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MEDICAL AND PHILOSOPHICAL

Journal and Review.

VOL. I.-No. 1.

To the Editors of the Medical and Philosophical Journal and

Review. GENTLEMEN, The following Theory of the Proximate Cause of Fever was

delivered by the Author while Professor of the Institutes of Medicine. It will be seen from the aphoristic form in which it is written, that it was originally intended rather as a text book for his lectures, than as a finished treatise on the subject. If, in this imperfect state, it is thought worthy of being published, you are at liberty to insert it in your Journal.

OUTLINES of a new THEORY of the PROXIMATE Cause of

Fever: By BENJAMIN De Witt, M. D. Professor of Chea mistry in the University of the State of New-York, and late

Professor of the Institutes of Medicine. 1.

As the circulation of the blood is necessary for the preservation of life and health ; so a perfect knowledge of that function is necessary to enable the Physician to prevent disease and death. Before the discovery of the circulation, doubts and difficulties attended the science of Medicine. Diseases in general, and those of a febrile nature in particular, were im. perfectly understood. Indeed, it was impossible for any one to comprehend their true cause, or to point out the proper reVol. 1.

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medies for their cure. But after that important discovery, it could not escape the most superficial observer, that fever invariably produced more or less disturbance in the sanguiferous system. Accordingly it has been the universal practice of Physicians, from Dr. Harvey down to those of the present day, to resort to the state of the pulse as a characteristic indication of the existence of the disorder. There are indeed many considerations which lead to the conclusion, that the blood vessels are the principal seat of fever; and this opinion is now so generally received, that I presume it will not be controverted.

2. To understand, therefore, the nature of fever, it is necessary to attend minutely to the physiology of the sanguiferous system, and to examine particularly the action of the heart and arteries.

3. The heart is a hollow muscle, whose action consists in alternate contractions and dilatations. The blood, after being received into the ventricles during the dilatation of the heart, is prevented by the valves from returning into the veins. The natural effect, therefore, of the contractions of the heart is to propel the blood into the arteries more or less forcibly, more or less frequently, or with greater or less regularity.

4. We distinguish accordingly three varieties of action in the heart different from each other. The first comprehends all the possible degrees of force in the contractions, from the strongest to the weakest action. 'The second includes every degree of celerity, from the slowest to the most frequent pulsations; and the last embraces every species of irregularity in motion.

5. The impulse given to the blood by each contraction of the heart, produces a mechanical dilatation of the elastic arteries into which it is propelled. These dilatations may be accurately felt by pressing the fingers on any one of the large arteries. Hence results the doctrine of the pulse so far as it relates exclusively to the action of the heart.

6. If, indeed, the arteries were mere elastic tubes, without any power of action in themselves, the pulse would be simple and easily understood. It would indicate the motions of the heart only, and mark the few varieties of action of which it is ca. pable.

7. But the mechanical dilatation of the arteries produced by the impulse of the blood, is variously modified and changed by the contractions of the arteries themselves. And this mus. cular action of the arteries in its turn again exerts an influence upon the action of the heart. The pulse therefore not only indicates the several varieties and degrees of action in the heart, but also the different kinds and degrees of action in the arterial system. And this combination of movements in the heart and arteries, acting and re-acting at the same time on each other, produces the endless variety of complicated motions distinguishable in the pulse.

8. These motions of the sanguiferous system, that is, of the arteries as well as of the heart, though complex in their nature, and difficult to be understood, are, nevertheless, of great importance, and should be accurately attended to in the science and practice of Medicine; especially in fever, which, being seated chiefly in the arterial system, immediately and greatly affects the action of the heart and arteries, and produces corres. ponding changes in the pulse.-Let us, therefore, examine more particularly the action of the arterial system.

9. Mr. John Hunter has remarked, that the elastic is almost the only power with which the coats of the large arteries are invested: while irritability is very apparent in those of a smaller diameter, and almost exclusively predominates in the capillary vessels. It is presumed accordingly, that in proceeding from the heart, the elastic power diminishes with the diminution of the size of the arteries, until it is lost in their extremities; and that the muscular power is increased in the same proportion, until it prevails exclusively in the termination of the capillaries : so that in the small arteries, at a medium between the two extremities, the two powers of elasticity and muscularity are equally balanced, and both operate equally on the circulation of the blood.

10. With a view, then, of speaking with greater precision on this subject, I shall divide the arteries into three systems of ves. sels: The system of large arteries; the system of small arteries; and the system of capillaries. And although the exact limits between these systems cannot be defined with anatomical precision, yet, in a physiological point of view, while we consider that they are capable of different kinds of action, subject to different influences, and liable to distinct habits of motion, this division seems to be appropriate and necessary.

11. Having premised thus much concerning the moving powers of the arterial system, I proceed to consider more particularly the muscular action of the arteries: and here I shall remark generally, that they are capable of three distinct kinds of actions, essentially different in their nature from each other. Their actions may be either natural, reversed, or convulsed. The first occurs always in a state of health ; the second takes place often in disease ; and the last seldom happens except at the approach of death. I shall "illustrate each of them in the order they are mentioned.

12. The natural action of the arteries consists principally in the successive contractions of their circular fibres in a progressive order and direction from the heart to their extremities : thus accelerating the motion of the blood, and co-operating with the action of the heart in promoting the circulation.

13. These successive contractions of the muscular fibres of the arteries being induced by the momentum of the blood from every pulsation of the heart, correspond for the most part with the action of that organ; that is, the sudden distention given to these muscular fibres, by the impulse of every wave of blood propelled from the heart, causes each one of them successively to contract, as soon as the wave reaches it; so that the velocity of these trains of contractions keeps pace with the velocity of the impulse given to the blood.

14. This is more especially the case in the large arteries ; on them the impulse of the blood is always great in proportion to the force of contraction in the heart, and their elastic predominates over their muscular power; so that the action of the moving fibres is subordinate to the contractile force of elasticity. The muscular fibres, therefore, do assist the contractions of these arteries, but can never control them. Hence the trains of contractions in these arteries are under the exclusive 'domi. nion of the heart, and are habitually regulated by its action..

15. The small arteries, as they are farther removed from the influence of the heart and the impulse of the blood than the large ones; and as they are endowed with a proportionally greater degree of muscular power; so they are capable of exerting a more independent and energetic action: and although the force and velocity of the trains of contractions in them may usually be governed by the impulse of the blood; yet it is evident that their action is occasionally increased or diminished in consequence of their connection with the capillaries, and from the influence of external causes. In confirmation of this fact it is to be observed, that as these small arteries occupy a middle position between the large and capillary vessels, and partake of the predominant moving powers of both; so they must necessarily be governed more or less by the causes which actuate both, in proportion as they approach nearer to the one or to the other of them.

16. The capillary arteries are so minute in their capacity, and so distant from the centre of action in the heart, that the impulse of the blood is scarcely perceptible in them, and so feeble that it is insufficient to govern their trains of contractions: and hence, particularly in those capillaries which are spread on the surface of the body, we observe a continual change of inotion without any corresponding change in the heart or large arteries. The action of these capillary vessels is influenced by every vicissitude of heat and cold, and they may be excited with great facility into preternatural activity by the slightest causes, without affecting the action of the heart. Hence, by the par

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