Changes After Death

Changes After Death

Dr Amit SharmaAssociate ProfessorDEPT. OF FORENSIC MEDICINEChanges After Death

The various changes produced in the body after death help in finding out the time since death that has a great value in medicolegal parlance. 1.Immediate changes: (i) Unconsciousness and loss of reflexes (ii) Permanent cessation of circulation (iii) Permanent cessation of respiration.2.Early changes: (i) Eye changes (ii) Skin changes (iii) Muscular flaccidity (iv) Contact flattening and pallor (v) Cooling of the body (vi) Cadaveric lividity (vii) Rigor mortis.3.Late changes: (i) Putrefaction (ii) Adipocere (iii) Mummification.

Unconsciousness and Loss of Reflexes

After death, there is loss of consciousness and spinal reflexes with no response to painful stimuli. Rarely after death, coordinated muscle group activity remains, that could be due to surviving cells in the spinal cord.

Permanent cessation of Circulation and Respiration

Tests for circulation: (i) Magnus test: This is done by tying a ligature lightly at the base of the finger, sufficient to cut off venous channels, without occluding arteries. The finger remains white if circulation has stopped. Otherwise, at the site of ligature a bloodless zone appears and the area beyond it gradually becomes blue and swollen. (ii) Diaphanous test (Transillumination test): The hand with closed fingers is to be held against a strong source of light. During life it is scarlet, red and translucent. (This colour is also seen in CO poisoning). However, after death it is opaque and yellow (yellowish colour is also seen in anemia and syncope). (iii) I cards test: Hypodermic injection of 20% alkaline fluorescein is given. There is no discolouration of skin if circulation has stopped. The skin is yellowish green if circulation is going on.

(iv) Finger nail test: When the pressure is applied on nail bed, it turns pale if circulation is going on but when the pressure is withdrawn it becomes red. (v) During life on the application of heat to the skin, true blister appears alongwith the line of redness. (vi) When a small artery is cut there is no jerky flow of blood after death. (vii) EEG shows an Isoelectric line after death.

Tests for respiration: (i) Mirror test: When a mirror is held in front of mouth and nostrils, it becomes dim due to condensation of warm moist air that comes from lungs indicating life. This test is quite useful in a cold weather. (ii) Feather test: There is no movement of cotton fiber or feather that is held in front of mouth and nostrils, if the respiration has stopped. (iii) Winslow test: A glass of water is placed on the chest, its surface will be seen to move if respiratory movements are continuing. Likewise if a mirror is placed on the chest the reflection of a beam of light focused on it will move, if the respiration is continuing.

Changes After Death (Early Signs)7Changes in the Eyes

1.Changes in cornea: After death the eyeballs become softened, cornea looses its luster and the corneal reflex is lost. The cornea becomes hazy and opaque like a dimmed glass. The rise in temperature and humidity hastens the process whereas closed eye delays it. In some conditions haziness of cornea can also be present before death like in uraemia, narcotic poisoning and cholera etc. The transparency is retained longer in cases of apoplexy, CO poisoning and HCN poisoning.2.Tache noire de la sclerotique: The formation of Tache noire de la sclerotique is also seen after death. it is an early and important sign of death. It appears after the passage of few hours to 2 days after death. It is believed to form due to the desiccation of tissues as it is formed only when the eyelids remain open after death. Tache noir is triangular in shape and is present over cornea, often outside the globe. It also undergoes colour changes from yellowish to brown to black .

3.Changes in pupil: Mid-dilated position may alter in position later on due to rigor. Pupil reacts to atropine and eserine resulting in dilatation and constriction of pupil after somatic death.The pupil responds to atropine for up to 4 hours and to eserine up to 1 hour. The shape of the pupil changes as a result of uneven relaxation from circular to oval, polygonal or triangular.

4.Intraocular tension: Intraocular tension becomes 14 g immediately after death from the normal value of 14-25 g and by the end of 2 hours it becomes zero. Intraocular tension is measured by tonometer. 5.Ophthalmoscopic examination of retinal vessels: The blood columns of the retinal vessels show fragmentation after death. This change is observed by an Ophthalmoscopic examination within 10 second after death. This is the well known trucking of blood in the retinal vessels, when loss of blood pressure allows blood to break up into segments, similar to trucks in a railway train.Retina appears pale for first two hours and then the optic disc outline becomes hazy in about 6 hours and finally blurred in about 8 to 10 hours after death.

Changes in the Skin

The skin becomes pale due to drainage of blood from small vessels and appears ashy white after death. It looses its elasticity due to which an incised wound will not gape. However, edges of ulcers and wounds caused during life retain blue or red colour after death. Even the icteric hue produced by jaundice and phosphorous poisoning is not affected. In deaths due to drowning, the skin retains its normal appearance. The pallor of the skin is hardly a reliable sign of death as in deaths due to CO poisoning, some colour remains on the face. Postmortem staining is of pinkish or cherry red appearance in carbon monoxide poisoning and in dead bodies left in cold storage.

Muscular (Primary) Flaccidity

Muscular (Primary) FlaccidityThis is also a sign of somatic death and lasts for one to two hours. At about the time of death all the muscles of the body relax and loose their natural tone. As a result the jaw drops, the thorax collapses and the limbs fall quite loose. There is relaxation of facial musculature and ironing out of skin creases resulting in a younger looking person. The smooth muscles of iris relax and the pupil assumes a mid position. The sphincters of the body relax and the wounds do not gape. This is known as primary flaccidity. This relaxation of the muscles is due to high ATP content that permits splitting of the actin-myosin cross bridges.

Postmortem Cooling of the Body (Algor Mortis)

The normal body temperature taken orally is 96.7-99F (36-37.2C) whereas the normal rectal temperature is 0.5-0.75F higher than the oral temperature that is 36.5-37.5C. During sleep, the temperature of the body is lowered by 1F and while exercising it is higher by 2-3F.

This temperature range is maintained in health and the balance of heat production and heat loss is also maintained. When the rectal temperature falls below 75 F, it is indicative of death and when it falls below 70F, it is an evidence of certain death. During life, the body looses heat due to radiation, convection and vaporization and heat loss by conduction is not an important feature.

After death, the production of heat ceases but loss of heat continues and the body keeps on cooling until the temperature of body is same as that of the environment. This fall of body temperature after death is due to radiation and convection. When body lies in a cool atmosphere, conduction also plays a role.

The surface of the body cools more rapidly than the interior. Within few hours, the body feels cold which is quite unreliable sign for estimating the time since death.

The ideal method to note the body temperature is by recording the visceral temperature. The visceral temperature is recorded by making a small midline incision in the peritoneal cavity and placing the bulb of thermometer in contact with the inferior surface of liver and taking the temperature in situ. In calculating the fall of temperature after death, it is assumed that body temperature was normal at the time of death. periphery will cool rapidly than the center, similarly in human body the peripheries cool rapidly and the temperature in the center of the body remains unchanged up to 4 hours after death.

The metabolic process like glycogenolysis provides some heat to the core of the body. The fall in body temperature is not uniform at the beginning and at the end, when the body temperature remains within 7F of the atmospheric temperature. Due to this drawback, postmortem cooling is not an ideal method of estimating time since death.

The disappearance of body warmth is one of the earliest sign of deaths. Today progressive fall of body temperature is accepted as a suggestive sign of death but its main value lies in the estimation of time since death.The use of a thermometer for measuring body temperature was first proposed by Dowler (1849-50). The temperature of the corpse is nowadays measured by inserting a chemical, 10 inches long thermometer with reading from 70-110F (21-44C), about 4 inches in to the rectum. The thermometer is inserted this much deep in the rectum enabling recording the temperature of the inner core of the body. The outer layer of the body that is 50% of the total body mass have low temperature and can easily be influenced by environmental conditions. In addition, the temperature of inner core varies from place to place.

This drawback can be overcome if the thermometer is left in situ for 3 minutes. Nowadays, electronic thermocouple with digital reading is a better way of recording the temperature.

The Newtons law that rate of loss of heat at any instance is directly proportional to the temperature difference between the surface of the object and its surrounding applies well to bodies after death. The loss of heat cannot be considered as a sure sign of death until the body has lost 15-20 degree of normal body temperature.

Variations of rectal temperature:

Low rectal temperature: Rectal temperature of 90o-94oF (32o-34.5oC) may be observed in (i) Cholera (ii) Long periods of exposure to cold (iii) Congestive cardiac failure and (iv) Cases of severe collapse.Elevated rectal temperature: Rectal temperature is elevated in (i) CO poisoning (ii) Coronary thrombosis (iii) Ruptured aortic aneurysm (iv) Heat stroke (v) Pontine haemorrhage (vi) Infections (vii) Asphyxial deaths.

Factors influencing the rate of cooling1.Environment temperature: In a body of 70 kg and 5.9" height lying in supine position facing air temperature between 40-75oF, the curve is of usual sigmoid shape. As the environmental temperature decreases, cooling quickens and at the temperature of 40oF, it is 2 times more rapid than when it was kept at 75oF.2.Body size: Body size is expressed as: The surface area exposed to coolingSize factor = _________________________________________________ Body massTotal surface area of the body is not radiating heat to the surroundings. For example, the inner aspects of arms and legs lie opposed to other skin surface, so heat radiated is again reabsorbed into the body. When body is in mummy position or supine position with arms by the sides, about 80% of the body surface looses heat and in crouched position only 60% loose heat. Therefore, in the former position cooling is rapid (because 80% is greater surface than 60%).3.Presence or absence of clothing or other covering on the body: In a clothed or covered body, the cooling is slow due to insulation.

4.Movement and humidity of the atmospheric air: When air movement occurs there is increased cooling due to the increased convection of heat. A body cools rapidly in the open than a closed room. In moist air there is increased cooling which is better conductor of heat. On the other hand, dry air retards cooling.

5.State of nutrition and development of body: The rate of cooling of a large body is slower than cooling of small body, because body fat retards cooling. Cooling of the large body as compared to small body depends not only on absolute body mass, but also on size or the surface area of the body relative to its mass. Therefore, cooling of infants is rapid than that of adults. They are not only smaller but the surface area of the body of a child relative to its mass is larger than adults.

6.Manner of death: In cases where death precedes with lot of muscular activity and the glycogen is exhausted resulting in minimal heat production by glycogenolysis, the cooling is rapid. There is also rapid cooling in case of deaths due to hemorrhage, wasting and chronic diseases. On the other hand, body remains warm for longer time in asphyxial deaths. Bodies immersed in water will cool rapidly than air, because water is a better conductor of heat than air. Bodies cool most slowly in water containing sewage or other putrefying organic material than fresh or seawater. Bodies cool more rapidly in running fluids than in the stagnant fluid.Medicolegal aspects: (i) Postmortem cooling of the body is a sure sign of death (ii) It is one of the parameters for estimating time since death.

Postmortem Caloricity

Postmortem caloricity is the rise of the body temperature for the first two hours or so after death. This rise in body temperature occurs due to various reasons: (i) Heat regulating center has been disturbed before death such as in cases of heat stroke (ii) Increased heat production in muscles due to convulsions in cases of tetanus and strychnine poisoning (iii) deaths due to excessive bacterial activity like septicemia, cholera and fever (iv) increased heat production due to glycogenolysis.

Postmortem lividity

Postmortem lividity is also known as hypostasis, livor mortis, subcutaneous hypostasis, postmortem staining, cadaveric lividity, suggilations, vibices etc. Postmortem lividity is the bluish purple discolouration, which appears under the skin of the dependent parts of the body after death due to capillovenous distention . The intensity of colour of hypostasis depends upon the amount of reduced haemoglobin in the blood. Large amount of reduced haemoglobin produces deep purplish blue colouration of the stain

Postmortem lividity is produced because of: (i) Stoppage of circulation (ii) Stagnation of blood in blood vessels (iii) Tendency of the blood to sink by force of gravity.

The dependent parts of the body attain a purplish blue hue while the pressure areas become pale due to drainage of blood from these areas. The colour of hypostasis is purplish blue due to the following reasons: (i) in recently dead or dying tissue oxygen dissociation takes place and this continues until equilibrium is reached between oxygen tension in the capillaries and the surrounding tissue

(ii) reflux of venous blood from the venular end of the capillaries, which adds to the blueness.

Distribution and location: The distribution of postmortem lividity is patchy to start but with passage of time, it gradually enlarges to cover all the dependent areas of the body. The colour of hypostasis blanches out on pressure. The purplish blue colour of hypostasis is more marked in fair coloured skin than the dark. The colour fades in persons suffering from anaemia, wasting diseases like lobar pneumonia, TB, cancer etc. In addition, postmortem staining may not develop in a body that has been in a constant motion after death. Hypostasis appears on dependent parts of body except pressure areas and its location and distribution depends upon the position of the body after death. In supine position, the postmortem staining appears on the back while in deaths due to hanging, it is well developed on the lower part of legs and forearms.

In deaths due to drowning, one can find the formation of hypostasis over the front of head, neck, upper part of chest and abdomen.

Time taken to develop: Postmortem staining appears shortly after death but may not be visible until 1/2-1 hour in plethoric individuals and 1-4 hours in anemic persons. It is well developed within 4 hours and the maximum development occurs within 6-12 hours after death of the person.

Extent and time of appearance: The extent and time of appearance of hypostasis depends upon: (i) volume of blood in circulation at the time of death, and (ii) fluidity of blood. In persons dying from conditions with slow circulatory failure such as cholera, typhus, tuberculosis or uraemia, hypostasis may appear shortly before death and is markedly developed shortly after death. The extent of postmortem lividity depends upon the amount and fluidity of blood at the time of death.

Fixation of P.M. lividity: Fixation of postmortem staining occurs when the body remains static for 6-8 hours at one place. This is due to the fact that the coagulation in the capillaries takes place in 6-8 hours making the staining permanent. Nevertheless, there will be no fixation if the blood remains persistently fluid due to fibrinolysis.

Shifting of P.M. lividity: Postmortem staining can shift from one part of the body to another due to the movement of the body after death. This is due to the fact that it takes about 6-8 hours for the stain to fix and prior to that period, the staining can keep on shifting as the blood remain fluid. In addition the shifting also occurs during decomposition as the clotting blood liquefies again. When the body is moved, areas of old staining will disappear and new ones appear on the dependent part.

Cause of death: It can be ascertained to some extent by examination of the colour of the PM staining. Certain poisons impart distinctive colour to the P.M. staining Medicolegal aspects of P.M. lividity:P.M. lividity is a sign of death It is suggestive of the time passed since death It can signify cause of death Distribution of hypostasis helps in elucidating the position of body after deathRigor Mortis

postmortem stiffening of voluntary and involuntary muscles of the body that develops at variable periods after deathRigor mortis first appears in involuntary muscles like heart and causes contraction of heart muscle that may rarely be mistaken for cardiac hypertrophy. Mechanism of development of rigor mortisAfter death, cellular respiration in organisms ceases to occur, depleting the corpse of oxygen used in the making of adenosine triphosphate(ATP) allowing the corpse to harden and become stiff. ATP is no longer provided to operate thepumps in the membrane of thesarcoplasmic reticulum, which pumpcalciumionsinto theterminal cisternae. This causes calcium ions todiffusefrom the area of higher concentration(in the terminal cisternae andextracellular fluid) to an area of lower concentration (in thesarcomere), binding withtroponinand allowing forcrossbridgingto occur between myosinandactinproteins, two types of fibers that work together in muscle contraction.

Starting between two to six hours following death, rigor mortis begins with the eyelids, neck, and jaw. The sequence may be due to different lactic acid levels among different muscles, which is directly related to the difference in glycogen levels and different types of muscle fibers. Rigor mortis then spreads to the other muscles within the next four to six hours, including the internal organs. The onset of rigor mortis is affected by the individual's age, sex, physical condition, and muscular build. Rigor mortis may not be perceivable in many infant and child corpses due to their smaller muscle mass.

Conditions that Influence rigor mortis:

Environmental temperatureDegree of muscular activity before deathAge: Nature of deathMedicolegal aspects: Rigor mortis is one of the sign of death Time since death can be calculated by ascertaining the presence of rigor mortis in various muscle groups of the bodyCadaveric spasm