The characters of the friction-sound in children are also peculiar. It is exceptional to hear the common rub or scrape which is so familiar a sign in the adult patient. In the child the friction-sound has often a crackling or crepitating character, which to the inexperienced ear is suggestive rather of intra- than of extra-pulmonary mechanism. It has not, however, the puffy character of pneumonic crepitation ; and is very superficial sounding, as if generated close to the ear. Often, from the character of the sound alone, it is difficult to say whether it is produced in the lung or in the pleura, especially as a large, hard, bubbling rhonchus is sometimes heard, which is evidently of intra-pulmonary mechanism and is due to catarrh of the air-tubes. This disappears after a cough.
The friction is not limited to spots in the pleura above the level of the fluid. In pleurisy, as in pericarditis, effusion does not necessarily suppress friction. It is not uncommon to hear an unmistakable friction-sound at a spot where immediately afterwards the aspirating needle withdraws several ounces of fluid.
In cases where the effusion is very copious the symptoms may be dis tressing, and the child's life be placed in the greatest danger. This is espe cially the case. when the fluid occupies the left side of the chest. In this situation it may push the heart so far to the right that the apex is felt. beating under the right nipple. Consequently, the large vessels may be bent out of their natural course, and great obstruction the circulation may result from the interference with their calibre. The healthy lung, hampered in its functions, may become engorged, and the difficulty in the return of blood to the heart may produce great congestion of the head, face, and extremities. The child is seen sitting up, gasping for breath, with an agonized expression on his dusky face. His eyes are star ing and congested ; his hands and feet are purple ; his skin is cold and bathed in sweat ; the veins of the neck are swollen ; his pulse is small, feeble, and frequent ; and unless the distress be quickly relievd death is. certain.
Terminations.—In cases where the fluid remains serous, it usually be-. comes rapidly absorbed. The general symptoms are slight and quickly subside, and the physical signs return to a state of health. In these cases dulness on percussion and weak breathing can be detected longer in the infra-axillary region than elsewhere. If absorption of the fluid be
slow, some retraction of the side is often observed for a time ; but in such cases it is usually slight, and is seldom noticed to the degree which is so common after removal of a purulent fluid from the chest. If absorption is complete, the deformity soon passes away and the chest recovers its symmetry.
When the fluid has become purulent, absorption goes on very slowly. It is only when the quantity is very small that anything approaching to completeness of absorption is found. It is in cases of empyema that distortion of the chest is commonly noticed. The spine becomes curved with the concavity towards the diseased side ; the shoulder, nipple, and inferior angle of the scapula sink, and the lower part of the shoulder blade projects backwards from the chest-wall. Such retraction of the af fected side takes place before absorption has ceased. Indeed, as Dr. T. Barlow has very justly pointed out, the fact that retraction of the side has occurred is by no means a positive proof that absorption has been com pleted. On the contrary, if the deformity continues without improvement, it rather tends to suggest the possibility of some unabsorbed purulent matter remaining at the base of the lung or between the lobes. In many of these cases a layer of cheesy matter is left coating the base of the lung ; and a quantity of thick creamy pus is often found on dissection collected in a limited abscess on the surface of the diaphragm.
If the amount of purulent fluid is large, it sooner or later, unless with drawn by the aspirator, points at some part of the chest-wall. If this oc cur in an upper intercostal space, the contained fluid cannot be completely evacuated, and a continuous discharge occurs through the opening. The child grows daily weaker and thinner. His breath is short ; his face gets sallow and often earthy in tint, with lividity about the eyes and mouth ; his fingers beconie clubbed ; his digestion is impaired, his tongue foul, and his breath offensive ; the liver and spleen become enlarged from al buminoid degeneration ; the cough is spasmodic and painful ; and the child sinks and dies from asthenia. Death may be preceded by profuse diarrhoea, which, sometimes at least, is due to albuminoid change in the coats of the bowel.