Part 27

“When air only moderately vitiated is breathed continuously for a greater length of time the results are still very injurious, and in the front rank of diseases so caused stand pulmonary consumption, and other destructive affections of the lungs. Perhaps no better example of this can be given than that of the monkey houses of the Zoological Gardens of London and Paris. While these houses were small and ill-ventilated the monkeys died in large numbers from pulmonary consumption, but after they had been enlarged and better ventilated the mortality from this cause nearly ceased. (Arnott.)”

“Town dairy cows which are packed in close ill-ventilated buildings and never allowed to go out are very subject to consumption, while horses kept in no better conditions, but spending nearly half their time in the open air, rarely have phthisis. (With lung plague it will be remembered that the out-door exercise and mingling of herds leads to an increase of the mortality.) Horses newly stabled suffer severely from diseases of the lungs. The same holds true of human beings. A long list of careful observers have noticed the essential connection of lack of ventilation and pulmonary consumption. Baudelacque, Carmichael, Arnott, Lepelletier, Allison, Sir James Clark, Toyubee, Guy, Greenhow, Sir Alexander Armstrong, Parkes, and Aitken have especially insisted upon consumption being a sequence of lack of ventilation. Dr. Cormac indeed insists with great force that consumption is originated by rebreathed air.”

“The notorious prevalence of consumption in sailors has been directly traced to the impure air in which they sleep, and an extensive outbreak of lung disease (not tubercular), leading to destruction of lung tissue, in the English Mediteranean squadron in 1860 was clearly traced by Dr. Bryson to the contamination of the air. In a nursery hospital at Dublin with entire neglect of ventilation, 2,944 children died in four years, whereas after the ventilation had been improved only 279 died in the same length of time.”

“Parkes (Practical Hygiene) says:

“‘But not only phthisis may be reasonably considered to have one of its modes of origin in the breathing of an atmosphere contaminated by respiration, but other lung diseases, bronchitis and pneumonia, appear also to be more common in such circumstances. Both among seamen and civilians working in confined, close rooms, who are otherwise so differently circumstanced, we find an excess of the acute lung affections.’

“In this connection, the statement of the air breathed by an ox per hour and that supplied him on board a ship with insufficient ventilation or none may be instructive. The ox takes in with each breath about 5 liters of air. This is at the rate of 50 liters per minute, or 3,000 per hour = 105.9 cubic feet. This amount of air is therefore rendered all but irrespirable by each animal in the course of an hour. And this, be it noted, is by breathing alone, and makes no account of the contamination by perspiration in the overheated hold, and by the emanations from the accumulating excrement.”

“On board the steamers we have found the space allotted to each bullock to vary from 150 to 240 cubic feet. On the steamship “Holland,” loaded at New York, August 21, 1881, we found the stalls amidships allowed the full space of 240 cubic feet per head. In the bow where there was less height between the decks the space was considerably less. On the lower deck, where 129 cattle were accommodated, the space allowed each was 217.4 cubic feet. The port-holes in the upper deck were nine inches in diameter and there was one for each pair of stalls—central and lateral—or for eight oxen. These being well above the water line would be available for ventilation in ordinary weather. The port-holes in the lower deck, similarly arranged, were about two feet above the water line, and consequently not available for ventilation, save in exceptionally calm weather. The temperature on the main deck of this ship (between the outer and main deck), when only half the cattle had been loaded, was in the neighborhood of 90° although she was lying in the center of the North River with port-holes and hatches open, and a fresh breeze blowing from the north.”

“On the ‘Assyrian Monarch’ the space per head was only 192 cubic feet, but this ship was supplied with a ventilating fan or blower capable of delivering over 50,000 cubic feet of fresh air per hour, so that her ventilation was abundantly provided for. In some smaller ships we found the space per head to exceed little, if at all, 150 cubic feet. In these, accordingly, a single hour without any change of air would threaten the life of every animal on board, and two hours would endanger those for which even the larger space is provided. It is true that such absolute seclusion is rarely required, and that a certain amount of ærial diffusion is always going on through imperfectly closed hatches, companion ways, and ventilators, yet that these are often insufficient has been amply shown by such losses as are reported above, as well as by the bronchitis and tuberculosis which Drs. Whitney, Lyman, and Williams have found in the lungs of American animals arriving in England.”

“ORGANIC MATTER IN EXPIRED AIR.”

“The decomposing organic matter given off by the lungs and skin is probably the most injurious of the animal excreta, when allowed to act on the system for a length of time. This exhaled organic matter is easily recognized in the air by chemical tests, or by the putrid odor evolved when cotton wool, that has been breathed through, is left to soak in otherwise pure water at a temperature of 70° to 80° Fahrenheit. The experiments of Gavarret and Hammond, in which expired air had its carbonic acid and water vapor removed, leaving only the organic matter, showed that the latter was highly deleterious. Hammond found that a mouse died in forty-five minutes in such an atmosphere. It has also been again and again demonstrated that air containing a given amount of carbonic acid as the result of respiration is far more poisonous than air which contains the same amount of carbonic acid as a product of combustion.”

“WATER VAPOR IN EXPIRED AIR.”

“The amount of water vapor given off by the lungs varies greatly according as the air is already more or less saturated with water. As the air in the stalls between decks is always saturated with water vapor, we may take the very lowest estimate for each animal, namely, 60 ounces in 24 hours, which for a cargo of 200 head would amount to over 93 gallons. And this is in addition to the exhalations from the skin and the bowel and kidney excretions. The air between decks is therefore constantly saturated with moisture which condenses and runs down in streams on every solid object. Among the ill effects of this saturation may be noted:”

“First. The saturation of the air with water vapor increases the exhalation of carbon dioxide from the lungs. This effect on the excretion of carbonic acid is usually so great as to counterbalance the tendency of warm air to reduce the production of this acid. This saturation, therefore, with water increases the danger of suffocation by the accumulation of the irrespirable carbon dioxide in the ship, unless the air is being constantly removed.”

“Second. The excess of moisture in the warm atmosphere hastens the decomposition of the organic matter derived from the lungs, skin, and manure. Sir Alexander Armstrong, head of the medical department of the British Navy, says: “There can be no more fertile source of disease among seamen, or, indeed, other persons, than the constant inhalation of a moist atmosphere, whether sleeping or waking; but particularly is this influence injurious when the moisture exists between a ship’s decks, where it may be at the same time more or less impure, and hot or cold, according to circumstances.” It has become an aphorism with sanitarians that “a damp ship is an unhealthy ship,” and many instances are adduced in which a sufficient renewal of the air between decks, with or without stoves to dry it, has transformed a naval pest-house into a salubrious vessel.”

“All such considerations must emphasize the demand for such a constant renewal of air between decks on steamers carrying cattle as shall serve to obviate all those conditions of ill-health, with congestion and inflammation of the lungs, as have proved in the past a serious drawback to our foreign cattle-trade. To accomplish this and at once remove from between decks the excess of carbon dioxide, of decomposing organic matter, and of humidity, and to furnish air approaching in purity and dryness that of the atmosphere outside, we can conceive of nothing more simple and effective than thorough ventilation by fan or heat extraction, as referred to below.” Report of the U. S. Treasury Cattle Commission, 1882.

The above quotations were written with special reference to cattle but the author reproduces them here as in principle applicable to horses as well.

In both horses and cattle treated as above it is common to find ingesta in the bronchia drawn in during the violent paroxysms of coughing. Here we have a direct mechanical irritant and a means of septic infection, highly calculated to induce unhealthy broncho-pneumonia. Williams quotes the case of a horse in which vomition was caused by an over dose of aconite, and a portion of the food entered the bronchi.

In this connection must be named the introduction into the bronchia of liquids forcibly administered to horses and cattle. In the horse the length of the soft palate enables him to hold liquids in the mouth during his pleasure, and among the expedients adopted to coerce him are the very dangerous ones of holding the nostrils and of pouring the liquid through the nose. When the nostrils are held the urgent demand for air leads to attempts to breathe through the mouth, and, whether he succeeds in this or not, the usual result is the drawing of a portion of the liquid into the lungs. When it is poured through the nose the animal cannot protect himself except by rapid gulping, and as he must breathe, a portion of the liquid is usually drawn into the lungs. Any irritant taken in this way will develop bronchitis, and some bland agents like melted lard are almost equally injurious. Cattle having a short palate can scarcely resist swallowing liquids that are poured into the mouth, but a cough with the succeeding quick inspiration will almost certainly draw a portion into the bronchia. To return to the influence of cold, exposed situations which receive the full force of cold winds, those from the north and west on the Atlantic slope are specially conducive to bronchitis. Exposure of newly clipped animals to stand without protection in winter or early spring, has the same tendency. Finally the inhalation of smoke or of heated and irritant gases and vapors, as in a burning building, is an effective factor.

Symptoms: In its mildest form bronchitis is a transient illness with some dullness, impaired appetite, hot, dry mouth, redness of the visible mucous membranes, a moderately strong, resonant cough, attended with slight pain, slight rise of temperature, accelerated breathing and pulse, and mucous discharge from the nose. Such an attack passes over in a few days and without any medicinal treatment if ordinary precautions are taken to avoid a repetition of its causes.

In severe cases the symptoms are more intense from the first. Besides the dullness and inappetence, hot, dry mouth, generally increased temperature of the body (102° to 104° F.), accelerated and labored breathing, and other manifestations of fever, there are more specific symptoms. The cough is dry, hard, painful, often paroxysmal, and appears as if it came from the very depth of the chest. A strong, harsh, bronchial sound is heard over the lower end of the trachea and the upper border of the middle third of the chest just behind the shoulder. Percussion detects no change from the natural resonance of the chest, nor auscultation any crepitating sound. Pressure in the intercostal spaces causes no suffering. The expired air feels hot. The pulse though accelerated is moderately soft and sometimes even weak, a condition which marks inflammations of mucous membranes as contrasted with those of the serous. The mucous membrane of the nose has a dark red hue, especially when the inflammation extends to the smaller ramifications of the bronchial tubes so as to impair the æration of the blood. In the same state there is excessive dullness and prostration because of the supply of partially venous blood to the brain. The head is held low, the nose often supported upon the manger, and the eyelids are semi-closed and injected.

From the second to the fourth day a free exudation takes place from the surface of the mucous membrane, and the symptoms are materially changed. The cough becomes more frequent but softer, looser, and attended with a rattle from the air passing through the abundant mucous secretion. The cooing or tubal sound heard at the lower end of the windpipe and behind the shoulder has now given place to a mucous râle. A nasal discharge appears at first watery, thin, of a whitish, glairy froth, but soon becoming more opaque, white, milky and flocculent and having little tendency to stick to the nostrils. This is often expelled with sneezing and accompanied by movement of the jaws. With the access of free secretion there is a great mitigation of the fever and the other distressing symptoms, and, if no relapse nor complication supervenes, recovery may be complete in a fortnight or three weeks from the onset.

From this time all the febrile symptoms decline and disappear, appetite and liveliness return, the discharge rapidly diminishes and finally disappears, when the patient may be said to have completely recovered.

=Capillary and pseudo-membranous bronchitis= are described by Reynal as occurring in young horses recently brought into the army and subjected to the hot and close stables in some of the French barracks. It began as ordinary bronchitis, which in place of tending to recovery, propagated itself to the most minute bronchial ramifications, and was frequently complicated by the formation of false membranes. The signs of its accession are an extreme intensity of the general symptoms, the rapid, labored, difficult breathing, accompanied by convulsive action of the pectoral and abdominal muscles; the frequent, painful, suffocating and abortive cough, which violently shakes the whole body; the extended head, open mouth, distorted nostrils, reddish brown protruding eyes; the pinched, haggard features, and the frothy mucous, nasal discharge striated with blood, and later interspersed with shreds of false membrane similar to those existing in croup. In connection with these are the symptoms of extreme oppression, partial sweats, tumultuous action of the heart and small, weak, rapid pulse. Death resulted from suffocation during a paroxysm of coughing.

Course. Duration. Termination. Bronchitis is not usually fatal, except in very young or old or worn out animals, or unless it assumes the capillary form or is complicated by pneumonia, pulmonary abscess or by metastasis to the bowels or feet. In the mildest cases health is re-established in three or four days, and in the severe, about the twelfth, fifteenth or twentieth day. In old and debilitated animals in which pure bronchitis proves fatal, the abundant effusion into the bronchial tubes, the influence of gravitation retaining this in the smaller tubes, the palsy of the cilia which normally carry it outward, and the want of power to expectorate by coughing, usually bring about suffocation. This is favored by the non-ærated state of the blood, which rapidly prostrates the already weakened nervous centres. The supervention of pneumonia will be marked by a new class of symptoms, especially labored breathing, dullness on percussion and crepitation on auscultation. The susceptibility of the bowels is so great in some cases of bronchitis, particularly in those associated with a low fever, that superpurgation, enteritis and death may result from the smallest dose of laxative medicine,—the author has seen a fatal result from the administration of two drachms of aloes in a case of this kind. In such circumstances the skin usually participates in an equal degree, and though the superpurgation be checked an extension of the disease to the feet may still prove fatal or induce such changes of structure as to leave the animal practically worthless. In old animals or after repeated severe attacks of bronchitis it may merge into the chronic form. Thick wind is a frequent sequel of severe cases from thickening or dilatation of the bronchial tubes, from collapse of the lung or from emphysema.

Postmortem appearances. In the bodies of animals that have died of bronchitis the air passages within the lungs are filled with a white or greenish yellow mucus. If this is washed from the tubes by a stream of water, the mucous membrane is often found to be injected, studded more or less profusely with red points or with branching red lines, and with petechia, and the mucous membrane is softened, sometimes thickened and friable. When, however, the bronchitis has been attended by a free purulent expectoration the mucous membrane may, when washed, show no perceptible alteration from the healthy standard as examined by the naked eye.

In the capillary form the blocking up of the smaller tubes by a tenacious frothy mucus, and by the false membranes which form complete casts of many of the tubes and the partial consolidation (collapse) of circumscribed pyriform masses of lung tissue with which such tubes communicate form the chief features on examination after death.

This state of consolidation or collapse of lung is frequently seen in simple bronchitis as well. It is then due to the blocking up of one or more bronchia by plugs of tenacious mucus which act as valves, preventing the entrance of air, though it may permit of its easy passage outward. This state of lung differs materially from the consolidation due to inflamed lung tissue (hepatisation). When cut it does not present the granular appearance of the latter, caused by the exudation into the minute air cells, but the cut surface has an uniform homogeneous aspect aptly likened by Lænnec to muscular flesh (splenisation). Mendelson, Traube and Gairdner have induced artificial collapse of the lung by introducing foreign bodies into the bronchia of animals.

Emphysema of the margins of the lung is a frequent concomitant of collapse. The cause is plain. The portion of lung, the subject of collapse, emptied of its air, does not occupy a tithe of the space it would normally fill. The rest of the lung tissue expands unduly to fill out the vacated portion of chest and the cells become overdistended and ruptured. The emphysematous lung is known by its lighter color, by its irregular bulging surface, by the subsidence of these elevations when pricked with a needle, and by a more marked crepitation when pressed. When the cells have burst and the air escaped into the areolar tissue between the lobes, it appears as dark lines circumscribing small portions of pulmonary tissue and collapsing when pricked.