Such is the pathological condition of the parts in the second stage of croup—a condition indicated by the increased difficulty of breath ing—the pale and swollen countenance—the straining eye—the dilated nostril and the purple lip ; by the occasional expectoration of some portions of the false membrane ; and (as hap pens in every affection of the larynx) by severe and protracted spasms of the glottis. If the patient still continues unrelieved, the third and last stage supervenes. The child still breathes with difficulty, but with increasing languor : its countenance is pale; its lip bloodless ; there are generally convulsions, in one of which the fatal event may take place ; or else he sinks gradually, exhausted and worn and dies comatose. And we are to look fur the actual and immediate cause of death not to the larynx but to the lungs and brain. No matter how much the membrane may be swollen, or how extensively the false mem brane may have been formed, the rima is not completely closed, and the patient dies, not because there is an absolute insufficiency of air to provide for the arterialization of the blood, but because some change has taken place in the organ by which this most important func tion is performed. When the thorax is opened the lung does not collapse under the influence of atmospheric pressure : when the lung is cut into, it is found to be loaded with dark blood and with frothy serum, the effusion of which latter is often so abundant as nearly to fill the trachea. The brain, if examined, is found congested, and not unfrequently is there an. effusion of serous fluid into its ventricles.
The acute inflammation of the mucous mem brane of the larynx bears no resemblance in the adult to that in the child, excepting only in, the agonizing difficulty of respiration and the. fatality of the result, but the pathological c• ditions are different, and therefore is the di' in the adult far more manageable. I scarcely conceive, much less describe the ex istence of acute laryngitis to any dangerou extent in the membrane alone without th participation of the submucous tissue, in which the perilous tumefaction is generally, if not al ways, seated ; I shall, therefore, as I have hi therto done, consider this affection in connee tion with its principal pathological result—the. formation of an oedematous effusion.
Mucous membranes in every situation seem, to be connected to the adjacent tissues by tha species of cellular membrane termed reticular as a provision that the courses of the canals o which they form so important a part should no be impeded by any accumulation of fat: and this reticular membrane is more or less lax according to the nature and consistence of the subjacent structure. Where mucous mein !mane is attached to bone, the nature of th connecting medium is so short and close, tlia in many instances it is scarcely observable, and the membrane, in addition to its own func tions, appears to perform that of a periosteurn, whilst in other situations, as in the intestine, it is so lax as to allow the organ to become dis tended to an almost unlimited extent. The usual effect of inflammation on this reticular tissue is an effusion of a serous fluid within its cells, and the production of oedema ; but this is of little consequence where the tissue isi dense and close, and perhaps of still less' where the organ is widely distensible. The larynx, however, presents an organ of a mixed character—the mucous membrane is here at tached to muscle and to ligament, and these again are supported and restrained by resisting cartilages externally, so that if the submucous tissue which is here so loose as to allow the membrane to be thrown into natural folds, should become the seat of infiltration, the swelling so produced cannot take a direction outwards, but must tend to compress and close the aperture of the glottis. This is the
oedema of the glottis, a formidable and too often a fatal affection, but nevertheless present ing very considerable pathological varieties. Thus it is sometimes attended by fever, and forms only part of a more extended inflamma tion, involving tonsils and fauces, pharynx and larynx : again, it is purely local, confined to the larynx alone, and so entirely free from any accompanying fever, that the patient only com plains of the difficulty of breathing and the cough. It is often idiopathic, but may be produced by injury, and is a common result of swallowing caustic poisons and boiling water ; nor is it in this latter respect confined to the adult, for I have thus seen the superior aper ture of the glottis, in a very young child, pursed up and closed as if by the drawing of a running string. It may be situated only in a part of the larynx, the rest remaining free ; thus it is no uncommon occurrence to see only one side of the glottis puffed and swollen, and the slit-like aperture thus converted into a curve ; but the most interesting because the most prac tical illustrations of partial oedema will be found in cases published by Sir Henry Marsh, in which the disease appeared to be confined to the epiglottis alone.* Lastly, I believe it is possible to have this oedema produced without any external evidence of inflammation. In the Museum of the School of Park-street there is a preparation sheaving it as apparently occa sioned by the vicinity of a large carcinomatous tumour.
Considering the pathology of this affection, the degrees of inconvenience and of danger likely to result from it will be easily under stood. The symptoms will be, a loss or imper fection of voice, which is generally very well marked, the utmost effort at articulation amount ing to no more than an indistinct whisper; • and difficulty of respiration, including cough and other signs of local irritation. The danger will probably be in proportion to the rapidity with which the effusion is formed, for life may be maintained with a wonderfully diminished supply of air to the lungs, provided the dimi nution takes place gradually and slowly: but it may not arise solely from this cause, for here, as in every other form of laryngeal disease, spas modic exacerbations are painfully frequent, and place the patient's life in momentary danger. Dissection, therefore, developer three different causes of death. One, the most infrequent where the patient has perished by spasm : the glottis, although swollen, is still pervious— perhaps apparently sufficiently so for the ordi nary purposes of respiration; but in order to observe the relaxation after spasm, several hours must be allowed to elapse between death and the post-mortem examination, for the bodies of those who of laryngeal disease become ex tremely rigid, and remain in this state a consi derable time. A second, in which the effusion having been poured out with great rapidity, the rima is found mechanically blocked up, and immediate suffocation occasioned: in this case neither the lungs nor brain are engaged, at least not necessarily. The third is, where the dis ease has lasted three or four days or more, the oedema has been developed but slowly, and the diminution of the supply of air been less sudden : in these cases, besides the symptoms of strangulationrdlhers, indicative of a con gested condition of the lung and brain, are observed during the latter periods of existence, and corresponding morbid appearances are dis coverable after death.