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the circulation of the blood. The contractility of the lungs is very insignificant when compared to that of the aorta; and even though it did produce an expansion of the thoracic aorta, such expansion would neither assist nor impede the circulation. Hence it appears, that the contractility of the lungs aids the circulation of blood in the systemic venous system, assists the filling of right auricle and ventricle, and the passage of the blood through the capillaries of the lungs; that it consumes a portion of the contractile power of the auricles and ventricles, and renders almost null the influence of the normal respiratory movements upon the circulation.

The actions which have been here ascribed to the contractility of the lungs are most manifestly shown during the act of impeded inspiration. If the cervical veins previous to such forced inspiration are filled with blood, they will be emptied during its act, and even compressed by atmospheric pressure. Such an inspiration, moreover, consumes a great part of the contractile power of the auricles and ventricles, and it is possible, that the diminution of the pulse, so often observed when the inspiration is impeded, is occasionally caused by such consumption of the contractile power of the left ventricle. Thus we see, that an impeded inspiratory movement hinders the circulation.

The increased velocity of the current of blood flowing from the cervical veins and inferior vena cava into the superior vena cava and right auricle does not increase the rapidity of the current in the other veins ; for these, on account of the yielding nature of their walls, whenever suddenly emptied of their blood, are compressed by the weight of the atmosphere, and the propagation of the increased velocity to the other portions of the blood thereby prevented. On the other hand, the loss of a part of the contractile force of the left ventricle necessarily causes a diminution of velocity in the systemic circulation. In like manner will the pulmonary circulation be retarded. The before mentioned inspiratory movements cause widening of the arteries, veins, and capillaries of the lungs, whereby the current is retarded. In addition to which there is also a corresponding diminution of the contractile power of the right ventricle.

An impeded expiration causes a like pressure upon the tensely rendered contents of the thorax and abdomen. The effect of this pressure must be different upon different parts of the circulating organs. The blood of the right auricle and the vena cava will be forced back into the venous trunks which open into these veins, until its reflux motion is arrested by their valves.

If the expiratory movement be of no great duration, its influence does not reach much beyond these valves; but when it is prolonged, the blood accumulates in all the veins which enter into the thorax and the abdomen, and this accumulation at length extends to the whole of the veins and the capillaries of the systemic circulation; increased pressure in the arteries is thereby required for its removal, and this takes place when, through the heart's movements a portion of

the contents of the vena cava are removed, and through their narrowing the influence of respiration upon them, lessened.

Expiration opposes the expansion of the auricles and ventricles, which therefore is effected solely by the vis a tergo: but on the other hand it assists their contractions, and is thus a frequent cause of the increase of the pulse which is felt at the moment of expiration, when the breathing is impeded; a sudden expiratory movement, indeed, under such circumstances, as, for instance, coughing, occasionally creates a strong pulsation in the arteries during the heart's diastole, which pulsation is evidently caused by the sudden compression of the distended left ventricle and aorta.

Expiration tends to produce a narrowing of the arteries, veins and capillaries of the lungs, and in this way increases the friction between the blood and the walls of the vessels. It impedes the pulmonary circulation, for the increase of the systolic power of the right ventricle produced by expiration is far from compensating for the increased friction between the blood and the vessels, which is also produced by it.

In like manner expiration impedes the systemic circulation. Thus it appears, that during a forcible inspiratory effort, the circulation of the blood is interfered with by the consumption of a portion of the heart's force, and that during a forcible expiration it is likewise impeded by increase of the friction between the blood and its vessels in one great division of the circulating system. The alternation between inspiration and expiration under such circumstances eases the circulation, inasmuch as at the conversion of one act into the other the impeding force of the one ceases before that of the other begins.

There is no impediment to the entrance of air into lungs which are highly emphysematous, but whose bronchial tubes are neither narrowed nor occluded; the expiration is performed by the muscles of expiration on account of the lung having lost its contractile power, and even here, when there is no febrile action and the patient in repose, the expiratory effort is not great. But on account of the want of contractile force, the air is not driven equally out of all parts of the lungs, but more particularly from its superficial portions and its borders, and so conversely is the air drawn chiefly into those parts during inspiration. In the central divisions of the lungs there is but little renewal of the air. Respiratory movements of this kind cannot facilitate the passage of the blood through the lungs; but on the contrary, the loss of contractility of the lungs causes the filling of the heart's cavities to be performed entirely by the vis a tergo. In such cases the circulation is not facilitated by the alternation of the inspiratory and expiratory movements; the cervical veins, particularly when the patient lies down, remain distended with blood, not only during expiration, but also during inspiration, and there is also a high degree of cyanosis present, even when the breathing does not appear much affected.Monthly Journal of Med. Science, Feb. 1854, p. 159.

34. THE CONDITION OF THE RESPIRATION IN DISEASE. By DR. SAMUEL WILKS, Physician to the Surrey Dispensary. [Dr. Wilks endeavours to show the increased number of respirations in all febrile affections. He was led to reflect upon this condition from reading in 'Carpenter's Physiology," "that sometimes in typhus the number of respirations is depressed from the influence of the morbid poison in the system."]

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It requires a little consideration to see clearly on what the number of respirations, either in health or disease, depends. The amount of the respiratory process might, I think, be correctly stated to be dependent upon the amount of blood to be aerated, or, in more precise terms, the degree of the respiratory process would be a measure of the amount of effete matter in the blood, or that part of it which is brought to the lungs. The impurity of the blood, and consequent increased work of the lungs, would depend upon many causes, the wear and tear of the body, various morbid conditions, the derangement of other organs, &c. The only means for measuring acurately the amount of work done, would be by the spirometer, which should calculate the quantity of carbonic acid and vapour given off by the lungs. I am not aware that of late any very lengthened or systematic observations have been made on this subject, and those formerly published by various experimenters were scanty, and to some extent contradictory; but that the function of respiration varies in different diseases, there cannot be a doubt. From all analogy, from the condition of other organs in disease, as the kidney and urine in febrile affections, it is just to suppose that the excrementitious matter in the blood is at one time more in quantity than at another, and consequently the lungs would have to take their part in an increased effort to remove it. One measure of the amount of aeration done by the lungs is the number of the respirations. For example: if a man breathing a certain number in a minute walks quickly, or exerts himself, and the number is increased, it is fair to suppose that during such time the whole respiratory process has been exalted; and this has been found by actual experiment to be true. The number of respirations, however, in itself is by no means a measure of the amount of the respiratory process. In children and infants, the number is much greater than in adults: also in the same person, from some accidental cause, the number may be augmented, when it is not probable that the function is increased. A pleurodynia, a pain in the abdomen or elsewhere, that is excited by a full inspiration, necessitates a shorter one; and, as a consequence, a larger number is required to make up the deficiency. Thus, two short inspirations may be equivolent to one deep one. In nervous hysterical women, we often see the whole chest not fully expanded, and quick hasty inspirations, interrupted with sighing, are required to make up the deficiency. Again, too, if the lung itself is impaired, so that only a part can work, as in

phthisis, or from the pressure of a pleuritic effusion, an increased number of respirations is requisite. It is clear that a certain amount of aeration is required; and if the inspirations be small, they must be increased in number to make up the quantity. Thus, a phthisical patient may be breathing at a rate twice that which is natural, and yet be quite unaware of the circumstance. If an impediment occur to the passage of air into the lungs, then, besides a quickened, there is a difficult respiration. In diseases of the bronchial tubes, the dyspnoea and shortness of breath are most marked, and the nonaeration of the blood is shown by the lividity of the skin and venous congestion of all parts. When the lungs are congested from heart disease, a difficulty arises in the same way. The besoin de respirer seems to depend upon the presence of venous blood in the lungs, which, while there, is ever seeking for air to purify it, in order to allow it to pass onward. In short breath, when no difficulty is experienced by the patient, and no lividity of the skin, we may suppose that the increased number of the respirations make up for the small individual ones. Whether the blood is sufficiently aerated, may be determined sometimes by another means, founded upon the well known experiments of Bernard upon the consumption of the hepatic sugar in the lungs. For example, a girl, eleven years of age, was the subject of pleuro-pneumonia of one lung, which rendered for a time that organ altogether useless. The breathing was at the rate of 50-60 a minute, yet even this did not satisfy the wants of the system with a supply of sufficient air. For two weeks, while the respiration was so affected, the urine contained a very notable quantity of sugar, and which only disappeared upon the subsidence of the pulmonary affection.

A diminished respiration is, as far as I know, always dependent upon a cause in the nervous system; and this, if not sufficient for the wants of the blood, produces a congestion in the lungs. Lately, there have been two cases under the care of Dr. Barlow, in Guy's Hospital, of disease at the base of the brain, which implicated the pneumogastric nerves. In one the respirations became more and more difficult; and a copious bronchial secretion was poured fourth, just as in Dr. Reid's experiments of the division of the nerve; and in the other case, a slow consolidation occurred from inflammation. The slow respiration produced by poisoning by opium is soon followed by a congestion of the lungs.

Apart, however, from all such causes as are above named, and many others which influence the breathing, an increased number of respirations must in many cases be taken as a proof of an increased function. When the lungs are healthy, and there is no impediment to a full inspiration, I take it that an increased number is significant of an increased action in those organs. Now, if the besoin de respirer is dependent upon the amount of blood to be aerated, or effete matter to be removed, an increase of morbid or excrementitious matter in the

blood must necessitate a greater number of inspirations. This I suppose to be the case in fever, where, with healthy lungs, a more rapid breathing always exists. In fact, in all febrile diseases, an increased number of respirations constantly prevails, and which I take as evidence of an increased respiratory function. By any one who has not examined the subject, it might be thought that this was merely owing to the general excitement of the system, and was a part of the more rapid circulation. This, however, is not the case; for, admitting that the actions of the lungs and heart do, to a certain extent, influence each other, as is seen after violent exertion where each may be doubled, yet, as regards the number of each, in many diseases, they are quite independent. One stroke of the heart throws out as much blood, whether that blood be comparatively pure, or loaded with effete material. In the latter case, however, more aeration and respiratory efforts would be required than in the former. The action of the heart and lungs, then, depending mainly upon different stimuli for their operation, we cannot expect to find any constant relation between them.

The constant increase in number of the respiratory act, in all febrile disease, I am surprised has not been more distinctly stated by authors. In fever it is the most constant symptom, excepting always the nervous depression, which is the only invariable phenomenon of this disease. I have before me a great many cases of fever, with a daily report, among other conditions, of the pulse and the respiration; and the latter shows very often much more marked change than the former. In an adult, the ratio of the respirations to the pulse is as 1 to 5 or 6, i. e., making the pulse about 70, and the respiration 12-14 per minute; while in children, it is as 1 to 3 or 4; and in young infants, as 1 to 23. In most cases of fever (excluding of course those with pulmonic complication), the pulse being about 100, the respiration is 25 or 30 per minute, being a much higher ratio than in health; the proportion, in fact, is doubled, being as much as 1 to 3. During the course of the fever, the respiration remains high, while the pulse may be natural, or below the standard; so that, in fact, no proportion can be obtained between them. A woman, aged 30, with typhus fever, a mulberry rash, and no chest or abdominal complication, had a pulse 116, while the respiration was 36 in the minute. The pulse soon became 100, and the respiration 32. The pulse sank next day to 90, and afterwards still lower, until it reached 52; while the respiration had only reached 26. The skin was still hot and dry. The pulse sank still lower, to 42, while the respiration was 22. The respiration is there seen to be as much above the standard of health, as the pulse below it. Perspiration broke out, and the patient convalesced, when the pulse got up and the respiration went down, until each had reached its natural standard. Such a case is an example of the rule in fever the independent course of the heart and the lungs in reference to their own peculiar duties. A man now under notice,

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