Testing For Electric Defects


Categories: ACQUIRING SKILL
Sources: A Manual Of Peroral Endoscopy And Laryngeal Surgery

These tests should be made

beforehand; not when about to commence introduction.



If the first lamp lights up properly, use it with its light-carrier to

test out the other cords.



If the lamp lights up, but flickers, locate the trouble before

attempting to do an endoscopy. If shaking the carrier cord-terminal

produces flickering there may be a film of corrosion on the central

contact of the light carrier that goes into the carrier cord-terminal.



If the lamp fails to show a light, the trouble may be in one of five

places which should be tested for in the following order and manner.

1. The lamp may not be firmly screwed into the light-carrier.

Withdraw the light-carrier and try screwing it in, though not too

strongly, lest the central wire terminal in the lamp be bent over.

2. The light-carrier may be defective.

3. The cord may be defective or its terminals not tight in the

binding posts. If screwing down the thumb nuts does not produce a

light, test the light-carrier with lamp on the other cords. Reserve

cords in each pair of binding posts are for use instead of the

defective cords. The two sets of cords from one pair of binding posts

should not be used simultaneously.

4. The lamp may be defective. Try another lamp.

5. The battery may be defective. Take a cord and light-carrier with

lamp that lights up, detaching the cord-terminals at the binding

posts, and attach the terminals to the binding posts of the battery to

be tested.



Efficient use of forceps requires previous practice in handling of

the forceps until it has become as natural and free from thought as

the use of knife and fork. Indeed the coordinate use of the

bronchoscopic tube-mouth and the forceps very much resembles the use

of knife and fork. Yet only too often a practitioner will telegraph

for a bronchoscope and forceps, and without any practice start in to

remove an entangled or impacted foreign body from the tiny bronchi of

a child. Failure and mortality are almost inevitable. A few hundred

hours spent in working out, on a bit of rubber tubing, the various

mechanical problems given in the section on that subject will save

lives and render easily successful many removals that would otherwise

be impossible.



It is often difficult for the beginner to judge the distance the

forceps have been inserted into the tube. This difficulty is readily

solved if upon inserting the forceps slowly into the tube, he observes

that as the blades pass the light they become brightly illuminated. By

this light reflex it is known, therefore, that the forceps blades

are at the tube-mouth, and distance from this point can be readily

gauged. Excellent practice may be had by picking up through the

bronchoscope or esophagoscope black threads from a white background,

then white threads from a black background, and finally white threads

on a white background and black threads on a black background. This

should be done first with the 9 mm. bronchoscope. It is to be

remembered that the majority of foreign body accidents occur in

children, with whom small tubes must be used; therefore, practice

work, after say the first 100 hours, should be done with the 5 mm.

bronchoscope and corresponding forceps rather than adult size tubes,

so that the operator will be accustomed to work through a small

calibre tube when the actual case presents itself.





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