A fibre—optic endoscope used for nasal intubation

Blind nasal intubation is a manoeuvre of undoubted value in circumstances where a direct view of the glottis is difficult or impossible but even diligent practice will not guarantee that the anasthetist will be able to pass a tube in this way in a desperate situation where time is pressing. Repeated thrusts with the endotracheal tube may tear the mucosa or excite glottic spasm. The development of sophisticated fibre-optic endoscopes which carry their own flexible illuminating and viewing systems in a tube of 6mm diameter for the first time permits a direct view through the endotracheal tube during nasal intubation. The particular instrument used was developed as a choledocoscope, It is described in detail elsewhere]. Basically it consists of a small central group of image-carrying fibres surrounded by lightcarrying fibres in a separate sheath. Both bundles are enclosed in a plastic sheath. The eyepiece and objective lens are focused separately. A light-box supplies the source of illumination which is carried to the instrument by a flexible fibre cable (figure 1). The instrument has very little elasticity of its own and can be bent into a circle of less than 5 inches (12.7cm) diameter. When placed inside an endotracheal tube it does not reduce the curvature or diminish the flexibility before the kinking point. The endoscope slips easily down a 7.5mm tube without lubrication. Sufficient extra length is available that the eyepiece may be turned back towards the operator in his customary position above the patient’s head. The focus of the lenses can be adjusted to give a depth of focus several inches beyond the objective lens. The endotracheal tube is passed as far as the naso-pharynx. The endoscope is then inserted until the end of the tube comes into view. Both are now advanced together. The chords come into view without any prior view of the epiglottis. If they appear to one side the tube is given a twist to turn it