B. The resonance is increased on both sides. This may vary very amount, and when bronchitis is present, emphy sema gives rise to all sorts of moist and sonorous sounds. When the latter predominate, the diagnosis is plain enough; with the former, if the excess of resonance be small, the fact that moist sounds are heard above as well as below may lead to the suspi cion that the case is one of very generally disseminated tubercle ; this is especially to be remembered in the emphysema of early life. The doubt is best solved by a comparison with the clavicular region, considering whether the sounds heard there would be best explained by the hypothesis of general emphysema or early tubercular deposit. Then, again, the moist sounds of early phthisis are usually fine, those of emphysema are essentially coarse, and bronchial effusion tends to accumulate in the lower or most de pendent part of the chest.
c. Both sides may be equally dull.
a. When double pneumonia or double pleurisy is its cause, the extent of the disorder and the severity of the general symp toms are generally such as to leave no doubt on the mind of the observer : the signs enumerated in § 1 are then found equally on both sides. It is highly probable, if the dulness be but slight, and the other signs obscure, that any sound which might be taken for crepitation is in reality only a form of fine moist sound.
b. Moist sounds limited to the base, while higher up the breath ing is not otherwise modified, except in being rather harsh, are very common in chronic bronchitis, with some degree of indura tion or senile atrophy. The very same indications, however, may be present when tubercle is limited to the lower lobes, and it is just possible that such might be their true interpretation; but the possibility is a rare one, because in general the alterations of Bounds are much more extensive when tubercular disease attacks the lower and back parts of the lung.
When moist sounds are heard on both sides throughout the whole of the posterior region, with some degree of dulness, they dust be dependent on one of the following conditions :—oedema, engorgement, induration with atrophy, or tuberculosis. The diagnosis of cedema of the lungs does not rest so much on any peculiarity of the physical signs, as on the circumstances of our being able to discover some present obstruction to the circulation, such as produces codema in other organs, especially disease of the heart or kidneys. Seconds.. nly, it would derive confirmation from the expectoration being watery in place of pnriform.
Engorgement, again, depends either upon obstruction to the circulation through the pulmonic veins, or upon gravitation of blood in fever, &c., when the patient is confined to bed. Superadded sounds are always present, which
partake of the character of crepitation, or fine moist sounds, and these have no distinctive marks. That they are not the consequence of genuine pneu monia, we only know from their extent, while the evidence of much consoli dation is wanting; that theyare not caused by bronchitis must be proved by a consideration of the relative severity of the symptoms.
Tuberculosis of the lower lobes can scarcely be distinguished from indura tion, because in both there are usually present the signs of general bronchitis. Perhaps on more careful percussion we may be able to detect some difference in resonance between the two sides in this form of phthisis ; perhaps. too, clicking or squeaking sounds may be heard : if cavities have been formed, the voice-sound may be locally increased at those spots, or generally louder at the base than at the middle of the lung; information may also be gathered from observing that prolonged expiration or vocal resonance is more distinct on one side than the other, especially when this occurs under the axilla at points furthest removed from the root of the lungs and the large tubes. But all these evidences may fail, and we turn to the clavicular region, and there per haps we find proof of more distinct consolidation on one side than the other, and we are satisfied that the disease is tubercular: on the contrary, we may find no great difference on percussion, each appearing somewhat dull; auscul tation may indeed reveal blowing expiration, and coarse moist sounds nearly allied to gurgling on one side, while the breathing is only harsh on the other, and yet this may be only caused by a dilated bronchus along with the indura tion, the apparent dulness being due to loss of elasticity of the ribs. It must be confessed that these cases give rise to very great difficulties in diagnosis ; the constitutional symptoms, however, very generally point more distinctly to one form of disease than the other, and if we follow this suggestion, in a careful analysis of each of the signs just enumerated, we shall probably come to a correct conclusion. Certainly the most trustworthy evidence of tuber cular disease at the posterior part of the chest is derived from the coincidence of signs in the clavicular region ; fallacy there (e. g., a dilated bronchus mis taken for a cavity) only arises from taking one sign as sufficient to prove the existence of tubercle. Sound principles demand that when we assign to blowing, breathing or gurgling sounds this cause, we should also have distinct evidence of very advanced consolidation, because tubercular matter is not evacuated until the separate masses have been closely aggregated together.