But there are other signs which are still more easily recognized when fluid is present as well as air. In the erect posture, if the, lung have shrunk so that its base does not reach the level of the fluid, we hear, on listening at the back of the chest, when the patient first rises up, a dropping of the fluid, in which its posterior portion was floating when the patient lay on his back : it has a metallic sound, and is known as metallic tinkling. At first the drops fall in rapid succession, gradually becoming fewer, until they cease altogether. This sound is very. characteristic ; and when observed along with the other signs of pneumothorax, the diagnosis amounts to a certainty. But it is not always heard, because the lung may touch the fluid even when the patient is erect. We may then move the upper part of the patient's body backwards and forwards as he sits, while the ear is applied to the chest, to catch the plashing sound of succussion. Doubt has been expressed whether the stomach-sounds might not be mistaken for those produced in the pleura; but they can only be so by one who has never heard true succussion: when heard and recognized, it affords as perfect confirmation of the other signs as metallic tinkling.
Air may be generated in the pleura by decomposition of fluid, or may be admitted by paracentesis : in such cases there must always have been previous pleurisy. The air rises to the top, causes a local tympanitic sound, and deadens the sound of breathing, because it is a bad conductor when interposed between two solid substances—the lung and the parietes. The fact is a mere curiosity, and has really no practical bearings. It might be mistaken for a cavity with unusual resonance, and so might lead a hasty person to say that there was phthisis coexistent with pleurisy. Such a diagnosis is always hazardous ; for what are supposed to be the most common signs of phthisis may be exactly simulated by those of pleurisy with accompanying bronchitis, while there is no tubercular deposit whatever in the lung. On careful con sideration of the condition referred to, it will not be difficult to perceive that the resonance is too great for anything but air in the cavity of the pleura, and that the auscultatory sounds are only deficient in distinctness : we may also generally cause this tympanitic resonance to change its place by altering the position of the patient.
§ 6. two forms of this disease, the acute and the chronic, may be recognized by their history; the auscultatory phenomena are sometimes exactly the same in each, and when they differ, they derive their distinctive characters rather from the qualities of the secretion than from the fact that the mem brane is in a state of recent or of long standing inflammation, except in so far as dilatation or rigidity of the tubes has been produced by repeated attacks.
In the acute form we obtain simply the history of cold followed by catarrh, which may have been, in the first instance, attended by a good deal of heat of skin and chilliness, by pain diffused over the front of the chest, and a tearing, or painful sense of tickling after coughing; there is, at first, no expectoration ; but the secretion gradually increases in amount, generally becomes glairy and transparent for some days, and subsequently yellowish and partly opaque. The cough commonly causes headache during
the febrile state, and there is some thirst and loss of appetite, without much acceleration of pulse.
An attack of influenza differs in no respect from this form of bronchitis, except in the severity of the concomitant fever; there is decided quickness of pulse, coating of tongue, and heat of skin, with more intense headache, general lassitude and depression, complete loss of appetite, &c. But, after all, the two diseases merge so completely into each other, that a case must be called influenza or bronchitis very often solely from the circumstance that the die order is or is not epidemic. The same depression will attend severe bronchitis in a feeble person that marks influenza in the robust; and hence the inquiry into the patient's previous health, unimportant as regards diagnosis, is of value in determining on treatment; and although it be a most dangerous error to treat the nomenclature of disease in place of the patient, the name of in. luaus sometimes serves 'to remind us of depression, and prevent unnecessary depletion.
The chest is perfectly resonant on percussion so far as the bronchitis is concerned. The breathing is at first accompanied by sonorous sounds, which are believed to be graver when formed in the large tubes, shriller when in the small: moist sounds are next heard ; which begin by accompanying the *sonorous, and mtlly supersede them altogether, until the declension of the when they are again heard ; the breathing first becomes natu.ral at the aylices, and the moist sounds linger longest at the bases ; the voice-sound remains as in he,alth. There may be some difference in degree, but these phenomena are usually met with on both sides alike in simple bronchitis.
If the moist sounds be confined to one side, the case may be mistaken for pneumonia, especially when they are fine and limited to the base of the lung ; the presence of sonorous sounds would be sufficient to prevent such an error ; but when these have ceased, the determination must rest on the absence of all dulness and of exaggeration of voice at any part, as well as on the charac ter of the expectoration, which is less adhesive and never rusty. Where it has been deeded that the case is one of bronchitii and not of pneumonia, we have still to account for the circumstance of one lung only being affected ; and this we may perhaps learn from the history, as it either indicates an attack of inflammation at some former period, or tells of gradual emaciation, hiemop tysis or some other symptom of commencing tubercular disease. It is often impossible to detect the signs of early phthisis while the bronchitis lasts ; but the circumstance of the morbid sounds being most distinct, and lingering longest at either apex, is quite enough to excite suspicion.