Diseases Of The Nose Throat And Ear

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 §ame_ 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"