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Combined anesthesia and integration of mechanisms. Mixing flavour for a better recipe
- Davide Cattano, Francesco Giunta (19 December 2006)
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Davide Cattano, Assistant Professor of Anesthesiology Department of Surgery, University of Pisa, Pisa, Italy, Francesco Giunta
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To the editor Sir, Rasmussen and collegues showed the potential use of xenon in non cardiac surgery, for routine supplementation of regional anesthesia in orthopedic surgery for the elderly, a population at higher risk for postoperative cognitive dysfunctio (POCD) after major surgery, extensively and previuosly studied by this group. However in our opinion there are some issues that warrant attention. Xenon has been claimed a better neuroprotectant, especially in excitotoxicity and NMDA over-stimulation, such as hypoxic ischemic and traumatic brain injury, at least in the adult, when the cellular mechanisms of adaptation are not apoptogenic. Moreover, while nitrous oxide and ketamine (such as other experimental NMDA antagonists) are accused to be neurotoxic,xenon seemed to be safe. In this work Abraini et al. claimed the potential neurotoxic effects of xenon when administered progressively over 70%. In our experience xenon has been proved an effective experimental neuroprotectant and safe anesthetic in rats at concentrations above 50% and with minimal effect at 35%. We recently measured the S100B protein in two elderly patients scheduled for major abdominal surgery and anaesthetized with xenon; Anaesthesia was induced using propofol/remifentanyl infusion(see table), reaching a mean concentration of 60%, showing no significant changes;one patient showed a longer wash out time but this was probably related to her peripheral vascular disease. However in considerations of different studies, we may suggest a more cautious use of higher concentrations of xenon in favor of concentrations between 35-40% that may still provide enough NMDA antagonism but integrated by GABAergic drugs which provide neuroprotection and provide NMDA antagonist protection as well. The choice of LMA and spontaneous ventilation seems to us not appropriate in consideration of the respiratory modifications that xenon induces in terms of viscosity. An assisted mechanical ventilation would be more appropriate. Last but not the least we believe that the emetic effect of xenon may be avoided if the gas is terminated earlier, substituted by 10 minutes of full oxygenation and maintaining propofol, which may be discontinued at last. Davide Cattano, MD Assistant Professor of Anesthesiology, Department of Surgery School of Medicine, University of Pisa, Pisa, Italy Clinical Instructor of Anesthesiology Department of Anesthesiology School of Medicine, Washington University of St Louis 660 South Euclid Avenue Campus Box 8054 St Louis MO 63110-1056 office 314 362 2345 pager 314 253 1250 mobile 314 601 4265 fax 314 362 1185 cattanod@msnotes.wustl.edu Francesco Giunta, MD Professor of Anesthesiology, Department of Surgery, School of Medicine, University of Pisa, Pisa, Italy S100 beta time 0 End of surgery 24 hours Pt 1 0.1 mcg/L 0.6 0.5 Pt 2 0.2 mcg/L 0.4 0.1 Rasmussen LS, Schmehl W, Jakobsson J. Comparison of xenon with propofol for supplementary general anaesthesia for knee replacement: a randomized study.Br J Anaesth. 2006 Aug;97(2):154-9. Preckel B, Weber NC, Sanders RD, Maze M, Schlack W. Molecular mechanisms transducing the anesthetic, analgesic, and organ-protective actions of xenon. Anesthesiology. 2006 Jul;105(1):187-97. Homi HM, Yokoo N, Ma D, Warner DS, Franks NP, Maze M, Grocott HP.The neuroprotective effect of xenon administration during transient middle cerebral artery occlusion in mice. Anesthesiology. 2003 Oct;99(4):876-81. Jevtovic-Todorovic V, Beals J, Benshoff N, Olney JW.Prolonged exposure to inhalational anesthetic nitrous oxide kills neurons in adult rat brain. Neuroscience. 2003;122(3):609-16. Abraini JH, David HN, Lemaire M.Potentially neuroprotective and therapeutic properties of nitrous oxide and xenon. Ann N Y Acad Sci. 2005 Aug;1053:289-300. Natale G, Cattano D, Abramo A, Forfori F, Fulceri F, Fornai F, Paparelli A, Giunta F.Morphological evidence that xenon neuroprotects against N-methyl-DL-aspartic acid-induced damage in the rat arcuate nucleus: a time-dependent study. Ann N Y Acad Sci. 2006 Aug;1074:650-8. Conflict of Interest:None declared |
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