der surface next to the light-carrier
canal. For ordinary work, however, secretion in the bronchus is best
removed by sponge-pumping (Q.V.) which at the same time cleans the
lamp. The drainage bronchoscope may be used in any case in which the very
slightly-greater area of cross section is no disadvantage; but in
children the added bulk is usually objectionable, and in cases of
recent foreign-body, secretions are not troublesome.

As before mentioned, the lower air passages will not tolerate
dilatation; therefore, it is necessary never to use tubes larger than
the size of the passages to be examined. Four sizes are sufficient
for any possible case, from a newborn infant to the largest adult.
For infants under one year, the proper tube is the 4 mm. by 30 cm.;
the child's size, 5 mm. by 30 cm., is used for children aged from one
to five years. For children six years or over, the 7 mm. by 40 cm.
bronchoscope (the adolescent size) can be used unless the smaller
bronchi are to be explored. The adult bronchoscope measures 9 mm.
by 40 cm.

The author occasionally uses special sizes, 5 mm. x 45 cm., 6 mm. x 35
cm., 8 mm. x 40 cm.

_Esophagoscopes_.-The esophagoscope, like the bronchoscope, is a
hollow brass tube with beveled distal end containing a small
electric light. It differs from the bronchoscope in that it has no
perforations, and has a drainage canal on its upper surface, or next
to the light-carrier canal which opens within the distal end of the
tube. The exact size, position, and shape of the drainage outlets is
important on bronchoscopes, and to an even greater degree on
esophagoscopes. If the proximal edge of the drainage outlet is too
near the distal end of the endoscopic tube, the mucosa will be drawn
into the outlet, not only obstructing it, but, most important,
traumatizing the mucosa. If, for instance, the esophagoscope were to
be pushed upon with a fold thus anchored in the distal end, the
esophageal wall could easily be torn. To admit the largest sizes of
esophagoscopic bougies (Fig. 40), special esophagoscopes (Fig. 5) are
made with both light canal and drainage canal outside the lumen of the
tube, leaving the full area of luminal cross-section unencroached
upon. They can, of course, be used for all purposes, but the slightly
greater circumference is at times a disadvantage. The esophageal and
stomach secretions are much thinner than bronchial secretions, and, if
free from food, are readily aspirat