Volume 1
The cyclopaedia of anatomy and physiology / Edited by Robert B. Todd.
- Date:
- 1836-59
Licence: Public Domain Mark
Credit: The cyclopaedia of anatomy and physiology / Edited by Robert B. Todd. Source: Wellcome Collection.
811/832 page 797
![more sensible of the loss of blood, the nervous symptoms, viz. vertigo and leipothymia, ap- pear, and immediately alterwards the pulse falls and becomes imperceptible. In corro- boration of this fact we might at first be inclined to mention that a diminution of Uie quantity of the blood, so far from depiessing the circulation, often appears to excite it violently, as in what has been denominated hcniiion’hogic veuctioii; but in such instances analogous effects have been also witnessed in the cerebral functions, namely, delirium and extreme sensibility, &c. On the whole we may conclude with regard to both these sys- tems that the depressing effect of haemorrhage depends rather upon the suddenness of the change, than upon the absolute diminution of the quantity of the fluid. 7. Si/ncope by poisons.—Some substances depress the action of the heart in the man- ner to which we had occasion to refer when speaking of syncope by mechanical injuries of the tissues generally. Of this kind are the mineral acids, oxalic acid, and the pure alkalies. They produce death, when taken in certain quantities, by means of that de- pression of the circulation which follows the destruction of the parts to which they are applied. In smaller quantities they may be more remotely fatal by exciting disease, gastro-enteritis for instance. One of the sub- stances mentioned, viz. oxalic acid, may in- duce direct depression of the circulation, un- attended by cerebral affection, even when its chemical effect upon the stomach is prevented by diluticn. In this form it must be classed with a large collection of substances which in certain doses subdue the moving powers of the circulation, without any previous coma, without any alteration of the tissues, and without any gastric irritation; such are arse- nic in large quantities, tobacco, digitalis, and most of the animal poisons. To the same class belong those malarious and contagious poisons which occasionally induce fatal syn- cope before any of their ordinary effects upon the general functions; we scarcely need to mention cholera, malignant typhus, plague, scarlatina, &c. I’he narcotic substances mani- festly act first upon the cer^bro-spinal system ; syncope follow's either with or without as- phyxia. Tiiose which act rapidly appear to strike the circulation before asphyxia has had time to transpire; we may instance hydro- cyanic acid, essential oil ot almonds, large doses of opium and of alcohol, certain gases, particularly sulphurtted hydrogen and cyanoger. 8. Syncope by cold and lightning. It is not clear whether these outward agents arrest the circulation through their influence upon the nervous system, or by, directly paralysing the irrltablity of the fibres of the heart. 9. Syncope by inanition.— In cases of this description it is probable that the failure of the heart’s action is a compound result of the prostration of the nervous system, and of the diminution of the [»roper stimulus of the circulation. 10. Syncope by disease.—All fatal maladies must terminate in cessation of the heart sa c- tion, but we limit the present category to those cases in which this event is unpreceded by asDhvxia. The others have been hinted at under the head of syncope by asphyxia. The diseases now under consideration may, we think, be conveniently arranged as follows I. Those which stop the motion of the lieart by obstructing its mechanism, e. g. collections of fluid in the pericardium, lesions of the val- vular apparatus ; accumulation of fat, &c., or by diminishing the contractility of the fibres, e.g. atrophy, or degeneration of the muscular substance f or by perturbing in some unex- plained manner the nervous influence, I functional form of angina pectoris. 2. Those which are attended with heemorrhage, e. g. aneurisms, and diseases of mucous suifaces. 3. Those which induce excessive and long-con- tinued discharges. Thus fatal syncope has sud- denly terminated afitof diarrhoea; but it must be borne in mind that in such instances the power of the circulation had previously been greatl^y enfeebled either by deterioration of the blood, or by causes acting on the innervation of the heart, or by the existence of irritation in some part of the system. 4. Diseases implicating the cerebro-spinal organs. Some of these ope- rate in the same manner as those accidental injuries which produce concussion, and which have been already adverted to. Thus in that species of apoplexy which terminates instan- taneously, {cipople<xie Jbudroyante ot French authors.) the sanguineous extravasation appears to have the same effect as a mechanical shock to the whole nervous mass. The more common form of apoplexy extinguishes life by impeding the respiratory movements. We have moie than once known cases of structural disease of the brain terminate by sudden syncope, but have learned nothing from the necroscopy capable of explaining why the fatal occurrence took place at the precise time when it did, rather than at any other moment in the peiiod during which the disease had existed, though it was easy to conceive that a lesion of this description must have been competent at any time to produce such changes in the cere- bral circulation as would induce the lesult in question. 5. Diseases attended with w'hat has been vaguely called irritation, either shoit and intense, or moderate but long-continued. This irritation consists sometimes of inflam- mation and its sequeltE, and sometimes of spe- cific structural alterations. A good illustration of the former of these is afforded by peritonitis, which frequently cuts off the patient by sub- duing the action of the heart, long before this effect could transpire from derangements of the organs contiguous to the seat of disease. Still more remarkable in this point of view are the effects of acute inflammation of a synovial capsule. It is true that these affections arc accompanied by violent ]>ain, which might be said in common language to exhaust the powers of the system, or in stricter phrase, to * See Mr. Chevalier’s interesting cases of sudden death in the Med. Ch. Trans, vol. i.](https://iiif.wellcomecollection.org/image/b22005444_0001_0815.jp2/full/800%2C/0/default.jpg)
