Chapter XI: Part 11

ETIOLOGY.--The causes of bronchitis, like those of all other acute diseases, may be divided into two classes--namely, predisposing and exciting. The first embraces all those influences that are capable of rendering the mucous membrane of the air-passages more susceptible to impressions, whether by direct increase of the irritability of the structure or indirectly by altering the quality of the blood and the tone of the smaller blood-vessels. The second embraces such influences only as are capable of exciting a direct increase of irritability of the lining membrane of the bronchial tubes, with congestion of {165} blood in its capillaries. Among the most common predisposing causes may be mentioned age, sex, occupation or modes of life, and climatic influences. As a general rule, the several grades of bronchitis are more prevalent during childhood and old age than during the active period of adult life. The British Registrar-General's Report for 1868 contained 33,258 deaths attributed to bronchitis, being 1344 for every million of inhabitants. Of the whole number, 10,550 died during the first three years of life, and 18,485 over forty-five years of age, leaving only 4223 to occur between the ages of three and forty-five years. This, however, is very far from indicating correctly the relative prevalence of the disease at the different periods of life, for the reason that the disease is far more fatal both in early life and in old age than in the early and middle periods of adult life.[1] During the months of February, March, and April, 1882, in San Francisco, there were 65 deaths reported from bronchitis, of which 37 were of children under five years of age, 25 adults over forty years, and only 3 persons between five and forty years. During the same months there were reported 154 deaths from bronchitis in the city of Chicago, with about the same ratio in regard to age. In the city of Philadelphia, during the seven years from 1862 to 1869, the deaths from bronchitis at all periods of life aggregated 969, of which 495 were of children under five years of age, 14 over five and under fifteen years, and 460 of persons over fifteen years of age.[2] These and similar mortuary statistics have led to the very general adoption of the opinion that early childhood and old age are pre-eminently susceptible to attacks of bronchitis. Yet my own clinical observations and records relating to the time and number of acute and subacute cases of bronchitis coming under my own care lead to a very different conclusion. By reference to those records I find a larger number of cases occurring between the ages of ten and thirty years than at any other period of life. Thus, during the first six months of the present year (1882) I recorded 59 cases of primary bronchitis; that is, cases not arising secondarily as complications of other diseases. Of this number, only 5 were children under ten years of age, 38 between ten and thirty years, and 16 over forty. It is probable that similar results will be obtained by all who will take the trouble to record the whole number of cases, instead of simply the number of deaths. The statistics of mortality in relation to this disease are deceptive, not only in regard to relative susceptibility of the human system to attacks at the different periods of life, but also in regard to the ratio of mortality of the disease itself. It is generally conceded that the chief mortality from this disease occurs during infancy or early childhood and in old age, cases rarely terminating fatally in youth or the more active period of adult life. Careful examination of cases will show that this fatality at the extremes of life is owing mainly to the greater tendency of the inflammation at those periods to extend directly from the bronchioles into the lobules of the lungs, thereby complicating the bronchitis with lobular pneumonia; and in more than half the cases reported under the head of bronchitis the fatal result was caused by the pneumonia instead of the bronchitis.

[Footnote 1: See _Reynolds's System of Medicine_, Amer. ed., vol. ii. p. 318.]

[Footnote 2: See _A Practical Treatise on the Diseases of Children_, by J. F. Meigs, M.D., and William Pepper, M.D., 4th ed., p. 189.]

Neither recorded facts nor my own clinical observations show any decided difference in the susceptibility of the sexes to attacks of bronchial inflammation.

Those occupations which confine the parties pursuing them much indoors, and at a temperature either too warm or too cold, strongly predispose to attacks of inflammation of the membrane lining the respiratory passages. Habitual exposure to a warm, confined air invites free exhalation from both the bronchial and cutaneous surfaces, with increased susceptibility, and {166} consequently renders the individual more susceptible to all external impressions. Habitual passive exposure indoors to a low temperature represses the exhalations and causes the retention of some of the products of tissue-change which by their presence in the blood render the individual more liable to attacks of inflammation on the supervention of any exciting cause. For the same reasons the habitual wearing of too much warm clothing on the one hand, or too little on the other, predisposes to attacks of bronchial disease. Another error of importance is the unequal adjustment of clothing to different parts of the cutaneous surface. In children especially we often see an abundance of warm clothing over the whole body, while the legs and feet and neck have but a single covering, and sometimes none. And even adult women often go out loaded with warm clothing, while their feet and ankles are protected only by thin shoes and stockings. All those occupations that surround the workmen with an atmosphere filled with irritating gases, floating particles of stone, metal, or charcoal, or with the dust from grain and many vegetable substances, increase the liability of such workmen to attacks of all grades of bronchial inflammation.

It is universally conceded that bronchitis, as well as inflammation of all other parts of the mucous membrane lining the air-passages, prevails most in such countries as are characterized by a cold, damp, and variable climate. This can be well illustrated by comparing the prevalence of this class of diseases in that belt of our own country lying north of the fortieth parallel of latitude and east of the Rocky Mountains with the prevalence of the same class in the belt south of the thirty-third parallel and bordering upon the Atlantic and Gulf of Mexico. In the former the summers are comparatively short, with brief periods of high temperature, the winters cold, and the transition seasons, spring and autumn, long and exceedingly variable, with a predominance of cold and dampness. In the latter all the conditions just mentioned are substantially reversed. Perhaps the earliest reliable statistics we have bearing upon this subject are those collected by Samuel Forrey from the several military posts occupied by the United States Army, and given in a series of articles in the _American Journal of Medical Science_, and subsequently in an octavo volume, on the climate of the United States and its influence over the prevalence of diseases. The valuable facts presented by Forrey were added to by Daniel Drake, and given in full in his large work on the topography and diseases of the great interior valley of this continent. From these sources we learn that the average annual number of attacks of inflammation of the mucous membrane of the respiratory passages in every 1000 soldiers at Fort Snelling, in Minnesota, latitude 44° 53' N., was 600. At Fort King, fifty miles from the Gulf of Mexico, latitude 28° 58' N., the annual number of attacks average only 101.2 in every 1000 persons. Again, at Madison Barracks, near Sackett's Harbor, New York, the average number of attacks for every 1000 persons was 637.2, while at Key West, Florida, the average number of attacks was 208.9, and at Baton Rouge, Louisiana, only 207.2. Lest it should be thought that these five posts had been selected for the purpose of showing the most extreme contrasts, it may be added that Drake, after a laborious comparison of the statistics at all the military posts in the great interior valley from Fort Snelling at the north to Fort Jessup in Louisiana, the most southern, makes the "ratio of decrease in bronchial inflammations" as we pass from the north to the south as 31.5 for each degree of latitude.[3] A similar comparison of the statistics of all the posts on the Atlantic Slope from Madison Barracks to Key West gives nearly the same results. The general inference here drawn concerning the much greater prevalence of bronchitis in the colder and more variable climate of the northern belt of our country {167} than in the southern is fully corroborated by all the facts to be gathered from observations in civil life.

[Footnote 3: See _A Systematic Treatise on the Principal Diseases of the Interior Valley of North America, etc., etc._, 2d Series, pp. 795, 796.]

A study of these same military statistics, representing the mean ratio of the prevalence of diseases of the respiratory passages for a period of ten years at nearly all the posts, will justify some other inferences of interest besides the one just stated. According to this general inference or rule, which is assented to by all the authors within my reach, the three important factors in the climates most favorable for producing bronchial inflammation are cold, variableness, and dampness, the latter being emphasized by most writers as of predominating influence. Yet the tables before us show that the highest ratio of prevalence of inflammatory attacks of the mucous membrane of the respiratory passages in the northern part of the interior valley was at Fort Snelling, in the immediate vicinity of St. Paul, Minnesota, being 600 attacks for every 1000 soldiers, while the lowest ratio was at Fort Dearborn, on the site now occupied by the city of Chicago, being only 102 for every 1000 soldiers. Looking at the posts in the eastern part of the northern belt of country, Madison Barracks, at Sackett's Harbor, at the eastern end of Lake Ontario, gives a ratio of 637 attacks for every 1000 soldiers, while Fort Niagara, at the mouth of the Niagara River, near the western end of the same lake, gives a ratio of only 355. Again turning to the posts in the southern belt of country, the tables show at Fort Jessup, in the interior of Western Louisiana, a ratio of 432.8, while at Fort Jackson the ratio was only 47.5 and at Fort King 101.2. As Fort Snelling is on the high rolling prairie of the interior of Minnesota, noted for its cold and dry air, and Fort Jessup on the elevated arid plateau between the head-waters of the Sabine and the Red River, they cannot be noted for a high degree of atmospheric moisture. On the other hand, Fort Dearborn was located on the south-west shore of Lake Michigan, on the borders of a low and wet prairie with a substratum of impervious clay, giving all the conditions favorable for the prevalence of a high degree of atmospheric moisture. And Forts Jackson and King are both on low alluvial lands only fifty miles from the Gulf. Again, Fort Niagara is surrounded by all the conditions favoring a high degree of atmospheric moisture, certainly equal to those surrounding Madison Barracks in nearly the same latitude, and yet the ratio of attacks in the latter was nearly double those in the former. It is evident, therefore, that there exists some important factor in the climatic relations of the inflammatory affections of the respiratory passages besides temperature, humidity, and changeableness. A glance at the topography of the whole country will show that each of the posts giving a high ratio of attacks--namely, Madison Barracks and Forts Snelling and Jessup, to which may be added Forts Gratiot, Crawford, and Wood--are so located as to be exposed to the prevalence of unusually severe winds or atmospheric currents either from the north-east or the north-west and west, with certain relations either to high mountain-ranges or ocean-currents. For instance, from Madison Barracks the open valley of the St. Lawrence River extends in a north-easterly direction to the Atlantic Ocean, where the cold ocean-current is from the north, favoring the pressure of cold atmospheric currents directly up the valley from the north-east, reaching its termination at the eastern end of Lake Ontario with but little diminution of force. The mountains of Northern New York, Vermont, and New Hampshire seem to prevent the deflection of these currents to the south, and help to keep them directly in the line of the valley. That the high ratio of attacks of bronchial and catarrhal affections at Madison Barracks is largely due to the influences here described is corroborated by the fact that the same class of diseases are much more prevalent in the province of Quebec, through which the valley of the St. Lawrence extends, than in the province of Ontario, as shown by the Registrar-General's Report in reference to the several {168} military posts in the Canadas. Turning to Forts Snelling and Crawford at the north and Jessup at the south, we find them so situated in relation to the great mountain-chains to the west as to be fully exposed to the cold and strong atmospheric currents that sweep over the Plains from the north-west and west with such force as to justify the popular title of blizzards. Without consuming more time in details, it may be said that the force and direction of atmospheric currents have quite as much to do with the development of inflammations of the air-passages, including all grades of bronchitis, as either temperature or humidity.

As might be inferred from what has already been said in relation to the influence of climatic conditions, season of the year is also found to exert a marked influence over the prevalence of bronchial affections. Those parts of the year characterized by a low temperature, high winds, and frequent thermometric changes are accompanied by the highest ratio of prevalence of inflammations of the respiratory passages. Thus, the statistics compiled from the records of all the military posts by Drake show an average ratio for the four quarters of the calendar year of 119.8 for the first quarter, 72.7 for the second, 48.7 for the third, and 99.6 for the fourth.[4] This corresponds closely with the results of clinical records kept under my own observation through a series of years.

[Footnote 4: See Drake on the _Principal Diseases of the Interior Valley of North America_, p. 792.]

That tubercular deposits in the lungs, cancerous growths, emphysema, and previous attacks of bronchitis, all strongly predispose the patient to further attacks of the last-named disease, is proved by universal clinical experience.

EXCITING CAUSES.--Exposure to sudden and extreme changes in atmospheric temperature from warm to cold is almost universally regarded as the chief exciting cause of inflammation of the bronchial as of all other parts of the mucous membrane of the air-passages. More accurate and detailed observations, however, show that such changes of temperature are seldom productive of diseases of this class unless accompanied by coincident high winds and humidity. My own studies concerning the relations between special meteorological conditions and the prevalence of particular diseases have led me to the following conclusions in regard to bronchitis and inflammation of the mucous membrane of the air-passages generally:

First. Many sporadic cases are caused, at any and all seasons of the year, by exposure of limited portions of the cutaneous surface to cool or cold currents of air while the rest of the body is well protected. Females going out with thin shoes and stockings or sitting before open windows with low-necked dresses, and children out on cold days with naked legs from short trousers and defective stockings, afford many and familiar examples of bronchitis from this cause.

Second. The sudden transition from a protracted period of intense dry cold to a higher temperature with increased atmospheric humidity. Almost every winter season, in the northern belt of the United States, east of the Rocky Mountains, is characterized by several periods of steady dry, cold air, varying from one to three weeks in duration, during which the mercury in the thermometer often descends more than 20° C. (8-10° F.) below zero, and which generally ends in a sudden change in the direction of the winds and a marked elevation of temperature, constituting what is popularly called a thaw. Such changes are very uniformly accompanied by a general prevalence of catarrhal affections of the air-passages, including many cases of bronchitis. This class of cases occur principally in the months of December, January, and February.

Third. The occurrence of those cold north-east winds that during the latter part of autumn and early part of spring so often sweep over the whole extent of our Atlantic coast and press up the valley of the St. Lawrence to {169} the great interior lakes, and the still more severe currents that come during the same seasons from the north-west and west, over all the wide plains that intervene between the great mountain-chains to the west and the upper lakes and Mississippi River to the east, are also accompanied by a high ratio of prevalence of bronchial affections, as has been already shown from the records of the several military posts. Most of these severe storms of wind are accompanied by either snow or rain and a marked increase of ozone or active oxidizers. In some of the severe snowstorms from the north-east, occurring in the latter part of February and in March, I have found an unusual amount of free ammonia. Whether either the ozone or the ammonia has had anything to do with the production of the bronchitis cannot be determined until the observations and records now being made under the auspices of the American Medical Association have been continued for a few years, by which adequate data will be furnished for reliable deduction.

Besides ordinary meteorological conditions, bronchitis may be produced by inhaling irritating substances, such as steam, irritating gases, steel-dust, or minute particles of other metals or stone in workshops, and the dust encountered in handling grain, etc. The disease has often occurred in epidemic form without the presence of an obvious exciting cause. It also frequently occurs in connection with certain general fevers, more particularly with typhoid, measles, influenza, and pertussis. It also sometimes, though more rarely, accompanies rheumatism, constitutional syphilis, and erysipelas. The presence of tuberculous and cancerous deposits in the lungs almost always provokes more or less bronchial inflammation during some part of their progress.

Acute Bronchitis.

SYMPTOMATOLOGY.--The most common form of acute bronchitis, by many writers styled catarrhal bronchitis, acute bronchial catarrh, etc., presents considerable variety of symptoms, according to the extent of the membrane involved and the intensity of the inflammatory process. As a general rule, the disease commences with slight chilliness or unusual sensitiveness to slight changes of temperature, accompanied by a sense of soreness and oppression behind the sternum and sometimes across the whole chest, with a frequent and rather dry, harsh cough. In many cases there is during the first day or two coincident congestion of the membrane lining the nostrils, fauces, and larynx, causing sneezing, with some feeling of soreness in the throat and hoarseness, also a heavy dull pain in the head, much increased by coughing. By the second day a moderate general fever has supervened, characterized by dryness and moderate heat of the skin, flushed face, slight increased frequency and fulness of the pulse, more sense of oppression and soreness in the chest, with a continuance of harsh, dry cough, which often causes soreness in the epigastrium, radiating laterally in the direction of the attachments of the diaphragm to the inner surface of the ribs. On the second or third day the inflamed membrane begins to be less dry and the paroxysms of coughing bring up a scanty expectoration of a tenacious, somewhat frothy mucus, which gradually increases until about the fourth or fifth day, when it becomes more opaque, sometimes yellowish, and much more easily expectorated. At the same time that the expectoration changes to a more opaque condition, the general febrile symptoms begin gradually to abate, and the cough is accompanied by less sore pain both in the chest and head.

In the milder class of cases, the decline in all the general symptoms is so rapid that by the seventh or ninth day, convalescence is established. But in the more severe cases the more important symptoms may continue through {170} two weeks, and convalescence not be complete until the end of the third week. And in some of the cases the inflammation does not disappear on the subsidence of the febrile symptoms, but degenerates into a chronic form, causing a continuance of cough, with some muco-purulent expectoration and slight soreness in the chest, through an indefinite period of time. The disease is most likely to take this course when it occurs in young persons having a scrofulous diathesis, or in connection with eruptive fevers or pertussis, or in the aged afflicted with rheumatism.

During the active stage of ordinary cases of bronchitis the urinary secretion is diminished in quantity, redder than natural, and deficient in chloride of sodium, and the bowels are inactive. But after the crisis of the disease is passed, as indicated by the character of the expectoration, the renal and intestinal discharges soon return to their normal condition.

The results of auscultation and percussion in ordinary bronchitis, limited to the membrane lining the larger bronchial tubes, are mostly negative. In some instances during the first or dry stage, the respiratory or vesicular murmur may be slightly harsher or more dry than natural, and after the exudation or secretion of mucus, as indicated by expectoration, there may be some coarse, moist râles, which are removed temporarily by coughing, but return again in a little time. These râles are heard much more in cases occurring either in infancy or in old age than in youth or the middle period of adult life. Percussion elicits only the natural degree of resonance throughout the whole course of the disease, except in those rare cases in which complete occlusion of the bronchial tube has taken place, causing exclusion of air from certain lobules of the lungs, and consequently a shade of dulness on percussion over such lobules.

Mechanical Bronchitis.

By mechanical bronchitis is meant those cases in which the inflammation is caused by the direct action of mechanically irritating substances floating in the inspired air, as fine particles of steel and other metals, particles of stone, charcoal, and various vegetable powders and fungi. Such substances, when inhaled, are liable to impinge on the surface of the bronchial membrane and produce direct irritation and inflammation, both acute and chronic.

Cases originating from this class of causes differ from ordinary acute bronchitis chiefly in the mode of beginning and in the greater tendency to continue in the chronic form. Instead of slight rigors, coryza, and early development of moderate general fever, the patient generally complains first, and for several days, of a sense of tickling or fulness in the air-tubes, with occasional paroxysms of violent coughing and little expectoration. Sometimes particles of the foreign substance that is producing the inflammation may be seen mixed with the mucus or matter expectorated. In many of these cases there is much soreness in the chest and considerable dyspnoea, especially during the night, followed by severe coughing in the morning, and a more free discharge of mucus occasionally containing little streaks of blood, but which is never intimately intermixed with the sputa as in pneumonia. If the patient, by change of occupation or otherwise, ceases to be exposed to the further action of the exciting cause, the symptoms soon begin to abate, and a complete recovery may take place in from two to four weeks. If exposure to the further action of the exciting cause is not avoided, the disease will necessarily assume a chronic form, and in many cases produce such changes as to materially shorten the life of the patient.

{171} Capillary Bronchitis.

By this term is meant inflammation in the smaller bronchial tubes, but not necessarily involving the true bronchioles as they terminate in the air-cells. It may arise from all the causes that are capable of exciting inflammation in the larger and medium-sized tubes. It may occur at any period of life, but is most frequent in infancy and early childhood, and next in persons past the middle period of life.

The chief differences in the clinical history of this and ordinary catarrhal bronchitis arise from the greater obstruction to the ingress and egress of air through the inflamed tubes. The same degree of tumefaction of the membrane that occasions but little obstruction in the larger tubes is capable of completely obstructing many of the smaller ones, and thereby causing much dyspnoea and sense of oppression, with frequency of respiration, accompanied at first by an abundance of dry râles in all parts of the chest, followed later by the complete intermixture of dry sounds and moist submucous râles, the latter caused by more or less exudation or secretion of mucus from the inflamed mucous membrane. The addition of the tenacious mucous exudation to the previous tumefaction of the membrane, often so far obstructs the ingress of air to the air-cells of the lungs that the respirations become short, very frequent and noisy, with blueness of the lips, coldness of the extremities, drowsiness, and soon death from suffocation. This result, however, is seldom met with except in quite young children and in persons enfeebled by age or by previous disease.

In cases which do not thus tend to an early fatal result from the direct obstruction of the bronchi the respirations continue frequent, in young children sometimes reaching 50 or 60 respirations per minute, with much dyspnoea and restlessness; the pulse is quick, but not in proportion to the respirations; the expression of countenance is anxious and often slightly bloated, with a leaden hue of the prolabia; the wings of the nose expand and the chest heaves with each inspiration, giving a great variety of dry, whistling sounds generally throughout the whole chest, which after the first two or three days become mixed with sharply-defined submucous râles, and in the later stages give place to the latter entirely. The cough is frequent and inefficient, on account of the difficulty of getting sufficient air to make it satisfactory. The temperature varies from 38° to 39.5° C. (101-103° F.), seldom rising above the latter figure unless complicated with lobular pneumonia. The urine is generally scanty and deficient in the chlorine salts, and the bowels are inactive. The labored efforts of breathing in many cases make the upper and anterior part of the chest appear more prominent than natural, and even more resonant on percussion on account of temporary emphysema from over-distension of the air-cells in those parts, while in some parts of the lower and posterior portions there is less expansion and less resonance than natural from the occlusion of some of the bronchi and the partial obstruction of others leading to those parts of the lungs.

Between the third and fifth days usually the mucous exudation, which up to that time had been scanty and tenacious, becomes more abundant and more opaque, and in two or three days more assumes a distinct muco-purulent character and is much more easily expectorated. As that which comes from the smaller bronchial tubes is less mixed with air, and consequently less frothy than that which comes from the larger tubes, the two qualities of matter may often be recognized in the same mouthful of sputa; and if the whole be placed in water, that from the smaller tubes will drop lower in the water, or sink to the bottom if detached from the other, which floats freely upon the surface.

In acute cases, at the same time that the expectoration becomes more opaque and more easily dislodged by coughing, all the more important {172} symptoms begin slightly to improve, and by the end of the second week convalescence is fairly established. Many cases, however, are less acute, slower in progress, and do not reach convalescence in less than two or four weeks; and many of this class manifest a strong tendency to continue indefinitely in a chronic form, more especially in persons past the middle period of life. In some of the cases that do not continue in a chronic form, the bronchial membrane is left in a condition of such susceptibility that the attack is renewed on the slightest exposure to the exciting causes.

Rheumatic Bronchitis.

Although many systematic writers on practical medicine make no mention of this form of bronchitis except as a complication of general rheumatic fever, yet cases both of acute and chronic inflammation of the bronchi, of unmistakable rheumatic character, have so often come under my observation that I am constrained to recognize it as a distinct form of disease. In regard to the relative frequency of the occurrence of this class of cases, I find in a brief report concerning 965 cases of chronic pulmonary disease, read in the medical section of the American Medical Association by F. H. Davis in 1877,[5] the following classification of the cases:

Chronic catarrhal bronchitis . . . . . . . . . . . . . . . . . . 403
Chronic rheumatic bronchitis . . . . . . . . . . . . . . . . . . 283
Chronic bronchitis accompanied by gastric derangement and
spasmodic dyspnoea . . . . . . . . . . . . . . . . . . . . . . 119
Chronic bronchitis, modified by syphilitic disease . . . . . . . 37
Hereditary pulmonary tuberculosis . . . . . . . . . . . . . . . 56
Inflammatory pulmonary phthisis . . . . . . . . . . . . . . . . 67
---
Total . . . . . . . . . . . . . . . . . . . . . . . . . . . 965

It will be seen that, of the 842 cases of chronic bronchitis included in the table, the writer classes 283, or a trifle more than 33 per cent., as of rheumatic character. That the relative proportion of acute cases of a distinct rheumatic character is less than those of a chronic grade I have no doubt, and yet their number is not so small as to be insignificant or unworthy of careful attention.

[Footnote 5: See _Transactions of American Medical Association_, vol. xxviii. p. 269, 1877.]

They differ in clinical history from ordinary acute bronchitis chiefly in the following particulars: Etiologically, a large proportion of them occur in persons of a rheumatic diathesis, either hereditary or acquired, and at those seasons of the year characterized by a predominance of cold and damp air with frequent changes of temperature.

Symptomatically, they are characterized from the beginning by more continuous dull pain in the chest, often extending to the attachments of the diaphragm, the shoulders, and the dorsal portion of the spine; by more persistent dry, harsh cough, often exhibiting a marked spasmodic character and accompanied by a great aggravation of the pains in different parts of the chest. When the smaller bronchi are involved the stage of dry râles is much more protracted, the dyspnoea and suffocative paroxysms of coughing more uniformly aggravated at night; and when mucous exudation does take place it remains scanty and viscid, rarely presenting a distinct muco-purulent character unless the case is protracted into a chronic form, and sometimes not then. During the active stage the urine is less in quantity and more decidedly acid in reaction than natural, and the bowels generally costive.

When not interfered with by appropriate treatment, these cases run a much more protracted course, and more frequently degenerate into a chronic form, {173} than those of an ordinary catarrhal character. When they are thus allowed to run a protracted course or to continue in a chronic form, they manifest another tendency of great importance--namely, to have the inflammation extend by continuity from the fibrous and muscular structures of the small bronchi into the connective tissue of the pulmonary lobules, inducing sclerosis of the latter tissue and consequent compression or obliteration of the alveoli or air-cells, and permanent contraction of the chest. Much and careful clinical observation has satisfied me that many of the cases now classed by writers as fibrous and inflammatory phthisis began as simple acute or subacute rheumatic bronchitis, which, being renewed at every return of the cold, damp, and changeable part of the year, not only ultimately caused permanent thickening of the bronchial structures, but gradually invaded portions of the connective tissue of the lungs, and induced similar pathological changes in it, constituting the sclerosis just mentioned.

Pseudo-membranous Bronchitis.

This affection has been described by different writers under the additional names of plastic, croupous or croupal, and diphtheritic bronchitis. The extension of the inflammation and membranous exudation to the bronchial tubes in cases of diphtheria and pseudo-membranous tracheitis and laryngitis or croup, is of frequent occurrence. But as a distinct disease limited to the bronchial membrane it is of comparatively rare occurrence.

In 1854, T. B. Peacock noticed in the _Transactions of the London Pathological Society_ 34 cases collected from European sources; Biermer in 1867 increased the number to 58; Kretschy in 1874 added 10, and Chevstok 4 more cases--making in all 72 cases in Europe. In 1879, W. C. Glasgow of St. Louis read to the medical section of the American Medical Association an interesting report on the subject of plastic bronchitis, in which he notices 23 cases which had occurred in this country, accounts of which were obtained from an extensive correspondence with leading physicians in all parts of the United States, as well as from reference to our periodical medical literature.[6] These statistics are certainly sufficient to justify the statement that the disease is of rare occurrence both in this country and in Europe.

[Footnote 6: See _Transactions of the American Medical Association_, vol. xxx. p. 177, 1879.]

The statistics thus far collected show a much greater prevalence of the disease in males than in females, and that the larger number of cases occur between the ages of fifteen and fifty years, although one case is reported by T. G. Simons of Charleston, S. C., as quoted by Glasgow, at four years of age, and Goumoens one at seventy-two. In a large proportion of the cases reported the disease existed in a chronic form. When acute, and affecting a large portion of the bronchial membrane, it is liable to lead to an early fatal termination from obstruction to the ingress of air to the air-cells of the lungs. But in many cases the disease has extended to only a limited number of the bronchi, and recovery has generally taken place in from two to three weeks.

The symptoms differ from those of ordinary bronchitis in only two important particulars--namely, the more violent and suffocative character of the cough, and the actual appearance of shreds, patches, or casts of pseudo-membrane in the matters raised and ejected by coughing. The latter is the only reliable diagnostic symptom by which it can be certainly differentiated from all other forms of bronchial inflammation. When the membranous exudation is discharged in shreds or small pieces, it may readily escape the attention of the physician, and even considerable casts when expectorated are in some cases so surrounded with mucus and collapsed into a slightly yellowish mass in the central part of the mouthful expectorated, that they might be regarded as only {174} a more muco-purulent part of the mucous secretion. If the whole is thrown into water, however, and agitated a little, the membranous patches and casts will be quickly unfolded in such a manner as to be easily recognized. It is distinguished from mucus by placing it in a solution of acetic acid, which causes it to swell, while mucus contracts in a similar solution. It has the appearance of having been formed in concentric layers, and is sometimes cast-off so complete as to present a continuous representation of one or both primary and several of the secondary bronchial tubes. Under the microscope it has the same fibrillated appearance as other pseudo-membranous formations.

Chronic Bronchitis.

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 {175} 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 {176} sometimes found enlarged, and either softened, colored with pigment, or, more rarely, calcified.

In addition to the foregoing changes, in many cases of the capillary form of bronchitis some lobules of the lungs are found collapsed from the complete occlusion of the bronchi leading to them by the accumulation of tenacious mucus with other inflammatory products. And in the same cases the air-cells in other parts of the lungs, more frequently the upper and anterior parts, are enlarged from over-distension, constituting a degree of emphysema.

In very chronic cases, especially of the rheumatic variety, considerable hypertrophy of the connective tissue of the bronchi has been found, and in other cases atrophy of the same tissue, the latter generally accompanied by more or less dilatation of the tubes.

In pseudo-membranous or croupous bronchitis the bronchial tubes are found lined, and in some cases filled, with a plastic exudate. Usually, only a limited number of the bronchi are affected. The tube-casts that may be expelled are generally in the form of balls, which may be unrolled, and which will then be found to be fragments or complete cylindrical casts of the tubes. They are, when expelled, usually yellowish and often sanious. When washed they are white. There are frequently points of enlargement along the casts which are caused either by the presence of air-bubbles within them, or by a more rapid exudation from that point on the bronchus. The largest casts are usually solid and laminated in structure; the smaller ones more frequently are hollow, containing a greater or less number of air-bubbles; the smallest consist of a single solid thread. Under the microscope the casts seem to be composed of a structureless or fibrinous substance holding numerous mucus and pus-cells, more or less numerous globules of fat, and occasional epithelial cells; seldom red blood-corpuscles, although these may be numerous on the surface. The casts are usually moderately compact, firm, and elastic. Toward the end of the disease, however, they may be less firm. In some cases toward the close of life epithelial cells are abundant in them, but in other cases on post-mortem examination the epithelial lining of the bronchi is found nearly or quite entire. The mucous membrane may be much reddened, or, on the other hand paler than normal. The submucous tissues are also sometimes involved in the swelling, and occasionally infiltrated with serum.[7]

[Footnote 7: For a representation of one of the most complete specimens of pseudo-membranous casts from the bronchi the reader is referred to the paper of Glasgow in the _Transactions of the American Medical Association_, already referred to.]

DIAGNOSIS.--The principal diseases from which acute inflammation of any part of the bronchial mucous membrane needs to be differentiated are pneumonia, pleurisy, laryngitis, tracheitis, and asthma, while it is still more important to keep a clear line of diagnosis between the chronic grades of bronchial inflammation and the earlier stages of pulmonary phthisis and of emphysema. From nearly all the diseases named it is separated by negative evidence or the absence of symptoms and physical signs characteristic of those affections. It neither presents the rusty expectoration or high temperature or fine crepitant râle of pneumonia, nor the acute pains or short stifled cough or friction-sounds of pleurisy in the early stage, and still less is there in the middle and later stages any of the dulness on percussion that characterizes the corresponding stages of the other two diseases. In true asthma the active symptoms are distinctly paroxysmal, without fever or increase of temperature, and the respiration during the paroxysms is slow, with marked prolongation of the expiratory act; while in bronchitis, both catarrhal and capillary, the symptoms are continuous, the temperature increased, and the respirations more frequent than natural. All grades of bronchitis are easily distinguished from laryngitis and tracheitis by auscultation, which enables us {177} to trace all the morbid sounds to the chest in the former, and to the front part of the neck in the two latter.

The great advantage of recognizing pulmonary tuberculosis and other forms of phthisis in the early stage of the disease makes the diagnosis between it and chronic bronchitis a matter of primary importance. This can be readily done by all practitioners who have acquired a reasonable degree of skill in the practice of auscultation and percussion. In all forms and stages of pulmonary phthisis, whether from primary tubercular deposits, pneumonic exudation followed by caseous degeneration, or from interstitial fibroid sclerosis, there is increased vocal fremitus and diminished resonance on percussion; neither of which is present in any grade of uncomplicated bronchitis. It is true that in the advanced stage of some very severe cases of capillary bronchitis there occurs sufficient pulmonary oedema to increase the vocal fremitus and diminish the resonance over some parts of the chest; but the accompanying symptoms and immediately preceding history of such cases are sufficient to separate them from any stage of phthisis. The same remark is applicable to those rare cases in which an attack of pseudo-membranous bronchitis results in the complete occlusion of one or more of the bronchi and the permanent collapse of the pulmonary lobules to which the occluded tubes lead. If in addition to the plain difference in the physical signs already mentioned we remember that in all the forms of phthisis there is progressive loss of flesh, some increase of temperature and acceleration of pulse, with a contraction of the upper and anterior part of the chest, while none of these changes result from bronchitis alone, there should be no difficulty in keeping the line of diagnosis clear between these two diseases. And yet there is probably no more frequent or important error committed in diagnosis than that of mistaking the early stage of pulmonary phthisis for bronchitis. This may arise in part from the fact that bronchitis often supervenes and continues coincidently with phthisis. But the practitioner should remember that whenever there is increased vocal fremitus and diminished resonance in any given case there is some altered condition of the lung-structure, and consequently some form of disease besides bronchitis, however plain the ordinary symptoms of the latter may be at the same time.

From pulmonary emphysema, chronic bronchitis is distinguished chiefly by the abnormally-increased resonance on percussion in the former, especially over the upper and anterior parts of the chest, and the peculiar depression of the spaces above the clavicles and between the ribs at the beginning of the inspiratory act, and their return to over-fulness near its close; while none of these changes accompany any grade of simple bronchial inflammation.

PROGNOSIS.--In the ordinary form of acute and chronic bronchitis there is very little tendency to terminate fatally except when it attacks infants or persons infirm from age. And even when it occurs at these extremes of life the fatal terminations are usually caused by the supervention of lobular pneumonia as a complication, and not from the bronchial inflammation alone. Severe cases of capillary bronchitis are more dangerous, and in young children and aged or debilitated persons often prove fatal before the end of the first week of their progress by the direct obstruction to the entrance of air into the air-cells of the lungs. The pseudo-membranous or plastic bronchitis is still more dangerous. It has been estimated that one out of every five dies. But the statistics concerning the number and character of cases are not sufficient to furnish a reliable deduction of the ratio of mortality.

The duration of acute attacks of bronchitis of all varieties from which recovery takes place is from one to three weeks. Uncomplicated cases of chronic bronchitis seldom prove fatal, neither is there any self-limit to their duration. Many cases undergo marked improvement during the warm {178} months of summer, but suffer a renewal of all the more severe symptoms on the return of the cold and wet weather of autumn. In other cases the symptoms continue nearly the same through all the seasons of the year and until an advanced period of life.

TREATMENT.--There are certain leading objects to be accomplished in the treatment of all grades of inflammation affecting the mucous membrane and connective tissue of the bronchial tubes--namely, _(a)_ to diminish or overcome the morbid excitability of the inflamed part; _(b)_ to relieve the vascular hyperæmia or fulness of blood in the vessels, and thereby limit the amount of exudation or morbid secretion and consequent dyspnoea; _(c)_ to counteract or relieve secondary functional disturbances, such as increased heat and dryness of the skin, diminished renal and intestinal activity, and nervous restlessness; _(d)_ to hasten the removal of such plastic exudations as may have caused thickening and induration of the inflamed structures or formed layers or patches of false membrane on the bronchial surface, and to lessen the tendency to establish a stage of purulent degeneration or suppurative action in the inflamed part; _(e)_ to regulate diet, drinks, exercise, and clothing in such a way as to sustain healthy nutrition and prevent the further action of predisposing and exciting causes.

The first three objects to be accomplished belong more particularly to the early stage of acute and subacute attacks, but are present in some degree throughout the whole course of the disease; while the last two belong to the latter stages of the acute and to all stages of the chronic grades of the inflammation. While the foregoing indications to be fulfilled or objects to be accomplished are present in all the various grades and stages of inflammation of the bronchi, the particular means for accomplishing them will be modified by the age and previous physical condition of the patient, the nature of the predisposing and exciting causes, the extent of the disease, and the stage of its advancement; or, in other words, the nature and extent of the pathological changes already accomplished. For instance: the same remedial agents that would be most efficient in relieving the morbid excitability and the vascular fulness of the first stage of acute inflammation in a young or middle-aged and previously healthy, vigorous subject might be positively injurious, or even fatal, if used in the same stage of inflammation in a subject previously anæmic and feeble or debilitated from age or from causes capable of impairing the quality of the blood and favoring a typhoid condition of the system. Consequently, the practitioner who not only sees clearly the objects most desirable to accomplish, but who most judiciously selects and adjusts the means or agents he uses to the special conditions of each patient, will meet with the highest degree of clinical success.