Cases of acute and subacute bronchitis belonging to either of the five varieties just described may be protracted until they assume a chronic form, and other cases of each variety are met with which have been chronic from the beginning. This form of the disease is met with in aged persons more frequently than at an earlier period of life. In children it sometimes follows as a sequel of measles and whooping cough, and in adults is often associated with tuberculosis, emphysema, and cardiac diseases.
ETIOLOGY.—Chronic bronchitis is capable of originating from any and all the causes that have been enumerated as capable of producing the more acute forms of the disease, and consequently prevails most under the same conditions of topography, climate, and social relations.
SYMPTOMATOLOGY.—The symptoms of ordinary chronic catarrhal bronchitis differ from those accompanying the acute form of the disease, chiefly in the absence of general fever and the existence of much less pain or feeling of soreness and oppression in the chest. The patient generally complains of a rather harsh, full cough, usually more severe on first retiring to bed at night and on rising in the morning, but occurring at intervals through the day, and accompanied by a mucous or muco-purulent expectoration varying much in its amount and tenacity. In the great majority of cases occurring in young persons and in the first part of adult life, the expectoration is simply a whitish or slightly opaque mucus, more or less frothy from the intermixture of minute bubbles of air, and easily dislodged, especially in the mornings. In old persons and in cases which have continued a long time, the expectoration often becomes more copious and more decidedly purulent, with slight feverishness at night and some loss of flesh.
In all the cases except those last mentioned the general health of the patient is but little impaired, the appetite and secretions usually remaining nearly natural. Those who pursue indoor occupations or are sedentary in their habits will be prone to constipation and imperfect digestion—more, however, from the circumstances just mentioned than from the effects of the bronchial disease. All cases of chronic bronchitis are subject to temporary aggravation by exposure to a cold and damp atmosphere, whether indoors or out, and are also very susceptible to increase from the inhalation of air containing dust or floating particles of solid matter or of irritating gases.
Cases of ordinary chronic bronchitis rarely prove fatal without the intercurrence of some other disease, and yet there is no natural limit to their duration. In many cases the symptoms almost disappear during the warm months of summer, but return with the first period of cold and wet weather of autumn. Such patients usually find permanent relief by changing their residence to a mild and dry climate.
The symptoms of the rheumatic grade of chronic bronchitis differ from those just described mostly in the more severe paroxysmal character of the cough, with either no expectoration or only a scanty quantity of a glairy, tenacious mucus; in the more soreness or dull pain in the intercostal muscles and attachments of the diaphragm; and in the more marked influence of sudden and severe meteorological changes. Perhaps the most marked and distressing cases of this variety of bronchitis are those we occasionally meet with in old persons whose joints, especially those of the extremities, have long been stiffened and sometimes enlarged from chronic rheumatism, and who are harassed and worn from a harsh, suffocative cough, the worst paroxysms of which are almost always during the latter part of the night and the early morning, accompanied by the expectoration of considerable quantities of a thick, viscid, and very tenacious mucus, which is dislodged with so much difficulty that in the midst of the more violent paroxysms of coughing the action of the stomach is reversed and its contents ejected by vomiting. This is very liable to happen just after breakfast, and to occasion the loss of the morning meal. The condition of these patients is very generally ameliorated during the warm months of summer, but on the whole they emaciate and grow more helpless from year to year, until they die either from exhaustion or the supervention of pulmonary sclerosis (fibroid phthisis), endocarditis, or chronic diarrhoea. There is one grade of rheumatic irritation which is liable to attack the fibrous texture of the smaller bronchi and to give rise to a very persistent form of asthma, which increases with every returning cold season of the year; but as asthma in all of its forms is treated in other parts of this work, I only allude to it in this connection.
PATHOLOGY AND MORBID ANATOMY OF BRONCHITIS.—The special pathology of inflammation involving the mucous membrane and other structures of the bronchi does not differ from that of similar grades of inflammation in any other structures of the body. It consists essentially of an increase or disturbance of those properties of living organized matter which regulate the molecular movements constituting nutrition, disintegration, secretion, and cell-evolution to such a degree as to cause accumulation of blood in the capillaries, followed by exudation and increased cell-proliferation, which may organize into plastic material or pseudo-membrane or degenerate into pus, according to the coincident circumstances and condition of the patient.
Consequently, the anatomical changes resulting from acute catarrhal bronchitis are, in the early stage, more or less intense congestion of blood in the vessels, causing redness and tumefaction of the membrane, soon followed by an increased flow of mucus, with increase or proliferation of mucous corpuscles and epithelium-cells, while leucocytes or white corpuscles are seen permeating the capillary walls and penetrating the submucous tissue or mingling with the increased epithelium upon the surface. These several inflammatory products are seen adhering to the surface of the inflamed membrane and in the smaller tubes, often so filling their calibre as to greatly interfere with the ingress and egress of air through them, and of course adding to the dyspnoea that characterizes the capillary form of bronchitis. During the latter stage of the disease pus-corpuscles are seen freely intermingled with the mucus, and, owing to the exfoliation of much of the epithelium, the surface of the mucous membrane often appears irregular, abraded, or ulcerated.
When the inflammation has been protracted into a chronic form, the vessels appear less congested, but the cell-proliferations continue both in the mucous and submucous structures, causing thickening and increased density, with a still more purulent quality of secretion. The bronchial glands are also sometimes found enlarged, and either softened, colored with pigment, or, more rarely, calcified.