British Journal of AnaesthesiaVolume 107, Issue 1, July 2011, Pages 116-117RetractionRETRACTIONAuthor links open overlay panelShow moreShareCitehttps://doi.org/10.1093/bja/aer068Under an Elsevier user licenseopen archivePrevious article in issueNext article in issueCited by (0)Copyright © 2011 The Author(s). Published by Elsevier Ltd. All rights reserved.