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Re: Isoflurane is pungent
- Tadashi Matsuura, Yutaka Oda (30 June 2009)
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Isoflurane is pungent
- Muhammad Rahim M Kayani (16 June 2009)
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Tadashi Matsuura Department of Anesthesiology, Osaka City University Graduate School of Medicine, Yutaka Oda
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Editor- We are grateful to the legitimate questions raised to our clinical study1 by Dr Kayani. Before sevoflurane became commercially available, we had mainly used isoflurane as an anaesthetic for both inhalational induction and maintenance of anaesthesia. As he pointed out, isoflurane is not currently used for induction of anaesthesia because its intense airway irritation could induce adverse effects such as cough reflex, breath-holding or laryngospasm during induction2. Despite these disadvantages, we still occasionally use isoflurane to patients during maintenance of anaesthesia for its least biometabolic rate in all anaesthetics as well as greater potency affecting the electroencephalographic indices compared with sevoflurane3. These underlying benefits of isoflurane promoted us to investigate the sedative potency of isoflurane relative to that of sevoflurane; however, no difference was evidenced between these two anaesthetics on the potency except induction time4 and minimum alveolar concentrations for maintaining bispectral index below 501. In our past study4,5 we employed isoflurane as an anaesthetic for induction whereby isoflurane exerted no adverse events including airway trouble. None of patients receiving isoflurane in the studies have complained of discomfort. T. Matsuura Y. Oda Osaka, Japan Email: odayou@msic.med.osaka-cu.ac.jp References 1. Matsuura T, Oda Y, Tanaka K, Mori T, Nishikawa K, Asada A: Advance of age decreases the minimum alveolar concentrations of isoflurane and sevoflurane for maintaining bispectral index below 50. Br J Anaesth 2009; 102: 331-5 2. Doi M, Ikeda K: Airway irritation produced by volatile anaesthetics during brief inhalation: comparison of halothane, enflurane, isoflurane and sevoflurane. Can J Anaesth 1993; 40: 122-6 3. Olofsen E, Dahan A: The dynamic relationship between end-tidal sevoflurane and isoflurane concentrations and bispectral index and spectral edge frequency of the electroencephalogram. Anesthesiology 1999; 90: 1345-53 4. Matsuura T, Oda Y, Ikeshita K, Nishikawa K, Ito K, Asada A: Differential electroencephalographic response to tracheal intubation between young and elderly during isoflurane and sevoflurane nitrous oxide anaesthesia. Br J Anaesth 2007; 99: 858-63 5. Oda Y, Tanaka K, Matsuura T, Hase I, Nishikawa K, Asada A: Nitrous oxide induces paradoxical electroencephalographic changes after tracheal intubation during isoflurane and sevoflurane anesthesia. Anesth Analg 2006; 102: 1094-102 Conflict of Interest:None declared |
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Muhammad Rahim M Kayani
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I have read your article with interest. I just want to know about your experience of using isoflurane for gas induction. As we know from the properties of inhalation agents isoflurane is a very pungent and not suitable for gas induction. Since in your study both isoflurane and sevoflurane were used for induction.Did you find any difference between these?. Dr.M. Kayani SAS Anaesthetics Ashford & St Peter's Hospital Conflict of Interest:None declared |
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