CHAPTER 41 ENDOSCOPY Peroral endoscopy comprises direct laryngoscopy, bronchoscopy and oesophagoscopy. It is the general term used for all these methods by which a direct examination of the hypopharynx, larynx, trachea, bronchi and oeso- phagus may be undertaken. ENDOSCOPIC INSTRUMENTS Formerly, endoscopy was performed with rigid tubes provided with a source of illumination which was either of the proximal or distal lighting variety. The rigid tubes (Fig. 104) still form the main part of an endoscopy set, but the lighting is now done almost exclusively from a fibreoptic source. This gives a much superior light than was ever possible from an electric light source. The introduction of fibreoptics has also led to a new series of instruments being devised. These are narrow flexible endoscopes which can be used more easily under local anaesthesia and can also enable the surgeon to look more closely at the larynx and oesophagus and more distantly into the bronchial tree. DIRECT LARYNGOSCOPY ANATOMY. See Chapter 30. ANAESTHESIA. This may be either local or general. The steps in applying local anaesthesia are: (a) The patient is preraedicated with atropine sulphate, morphine sulphate and chlorpromazine with doses adjusted to weight and sex; (b) The patient should suck a benzocaine lozenge and then 2 per cent cocaine hydrochloride is applied to the base of the tongue and the palate; (c) A superior laryngeal block is achieved by holding with special forceps a cotton-wool ball soaked in 5 per cent cocaine hydrochloride in each pyriform fossa for 3 minutes; (d) Finally, to anaesthetize the subglottis the patient holds his own tongue forwards and the surgeon, holding a laryngeal mirror in one hand and a syringe with 1 ml of 10 per cent cocaine hydrochloride in the other, instils the cocaine under vision between the vocal cords into the trachea. When general anaesthesia is used both the surgeon and the anaesthetist are competing for the žame_ airway. The surgeon wants to examine all the laryngeal structures and the anaesthetist wants to keep the patient well ventilated and asleep. The anaesthetist should use the smallest diameter tube compatible with adequate anaesthesia and should place the inflatable cuff well down the trachea to permit adequate examination of the subglottic region. The larynx and trachea should also be sprayed with 5 per cent cocaine hydrochloride prior to starting the examination. 207"