Popular Science Monthly/Volume 18/January 1881/Distinctions Between Real and Apparent Death
|DISTINCTIONS BETWEEN REAL AND APPARENT DEATH.|
A SATISFACTORY definition of life should express conditions involved in every phase of vital development, but never identified with any mode of inanimate existence. Transmutation represents one such fundamental distinction between animate and inanimate objects; for, although some inorganic combinations possess a degree of permutability consistent with substantial integrity, this in particular cases is always uniform in character and limited in extent. Ice, for example, may become successively changed into the liquid and gaseous state without chemical decomposition, but there is an intrinsic limit to such permutation, for under similar circumstances of pressure, at an unalterably fixed elevation of temperature, it invariably becomes resolved into simpler constituents.
There are apparently no such inherent restrictions to organic transmutations, which may be perpetuated indefinitely, under appropriate supplementary conditions, without perceptible intrinsic exhaustion. Yet organisms are never sufficiently independent to spontaneously evolve such progressive results, but require the constant accession of extrinsic energy to develop their included potentialities.
The sun is the physical source of extraneous energy for every species of vital change occurring on the earth's surface, as through the immediate agency of its rays vegetables are enabled to abstract from the surrounding medium those elements adapted to their special needs; and, although animals can not thus directly appropriate solar energy, yet they are enabled to utilize it by the assimilation of certain of these vegetable products which it has previously served to elaborate.
As all the progressive transmutations which indispensably constitute individual life are dependent on the constant incretion of material energy, integration is also a universal concomitant of vitality, so that for practical purposes life may be provisionally defined as the continuous individual integration and differentiation of material energy.
While these two correlated processes pertain to every variety of life, the physiological expedients by which their respective activities are sustained must vary in conformity with the specific requirements of different structures. A simple unit of protoplasm effects all its vital purposes through direct interchange with its environment, without the necessity of any intermediate provision. But, in higher organisms, life is indissolubly associated with certain accessory processes, and, in these cases, though the molecular interactions on which its essential attributes immediately depend are directly imperceptible, yet it is possible to prove its existence or non-existence by sensibly demonstrating the presence or absence of these its inseparable concomitants.
Man with his powers unimpaired manifests his vitality in unmistakable terms, but conditions not incompatible with resuscitation may occur wherein all his functions are so reduced as to be directly imperceptible. In such cases, to prevent premature burial, it is important to discover some sign absolutely diagnostic of real or apparent death.
An essential characteristic of living bodies is their power of actively maintaining a degree of varying integrity of constitution in opposition to destructive influences. This requires the incorporation of extraneous materials and their conversion into definite specific structures, and always involves the immediate apposition of ingredients, as well as a reciprocal state of the parts to be nourished. Although such intimate reciprocation of living structures and nutrient materials must always exist, the means whereby it is effected varies exceedingly in different instances. In the lower order of beings it is accomplished very simply, the medium which they inhabit offering directly the requisite pabulum, which their own condition enables them to assimilate without any preparatory elaboration. In more complex organisms a definite correlation of parts is necessary to elaborate the crude materials of food, as well as to bring them into immediate relation with the various tissues.
In some simple forms vital action may be suspended indefinitely by desiccation, being restorable by moisture, and even in some higher cold-blooded animals a state of temporary negation may be induced by congelation, the vital powers returning concurrently with the absorption of heat. In man it is quite different: the animal functions may be suspended, and even some of the organic processes interrupted, without extinguishing life, but there are certain of his functions the cessation of which for a limited period must inevitably cause death.
As to their vital significance, man's functions may be classified into essential and supplemental—the former including such as can not be discontinued beyond a brief interval without fatal consequences, the latter such as may be suspended or even destroyed without involving general dissolution. Thus, although eight is important to comfort, it may be lost without affecting vitality; the hepatic function may be vicariously performed; even the renal secretion may be suspended for a considerable period without death: but the complete cessation of any of the essential functions of circulation, innervation, or respiration must be speedily followed by such a result. By the circulatory forces, a constant flow of blood is directed to and from all the parts; by the nervous system, an alternating effect is produced on the tissue-elements, whereby at one time they assimilate, at another disintegrate; by the respiratory apparatus, certain of the resultant products are incessantly eliminated. These three complemental functions are so interdependent that the complete interruption of either necessarily leads to arrestment of all, and consequent death.
Human blood is of a highly complex nature, as through it the textures receive all the materials adequate to their continued maintenance and repair. Its chemical composition is never definite, varying in different individuals and in the same individual on different occasions. The relative uniformity, however, of some of its physical characters is indispensable to its vital efficiency. It is semi-solid, containing innumerable white and red corpuscles, the latter constituting nearly one half its mass. The absolute number of these corresponds with the degree of general vitality; their local aggregation fluctuates with varying contingencies.
This fluid is the seat of two distinct modes of motion—a sensible circulation through the heart and vessels, and a subtiler interchange with tissue-elements. Several causes conspire toward its circulatory mass-motion, the heart's action being a sine qua non. The molecular motions being invisible, an explanation of their modus operandi must be partly hypothetical. There are, however, certain associated phenomena admitting of direct observation under certain circumstances which serve to throw light on the physico—vital relations of the blood. Thus, besides its general distribution, it is subject to local variations in the total quantity of its mass, and in the relative proportion of its various constituents. As there are means of artificially exciting preternatural activity of the circulation to a recognizable extent, in parts open to observation, during the minimum degree of vitality, such a possibility affords a reliable method of infallibly deciding in any particular case as to the existence or non-existence of this vital process.
Tissues are divisible into vascular and non-vascular, according to the mode and extent of their nutritive supply. The latter, being destitute of capillaries, receive their nourishment from the neighboring vessels by endosmosis. The former are pervaded by those minute vessels, which admit red corpuscles in a lesser or greater number, accordingcording to the degree of functional exaltation. The cutis vera being a superficial vascular tissue, the excessive accumulation of red corpuscles in its capillaries is readily perceived by the consequent Acridity of surface. Such sensible reaction to direct irritation implies the concurrence of several determinate acts in the structures directly involved, as well as the cooperation of more remote parts. Thus the tissue-elements must possess a responsive power to become exalted in function, and to solicit a surplus of blood-ingredients they must also retain a continuity with the presiding nerve-center, whereby the peripheral impression may be centripetally transmitted along the afferent nerve to this point, thence reflected along the vaso-motor nerve, causing relaxation of the arteriolar muscles, enlargement of caliber, and a freer flow of blood into the part. Cardiac contractions are also necessary to propel the corpuscles into the capillaries, as the attraction of the tissue-elements for these minute bodies can act only at insensible distances.
Man's structure conceals the changes which occur within the minute blood-vessels, but some animals admit the examination of the interior processes which accompany and conduce to the external manifestations of capillary congestion. Observing the circulation in the web of the frog's foot under the microscope, fluctuations in its current are noticed independent of the heart's action. The corpuscles, perhaps flowing uniformly at first, may slacken their speed, then oscillate or even retrograde. Apply an irritant to the part, the flow soon increases, and a greater number of red corpuscles pass through in a given time; they also show a tendency to cohere as well as to adhere to the walls of the vessels, which may proceed so far as to choke up their caliber and prevent the transmission of blood. As the effect passes off, the corpuscles gradually separate, move on, and at length the circulation resumes its normal state. Such investigation explains the nature of the changes which occur in the capillaries of the human skin under artificial stimulation.
Heat, which is the most potent and available form of irritant, when applied to the skin so as to considerably elevate its temperature above the normal point, causes first an efflorescence of surface, deeper at the center and shading off gradually toward the circumference. This redness can be temporarily displaced, leaving a white impression, which disappears on removal of the pressure, the part resuming its floridity with a rapidity commensurate with the activity of the capillary circulation. By increasing the heat or prolonging its action the color becomes more distinct, till at the point of greatest intensity the cuticle becomes detached from its subjacent cutis by the gradual exudation and accumulation of a fluid which thus forms a true vesicle. A spurious vesicle may be similarly produced on the dead subject, but such is a purely physical and local effect, entirely different from the more comprehensive action and characters of the physiological process.
In post-mortem vesication the contents are generally gaseous from decomposition, and even if fluid, from infiltration in an œdematous or dependent part, this is always serum, unlike the vital fibrino-albuminous solution coagulable by heat. The pathognomonic distinction, however, is the difference presented by the underlying cutis on removing the loosely adherent cuticle. This, after death, has an unalterable yellowish-white, crisp, horny appearance, in obvious contrast to the efflorescence of vital active congestion, which can be repeatedly displaced and renewed by recurrent pressure.
Although circulation is a vital necessity, the chemical products of its activity would of themselves speedily destroy life except for the concurrent exercise of the respiratory and other functions.
Tissues, such as the nervo-muscular, which perform some specific action, may be classed as active in contrast to passive, such as the osseo-fibrous, which merely subserve some mechanical office. When the ultimate particles of passive tissues are fully developed, they remain in that state for a longer or shorter period, and then gradually decay. Active tissues, during their development, appropriate a store of energy which, at maturity, they are capable of instantly expending in the manifestation of their special powers. Such exertions are inevitably attended by degradative transformations of their material elements. Cardiac movements and their associated vital coordinations involve the expenditure of nervo-muscular energy, and consequent production of simpler compounds, such as carbonic acid, the undue retention of which in the blood would cause certain death. Such a fatal contingency is prevented by the circulatory forces propelling the carbonized blood into the pulmonary capillaries, where an interchange with the oxygen of the air takes place through the intervening membrane till the vesicles become surcharged with carbonic acid, which is then expelled by the expiratory forces through the anterior openings of the air-passages, where its detention is evidence of vitality, while its utter absence under adequate tests is undeniable proof of the opposite condition. For, though certain cold-blooded animals can exhale a sufficient quantity of this product through their skin to permit a reduced vitality, in man such a cutaneous transpiration is exceedingly minute and altogether inadequate to the maintenance of life, and it may continue even after death as a merely physical property of tissue.
Innervation is blended with and controls all the vital operations, being conspicuously implicated with muscular contraction, an act primarily concerned in the various movements of respiration and circulation. The frequently-repeated transmission of intense electric currents is the most powerful stimulus of contractility, and, when such a measure fails to excite contraction in muscles essential to life, death must have occurred.
"When rigidity and putrefaction are actually established, they may be accepted as infallible post-mortem indications. The former state arises from the muscles and other soft tissues becoming so stiffened as to resist flexion of the joints, the muscles of the lower jaw and neck being generally first involved, those of the lower extremity last. It might possibly be confounded with stiffening from extreme cold or spasms; but frozen limbs yield a creaking noise when forcibly flexed, from breakage of the congealed moisture, and spasmodic contraction resumes its morbid position on removal of the correcting force. Not so post-mortem rigidity.
Putrefaction succeeds rigidity as a bluish-green tint of skin, commencing usually on the lower part of the abdomen and spreading over the body. Similar gangrenous appearances may occur during life, but, besides their more circumscribed extent, the invariable presence of a line of displaceable redness at the confines of the living tissues is a constant and characteristic distinction.
The desideratum, however, is some infallible proof of death whereby this state can at once be decided without waiting for the more tardy supervention of these positively post-mortem phenomena.
Neither the cadaveric aspect nor coldness and lividity of surface are constant or unequivocal signs. The cessation of the heart's action beyond five minutes is undoubted evidence, but it is impossible to acoustically determine this with absolute certainty, even when aided by the stethoscope, as the sense of hearing may be fallacious in delicate cases. Neither is the imperceptibility of the respiratory movements of the chest perfectly decisive. Conclusions from experiments on the eyes, by trying to excite the pupillary muscles by physiological agents, or by examining the fundus with the ophthalmoscope so as to observe certain changes supposed to be essentially post-mortem, are invalidated by the comparative unimportance of these organs to general vitality. The same uncertainty holds as to the effects produced by tightly ligaturing a limb, as there might be complete occlusion of its vessels and consequent arrest of its circulation without necessarily fatal results. The changes induced in a polished needle inserted deeply into the living tissues may be closely simulated by non-vital causes. Circumstances might also obscure the difference between the contents of vital and post-mortem vesication.
The possibility of absolutely deciding, in doubtful cases, as to the presence or absence of vitality depends on the possession of artificial means wherewith to sensibly demonstrate the minimum activity of each of the essentially vital processes, the utter negation of the various specific reactions under their appropriate tests being infallible evidence of death. The different available measures vary in their degree of simplicity and facility of application, but the results are all equally conclusive.
The validity of the respiratory test results from the fact that even during the most reduced state of vitality carbonic acid is perpetually generated in the system, and extricated therefrom through specially adapted air-passages, where its escape can invariably be detected by proper appliances.
Allowing a few hours to elapse after apparent death, so that an equilibrium may be established between the carbonic acid in the air-chambers and the atmospheric air, if death is real the amount of this product exhaled from the anterior opening of the air-passages will exactly correspond with that transpiring from an equal area of the skin; but, if the slightest vital action continues, the proportion thus expired in a given time will far exceed the whole cutaneous transpiration. Collecting it at its point of exit, by a suitable contrivance, into a small transparent vessel containing clear lime-water, its merest presence, in contrast to any other reagent, will change this fluid at once, on shaking, into an opaque, milky solution.
The innervation test is rendered practicable through the inseparable connection of this attribute with muscular contraction; for, even if contractility is inherent in muscle, its excitation is possible only through the incorporation of nerve-elements. As this manifestation of nervo-muscular energy can always be sensibly excited by electrification during the persistence of the feeblest vitality, the utter failure to obtain such a result in parts the activity of which is essential to life, affords conclusive evidence of vital extinction. The respiratory arrangements of the glottis present a favorable opportunity for prosecuting this special mode of experiment. At every inspiration the contractions of the associated muscles stretch and separate the vocal chords, thus, nearly doubling the area of aperture. In expiration the muscles relax, allowing the parts by their elasticity to resume their natural collapsed appearance. These changes can be observed by placing the body before a bright light, and introducing a laryngoscope well back into the pharynx, so as to bring the superior laryngeal aperture into view. After death the rima glottidis presents the elongated narrow form, from the close approximation of its chords. If, under the repeated transmission of intense electric currents, properly directed, there is no responsive contraction so as to sensibly widen the aperture, death is certain.
The circulatory test, or the attempt to excite an actively congested state of the cutaneous capillaries, is preëminently the best, as it requires only simple and easily procurable appliances, which always yield decisive results either in the living or dead subject. The application of heat and the act of cupping are both effective topical means for perceptibly arousing this preternatural activity of the cutaneous circulation, even in the most languid condition of the system compatible with vitality. The entire absence of such distinctive physiological reactions and the occurrence of merely physical alterations, under the proper use of these respective measures, is undeniable proof of death. Over the heart is the most suitable region whereon to operate, as there the skin longest retains its vital warmth; but corroborative experiments may be performed over other parts of the trunk.
Hold the flame of a candle close to (but not in contact with) the skin sufficiently long to render the cuticle easily detachable from its subjacent connections: if the body is dead, the parts beneath will present a crisp, yellowish-white, horny appearance, unaffected by pressure; if alive, there will be readily perceptible a vital redness, distinguishable from all post-mortem discolorations by its repeated displacement and reappearance under alternating pressure by tip of the finger or otherwise. Exposing the part to a bright light, and examining it through a magnifying-glass, will render the different phenomena more evident. Kindle a piece of paper soaked in any alcoholic liquor, put it in an ordinary drinking-glass or goblet, and invert this over a part of the cutaneous surface where all its edge will come into accurate contact with the skin: if there remains a minimum degree of vitality, a state of superficial capillary congestion will be induced, with its unmistakably recurrent characters; whereas the absolute inability to excite such vital reaction in any part of the trunk's surface, and the production of solely physical effects by such potent agencies, are infallible evidence that all vital correlations are irreparably destroyed.