240 



AUSCULTATION. 



drive his nail " in a sure place." The spirit-dealer 

 kuix'k* upon the head of his cask, to learn the 

 quantity of liquor contained in it. With precisely 

 the same view, the physician thumps the chest of 

 his patient, that he may judge of the state of the 

 organs by the sound which is given forth. 



The chest is an enclosed cavity, containing, and 

 in the natural state filled by, several organs of 

 different degrees of density. Of course, the part 

 corresponding to each organ gives a dull or a reso- 

 nant sound, according as the organ is firm and 

 solid, or light and porous. Much the greater por- 

 tion of the chest is occupied by the lungs. They 

 are of a light and spongy texture, partly filled with 

 blood, and partly with air. The sound they emit 

 is intermediate between that of an empty cavity, 

 or one filled with air only, and a collection of fluid, 

 or a solid organ. In the neighbourhood of the 

 lungs is the heart on one side, and the liver on the 

 other, both solid organs; the latter, indeed, not 

 strictly in the same cavity, but capable of pressing 

 upon the others. If either of these is increased in 

 size, so as to encroach upon the lungs, the exis- 

 tence and the extent of the encroachment will be 

 shown by a flat sound in the place of the natural 

 resonance. 



If the membrane which lines the cavity of the 

 chest becomes inflamed, a fluid is gradually poured 

 out into the cavity, compressing the lungs, and 

 occupying their space ; and then a flat sound is the 

 consequence. Or, the same space may be filled by 

 air, introduced either by a wound, or as the effect 

 of disease ; and then the sound on the other hand 

 is unnaturally resonant. The structure of the 

 lungs itself is also liable to be changed by disease. 

 On the one hand it may be emphysematous, too 

 much distended by air, when the sound is hollow. 

 On the other hand, it may be rendered unnaturally 

 solid, either by a pressure of blood, or by inflam- 

 mation, or by the formation of tubercles ; either of 

 which will cause the sound to be dull or flat in 

 proportion to the extent of the disease. 



It is not our purpose to go into particulars, and 

 show how all the several affections are distinguished 

 from each other. Such details belong to the phy- 

 sician, and must be studied by him with industry 

 and care. The distinction is made partly by other 

 considerations, and partly by differences in the per- 

 cussion itself, We may give an example by way 

 of illustration, of the extent to which this mode of 

 investigation may be carried. We have said, that 

 fluid in the chest, congestion of the lungs, inflam- 

 mation, and tubercles, all cause a flat sound. How 

 shall we know one of these from the rest ? The 

 formation of tubercles is a slow process, and the 

 disease they produce is chronic ; and it is attended 

 by circumstances quite unlike those which ordi- 

 narily accompany the others. For this reason there 

 can generally be little question between them. 

 Bat this is not all. Tubercles are almost always 

 first deposited in the upper portions of the lungs, 

 while inflammation as generally occupies the middle 

 and lower portions. In any case, therefore, where 

 the disease has not advanced so far as to leave no 

 room for doubt, if the flatness be in the upper part 

 of the chest, the presumption is strong in favour of 

 the existence of tubercles ; if in the lower part, it 

 is something else. In like manner, a crowded state 

 of blood in the lungs is ascertained, chiefly by means 

 other than those we are now considering. Between 

 a collectioin of fluid in the chest, the result of acute 

 inflammation of the lining membrane, and inflam- 



mation of the lung itself; that is, between pleurisy 

 and pneumonia, the distinction is not so easy. Both 

 are acute diseases; and both give rise to many of 

 the same symptom-. Imiivd, so much alike are 

 they in these respects, that it was formerly said to 

 he impossible to distinguish them. Yet the im- 

 portance of their I'lferts is widely different. The 

 one is a grave disease and often destroys life, the 

 other is rarely fatal. And the treatment required 

 by each is often very unlike. Here, too, we are 

 by no means restricted to the HBO of percussion. 

 Other modes of examination serve to explain, or 

 correct, or confirm, as the case may be, the results 

 of this. But we must show what this can do. 



We have seen that, in pleurisy, the flatness of 

 sound is caused by a fluid poured out into the cavity 

 of the chest, taking the place of a portion of the 

 lung. The flatness is consequently complete so far 

 as the fluid extends, and there stops abruptly. In 

 inflammation of the lung the condensation, and the 

 consequent flatness, are complete only at the part 

 most highly inflamed, and diminish by a more or 

 less gentle gradation towards the healthy portions. 

 This flatness, too, is constantly observed in the 

 same place, whatever may be the position of the 

 body, whereas in pleurisy every movement of tin: 

 body causes the fluid to flow "to the lowest part, 

 and consequently changes the seat of the flat sound. 

 These different circumstances are not always enough 

 of themselves to establish a perfect diagnosis 

 between the two diseases. But they go far towards 

 it ; and, taken in connection with the results of the 

 other principal mode of exploration, they rarely 

 leave any just cause of doubt between them. 



In detecting diseases of the heart, percussion, 

 regarded by itself alone, will do little more than 

 to point out an enlargement, without showing its 

 precise character, or whether it be an enlargement 

 of the heart itself, or a distention of the pericar 

 dium by a fluid. There are other means of mak 

 ing these distinctions, with a greater or less degree 

 of certainty. 



The organs cf the abdomen are less concealed 

 from observation than those of the chest. The 

 walls of the cavity are yielding, so that any con- 

 siderable change in the size, or texture, or posi- 

 tion, may be detected by pressure ; a mode of 

 examination now learnedly called palpation. Per- 

 cussion is often useful, however, in diseases of these 

 organs. It enables the physician to discover their 

 precise condition with greater accuracy, to detect 

 with more certainty the nature and extent of any 

 enlargement of an organ, or the existence of any 

 morbid growth, or the accumulation of a fluid. 



At first, percussion was performed with striking 

 with the ends of the fingers directly upon the part 

 examined. But this is liable to serious objections. 

 Besides that it sometimes gives pain, there is an 

 uncertainty in the resonance, in consequence of the 

 difference of texture in the several parts struck 

 upon. The present practice is, therefore, always 

 to interpose something to receive the blow. A 

 variety of substances have been used for this pur- 

 pose. An ivory plate has been much commended 

 and much used ; others prefer a piece of India rub- 

 ber; and many use only a finger of the left hand. 

 The circumstance, that the finger is always at 

 hand, while any other pleximeter adds something 

 to the already cumbersome apparatus of the physi- 

 cian, is much in its favour; though in general, that 

 will practically be the best in the hands of any 

 practitioner, which be is most accustomed to ue. 



