In attempting to discriminate between croup and acute laryngitis, we have first the very broad distinction that the one is a disease of childhood, the other of adult life; a form of tracheitis is indeed sometimes found in young adults, in which fibrinous exudation lines all the tubes, even to their minute ramifications; but this is confessedly so rare that it may be left out of account. Next we have the circumstance that, except when lymph is visible in the faeces, there is no sore throat or difficulty in swallowing ; and lastly, the stethoscopic signs of affection of the tubes, which, though obscured by the noisy breathing, are nevertheless capable of being discriminated. These in dications also bear upon the important question of tracheotomy. Powerful to save life, when the larynx only is involved, it is generally absolutely use less when the bronchi are implicated, and not unattended with danger; the absence of stethoscopic evidence of bronchial inflammation, and the existence of sore throat, or lymph on the fences, would justify our entertaining the proposition if it ever ought to be practised in croup; the more abundant the lymph about the lances the less probability is there of its having passed to any considerable distance along the trachea. Both affections are alike liable to exacerbations and remission, which are probably of spasmodic character; but in croup there are also violent fits of coughing, which are comparatively rare in laryngitis.
Crowing inspiration, or false croup, is often mistaken for the true,ially by those who are content with solitary indica tions of impending suffocation is even greater in the spasmodic disease, and the inspiration following the temporary closure of the glottis, from which it derives its name, sounds very similar to that following a fit of coughing in croup; but in other respects the diseases differ very widely. The crowing inspiration rarely extends beyond the period of dentition, with the irritation of which it is closely connected: it comes on suddenly, without preliminary catarrh, cough, or hoarseness; it is not accompanied by inflammatory fever, and as soon as the paroxysm has passed, the breathing is completely free from obstruction. In all these respects it stands in complete antagonism to the true croup. It is evidently a paroxysmal disease, and more nearly related to the convulsions than the inflammations of childhood, as shown by spasms of the flexors of the thumbs and great toes, which is so frequently observed during the attack : it is especially associated with disorder of the prime vice, inflamed gums, and impetigo capitis leading to enlarged cervical glands. By some pathologists enlargement of glands has been supposed to be its ultimate cause; that of the thymus gland, especially, tending to produce pressure on the laryngeal nerves: probably the two affections only stand to each other in the relation of common effects from the same cause; imperfect nutrition alike manifesting itself in convulsion, in cutaneous eruption, enlargement of glands, and faulty assimi lation.
§ 8. of the substance of the lung generally presents itself to our notice only in the acute form; chronic pneumonia is sometimes the accompaniment of rapid tuberculosis, and will only occupy our attention as one of the complications of that disease. Its history is, therefore, recent;
nor do we find that the patient has been liable to similar attacks at previous periods. We only learn that, after some sort of ex posure, severe cold has been caught : in its commencement there may have been rigor, or pain in the side; but these phenomena are often absent. It is always attended with more or less of inflammatory fever, as indicated by the heat of surface, coated tongue, quick pulse, &c.: occasionally the combination of in creased arterial action and insufficient aeration of the blood toge ther produce a peculiar dusky flush on the cheek, which is very striking. The breathing is hurried, and in severe cases the number of inspirations in a given time exceeds the normal stand ard in a much higher ratio than the acceleration of pulse. The cough is hard and dry, especially in the earlier stages, the tough adhesive phlegm being brought up with difficulty, and presenting very soon a rusty color from an intimate admixture of blood: the expectoration is much more abundant and more distinctly blood-tinged when the type of the inflammation is lower in de gree. Pain is sometimes complained from the presence pro bably of slight complication of pleurisy, and the patient has a general sense of illness much more decidedly than in bronchitis, for example.
The distinctness of the auscultatory signs depends very much upon the position of the inflammation, whether -near the surface or deeply seated. It attacks the lower and back parts of the lungs very much more frequently than the upper and anterior portions, and we have therefore much more confidence in the diagnosis when observed somewhere behind or to either side: the percussion dulness is not complete, and generally not very extensive: in parts the breathing is suppressed, in parts much exaggerated, but nowhere entirely absent, even down to the very edge of the diaphragm ; the expiratory sound is longer in pro portion to the inspiratory than in health, and when much exagge rated it becomes very loud and blowing, with a whiffing metallic or brassy character, commonly called tubular breathing. The voice-sound is increased, and becomes diffuse, ringing, or metallic; but it has neither the sharpness of that produced in a large cavity, nor the shakiness of that which accompanies the effusion of fluid. When fine crepitation is distinctly heard as accompanying the foregoing phenomena, the diagnosis may be pronounced with certainty : the sound is not heard over the whole of the hepatized portion of the lung, but more commonly towards its 'edges, and sometixnes only when a deep inspiration is made. The period of the disease during which really fine crepitation is audible—that form of it which consists of very fine crackling, heard only at the end of each inspiration—is limited, and is soon succeeded either by its almost total cessation, or by its gradual transition through coarse crepitation into true moist sound. Sonorous sound is sometimes heard in consequence of the presence of bronchitis ; and not only does acute bronchitis accompany pneumonia, but it may precede it, and among the aged is very often its exciting cause. In such cases the history is a good deal modified, and the auscultatory phenomena are not so distinct.