Development of the ‘gum‐elastic bougie’

Your correspondent (Toyoyama et al. Anaesthesia 2002; 57: 932) seek information about the development of the ‘gum-elastic bougie’. I have researched this subject for a chapter ‘Intubation techniques for unanticipated difficult direct laryngoscopy: Stylets and introducers’ in a forthcoming book ‘Der schwierige Atemweg, ed. Paschen and Dörges’, to be published by Springer. There is a historical explanation for the inaccurate and confusing terminology relating to the ‘bougie’. The ‘gum-elastic bougie’ used so widely in the UK is not made of gum-elastic, and is not used by anaesthetists as a bougie (a device for serial dilation of strictures). The so-called ‘bougie’ is an introducer and the product used in the UK is described by the manufacturers as an introducer. Before introducers designed specifically to facilitate tracheal intubation were available, anaesthetists would use whatever was available in the operating theatre, often a gum-elastic bougie. Macintosh is given credit for the first use of introducers to facilitate tracheal intubation [1], and his publication was followed by similar descriptions [2–4] (although Duckworth used the term stilette, she described use of a ‘gum elastic olivary tipped bougie’). However, others were already using introducer techniques. For example, a textbook published the year before Macintosh's description of the technique states in relation to passage of a tracheal tube with the Macintosh laryngoscope: ‘This is an easy matter when a semirigid gum elastic catheter is passed’[5]. Use of the introducer technique did not become widespread until the Eschmann introducer was available; there is no mention of the technique in the 1968 edition of ‘Lee's Synopsis' [6]. Some details of the development of the Eschmann introducer are already published [7] and I am grateful to Dr Venn for further information. Dr Paul Hex Venn, when a consultant in Eastbourne District General Hospital, acted as anaesthetic adviser to Eschmann Bros. & Walsh Ltd. of Shoreham-by-Sea. Several of Dr Venn's inventions were successful for a number of years. One of these, the Intravenn, was a self-sealing LuerLok disposable valve for which multiple uses were suggested. This device was ahead of its time; modern equivalents are widely used to allow needle-free injections into cannulae. One Friday afternoon in the early 1970s, Dr Venn considered the design of a tracheal tube introducer. It had long been recognised that angled (coudé) tips could help the user to steer devices past obstructions, for example in urethral catheterisation. Dr Venn was familiar with the ‘Toronto catheter’, a long, angled rubber suction catheter, which he used for bronchial suction during thoracic anaesthesia. Coudé and bicoudé prototype introducers were made, but the tip of the bicoudé device tended to double up on itself. The superiority of the coudé device was clear and Eschmann accepted this design in March 1973. Dr Venn's introducer went into production shortly thereafter. It was called an ‘endotracheal tube introducer’ when it was marketed by Eschmann Bros. It is now called the ‘Eschmann Tracheal Tube Introducer’ and is marketed by Smiths Instruments Medical Systems (Portex Ltd). There is no doubt that the angled tip contributes to the success of the device [8,9]. However, it differs from the introducer used by Macintosh in design features other that the angled tip. The material probably contributes to its success. It gives moderate stiffness yet holds a new shape at body temperature. It is flexible enough to follow a tortuous course but to yield if pressed gently against soft tissues. Perhaps even more important than the material is its length. Early introducers were relatively short, and were passed with the tracheal tube as a single unit, the tip of the introducer protruding several centimetres beyond the tip of the tracheal tube. Dr Venn describes such a technique of using his introducer [7]. However, the greater length of Dr Venn's introducer led to development of a technique, described in the manufacturer's original literature, of first positioning the introducer in the trachea and then passing (‘railroading’) the tracheal tube over the introducer into the trachea. Initial passage of the introducer alone probably uses its characteristics to their best advantage as gentle passage allows verification [10,11] of blind placement in the trachea, and the angled tip and narrow, flexible nature of the introducer contribute to successful entry into the trachea. Dr Venn's contribution, much greater than the angled tip alone, has never been properly recognised. Dr Venn is now 80 years old, but he has accepted our invitation to be a guest at the Difficult Airway Society meeting in Glasgow in December 2003. A guest lecture on the ‘bougie’ is planned for that meeting.