A system of practical medicine. By American authors. Vol. 3

by Unknown

In addition to the part played by bronchitis and atelectasis of the lung in occasioning bronchial dilatation, another important factor in its production is to be found in the condition described by Corrigan in 1838 as cirrhosis of the lung, and since recognized as interstitial pneumonia or fibroid phthisis. In this affection there is formed around the blood-vessels and terminal bronchi, as well as around the air-vesicles, a hyperplasia of the connective tissue, which, as is the case with connective-tissue formations in other situations, ultimately contracts, obliterating the air-cells, smaller bronchi, and blood-vessels, and thus converts the lung-tissue into a tough, fibrous mass. By the contraction thus produced the bronchial tubes of a larger size, which have been previously weakened by bronchitis and have lost their elasticity, are subjected to traction on all sides, and thus become dilated. Dilatations of all forms may thus be produced, cylindrical, sacculated, or beaded, according to the amount of lung involved in the contracting process and to the degree and situation of the bronchitis which favors the dilating action.

The determining causes, then, of bronchial dilatation are—1st, chronic bronchitis; 2d, atelectasis; and, 3d, fibroid phthisis or cirrhosis of the lung.

SYMPTOMATOLOGY.—The general symptoms of bronchial dilatation, as well as the course and duration of the affection, are such as belong to the pulmonary diseases favoring its production, especially chronic bronchitis and fibroid phthisis. The cough and dyspnoea of these diseases are aggravated by bronchial dilatation; but these symptoms, together with the impairment of nutrition, are due rather to the underlying affections than to the mere fact of dilatation. Increased and fetid expectoration, which often occurs in bronchial dilatation from retained and altered secretion, is by no means characteristic of this condition, since it may occur where no sign of dilatation exists.

There is generally some degree of dulness on percussion over a dilated bronchial tube, due to the condensation of the lung-tissue surrounding it, and varying in extent and degree with the amount of that condensation, and also with the amount of secretion retained within the tube. Sometimes, however, increased resonance of a tympanitic character is observed, especially if the dilatation be of the saccular form and near the surface of the lung. Such differences in the percussion sound are analogous to what occurs over a pulmonary vomica, which will generally give a dull sound, though, if the cavity be superficial and thin-walled, it may yield a tympanitic resonance. On auscultation bronchial respiration may be heard along the course of tubes affected with cylindrical dilatation when they are free from secretion; and this is more intense in proportion as the tube is more dilated and the lung-tissue around it more condensed. Bronchophony and increased vocal resonance also occur, and if mucus be present in the dilated tubes coarse moist râles will be heard. In a saccular dilatation there may be true amphoric breathing, with the gurgling sounds heard in a vomica. In some cases there is an alteration in the appearance of the chest-wall, which is retracted by the shrinking of the condensed lung beneath.

Now, of the auscultatory signs that have been mentioned, the bronchophony and increased vocal resonance, together with the percussion dulness, belong also to pneumonia, which, however, at least in its acute form, can be distinguished from bronchial dilatation by the previous history, the febrile movement, and the general phenomena of the case, and by the fact that the tubal breathing of pneumonia, besides being less persistent, is most frequently met with in the lower part of the lung, and that of bronchial dilatation in the upper part.

But the diagnosis between a dilated bronchus and pulmonary phthisis is in some cases a very difficult problem, the signs of the cylindrical form closely simulating those of the stage of deposit in phthisis, because involving the same physical condition, and those of the saccular variety corresponding often with the auscultatory signs of a cavity. In the former case there may be the same localized dulness on percussion, the same bronchial or broncho-vesicular breathing, and the same sinking or contraction of the chest-wall apparent on inspection. In the latter case there may be equally in saccular dilatation and in a vomica amphoric breathing, gurgling, and pectoriloquy. In the establishment of the diagnosis between these two conditions Austin Flint, Sr.,¹ justly attaches importance to the circumstance that there is in general a greater degree of percussion dulness over a cavity than over a dilated bronchus, so that a relatively greater prominence of the auscultatory signs as compared with the degree of dulness makes the diagnosis of dilatation more probable. But the most important evidence on the point is to be gotten from the history of the case. If in a case where the auscultatory signs would leave the examiner in doubt there were found loss of flesh, fever, night-sweats, quickened pulse, and the other general phenomena belonging to phthisis, the existence of this affection would be rendered probable in the highest degree, and the auscultatory signs should be taken as corroborating an opinion founded on the general symptoms.

¹ Dis. of Resp. Organs, p. 353.

Positive evidence, again, may be furnished by a microscopic examination of the sputa; the discovery of particles of lung-tissue or the so-called bacillus tuberculosis pointing clearly to phthisis. Conversely, the absence of the general symptoms of phthisis would, in a case presenting the above auscultatory signs, render it probable that they are due to bronchial dilatation. Long-continued cough and abundant expectoration are the chief symptoms common in both forms of disease. There are, however, some cases in which even with the most careful examination and weighing of evidence the physician will be left in doubt, inasmuch as in some cases of otherwise well-marked phthisis the usual constitutional symptoms are absent or imperfectly declared. In such exceptional cases the estimate of probabilities is to be based on the fact that while bronchial dilatation is comparatively rare, pulmonary phthisis is extremely common.

PATHOLOGY AND MORBID ANATOMY.—Enlargement of the bronchi may be met with throughout almost the entire extent of a lung; when limited to a part of the organ the change most frequently occurs, according to Laennec, Rokitansky, and other observers, in the superior lobe and toward the anterior border. The tubes of the third or fourth order in respect to size are most frequently affected, the primary bronchi being never involved except in association with tracheal dilatation.

In the different forms of dilatation the bronchial walls are found in various states. In the cylindrical variety they are for the most part thickened and hypertrophied, both as to the mucous and the fibrous coats; the mucous membrane being in a catarrhal state, covered often with muco-purulent discharge, and easily broken down and detached, while underneath the white fibrous coat is sensibly thickened.