The best manner of demonstrating the movement of the exudate is to examine the patient first sitting and then prone. The sero-fihrinous exudation changes its position with that of the body when it is small in quantity or when medium in amount, and no strong pressure on the parenchyma of the lungs is occasioned. The thin serous change their position faster than the sero-fibrinous Baceelli (llevista Clin. e Ter., Sept., '90). Cases of collection of fluid in the pleura sometimes occur where the pres ence of lymph adherent to the visceral or parietal pleura, or thickening of the pleura itself, gives signs which so closely resemble them that the differential diag nosis becomes a matter of some diffi culty. In such cases the presence or ab sence of the following physical sign has been found useful: The patient should be standing, or in the sitting position, with the head and neck inclined forward so as to render the skin and muscles of the back somewhat tense. The observer stands on the left side of the patient and, placing the left hand flat and fairly firmly on the lower part of the thoracic wall just below the nipple, percusses sharply either with a anger of the right hand or with a pleximeter on the ribs of the same side, striking them just pos terior to the angles, when, if no fluid be present, a very slight vibration of the rib which is struck posteriorly is felt by the left hand in front; but if there be fluid in the pleura the vibration of the . rib is much greater, and if the quantity of fluid be at all considerable the differ ence between the sensations experienced by the left hand when examining the sound and affected sides is most marked. 'I'. H. Kellock (Lancet, Mar. 28. '96).
One of the symptoms which indicates the early stage of pleurisy is the atti tude of the patient, who lies upon the affected side or bent toward that side or pressing that side. In children when the effusion appears the patient distinctly turns and prefers to lie upon the back or to be propped up high in bed. This is a reliable sign of an effusion of consider able bulk in children, and an effusion poured out with a degree of rapidity. S. W. Kelley (Archives of Pediat., Oct., 1902).
Vocal thrill is at first weakened and later, with increase of exudation, lost over the area of dullness. In rare cases it remains unaffected, especially in chil dren. This may be due to conduction of vibration from the spine along the ribs.
As regards auscultation, for the first few hours or more, before the effusion is sufficient to separate the pleural surfaces, a friction-rub may usually be heard over the affected area. The rub is a to-and fro sound heard in inspiration and ex piration, but may be heard only on deep inspiration. It is superficial, being quite
close to the ear, and has a creaking qual ity; more often, owing to the exudate containing much serum from the first, the friction is soft and crepitant, resem bling the crepitation of pneumonia. Friction often returns as the fluid is ab sorbed and the surfaces come into con tact again.
The respiratory sounds are weak or ab sent below the level of the exudate, but often in children and occasionally in adults tubular breathing is audible all over the dull area, especially if the pleu ral cavity is so full as to collapse the lung, but not to compress the bronchi. Only a puffing expiration of amphoric quality may be present, or the breath-sounds may be intensely amphoric or cavernous and may lead to a diagnosis of cavity, or pneumothorax.
Vocal resonance is usually weak or ab sent over the effusion. Like the breath sounds, it may also be bronchial. In moderate effusions there may be goph ony, heard most commonly about the angle of the scapula. It is not a sign of importance, because it is often absent in this and present in other affections. The whispered voice, it is said, may be clearly transmitted through serous, but not through purulent, exudations (Bac celli's sign). It is, however, in some cases transmitted through purulent exu dations.
The coin sign is obtained by laying a coin on the front of the chest and strik ing it with another; the ear placed at the back of the chest has transmitted to it in some cases a clear metallic sound, if a pleural effusion is present.
PUNCTURE.—Exploring the chest with the aspirator affords the most positive means of determining the existence of fluid and its character. If the needle is absolutely aseptic and the part of the chest to be punctured carefully disin fected, aspiration may be resorted to with impunity in all cases. Certain er rors have to be guarded against in ex ploring the chest with the aspirator. The exudate may be capsulated and the needle pass to one side of the cavity. The pus may be too thick to enter a needle unless of large calibre; for this reason a large needle should, as a rule, be used, especially as it causes but little more dis tress than a small one. Even a large needle may be plugged by the false mem brane in piercing it, so that no pus can pass. In such a case the suction should be cut off and the needle withdrawn, when the plug of purulent fibrin will be found in the needle and confirm the diag nosis. The needle may enter a purulent cavity in the lung resulting from tuber culosis, pneumonia, actinomycosis, etc. It may draw off pus from a subphrenic abscess, from a purulent pericardial exu date, or from a bronchial tube.