rom one location to another; the foreign body
may change its position admitting more, less, or no air, or it may
shift to a new location in the same lung or even in the other lung. A
recently aspirated pin may produce no signs at all. The signs of
diagnostic importance are chiefly those of partial or complete
bronchial obstruction, though a non-obstructive foreign body, a pin
for instance, may cause limited expansion (McCrae) or, rarely, a
peculiar rale or a peculiar auscultatory sound. The most nearly
characteristic physical signs are: (1) Limited expansion; (2)
decreased vocal fremitus; (3) impaired percussion note; (4) diminished
intensity of the breath-sounds distal to the foreign body. Complete
obstruction of a bronchus followed by drowned lung adds absence of
vocal resonance and vocal fremitus, thus often leading to an erroneous
diagnosis of empyema. Varying grades of tympany are obtained over
areas of obstructive or compensatory emphysema. With complete
obstruction there may be tympany from the collapsed lung for a time.
Rales in case of complete obstruction are usually most intense on the
uninvaded side. In partial obstruction they are most often found on
the invaded side distal to the foreign body, especially posteriorly,
and are most intense at the site corresponding to that of the foreign
body. A foreign body at the bifurcation of the trachea may give signs
in both lungs. Early in a foreign body case, diminished expansion of
one side, with dulness, may suggest pneumonia in the affected side;
but absence of, or decreased, vocal resonance, and absence of typical
tubular breathing should soon exclude this diagnosis. Bronchial
obstruction in pneumonia is exceedingly rare.

Memorize these signs suggestive of foreign body:
1. Expansion--diminished.
2. Percussion note--impaired (except in obstructive emphysema).
3. Vocal fremitus--diminished.
4. Breath sounds--diminished.

The foregoing is only for memorizing, and must be considered in the
light of the following fundamental note by Prof. McCrae "There is no
one description of physical signs which covers all cases. If the
student will remember that complete obstruction of a bronchus leads to
a shutting off of this area, there should be little difficulty in
understanding the signs present. The diagnosis of empyema may be made,
but the outline of the area of dulness, the fact that there is no
shifting dulness, and the greater resistance which is present in