children’s Medical Center Nation Center for Child Health and Development Tokyo, Japan

References 1 Jo¨hr M. Postanaesthesia excitation. (Editorial). Paediatr Anaesth 2002; 12: 293–295. 2 Muto R, Miyasaka K, Takata M et al. Initial experience of complete switchover to sevoflurane in 1550 children. Paediatr Anaesth 1993; 3: 229–288. 3 Murray DJ, Cole JW, Shrock CD et al. Sevoflurane versus halothane: effect of oxycodone premedication on emergence behaviour in children. Paediatr Anaesth 2002; 12: 308–312. 4 Shandling B, Steward DJ. Regional analgesia for postoperative pain in paediatric outpatient surgery. J Pediatr Surg 1980; 15: 477–480.

Authors’ reply SIR—Thank you for the opportunity to reply to Dr Yamashita and Dr Miyasaka I appreciate that the huge Japanese experience with sevoflurane receives more attention than it did in my editorial (1) and that additional references are cited. I apologise if this editorial appeared not to sufficiently honour the Japanese experience. This editorial was based on five years’ experience after a complete switch from halothane to sevoflurane in the authors’ own institution – sevoflurane has undoubtedly led to increased safety – and on a complete MEDLINE search; most of the relevant literature is included. It is undoubtedly correct that restlessness and agitation were reported before the randomized, controlled trial of Aono et al. (2), however, this was not greatly emphasized. As early as 1991, Naito et al. (3) reported agitation in 9 ⁄ 15 children with sevoflurane compared with 3 ⁄ 15 after halothane. This difference did not reach statistical signi-

ficance and was attributed to pain and apparently treated effectively with indomethacin in all patients. This striking effectiveness of nonsteroidals probably does not reflect the experience of the majority of paediatric anaesthesiologists today, at least in Europe. In 1993 Muto, Miyasaka et al. (4) reported in this journal, not yet indexed in MEDLINE, that special care needs to be taken during emergence from sevoflurane anaesthesia because children occasionally became agitated in the recovery room. Fortunately, common sense in paediatric anaesthesia could easily overcome the situation: the authors reported that minimal stimulation during transfer to the recovery room and emergence from anaesthesia might be beneficial, in addition to anticipatory administration of analgesics. This editorial (1) concentrated on the convincing evidence that agitation unrelated to pain occurs after sevoflurane- or desfluranebased anaesthetics. Therefore, strategies for active prevention and treatment must be familiar to every anaesthetist using these newer agents. Opioids and clonidine have been reported in the literature to be effective. Small doses of thiopentone or propofol are used in our institution, as unstimulated recovery has not been proven to be reliably successful. This discussion on agitation in children after sevoflurane- or desflurane-based anaesthetics shows that it may take several years until even very common sideeffects are clearly recognized by the anaesthetic community: it took nearly eight years from the release of sevoflurane in Japan in January 1990 to the publication of the first paper focusing on agitation in pain-free children (December 1997) (2). This delay of years or even decades until recognition is not unusual for drug-related phenomena, e.g. etomidate and cortisol biosynthesis, propofol and its infusion syndrome, or – in view of the severity, more comparable – spinal lidocaine and transient neurological symptoms. The importance of close collaboration and continuous exchange of information among paediatric anaesthetists worldwide has to be emphasized in order to minimize this delay. Therefore, I would like to thank Dr Yamashita and Dr Miyasaka for their contributions. M a r t i n J o¨ h r Department of Anaesthesia Kantonsspital Luzern, Switzerland

References 1 Jo¨hr M. Postanaesthesia excitation. Paediatr Anaesth 2002; 12: 293–295. 2 Aono J, Ueda W, Mamiya K et al. Greater incidence of delirium during recovery from sevoflurane anesthesia in preschool boys. Anesthesiology 1997; 87: 1298–1300. 3 Naito Y, Tamai S, Shingu K et al. Comparison between sevoflurane and halothane for paediatric ambulatory anaesthesia. Br J Anaesth 1991; 67: 387–389.  2003 Blackwell Publishing Ltd, Paediatric Anaesthesia, 13, 640–648

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4 Muto R, Miyasaka K, Takata M et al. Initial experience of complete switchover to sevoflurane in 1550 children. Paediatr Anaesth 1993; 3: 229–233.

Comment on Matsota et al. SIR—As an anaesthetist with practice in the areas of adult neuroendocrine surgery and paediatric oncological surgery I was interested to read the description of anaesthesia for phaeochromocytoma surgery (1) in a 5-year old. The authors described a spectacular increase in haemodynamic parameters during tumour manipulation which would lead me to believe that the pre- and intraoperative catecholamine blockade was inadequate. I feel that the criteria for adequate alpha blockade should include nasal stuffiness as well as the more obvious postural hypotension. Intraoperative haemodynamic control can be much smoother if intravenous magnesium sulphate is employed. This may be given as an initial bolus of 50 mgÆkg)1 over 10 min before induction of anaesthesia followed by a continuous infusion of 15 mgÆkg)1Æh)1 plus bolus doses of 15 mgÆkg)1 if required. A serum level of 2–4 mmolÆl)1 should be aimed for if monitoring is available. Care must be taken with nondepolarizing muscle relaxants which should be used in lower doses with peripheral nerve stimulator monitoring. I routinely use an intraoperative low thoracic epidural for open phaeochromocytoma surgery but not for laparoscopic resections. It should not produce a fall in blood pressure due to afterload reduction if full alpha blockade and fluid replacement have been successful preoperatively. I would be interested to know if other anaesthetists would consider using magnesium in this context. Patrick Butler Shackleton Department of Anaesthetics Southampton General Hospital Tremona Road Southampton UK (Email: [email protected])

Reference 1 Matsota P, Avgerinopoulo-Vlahou A, Velegrakis D. Anaesthesia for phaeochromocytoma removal in a 5-year-old boy. Paediatr Anaesth 2002; 12: 176–180.

Authors’ reply SIR—We would like to thank you for your valuable remarks, although we have already pointed out the lack  2003 Blackwell Publishing Ltd, Paediatric Anaesthesia, 13, 640–648

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of our experience, as this case was the first one in our hospital for the past 20 years. Our perioperative management was according to the bibliography and the medical publications until 1999, and our criteria, for the perioperative adrenergic blockade’s efficacy was based on the posture hypotension and on the Hct fall. We agree that the adrenergic blockade was not appropriate and that therefore the child was unstable intraoperatively. Concerning the role of Mg++ in phaeochromocytoma management, we have no personal experience. We are aware of the hypomagnesaemia that occurs in patients with elevated blood catecholamines. As far as we know, there are only experimental data regarding magnesium administration in children and there is a lack of clinical reports about this matter. In case we have to handle another childhood phaeochromocytoma in the future we will consider your remarks. P. Matsota* A. Avgerinopoulou-Vlachou D. Velegrakis Department of Anaesthesiology Children’s Hospital ‘P & A Kyriakou’ Athens Greece *(Email: [email protected])

A double bloody tap on epidural insertion SIR—A complication that occurred on attempted insertion of epidural is reported. In this instance, the patient’s underlying pathology possibly predisposed him to this complication. An 18-month-old, boy (weight 6 kg) was anaesthetized for a fundoplication. He was born preterm at 29 weeks gestation with severe intrauterine growth retardation and required ventilation for the first 4 months of life. The patient suffered from chronic neonatal lung disease, was oxygen dependent and had documented significant pulmonary hypertension with right ventricular fibrosis. Following induction of anaesthesia, epidural insertion was attempted at the L2 ⁄ L3 interspace. An 18G paediatric Tuohy needle (Portex, Hythe, UK) was inserted using the loss of resistance to saline technique. On entering the epidural space, blood appeared at the hub of the needle. The needle was withdrawn and reinserted at the L1 ⁄ L2 interspace. Entering the epidural space was uneventful. However, after insertion of the 21G epidural catheter, blood was aspirated through the catheter. The procedure was abandoned. Inadvertent cannulation of an epidural blood vessel is a recognized complication of this procedure however, its

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occurrence in paediatric practice is uncommon. In his series of 650 paediatric epidurals, Dalens reported an incidence of blood reflux of 0.9% (1). It could be postulated that in this patient, the high pulmonary artery pressures were directly transmitted to the thin-walled valveless epidural veins causing them to be engorged thus directly contributing to this complication. It is recommended that anaesthetists be aware of the potential for this complication in this specific group of patients. Mark Sacks Department of Anaesthesia St Mary’s Hospital, Praed Street London, W2 1NY UK (Email: [email protected])

Reference 1 Dalens B, Chrysostome Y. Intervertebral epidural anaesthesia in paediatric surgery: success rate and adverse effects in 650 consecutive procedures. Paediatr Anaesth 1991; 1: 107–117.

Response to editorial by Davidson SIR—We were very interested in Dr Davidson’s recent editorial arguing for an urgent redress of the lack of knowledge available on the incidence and psychological impact of awareness during paediatric anaesthesia (1). We would like to make colleagues aware of our ongoing work on this important topic. With the help of a substantial grant from the Wellcome Foundation, we recently commenced a large-scale study of approximately 600 hundred children to determine the incidence of awareness in paediatric anaesthesia using the isolated-forearm technique (2,3). We consider the isolatedforearm technique to be the ‘gold standard’ by which to detect awareness (4). Unlike the measures derived from the auditory evoked response and bispectral index, this technique does not require calibration for use with children. As noted by Dr Davidson, there are differences in memory formation in children and adults. Explicit memory, which refers to conscious recollection, is generally better in adults. However, implicit memory, which influences behaviour in the absence of conscious recollection, is usually as good in children as in adults (5). Implicit memory for information presented during anaesthesia has been demonstrated in adults (6). Thus children are as likely to have implicit memory for the intraoperative period as adults. In addition to using the isolated-forearm technique to assess intraoperative awareness, our study tests whether implicit memory

may result from awareness or unconscious processing. The psychological impact of awareness and implicit memory will be examined using a postoperative behavioural questionnaire (7). We look forward to presenting the results of our study in the not too distant future. Dr Ian Barker* Dr Catherine Deeprose† Dr Jackie Andrade‡ *Consultant Anaesthetist, Sheffield Children’s Hospital †Research Associate, Department of Psychology University of Sheffield (Correspondence) ‡Senior Lecturer, Department of Psychology University of Sheffield, Sheffield, UK

References 1 Davidson AJ. Awareness and paediatric anaesthesia. Paediatr Anaesth 2002; 12: 567–568. 2 Russell IF, Wang M. Absence of memory for intra-operative information during surgery with total intravenous anaesthesia. Br J Anaesth 1999; 86: 196–202. 3 Byers GF, Muir JG. Detecting wakefulness in anaesthetised children. Can J Anaesth 1997; 44: 486–488. 4 Jones JG, Aggarwal SK. Monitoring Depth of Anesthesia. In: Ghoneim, MM, eds. Awareness during anesthesia. Oxford: Butterworth-Heinmann, 2001: 69–92. 5 Naito M, Komatsu S. Processes involved in childhood development of implicit memory. In: Graf, P, Masson, MEJ, eds. Implicit memory. New Directions in Cognition, Development and Neuropsychology. Erlbaum: Hillsdale, NJ, 1993: 231–260. 6 Merikle PM, Daneman M. Memory for unconsciously perceived events: Evidence from anesthetized patients. Conscious Cog 1996; 5: 525–541. 7 Kotiniemi LH, Ryhanen PT, Moilanen IK. Behavioural changes in children following day-case surgery. a 4-week follow-up of 551 children. Anaesthesia 1997; 52: 970–976.

Comment on Cohen et al. SIR—The increasing coverage of emergence agitation in the paediatric anaesthetic literature is to be welcomed. We feel, however, that we must disagree with the assertion by Cohen et al. (1) that ‘these agents (midazolam and propofol) are not recommended for reducing emergence agitation in children…’. A consideration of the pharmacokinetics of intravenous anaesthetics would suggest that any clinically useful result could not have been achieved given the construction of their study. We would suggest that the effect site concentrations of midazolam and propofol in the doses described would have been insufficient to demonstrate a response, given that their time of administration was immediately after induction.  2003 Blackwell Publishing Ltd, Paediatric Anaesthesia, 13, 640–648

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It is our personal experience that small doses of propofol, as low as 0.5 mg kg)1 given intravenously immediately prior the removal of a laryngeal mask or tracheal tube, effectively reduces the incidence of emergence agitation following sevoflurane anaesthesia. Following positive feedback from our recovery staff, we are currently awaiting ethics committee approval for a study which we hope will provide scientific evidence that appropriately timed administration of propofol may have an important role in the prevention of this distressing phenomenon. P.C. Stewart FFARCSI* P. Cunnington FRCA† R. Martin FRCA† Consultant paediatric anaesthetists *Department of Anaesthesia The New Children’s Hospital Sydney New South Wales †Department of Anaesthesia, Princess Margaret’s Hospital for Children, Perth Western Australia, Australia

Reference 1 Cohen IT, Drewsen S, Hannallah RS. Propofol or midazolam do not reduce the incidence of emergence agitation associated with desflurane anaesthesia in children undergoing adenotonsillectomy. Paediatr Anaesth 2002; 12: 604–609.

Authors’ reply SIR—We appreciate Dr Stewart and his associates’ comments concerning our paper (1). We agree that hypnotics and sedatives given during the immediate pre- and postemergence period can reduce the incidence of agitation associated with desflurane and sevoflurane. Unfortunately, as described by Welborn et al. (2), recovery in these cases is prolonged. The aim of our study was to reduce the incidence of emergence agitation while preserving rapid recovery and extubation. In our discussion we commented that although the timing and doses of propofol and midazolam may not have been sufficient to reduce agitation, they did delay awaking and time to discharge. This is why we state that, with our technique, these medications are not recommended. We look forward to the results of Dr Stewart et al.’s proposed study. Ira Todd Cohen, MD Associate Professor of Anaesthesiology and Tediatrics The George Washington University Medical Center Staff Anaesthesiologist Children’s National Medical Center  2003 Blackwell Publishing Ltd, Paediatric Anaesthesia, 13, 640–648

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References 1 Cohen IT, Drewsen S, Hannallah RS. Propofol or midazolam do not reduce the incidence of emergence agitation associated with desflurane anaesthesia in children undergoing adenotonsillectomy. Paediatr Anaesth 2002; 12: 604–609. 2 Welborn LG, Hannallah RS, Norden JM et al. Comparison of emergence and recovery characteristics of sevoflurane, desflurane, and halothane in pediatric ambulatory patients. Anesth Analg 1996; 83: 917–920.

Response to editorial by G. Chalkiadis SIR—I read with interest and chagrin the editorial ‘The rise and fall of continuous epidural infusions in children’ by George Chalkiadis (1). He states that epidural analgesia in children is unreliable, labour intensive, inadequate for pain relief, risky to children and costly. He has ‘thrown down the gauntlet’ to his colleagues to demonstrate improved clinical outcomes and the cost benefits of this analgesic method. It seems Dr Chalkiadis is unaware of the more recent literature in this area that has seen the development of a new approach to epidural placement in children, and to the attempts to quantify clinical outcomes. I am referring to the placement of epidural catheters via the caudal space in the thoracic or lumbar area with the aid of electrical stimulation (2). Dr Chalkiadis correctly refers to epidural analgesia being reliant upon optimal positioning of the catheter tip within the epidural space. With our colleague’s (Dr B.C.H. Tsui) innovation, we improved our epidural success rate from 68% to 86% in the first year of its use with gradually increasing success in 2002 of 91% (unpublished data collected from prospective pain service database). Improved epidural catheter positioning improves analgesia and the use of the caudal insertion site reduces the risks of needle trauma quoted. Dr Chalkiadis does note that side-effects are no more common with epidurals than with intravenous opioids, however, with optimal catheter positioning opioids can be used in smaller amounts or not at all further reducing side-effects. In prospectively collected data on 289 patients receiving caudal placement of a lumbar or thoracic catheter the incidence of nausea ⁄ vomiting, pruritus and respiratory depression are all less in our patients with epidurals than those with patient controlled analgesia (3). Dr Chalkiadis concedes there are patient subgroups for which the risk ⁄ benefit ratio is acceptable for epidurals but that improved clinical outcomes and cost benefits have not been shown. Several authors have examined the patient outcomes of epidural analgesia in such

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groups. Two retrospective studies of patients undergoing Nissen fundoplications compared postoperative pain management with epidural analgesia to intravenous opioids. One study showed comparable mortality and complication rates as well as a shorter hospital stay in the epidural group (4). The other showed decreased duration of mechanical ventilation, reduced overall hospital charges and a shorter hospital stay (5). While these are not large randomized controlled trials, they show clear benefits of epidural analgesia in selected populations. We recommend Dr Chalkiadis try this more certain method of catheter placement before broadly condemning epidural analgesia in children. Dr Ramona A. Kearney, MD, FRCPC Associate professor, University of Alberta Department of Anaesthesiology and Pain Medicine Clinical Sciences Building, Room 8-120 Edmonton, Alberta T6G 2B7 Canada (Email: [email protected])

References 1 Chalkiadis G. The rise and fall of continuous epidural infusions in children. Paediatr Anaesth 2003; 13: 91–93. 2 Tsui BCH, Seal R, Koller J et al. Thoracic epidural analgesia via the caudal approach in pediatric patients undergoing fundoplication using nerve stimulation guidance. Anesth Analg 2001; 93: 1152–1155. 3 Tsui BCH, Wagner A, Cave D et al. Thoracic and lumbar epidurals via caudal using electrical stimulation. Guidance in Pediatric Patients: a Review of 289 Patients. Can J Anaesth 2003; 50: in press. 4 Wilson GAM, Brown JL, Crabbe DG et al. Is epidural analgesia associated with an improved outcome following open Nissen fundoplication? Paediatr Anaesth 2001; 11: 65–70. 5 McNeely JK, Farber NE, Rusy LM et al. Epidural analgesia improves outcome following pediatric fundoplication. A retrospective analysis. Reg Anesth 1997; 22: 16–23.

Response to editorial by Chalkiadis SIR—We read with interest the editorial by Dr Chalkiadis (1). We in the United Kingdom and Ireland also wish to determine the incidence of severe complications of epidural analgesia in children. Thus we have instigated a multicentre prospective audit of epidural analgesia in children. We have so far enrolled 3000 patients out of the 10 000 required. We expect to publish our results in 2005.

A. Moriarty and Birmingham Children’s Hospital Acute Pain Service for and on behalf of the audit participants Department of Anaesthesia Birmingham Children’s Hospital Birmingham, B4 6NH, UK

Reference 1 Chalkiadis G. The rise and fall of continuous epidural infusions in children. Paediatr Anaesth 2003; 13: 91–93.

Analgesia for cleft lip and palate: comment on Takemura et al. SIR—I read with interest the article ‘Correlation of cleft type with incidence of perioperative respiratory complications in infants with cleft lip and palate’ recently published in Paediatric Anaesthesia (1). The correlation among the groups of cleft lip and palate, the assessment of common cold symptoms in the preoperative period, using the Common Cold Score and the perioperative respiratory complications are all most interesting. However, I am interested to know what form of analgesia was used for these patients introperatively as the current trend is to rely more on nerve blocks such as bilateral infraorbital blocks for the lip repair and pharyngeal blocks for the cleft palate repair. The authors state that the ‘concentration of sevoflurane was adjusted between 1.5 and 3% to maintain anaesthesia’ but sevoflurane has no analgesic properties and children require some form of analgesia intraoperatively. Were opioids used intraoperatively and do the authors have haemodynamic data (blood pressure, heart rate) available from the operative period? Mariano Castilla Spanish Representative Federation of European Association of Paediatric Anaesthesia Divisional Chief (Consultant) Paediatric Anaesthesia Children’s Hospital Carlos Haya Ma’laga, Spain (Email: [email protected])

Reference 1 Takemura H, Yasumoto K, Toi T et al. Correlation of cleft type with incidence of perioperative respiratory complications in infants with cleft lip and palate. Paediatr Anaesth 2002; 12: 585– 588.

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Reply to Dr Castilla SIR—We appreciate the interest and comments of Dr Castilla in response to our work (1). We recognize that the analgesic properties of sevoflurane are weak. At light planes of anaesthesia with inhaled agents, adverse respiratory events such as breatholding, coughing and laryngeal spasm may occur (2). The duration of primary plastic surgery for cleft lip and palate (CLP) is comparatively short, but we do not have a shortacting opioid. Furthermore, the surgical field coincides with the upper airway. At extubation, sufficient awareness and absence of residual muscle relaxation are indispensable to prevent any postanaesthesia complications of the upper airway, which is the reason why we do not administer opioids or neuromuscular blocking agents intraoperatively. We have used sevoflurane alone in a mixture of O2 and N2O in infants who undergo primary repair of CLP and we adjust the concentration of sevoflurane to between 2.5 and 3% before suture of the skin and between 1.5 and 2% during skin closure. We would like to emphasize that we believe that sevoflurane should be used in high concentrations until the end of surgery when anaesthetizing infants for CLP who may be harbouring an upper respiratory tract infection. As far as judging from intraoperative haemodynamic responses, which we did not show in our paper, we believe that a sufficient depth of anaesthesia can be obtained by using this simple technique. Of course, after establishing the absence of immediate postoperative complications, we administer acetaminophen for the management of postoperative pain. Hiroshi Takemura Kazumasa Yasumoto Takashi Toi Akiyoshi Hosoyamada Department of Anaesthesiology Showa University School of Medicine Shinagawa-ku, Tokyo, Japan (Email: [email protected])

References 1 Takemura H, Yasumoto K, Toi K et al. Correlation of cleft type with incidence of perioperative respiratory complications in infants with cleft lip and palate. Paed Anaesth 2002; 12: 585–588. 2 Stanski DR. Monitoring depth of anesthesia. In: Miller RD, ed. Anesthesia, 5th edn. Philadelphia, PA: Churchill Livingstone 2000: 1087–1116.

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Scented vapours and endtidal inhalation agent monitoring system SIR—Inhalational induction of anaesthesia is commonly used in paediatric practice. Scented substances with different flavours are often applied to the inside of the anaesthesia mask. This makes the mask more acceptable to the child. We recently noticed that these scents caused the endtidal agent monitors to display the presence of volatile agents. This was in spite of the fact that no volatile agent was present. It was found to be reproducible. Two different makes of endtidal agent monitors (Ohmeda 5250 RGM, Louisville, CO, USA and the Datex Capnomac Ultima, Helsinki, Finland) were tested. It was repeated (with different flavoured vapours e.g. bubble gum, strawberry, watermelon) many times with different rates of fresh gas flow using new anaesthesia circuit, facemask and endtidal tubing and more than one anaesthesia machine and endtidal monitor of each brand. At each flow rate the agent analyser was adjusted to measure one of the volatile agent e.g. halothane, sevoflurane, isoflurane, enflurane and desflurane. All of them showed very high readings for these agents. All these repeated experiments were carried out without any patient involvement. All these scented oils contained propylene glycol (an alcohol); and most of them contained alcohol or ethyl alcohol in addition to artificial flavouring agents. We performed a literature search and found that alcohols (ethanol, methanol, isopropanol), methane or acetone in sampled gases can cause spuriously high volatile agent readings (1–3). Alcohol vapours present in the scented vapours affect the accuracy of readings (4). Therefore, we would like to caution other practitioners to be cautious in interpreting endtidal anaesthetic agent values when scented flavours are used while practicing anaesthesia. M u h a m m a d B . R a fi q u e Clinical Instructor Tufts University School of Medicine Department of Anesthesiology Tufts-New England Medical Center 750 Washington St., Box 298 Boston, MA 02111 USA (Email: [email protected])

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References 1 Dorsch JA, Dorsch SE. Understanding Anesthesia Equipment. Philadelphia: Lippincott, Williams and Wilkins, 1999: 700–704. 2 Foley MA, Wood PA, Peel WJ et al. The effect of exhaled alcohol on the performance on the Datex Capnomac. Anaesthesia 1990; 45: 232–234.

3 Guyton DC, Gravenstein N. Infrared analysis of volatile anesthetics: impact of monitor agent setting, volatile mixture and alcohol. J Clin Monit 1990; 6: 203–206. 4 Yamashita M, Tsuneto S. ‘Normac’ falsely recognizes ‘fruit extract’ as an anesthetic agent. Anesthesiology 1987; 66: 97–98.

 2003 Blackwell Publishing Ltd, Paediatric Anaesthesia, 13, 640–648