If you wish to respond to a paper or other item already published in the BJA, please go to the abstract/full text version of that item and click on the link "E-Letters: Submit a response to the article".
Electronic Letters to:
|
|
E-letters: Electronic letters published:
-
![[Read E-letter]](/icons/misc/sectionDOWN.gif)
Reply to: Neurotoxicity and epidural dexmedetomidine.
- Hala S El-Ozairy (20 October 2009)
-
Neurotoxicity and epidural dexmedetomidine
- Christopher J King (14 October 2009)
-
Reply to the e-letter
- Hala Salah El-Ozairy (7 August 2009)
-
Adjuvants for analgesia following caudal blockade: Should this become the norm?
- Amar Minhas, Santhanam Suresh, MD (21 July 2009)
|
|
|||
|
Hala S El-Ozairy, Lecturer of anesthesia-Ain Shams University
Send letter to journal:
|
In reply to Dr. King, We actually started our study in December 2007 (before the results of Konaki and coworkers 1 was published). At that time, the available studies concerning epidural administration of dexmedetomidine did not mention any neurotoxic side effects.2-5 In fact; animal studies revealed that dexmedetomidine has neuroprotective effects.6, 7 More recent studies discussed the benefits of adding dexmedetomidine to the local anaesthetic during epidural anaesthesia without mentioning any neurotoxic side effects.8, 9 Konaki et al. mentioned in their study that dexmedetomidine does not have motor or sensory effects which contradict the results obtained by Burmmett and colleagues.10 They attributed the neurotoxicity of dexmedetomidine in their study to its low pH (4.5-7). However, clonidine with similar pH (5- 7) does not exert neurotoxic side effects.11-13 We agree that further studies are necessary to ensure the safety and benifits of dexmedetomidine application via the epidural route. References: 1- Konaki S, Adanir T, Yilmaz G, Rezanko T. The efficacy and neurotoxicity of dexmedetomidine administered via the epidural route. Eur J Anaesthesiol2008; 25: 403–9. 2- Eisenach JC, Shafer SL, Bucklin BA, Jackson C, Kallio A. Pharmaco-kinetics and pharmacodynamics of intraspinal dexmedetomidine in sheep. Anesthesiology 1994; 80(6): 1349-1359. 3- Vieira AM, Schnaider TB, Brandao ACA, Pereira FA, Costa ED, Fonseca CEP. Epidural clonidine or dexmedetomidine for postcholecystectomy analgesia and sedation. Rev Bras Anestesiol 2004; 54:473–8. 4- Salgado PF, Nascimento P, Modolo NS, Sabbag AT, Silva PC. Adding dexmedetomidine to ropivacaine 0.75% for epidural anesthesia. Does it improve the quality of the anesthesia? Anesthesiology 2005; 103: A974 5- Schnaider TB, Vieira AM, Brandao ACA, Lobo MVT. Intraoperative analgesic effect of epidural ketamine, clonidine or dexmedetomidine for upper abdominal surgery. Rev Bras Anestesiol 2005; 55: 525–31. 6- Halonen T, Kotti T, Tuunanen J, Toppinen A, Miettinen R, Riekkinen P. α2 –Adrenoceptor agonist, dexmedetomidine, protects against kainic acid-induced convulsions and neuronal damage. Brain research 1995; 693; 217-224. 7- Paris A, Montaz J, Tonnen PH, Hein L, Brede M, Gressens P. The effect of dexmedetomidine on perinatal excitotoxic brain injury are mediated by the α2A-adrenoceptor subtype. Anesthesia analgesia 2006; 102: 456- 461. 8- Saadawy I, Boker A, El-Shahawy MA, et al. Effect of dexmedetomidine on the characteristics of bupivacaine in a caudal block in pediatrics. Acta Anaesthesiol Scand 2008; 53: 251–6. 9- Salgado PF, Sabbag AT, Silva PC, Brienze SL, et al. Synergistic effect between dexmedetomidine and 0.75% ropivacaine in epidural anesthesia. Rev Assoc Med Bras 2008; 54(2): 110-5. 10- Brummett CM, Norat MA, Palmisano JM, Lydic R. Perineural administration of dexmedetomidine with bupivacaine enhances sensory and motor blockade in sciatic nerve block without inducing neurotoxicity in rat. Anesthesiology 2008; 109(3): 502-11. 11- Gordh TE, Ekman S, Lagerstedt AS. Evaluation of possible spinal neurotoxicity of clonidine. Ups J Med Sci 1984; 89(3): 266-73. 12- Gordh TE, Post C, Olsson Y. Evaluation of toxicity of subarachnoid clonidine, guanfacine, and a substance P-Antagonist on rat spinal cord and nerve roots. Anesthesia analgesia 1986; 65: 1303-1311. 13- Eisenach JC, Grice SC. Epidural clonidine does not decrease blood pressure or spinal cord blood flow in awake sheep. Anesthesiology 1988; 68:335-340. Conflict of Interest:None declared |
|||
|
|
|||
|
Christopher J King, Consultant Anaesthetist NUH, Singapore
Send letter to journal:
|
Dear Editor
In the discussion the authors acknowledge that there are still some concerns regarding the safety of dexmedetomidine and reference the paper of Konaki et al. These workers demonstrated that 10 mcg of dexmedetomidine HCl produces moderate to severe demyelination of spinal cord white matter in rabbits following epidural administration. The authors postulate that the low pH of 4.5- 7.0 of Precedex (dexmedetomidine HCl) is responsible for the injury to the myelin sheath. Precedex is isotonic, preservative- free and contains no additives. Precedex is not licensed for epidural use and clearly further studies regarding its safety via the epidural route are required. Presumably the results of El-Hannawy et al were obtained before Konaki et al’s paper was published. Reference: Konaki S, Adanir T, Yilmaz G, Rezanko T. The efficacy and neurotoxicity of dexmedetomidine administered via the epidural route. Eur J Anaesthesiol 2008; 25: 403-9. Conflict of Interest:None declared |
|||
|
|
|||
|
Hala Salah El-Ozairy
Send letter to journal:
|
As regards the e-letter concerning our article written by Dr. Minhas A and Dr. Suresh: The study conducted by Wheeler and colleagues in 2005 has also attracted our attention and we’ve referred to in the discussion section of our study. However, our results come along with the results of many other studies 1-10, and this was one of the points that raised our attention to carry out the study, that there is still an argument about whether the alpha-2 agonists when used as adjuvant to local anaesthetics can prolong the duration of the block. We noticed also that Wheeler’s study used bupivacaine 0.125% while we used bupivacaine 0.25% which raises a question whether the concentration of the local anaesthetic used make the difference? As for routine adding adjuvant alpha-2 agonist to all central neuraxial blocks, we think that this needs a cost-benefit study. We do think that adding adjuvant alpha-2 agonist should be considered in long painful procedures. 1 Lee JJ, Rubin AP. Comparison of a bupivacaine-clonidine mixture with plain bupivacaine for caudal analgesia in children. Br J Anaesth 1994; 72:258-262. 2 Jamali S, Monin S, Begon C, Dubousset A-M, Ecoffey C. Clonidine in paediatric caudal anaesthesia. Anesth Analg 1994; 78:663-666. 3 Constant I, Gall O, Gouyet L, Chauvin M, Murat I. Which adjuvant for caudal anesthesia in children: clonidine vs fentanyl. Anesthesiology 1996; 85:A1103. 4 Beauvoir C, Rochete A, Ricard C, Canaud N, D’Athis F. Clonidine prolongation of caudal anesthesia in children. Anesthesiology 1994; 81: A1347. 5 Constant I, Gall O, Gouyet L, Chauvin M, Murat I. Addition of clonidine or fentanyl to local anaesthetics prolongs the duration of surgical analgesia after single shot caudal block in children. British J Anaesthesia 1998;80:294-298. 6 Ivani G, De Negri P, Conio A, Amati M, Roero S, Giannone S, Lonnqvist PA. Ropivacaine-clonidine combination for caudal blockade in children. Acta Anaesthesiol Scand 2000; 44:446-449. 7 Klimscha W, Chaiari A, Michalek-Sauberer A, et al. The efficacy and safety of a clonidine/bupivacaine combination in caudal blockade for paediatric hernia repair. Anesth Analg 1998; 86:54-61. 8 Vieira AM, Schnaider TB, Brando ACA, Pereira FA, Costa ED, Fonseca CEP. Epidural clonidine or dexmedetomidine for postcholecystectomy analgesia and sedation. Rev Bras Anestesiol 2004; 54:473-8. 9 Saadawy I, Boker A, El-Shahawy MA et al. Effect of dexmedetomidine on the characteristics of bupivacaine in a caudal block in pediatrics. Acta Anaesthesiol Scan 2008; 53:2: 251-256. 10 Vetter TR, Carvallo D, Johnson JL, Mazurek MS, Presson RG. A comparison of single-dose caudal clonidine, morphine, or hydromorphone combined with ropivacaine in pediatric patients undergoing ureteral reimplantation. Anesthesia and Analgesia 2007; 104: 6: 1356-1363. Conflict of Interest:None declared |
|||
|
|
|||
|
Amar Minhas, Research Associate Children's Memorial Hospital, Santhanam Suresh, MD
Send letter to journal:
|
We read with interest the article by El-Hennawy in this month's issue of the BJA on the addition of clonidine or dexmedetomidine, both alpha 2 agonists for pain control following caudal blockade. We, in our own experience did not see much improvement with the use of clonidine in caudal blocks.(1) One of the main issues was the presence of hypotension which the authors have demonstrated to be relatively rare in their cohort. If this indeed is giving us the duration of analgesia as demonstrated by the Kaplan Mier curve, maybe we should be thinking about adding adjuvant alpha 2 agonists to all our central neuraxial blocks. 1. Wheeler M, Patel A, Suresh S: The addition of clonidine 2 mug.kg does not enhance the postoperative analgesia of a caudal block using 0.125% bupivacaine and epinephrine 1 : 200 000 in children: a prospective, double-blind, randomized study. Ped Anesth 15(6) 476-483, 2005 Conflict of Interest:None declared |
|||