Pulmonary circulation

“ Very important is the relation between the pulse and respiration. Normally, four pulsations occur to each respiratory act. In pulmonary affections, while the circulation is often disturbed pari passu with the breathing, it may be quite otherwise. Great acceleration of the rate of breathing, with little increase in the rapidity of the pulse, should lead us to suspect disease involving the respiratory organs. Conversely, a much hurried or otherwise perturbed pulse, with little or no change in the breathing, points toward the heart as either functionally or organically the seat of disorder. ”

“ Another condition which contributes to pulmonary congestion is a full stomach. The plentitude of the abdominal organs leads to compression of the lungs and hampered circulation, and when to this is added over-exertion and exhaustion acute congestion is speedily induced. ”

“ During the night the force of the current through the lungs is relaxed and consequently they are able to remain in the pulmonary capillaries and do not appear in the capillaries of the systemic circulation. ”

“ Although a centre has been thought to exist controlling the circulation in the lungs, whose paralysis has been supposed to explain the occurrence of sudden pulmonary œdema without other known cause, no definite facts regarding it are known. That the action of the heart is under the control of the medulla is a fact too well known to require more than a mention. ”

“ The backward pressure of the fluid upon the bronchi, trachea, aorta, and oesophagus interferes with their functions and actions. There may be bronchial or blowing respiration heard over the lung, due to compression of the parenchyma. The fluid around the heart prevents free motion of the organ, although not to so great an extent as in adherent pericardium; complete diastole does not occur; the auricles and ventricles are not completely filled; the systemic and pulmonary circulations become engorged, and pressure is exerted upon the coronary arteries, thus disturbing the nutrition of the heart. ”

“ Valvular insufficiency of the left heart and tumors or aneurisms interfering with circulation through the aorta, cause passive congestion of the pulmonary veins and œdema of the lung.
5th. Tumors and diseases of the liver determine passive congestion of the portal system and ascites.
6th. Passive congestion is very liable to take place in an organ the functions of which are impaired as in a paralyzed part. In this the hyperæmia may start in the capillaries and extend to the veins or even to the arteries. ”

“ A common catarrh will not prevent a man from running up-stairs or walking up-hill for minutes together, without anything like visible distress; subjected to the same test, a person whose lungs are studded with tubercles will pant like a swimmer after a long dive, and his pulse will rise from an average of 65 to 110 and even 140 beats per minute. Combined with a hectic flush of the face, night sweats, or general emaciation, shortness of breath leaves no doubt that the person thus affected is in the first stage of pulmonary consumption. ”

“ In consequence of this deprivation of air, venous blood circulates through the arterial system, whilst the pulmonary vein ceases to convey oxygenated blood to the heart. Under ordinary circumstances, in the course of 4 or 5 minutes after the access of air has been cut off, life becomes extinct. ”

“ Later observers have confirmed my original observation, that if the body be opened directly after death the left ventricle will be found firmly contracted, though the right heart and the pulmonary arteries, with their branches, are gorged with dark fluid blood. In my cases the lungs did not present at all the appearance of congestion of their minute capillaries, but when they were cut the blood poured from them abundantly, seemingly from their larger vessels. Not only do the lungs suffer from venous congestion, but the whole body also. ”

“ In health the two pleural surfaces of the lungs are always in contact, and they secrete just enough serous fluid to allow the surfaces to glide smoothly upon each other. Inflammation of this membrane is called pleurisy. In this disease the breathing becomes very painful, as the secretion of glairy serum is suspended, and the dry and inflamed surfaces rub harshly upon each other.
The root of the lung, as it is called, is formed by the bronchi, two pulmonary arteries, and two pulmonary veins. The nerves and lymphatic vessels of the lung also enter at the root. ”

“ The lungs also receive blood from two (in some individuals three) small arteries branching from the aorta, known as the bronchial arteries. These convey to the lungs blood that has already been supplied with oxygen, passing it into the capillaries in the walls of the bronchi, bronchial tubes, and large blood vessels, as well as the connective tissue between the lobes of the lungs. This blood leaves the lungs partly by the bronchial veins and partly by the pulmonary veins. No part of the body is so well supplied with blood as the lungs. ”

“ Functional murmurs are frequent in the advanced stages. Pulsation of the neck veins is also common. The pulse rate averages about 110 and the blood pressure is low. There is frequently some right side dilatation of the heart. A high pulse pressure is common in severe cases. Shortness of breath on slight exertion is the most common respiratory symptom. There are at times cough and bronchitis, probably induced by the irritation of the larvae in the pulmonary alveoli. ”

“ Blood spit up from the lungs is florid, because it has just been exposed to the influence of the air in its passage through the extremities of the pulmonary artery; it is frothy, from the admixture of air with it in the bronchia. The patients frequently vomit at the same time from the disagreeable titillation of blood about the fauces; and are thence liable to believe, that the blood is rejected from the stomach. ”

“ But sometimes, from the extent of the congestion, respiration is interrupted to such a degree that life is quickly destroyed. In such cases the affected portion of the lung is of a dark color from being engorged with blood, which flows from it if an incision is made. The part is heavier and crepitates less than normal lung-tissue. The bronchial mucous membrane is apt to be hyperæmic, as might be expected from the communication that exists between the pulmonary and bronchial vessels, and the tubes themselves are filled with mucus and sometimes with frothy and bloody serum. ”

“ If fumes or fuliginous vapours and air permeate this vessel, as they do the pulmonary bronchia, wherefore do we find neither air nor fuliginous vapours when we divide the arteria venosa? why do we always find this vessel full of sluggish blood, never of air? whilst in the lungs we find abundance of air remaining. ”

“ The blood coming from the stomach too, is generally in larger quantity than that from the lungs.
In addition to these symptoms, the patient is often affected by an increased sensibility of the lungs, observable on any exposure to cold, change of dress, or going from a warm to a cool apartment. There is a sense of soreness in the lungs attended with a sensation of stricture about the chest. Pain is felt in the side or breast, and the patient lies with difficulty on the side affected. ”

“ The varices of the pulmonary vein not only retarded the blood in its passage to the left auricle of the heart; but, occupying a much larger space in the lungs than they naturally should, they left less room for the minute ramifications of the bronchia to extend themselves; and consequently a less quantity of air was taken in at every inspiration than was necessary for the ordinary purposes of life.
But the disorder of the lungs from the varices was made infinitely worse by the emphysema. ”

“ When this compressed air has been drawn off, as in the case of Lord Beaumont, the compressing power being removed, the lung expands in part, if not entirely, in spite of the breach in it, and the mediastinum and heart return to their natural situation, the distress in breathing is removed, the failing circulation is restored, and the opposite lung resumes its functions. ”

“ Sedentary habits of life, accompanied with hard study, and too intense application of mind, predispose literary men to Consumption. Loud public speaking, blowing on wind instruments, glass blowing and other circumstances requiring a laborious and continued action of the lungs, produce the same effect. Any one of these causes may frequently exist without injury, but their combined action seldom fails to produce pulmonary disease. ”

“ Since the circulation, no less than the breathing, is concerned in the supply of oxygen to and removal of carbon dioxide from the tissues, it can readily be understood that defective circulation, such as occurs, for instance, in uncompensated valvular affections of the heart, may affect the breathing and hinder the normal respiratory exchange. Conversely, also, defects in the aeration or oxygen-carrying power of the blood may be compensated for by increase in the circulation. ”

“ Why vascular congestion should occur in a greater degree and more readily in the lungs than elsewhere from the effect of cold is sufficiently evident when it is considered that the pulmonary capillaries are not supported by surrounding tissue, as those of other parts are. And for the same reason the direct action upon them of cold air or of certain irritant gases, such as ammonia or chlorine, may suffice to cause an undue afflux of blood to them. ”

“ The lungs, subject as they are to alternate distension and compression, from receiving and discharging both the blood and the breath, require the most perfect freedom. But when the chest is so compressed as to prevent the free play of the lungs, the whole system of respiration and circulation is deranged. ”

“ If the pulmonary artery becomes suddenly impermeable, the pressure in the collateral arteries, which originates partly from the bronchial artery, and partly from those outside of, but in connection with, the lungs, as the pleural, etc., is sufficient to prevent a venous reflux, but not sufficient to overcome the entire resistance in the lungs and to drive the blood beyond the capillaries into the left auricle. ”

“ The lungs in their natural state are charged with a large quantity of impure air; this being a portion of the carbonic acid gas which is formed during respiration, but which, after each expiration, remains lodged in the involved passages of the pulmonary tubes. By breathing hard for a short time, as a person does after violent exercise, this impure air is expelled, and its place is supplied by pure atmospheric air, by which a person will be enabled to hold his breath much longer than without such precaution. ”

“ But this office of the pulmonary veins, namely, the ransference of air from the lungs of the heart, is held of such importance, that Hieronymus Fabricius of Aquapendente, contends that the lungs were made for the sake of this vessel, and that it constitutes the principal element in their structure. But I should like to be informed why, if the pulmonary vein were destined for the conveyance of air, it has the structure of a blood—vessel here. Nature had rather need of annular tubes, such as those of the bronchi in order that they might always remain open, and not be liable to collapse ”

“ The pulmonary tissues are endowed with great elasticity, in consequence of which the lungs collapse to about one-third of their bulk when the thorax is opened.
The root of each lung consists of bronchi, arteries, and veins, together with the nerves, lymphatic vessels, and glands, connected by areolar tissue, and inclosed in a sheath of the pleura.
Respiration consists of an expiration and an inspiration. The air passes in through the nose or [276] mouth, through the larynx, trachea, bronchi, into the lungs. ”

“ When we consider the size and peculiar construction of the lungs, their perpetual motion, the chemical process going on in them, and their exposure to the action of contaminated air, or sudden changes in its temperature, it can be no matter of surprise that Pulmonary Complaints are so frequent; and the lungs, not possessing the same natural powers of removing diseased structure, or of mutation as other parts of the body, we may account for their fatal termination from the want of application of proper auxiliaries, as counteractives. ”

“ In this respect, those who open dead bodies, and examine the state of the lungs, should carefully distinguish the congestion that arises from the disease, from that which may be perhaps the effect of the interruption of the circulation in the last moments. ”

“ The tremendous evils of confining the lungs have been adverted to at sufficient length. In reference to that general subject, I need only add, that if the chest be not duly exercised and expanded, the liver, the lungs, the stomach, digestion, absorption, circulation and perspiration, are all hindered. And even so far as the various internal organs of the body are active, they act at a great disadvantage. The blood which they "work up," is bad blood, and must be so, as long as the lungs do not have free play. ”

“ Too little importance is attached to physical development, and well-developed lungs can only be found in a well-developed chest; too little time is spent in outdoor exercise; and private houses, public conveyances, and public assembly rooms are not properly ventilated.
Good development of the chest and lungs, and thorough and systematic ventilation of the lungs, are essential to a strong heart, a vigorous circulation, and power of the tissues to resist disease. ”