Research Article Procedures in practice. Laryngoscopy. Br Med J 1980; 280 doi: https://doi.org/10.1136/bmj.280.6214.629 (Published 01 March 1980) Cite this as: Br Med J 1980;280:629 Article Related content Metrics Responses Peer review This article has a correction. Please see:Errata - April 26, 1980 This is a PDF-only article. The first page of the PDF of this article appears below.