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Putrefaction:
It is the final stage following death, mainly by the action of
bacterial enzymes, mostly anaerobic organisms derived from the
bowel.
Putrefaction is delayed after death due to poisoning by:
Carbolic acid, Zinc chloride, Strychnine, Heavy metal poisoning
e.g. Arsenic, Antimony.
The chief destructive bacterial agent is Cl.
Welchii which causes marked hemolysis, liquefaction of
post-mortem clots and of fresh thrombi and emboli,
disintegration of tissue and gas formation in blood vessels and
tissue spaces. Enzyme Lecithinase produced by Cl. welchii is
most important.
The characteristic features of putrefaction are
: (i) changes in the colour of the tissue,
(ii) collection of gases in the tissues, (iii) liquefaction of
tissues.
(i) changes in the colour of the tissue: The first external sign
of putrefaction in a body lying in air is a greenish
discolouration of skin over caecum i.e. right iliac fossa, where
the contents of the bowel are more fluid and full of bacteria.
The colour appears in 12 to 18 hours in summer and one to two
days in winter. The greenish discoloration then spreads over the
entire abdomen, external genitals and then patches appear
successively on the chest, neck, face, arms and legs. The
patches become dark-green and later purple and dark blue. The
marbled appearance is prominent in 36 to 48 hours. The earliest
internal change is reddish brown discolouration of the inner
surface of the vessels, especially the aorta.
(ii) Collection of gases in the tissue: Gases collect in the
intestines in 6 to 12 hours in summer. From 18 to 36 hours after
death, the gas collects in the tissues, cavities and hollow
viscera under pressure and the features become bloated and
distorted. After 3 days, the face is so discoloured and bloated
that identification becomes difficult. The hair becomes loose
and is easily pulled out.
(iii) liquefaction of the tissues: Colliquative putrefaction
begins from 5 to 10 days or more after death.
Skeletonisation: In India, an unconfined buried
body is reduced to a skeleton within a year.
Internal phenomenon:
The organs show putrefactive changes in the following order :
1. Larynx and trachea, 2. Stomach, intestines, spleen, 3. Liver
and lungs, 4. Brain,
5. Heart, 6. Uterus, prostate, kidney, 7. Skin, muscle, tendon,
8. Bone.
In putrefaction, when bubbles appear the organ has a honey
combed, foamy appearance. Prostate and virgin uterus resists
putrefaction for a very long time. Putrefaction begins above
10°C and optimum between 21 °C and 38°C. A body decomposes in
air twice as rapidly as in water and eight times as rapidly as
in earth; formula is given by Taylor. Putrefaction is the surest
sign of death. After death, the onset of putrefaction is in the
stage of secondary relaxation. Gas rigidity appears after 72
hours.
Entomology of cadaver: Is the study of insects
and maggots that infest the dead body.
Bones begin to decompose after death in 3-10 years. Less than 7
amino acids in bone suggest the age of bone to be (after death)
more than 100 years. Total ultraviolet fluorescence of cut
surface of bones is seen in 35-100 years. Foamy liver is due to
bubbling up of gas. Putrefaction is affected by age, clothing
and moisture. Maggots in a dead body do not appear before 48
hours.
Adipocere (Saponification)
In this, the fatty tissues of the body changes into a substance
known as adipocere. The change is due to gradual hydrolysis and
hydrogenation of pre-existing fat such as olein, into higher
fatty acids, which combine with calcium and ammonium ions to
form insoluble soaps, which being acidic, inhibit putrefactive
bacteria. Adipocere is delayed by cold and formed rapidly by
warm humid climate and moist damp soil.
Fresh adipocere is soft, moist, whitish and translucent
but old samples are dry, hard, cracked, yellowish and brittle.
It is inflammable and burns with a faint yellow flame. It floats
in water and dissolves in alcohol and ether. It is formed first
in subcutaneous tissue. The face, buttocks, breast, abdomen are
the usual sites. In temperate country, the shortest time for its
formation is about 3 weeks in summer. Foetuses under 7 months do
not show this change. In India, it has been observed within 3
days.
Mummification: It is a modification of
putrefaction.
Dessication or, Dehydration or drying and
shrivelling of the cadaver occur due to evaporation of water but
the natural appearance and features of the body are preserved.
It begins in the exposed parts of the body such as face, hands
and feet and then extends to the entire body including the
internal organs. A mummified body is practically odourless. The
time required for complete mummification of a body varies from
three months to a year or two. Two factors are necessary for the
production of mummification: (1) The absence of moisture in the
air, and (2) The continuous action of dry or warmed air.
Embalming:
In this, the contents of the body cavities are removed
and the vascular system is injected with an embalming fluid
containing 40% formaldehyde and 10% methyl alcohol.
MECHANICAL INJURIES
Mechanical injuries (wound) are injuries produced by physical
violence.
An injury is any harm, whatever illegally
caused to any person in body, mind, reputation or property (S.
44, IPC)
A wound or injury is a break of the natural continuity of any of
the tissues of the living body.
Classification:
(I). Mechanical:
1. Abrasions 2. Contusions 3. Lacerations 4. Incised wounds
5.Stab wounds 6. Firearm wounds 7. Fractures and dislocations
(II) Thermal:
1. Due to cold-
(a) Frost bite (b) Trench foot (c) Immersion foot.
2. Due to heat—
(a) Burns (b) Scalds.
III. Chemical: (a) Corrosive acid (b) Corrosive alkalies.
IV. Injuries due to lightning, electricity, X-ray and
radio-active substances..
Abrasions
An abrasion is a destruction of the skin, which involves
super¬ficial layers of epidermis only. They are caused by a
blow, a fall on a rough surface, by being dragged in a vehicular
accident, finger nails, thorns or teeth-bite. The exposed raw
surface is covered by exudation of lymph and blood, which
produces a protective covering known as scab or crust. They are
simple injuries, bleed slightly, heal rapidly and leave no
permanent scar.
Types: Abrasions are of four types.
1. Scratches: These are caused by a sharp
object passing across the skin, such as finger nails, pin or
thorn.
2. Grazes (sliding, scraping or grinding
abrasion): They are most common type of abrasions. They show
uneven, longitudinal parallel lines (grooves or furrows) with
the epithelium heaped up at the ends of these lines, which
indicate the direction in which the force is applied.
An abrasion caused by violent friction against a broad rough
surface as in dragging over the ground is called brush burn.
3. Pressure abrasion (Crushing or friction
abrasion): Ligature mark. They are caused by crushing of the
superficial layers of the epidermis and are associated with a
bruise of the surrounding area.
4. Impact abrasions or Imprint abrasions— they
are caused by impact of a rough object, such as a person knocked
down by a motor car. They are also called pattern abrasions.
Age of Abrasions:
1. Fresh — Bright red.
2. 12 to 24 hours — Lymph and blood dries up leaving a bright
scab.
3. 2 to 3 days — Reddish-brown scab.
4. 4 to 7 days — Epithelium grows and covers defect under the
scab.
5. After 7 days — Scab dries, shrinks & falls off.
In ante-mortem abrasions, intravital reaction and conges¬tion is
seen.
Erosion of the skin produced by ants, excoriations of the skin
by excreta and pressure sores resemble abrasions.
Contusions (BRUISES)
A contusion is an effusion of blood into the tissues, due to
rupture of the subcutaneous vessels, caused by blunt trauma.
This is accompanied by a painful swelling and crushing or,
tearing of the subcutaneous tissues usually without destruction
of the skin. A contusion is a superficial injury. When a large
blood vessel is injured, a tumour-like mass called haematoma is
formed. The size of the bruise is slightly larger than the
surface of the agent which caused it, as blood continues to
escape into the area.
If the part is vascular and loose, such as face, vulva, scrotum,
a slight degree of violence may cause a large bruise. If the
tissues are strongly supported and covered by thick dermis, such
as abdomen, back, scalp, palm and soles, moderate violence may
produce a small bruise.
Bruising is more marked on tissue overlying
bone. Children and old people bruise more easily. Hemorrhages in
the soft tissues around the eyes and in the eyelids (black-eye)
may be caused by blunt impact to the forehead.
The Age of Bruise:
A bruise heals by destruction and removal of the extra-vasated
blood.
At first (1-2 hours)—Red.
Few hours to 3 days—Blue
4th day — Bluish-black to brown (haemosiderin).
5 to 6 days — Greenish (haematoidin).
7 to 12 days—Yellow (bilirubin).
2 weeks—Normal.
In ante-mortem bruising there is swelling, damage to epithelium,
extravasation, coagulation and infiltration of the tissue with
blood and colour changes.
Bruises are of less value than abrasions. In self inflicted
bruises, typical colour changes are not seen.
Artificial bruises: Some irritant substances when applied to
skin produce injuries, which simulates bruises. Artificial
bruises are dark brown and true bruises show typical colour
change.
Incised wounds
An incised wound (cut, slash or slice) is a clean cut through
the tissues, which is longer than it is deep. It is produced by
pressure and friction against the tissue by object having a
sharp cutting edge such as knife, razor, scalpel, sword, etc.
Incised wound appears lacerated on testes. Incised wounds are
deeper at their beginning, because more pressure is exerted on
the knife at this point, known as the head of the wound.
Towards the end of the cut, the wound becomes shallow, called
tailing of the wound.
Age of incised wound:
Fresh—Hernatoma formation.
12 hours—Edges are red, swollen, adherent with blood and-lymph.
24 hours—A continuous layer of endothelial cells cover the
surface.
36 hours—The capillary network is complete.
48 to 72 hours—The wound is filled with fibroblasts.
3 to 5 days—Definite fibrils running parallel to the vessels are
seen; vessels show thickening and obliteration.
1 to 2 weeks—Scar tissue is formed.
Hesitation marks or tentative cuts or
trial wounds—They are cuts which are multiple, small and
superficial, often involving the skin and seen at the beginning
of the incised wound. They are seen in suicidal wounds.
Chop wounds: They are wounds caused by a blow with the sharp
cutting edge of a fairly heavy weapon like a hatchet, axe, a
sword etc.
Wound produced by a curved weapon such as sickle is both stab &
incised wound.
Stab or Puncture Wounds
Stab wound is a penetrating injury caused by sharp-pointed
objects, such as knife, dagger, nail, needle, arrow, screw
driver, etc. penetrating the skin and underlying tissues that is
deeper than its length and width of the skin.
Most important dimension in stab wound is depth. Punctured wound
is deeper than its width and length on skin. The length of wound
is less than width. If a single edged weapon is used, the
surface, triangular or wedge shaped, one angle of the wound will
be sharp, the other blunt or torn.
Harakiri: It is an unusual type of suicide, in
which the victim inflicts a single large wound on the abdomen
with a short sword while in a sitting position or falls forward
upon a ceremonial sword and pulls out intestines. The sudden
evisceration of the internal organs causes a sudden decrease of
intra-abdominal pressure and cardiac return, producing sudden
cardiac collapse.
Lacerations
They are open wound.
Lacerations are tears or splits of skin, mucous membrane, muscle
or internal organs produced by application of blunt force to the
broad area of the body. Displacement of tissues occurs most
commonly when soft tissues are crushed against bone, e.g.,
scalp, shins, shoulders, and face. They are caused by blows from
blunt objects, by falls on hard surfaces, by machinery, traffic
accidents, etc.
If the force produces bleeding into adjacent tissues, the injury
is a ‘contused-laceration’ or ‘bruised tear’. If the blunt force
produces extensive bruising and laceration of deeper tissues, it
is called ‘crushing’ injury.
Incised like or incised looking wounds: Lacerations produced
without excessive skin crushing may have relatively sharp
margins. The sites are the scalp, eyebrows, cheek bones, lower
jaw, iliac crest, perineum, and shin.
Stretch lacerations: is seen in the running
over by a motor vehicle, and the flap may indicate direction of
the vehicle.
Avulsion is a laceration produced by sufficient
force (shearing force) delivered at an acute angle to detach
(tear off) a portion of a traumatised surface or viscus from its
attachments.
Defense wounds
It results due to immediate and instinctive reaction of the
victim to save himself, either by raising the arm to prevent the
attack or by grasping the weapon.
Self-inflicted wounds are those inflicted by a
person on his own body.
Fabricated wounds (fictitious, forged or
inverted wound) are those which may be produced by a person on
his own body or by another with his consent.
REGIONAL INJURIES
Most fragile bone in the skull to get fractured is — temporal
bone.
Depressed fractures -» The outer table is driven into the diploe
and inner table is fractured irregularly. Depressed fracture is
also called signature fracture. Localised depressed fracture are
caused by blows from heavy weapon with a small striking surface
e.g. stone, stick, axe. hammer etc.
Pond or Indented fractures —> They occur only in skulls which
are elastic i.e. the skulls of infants.
Gutter fractures - They are formed when part of the thickness of
the bone is removed so as to form a gutter e.g. oblique bullet
wound.
Countre-coup lesions fracture means that the lesion is present
in an area opposite the side of impact in head injury.
Concussion is a state of temporary unconsciousness, which
results from violence applied to the skull. Concussion of the
spinal cord is called railway spine.
In fracture, X-ray examination, callus is not readily visible
for 3 weeks.
Whip lash injury is due to violent acceleration or deceleration
force.
In Boxing injuries fracture of the skull is rare but sub-dural
hemorrhage occurs. It is most common type of hemorrhage.
Deterioration of speed and co-ordination are the chief symptoms
of the onset of punch-drunk (traumatic encephalopathy)
condition. Repeated blows to the head produce small hemorrhages
and degenerative changes in brain.
— The specific pulmonary injury of air blast is called 'blast
lung'.
— Most common mechanism of fracture of spine is hyperflexion.
— Most common site of spinal cord injury is thoracolumbar
junction (T10- L1).
— Best method of assessing spinal cord injury is MRI.
Intracranial Hemorrhage
1. Extradural hemorrhage: — It is caused always due to trauma.
Most common artery causing extradural hemorrhage is anterior
branch of middle meningeal artery. Most common site of
extradural hemorrhage is Temporo-parietal area where main source
of bleeding is middle meningeal artery. There is a history of
head injury which causes the bleeding and temporary
unconsciousness usually. This is followed by a period of normal
consciousness, the lucid interval of few hours to a week.
2. Subdural hemorrhage:
May occur from relatively mild trauma. It is essentially venous
or capillary, not arterial.
3. Subarachnoid hemorrhage
This is the most common form of traumatic intracranial
hemorrhage.
4. Intracerebral hemorrhage
Most common cause of intracerebral hemorrhage is hypertension.
Most common site of intracerebral hemorrhage is putamen (corpus
striatum).
Most common blood vessel leading to intracerebral hemorrhage is
lenticulo striate branch of middle cerebral artery.
MEDICO-LEGAL
ASPECTS OF WOUNDS
Homicide: is
killing of a human being by another human being.
Types of homicide:
(1) Lawful (a) Excusable (b) Justifiable
(2) Unlawful (a) Murder (b) Culpable homicide (not amounting to
murder/ amounting to murder) (c) Rash or negligent homicide.
Justifiable homicide: This is the homicide
which is justified in the circumstance which led to the killing
of a person. This may occur; (a) In the administration of
justice, like execution of sentence of death (b) The maintenance
of justice, e.g., in suppressing riots, or executing arrest, or
killing in course of violent crime, e.g., a woman who kills a
person who attempts to rape her.
Excusable homicide: This is the homicide caused
unintentionally by an act done in good faith. This includes: (a)
Killing in self-defense when attacked, provided there is no
other means of defense (b) Causing death by accident or
misadventure (c) Death following a lawful operation (d) Homicide
committed by an insane person.
Murder: S. 300,
IPC
Culpable homicide: S. 299, IPC
Punishment for murder: S. 302, IPC – Imprisonment for life, and
also fine.
Punishment for culpable homicide: S. 304, IPC – Imprisonment for
life, or for a term which may extend to 10 years and also fine.
Causing death by negligence: S. 304 – A, IPC – Imprisonment for
a term, extend to 2 years or/with fine, or with both.
Grievous Injury
According to 320 I.P.C., anyone of the following injuries is
grievous:
1. Emasculation (Ioss of potency).
2. Permanent privation (loss) of sight of either eye.
3. Permanent privation of hearing of either ear.
4. Privation of any member or joint.
5. Destruction or permanent impairing of the power of a member
or joints
6. Permanent disfiguration of the head and face.
7. Fracture or dislocation of a bone or tooth.
8. Any hurt which endangers life or, which causes the victim to
be in the severe bodily pain or, unable, to follow his ordinary
pursuits for a period of 20 days.
Hurt means bodily pain, disease or infirmity
caused to any person (S. 319, IPC)
Punishment for voluntarily causing hurt: Imprisonment up to one
year, or with fine up to one thousand rupees or both (S. 323,
IPC)
Injury is any harm whatever illegally caused to any person in
body, mind, reputation or property (S. 44, IPC)
Punishment for voluntarily causing grievous hurt: Imprisonment
for a term extending to seven years and also fine (S. 325, IPC)
Punishment for voluntarily causing grievous hurt by dangerous
weapons or means: Imprisonment for a term up to 10 years and
also fine (S. 326, IPC)
Dangerous weapons or means: According to Sec.
324 and 326, IPC, dangerous weapons or means include any
instrument for shooting, stabbing or cutting or any instrument,
which used as a weapon of offence, is likely to cause death;
fire or any heated substance; poison or any corrosive substance;
explosive substance or any substance which are harmful to human
body to inhale, to swallow, or to receive in to the blood or by
means of any animal.
Voluntarily causing hurt by dangerous means:
Imprisonment for a term up to 3 years or with fine, or both (S.
324, IPC)
Assault is an offer or threat or attempt to
apply force to body or another in a hostile manner (S. 351, IPC)
Dowry death
Sec. 304 B, I.P.C., where death of the women occurs under
abnormal circumstances within seven years of her marriage.
Punishment: imprisonment not less than 7 years, but may extend
to life imprisonment. Sec. 498-A, IPC “Whoever, being the
husband or relatives of the husband of a woman, subjects such
women to cruelty shall be punished with imprisonment up to 3
years”.
Causes of death from wounds: (1) Immediate or
direct (2) Remote or indirect
(1) Immediate causes: (a) hemorrhage (b) reflex vagal inhibition
(c) shock (d) mechanical injury to a vital organ
(2) Remote causes: (a) infection (b) gangrene or necrosis (c)
crush syndrome (d) neglect of injured person (e) surgical
operation (f) natural disease (g) supervention of disease from a
traumatic lesion (h) thrombosis (i) fat embolism (j) air
embolism.
Causes of fat embolism: (1) Fracture of a long bone (2) an
injury to adipose tissue which forces liquid fat into the
damaged blood vessels, (3) injecting oil into circulation, e.g.,
in criminal abortion (4) occasionally due to natural disease
without trauma as in sickle cell anaemia (5) in case of burns.
FIRE-ARM INJURIES
A firearm is any instrument which discharges a
projectile by the expansive force of the gases produced by
burning of an explosive substance. Forensic ballistics is the
science dealing with the investigation of firearms, ammunition
and the problem arising from their use.
Classification:
(I) Rifled weapons: (1) Rifles: (a) Air and gas-operated rifles
(b) 0.22 rifles (c) Military and sporting rifles (2) Single-shot
target practice pistols (3) Revolvers (4) Automatic pistols (5)
True automatic weapons (machine guns)
(II) Smooth-bored weapons (shotgun) (1) Single barrel (2) Double
barrel (3) Slide action (4) Bolt – action (5) Semi-automatic (6)
Automatic.
Choking is a constricting device at the muzzle
end of shot gun.
Muzzle-loading guns are loaded entirely from muzzle end with the
help of a rod using gunpowder, pieces of cloth, stones, metal
fragments, seeds, bolts, wood, screws, etc. When the entire
barrel from breech to the muzzle end is of same diameter, it is
called cylinder-bore. In choke-bore, the distal 7.5 to 10 cm. of
the barrel is narrow. There are some shotguns which have small
portion of their bore near the muzzle end rifled, which are
called “paradox guns”. A musket is a military shoulder arm. It
has a long fore-stock and usually takes a bayonet at the muzzle.
Shot guns are effective up to 30 metres (30-40 yards). 12 bore
gun means that a sphere of 1/12 pound of lead will exactly fit
the bore of the gun. Markings in projectile occur in Rifle.
Rifle:
A Rifle is a gun with a long barrel, the bore of which is
rifled. A Carbine is a short barrelled rifle or a musket. It is
effective upto 300 metres. The military rifle has a magazine and
bolt action and can kill at a range of 3,000 metres. The
pressure in the firing chamber is about 20 tonnes per square
inch. The bullet as it leaves the barrel rotates at about 3,000
revolutions persecond. Rifles may be single-shot, repeating,
semi-automatic and automatic.
Revolver:
Revolvers are so called because the cartridges are put in
chambers in a metal cylinder, which revolves or rotates before
each shot, to bring the next cartridge opposite the barrel,
ready to be fired. It has a cylindrical magazine situated at the
back of the barrel, which is capable of revolving motion. The
bores vary from 5.6 to 11.4 mm (0.22 to 0.45 inch). The muzzle
velocity is 150 to 180 metres per second. The effective range is
100 metres.
Air rifle and Air pistol
In these compressed air is used to fire lead slugs. Their range
is about 40 metres.
Cartridge: is used in shot gun. Detonator cap is situated at the
base of the rim. Soiling in a gun shot wound is due to lead
content, more marked in distant shot gun wound. Ring of grease
occurs at a distance beyond 2 feet.
Powders
1. Black gun powder—It consists of potassium nitrate 75%,
sulphur 10% and charcoal 15%.
Except— Lead peroxide.
2. Smokeless: it consists of nitrocellulose (single base) or,
nitroglycerine and nitrocellulose (double base) powder which
produces much less flame and smoke and are more completely burnt
than black powder.
Bullets:
The traditional bullet is made of soft metal and has a round
nose. This is known as the round-nose soft bullet, and is
usually used in rifles and revolvers. In revolver and pistol,
the bullet is short and the point usually round or ogival. In
rifle, the bullet is elongated with pointed end. Rifle bullet
weight ranges from 2 to 33 grams. The extent of muscle damage by
a bullet depends primarily on the velocity.
A dumdum bullet, so called because tip is chiselled
out, is one which fragments extensively upon striking and
produces extensive wounds with ragged margins.
Incendiary bullets contain phosphorus. Gun shot
wound is a perforated wound. Glance bullet causes gutter
fracture. In case of shot by bullet, the presence of singeing
(of hair) and charring (of skin) indicates a distance up to 6
inches.
Near wound caused by fire-arms is characterised
by— (i) Tattoing by unburnt powder,
(ii) Presence of grease collar and abrasion collar, (iii)
Presence of carbon monoxide in the blood of the injured tissues
in the track of the bullet.
Bevelling of the skull in bullet injury:
(i) At broad end of the entry point, inner table shows bevelling,
(ii) At exit point of bullet, outer table shows bevelling.
In close shot, the victim is within the range
of the frame i.e. few feets.
The term point blank is used when the range is very close to or
in contact with the surface of the skin. Blasting effect is
usually seen.
The entrance wound is circular, with inverted edges and is
surrounded by blackened and singed area. Abraded collar and
grease or, dirt collar are present in gun shot entrance injury.
Some contusion is present in abraded collar, called contusion
collar. The abrasion collar and contusion collar are proof of an
entrance wound.
Skull—In the skull, the wound of entrance shows
a punched hole in the outer table. Opening in the inner table is
large and shows beveling (sloping). At the point of exit, a
punched-out opening is produced in the inner table and beveled
opening on the outer table. Greater damage is produced by Dumdum
bullet, larger bullet and round bullet.
A bullet traveling in an irregular fashion
instead of traveling nose-on is called a yawning bullet. A
bullet that rotates end-on-end during its motion is called a
tumbling bullet.
Ricochet bullet is one which before striking
the object aimed at, strikes some intervening object first, and
then after ricocheting and rebounding from these, hits the
object.
Tandem bullet or piggyback bullet (one behind
the other).
Souvenir bullets: if a bullet is present for a
long time in the body, there will be no fresh bleeding in the
surrounding area.
THERMAL DEATH
Cold:
Trench foot and Immersion foot are the result of prolonged
exposure to severe cold (5 to 8°C) and dampness. The term
Immersion foot is used for cases with frost bite. In frost bite,
skin becomes hard & black in about 2 weeks. Frost bite occurs
due to exposure to extremes of cold (- 2.5°C).
Heat:
1. Heat cramps (miner's cramps or, fireman's
cramps): They are caused by rapid dehydration of body through
the loss of water and salt in the sweat.
2. Heat hyperpyrexia or Heat stroke: The term
thermic fever or sunstroke is used when there has been direct
exposure to the sun. High temperature, increased humidity, minor
infections, muscular activity, and lack of acclimatisation are
the principal factors of the initiation. Failure of cutaneous
blood flow and sweating leads to breakdown of heat regulating
centre of hypothalamus.
C/F: In some cases, symptom are headache,
giddiness, nausea, vomiting, weakness, staggering gait, mental
confusion, muscle cramps, restlessness and excessive thirst
occur. The skin is dry, hot and flushed with complete absence of
sweating.
3. Heat prostration (heat exhaustion and heat
syncope): Heat prostration is a condition of collapse without
increase in body temperature, which follows exposure to
excessive heat. Main cause of death is vascular collapse and
syncope. Muscle cramp is due to loss of Na+ ion.
BURNS
A burn is an injury which is caused by application of heat or
chemical substances to the external or internal surfaces of the
body.
Burns due to X-rays and radium vary from
redness of the skin to dermatitis, with shedding of hair (epilation)
and pigmentation of surrounding skin. Curling ulcer is seen in
burn patient.
Degrees of Burns
Dupuytren recognised six degrees of burns but they were
merged into three groups by Wilson.
1. Epidermal (First and Second degree Dupuytren):
Usually a blister (vesicle or bulla) is formed which is covered
by white, avascular epidermis, bordered by red, hyperaemic skin.
These burns are very painful. Repair is complete without scar
formation.
2. Dermo-epidermal (Third and Fourth degree
Dupuytren): Whole thickness of skin is destroyed. Skin and
subcutaneous tissue is affected. In Dermo-epidermal, pain and
shock are greater than in first degrees burns (most painful).
3. Deep (Fifth and Sixth degree Dupuytren): In
this, there is gross destruction not only of the skin and
subcutaneous tissue but also of muscles and even bone. Nerve
endings are also destroyed and as such, the burns are relatively
painless.
The extent of the surface
The estimation of the surface area of the body involved is
worked out by the 'rule of nine by Wallace.
9% for head and each upper limb,
9% for front of each lower limb,
9% for back of each lower limb,
9% for front of chest,
9% for back of chest,
9% for front of abdomen,
9% for back of abdomen i.e. 99% of the body.
Remaining 1% for external genitalia.
Involvement of 50% of burn proves fatal, even of first degree.
Causes of death in burns
(i) Primary (neurogenic) shock due to pain,
(ii) More, than half of deaths from burns occur from secondary
shock due to fluid loss from burnt surface.
(iii) Toxaemia.
(iv) Sepsis —> It is late cause of death due to burn.
(v) Acute renal failure,
(vi) Pyemia.
(vii) Suffocation.
Flash burns refer to thermal burns due to
sudden exposure to flame.
Presence of carbon particles in trachea and an
elevated CO saturation together are absolute proof that the
victim was alive when fire occurred. The exudate begins to dry
in 12-24 hrs. from dry brown crust within 2-3 days; pus may form
under slough in 36 to 72 hours; slough falls off in 4 to 6 days.
Pugilistic attitude (boxing, fencing, or
defence attitude)
Pugilistic attitude is due to heat stiffening, seen both in AM
and PM burns. This stiffening is due to coagulation of protein
albumin of the muscles which causes contraction. Heat stiffening
is due to exposure of the body to temperature above 75°C.
Pugilistic attitude is seen in those dying due to burns, and
sudden immersion in boiling liquid. In heat stiffening, body
assumes a posture of generalised flexion.
Scalds:
A scald is an injury which is caused by application of liquid
above 60°C or from stream.
Electrical injuries: The electric mark (Joule
burn) is specific and diagnostic of electrical bum. Joule burn
is both exogenous and endogenous burn. High tension electric
currents may produce multiple burns or punched out lesions due
to arching from conductor to the body without contact, which
present crocodile flash burns. Crocodile flash burn is due to
high voltage flash burn. Most common cause of death in
electrocution is ventricular fibrillation.
Death may occur from paralysis of medullary (respiratory centre)
or from ventricular fibrillation and cardiac arrest.
Lightning stroke
A flash of lightning is due to an electrical discharge from a
cloud to the earth. The burns may be Arborescent or Filigree
burns (Lichtenberg's flowers). Arborescent
burns are superficial, irregular, thin, resembling the branches
of a tree.
STARVATION
In acute starvation, there is a feeling of hunger for the first
30 to 48 hours, followed by pain in the epigastrium which is
relieved by pressure. After 4 to 5 days of starvation, general
emaciation and absorption of the subcutaneous fat begins to
occur. The tongue is coated and dirty and thirst is intolerable.
Usually the loss of 40% of body weight is fatal. The intellect
remains clear till death. Death occurs from exhaustion,
circulatory failure due to brown atrophy of the heart, or
intercurrent infection. Ammonia in brain is detoxified in to
Glutamine. During starvation the substance which heart uses as
energy source is acetoacetate. If starvation exceeds 7 days then
the major nutritional supply of brain comes from ketone-bodies.
Absorption of Vit. B12 occurs in ileum.
The changes in starvation seen are
Hypoglycemia, Hyper-triglyceremia and Ketoacidosis.
(except—Hyper cholesterolemia). Iron absorption is decreased by
phosphates, phytates, oxalates (except—ascorbic acid).
Fatal period: If both water and food are
completely stopped, death occurs in 10 to 12 days.
If food alone is stopped, death occurs in 6-8 weeks or even.
On P-M examination, the heart is small (from brown atrophy), and
chambers are empty. The gall bladder is distended with bile.
MECHANICAL ASPHYXIA
Asphyxial deaths:
1. Suffocation—Mechanical obstruction to airways other than by
hanging, strangulation and throttling. MC cause is inhalation of
irritant gas.
2. Smothering—Closing the external respiratory orifice by hand
or by other means.
3. Gagging—Closing mouth and nose with cloth etc. and tying
around head or stuffing it into mouth.
Hanging:
Hanging is that form of asphyxia which is caused suspension of
the body by a ligature, which encircles the neck, the
constricting force being the weight of the body.
In partial hanging, the bodies are partially
suspended; the weight of the head (5-6 kg) acts as the
constricting force.
Typical hanging: In typical hanging, the
ligature runs from the midline above the thyroid cartilage
symmetrically upward on both sides of neck to the occipital
region.
Causes of Death:
1. Asphyxia: A tension of 15 kg on ligature blocks the trachea.
2. Venous congestion: The jugular vein is closed by a tension in
the rope of 2 kg.
3. Combined asphyxia and venous congestion: this is the
commonest cause.
4. Cerebral anemia: A tension of 4 to 5 kg on ligature blocks
carotid arteries, and 20 kg
blocks the vertebral arteries.
5. Reflex vagal inhibition from pressure on the vagal sheath or
carotid bodies.
6. Fracture or dislocation of the cervical vertebrae.
Fatal period: The usual period is 3 to 5 minutes.
Post-mortem appearance:
The ligature mark in the neck is the most important and specific
sign of death from hanging. The ligature mark is situated above
the level of thyroid cartilage between the larynx and the chin
in 80 percent cases. In partial hanging, the feet touch the
ground. Le facie sympathique (it the ligature knot presses on
cervical sympathetic, the eye on the same side may remain open
and its pupils dilated) is seen in ante-mortem hanging. The eyes
are frequently protruded and firmer and the conjunc¬tiva
congested, the pupils are usually dilated. Saliva may be found
dribbling from the angle of the mouth (due to stimulation of the
salivary glands by the ligature). Seminal emission is common. In
rare cases (5 to 10%), the intima of the carotid arteries show
transverse split. Hyoid bone is fractured in 15 to 20% cases.
Are seen in persons above 40 years; involves the great horn at
junction of the inner two-thirds and outer one-third.
Judicial hanging: Justifiable homicide is
judicial hanging and death of a suspected criminal while
executing arrest. Legal death sentence is carried out by hanging
the criminal. The cause of death in judicial hanging is fracture
dislocation at the level of second and third or third and fourth
cervical vertebra.
Lynching is a type of homicidal death by hanging by large group
of people.
Strangulation:
Strangulation is that form of asphyxia, which is caused from
constriction of the neck by a ligature without suspending the
body.
It is of two types: (1) Strangulation by ligature, and (2)
manual strangulation or throttling.
Cause of death: Death may be due to (1) asphyxia, (2) cerebral
anoxia or venous congestion (3) combined asphyxia and venous
congestion, and (5) rarely fracture – dislocation of cervical
vertebrae.
The mark in strangulation completely encircles the neck
transversely. Classical signs of asphyxia are seen in about 50%
of victims.
Doing a post-mortem on a suspected case of strangulation in situ
examination of neck structures is done after opening the skull
and the chest, to allow blood to drain from the neck blood
vessels. Most important sign of strangulation is ligature mark.
Hyoid bone may be fractured in older persons in 10 to 15% cases.
The common methods of homicidal strangulation
are: (1) Strangulation by ligature, (2) Throttling, (3) Bansdola,
(4) Garrotting, and (5) Mugging
Mugging is homicidal strangulation caused by
holding the neck of the victim in the bend of the elbow.
Bansidola is a type of homicidal strangulation
caused with sticks.
Garroting is type of homicidal strangulation
caused by twisting a lever like torniquet.
(Signs of Strangulation) Signs of Asphyxia:
Intense maximum congestion and deep cyanosis of the head and
neck is seen in strangulation. The eyes are wide open and pupils
dilated. The tongue is swollen and protruded. Petechial
hemorrhages are common in to the skin of the eyelids, face,
forehead, behind the ears and scalp. Blood stained froth may
escape from the mouth and nostrils and there may be bleeding
from nose and ears. There is severe congestion and hemorrhage
into the subcutaneous tissue in and above the area compressed.
The intima of the carotid artery are not usually damaged. Injury
of hyoid bone is not common in strangulation because the level
of constriction is below the bone. Fracture of the thyroid
cartilage is more common. Pulmonary oedema may be present.
Throttling
Throttling is manual strangulation. Fracture of the hyoid bone
in 30-50% cases. Fracture of the thyroid cartilage and hyoid
bone are usually found in above 40 years. Hyoid bone fracture
does not occur in choking. It is always homicidal.
Hyoid bone fractures can be classified in to
three groups: (1) Inward compression fractures, (2) Antero-posterior
compression fractures, (3) Avulsion fractures.
Inward compression fracture is seen in
throttling, where the main force is an inward compression acting
on the hyoid bone. Antero-posterior compression fractures is
seen in case of hanging, the hyoid bone is forced directly
backwards, due to which the divergence of greater horns is
increased which may fracture with outward displacement of the
posterior small fragment. Avulsion fractures occur due to
muscular over-activity, without there being direct injury to the
hyoid bone. They are also called “tug” or “traction” fractures.
Suffocation:
Suffocation is a general term to indicate that form of asphyxia,
which is caused by deprivation of oxygen, either due to lack of
oxygen in the environment or from obstruction of the
air-passages.
Smothering:
Smothering is a form of asphyxia which is caused by closing the
external respiratory orifices either by the hand or by any other
means, or blocking up the cavities of the nose and mouth by the
introduction of a foreign substance, such as mud, paper, cloth,
etc.
Gagging: is a form of asphyxia which results
from forcing a cloth into the mouth, or the closure of mouth and
nose by a cloth or similar material, which is tied around the
neck.
Overlaying:It is a type of smothering.
Overlaying or Compression suffocation results due to compression
of the chest, so as to prevent breathing. Overlaying by mother
is common in European countries. The usual findings are those of
asphyxia.
Burking:It is a method of homicidal smothering
and traumatic asphyxia.
Homicidal choking
In choking, there is obstruction within airways. It is very rare
and is practicable only when the victim is an infant or
suffering from disability or, disease or, under the influence of
alcohol.
Cafe Coronary:
This is a condition in which a healthy but grossly intoxicated
person, who begins a meal, suddenly turns blue, coughs
violently, then collapse and dies due to asphyxia. Death appears
to be due to sudden heart attack. A blow on the back or on the
sternum may cause coughing and expel the foreign body.
Traumatic Asphyxia
Traumatic asphyxia results from respiratory arrest due to
mechanical fixation of the chest, so that the normal movement of
the chest wall is prevented. Common cause is crushing by falls
of earth in a coal mine or during tunneling or in a building
collapse. An intense cyanosis of deep purple or purple-red
colour of the head, neck and upper chest, above the level of
compression is the prominent feature.
Sexual Asphyxia
Partial asphyxia causes cerebral disturbance with feeling of
sexual gratification. These cases are associated with some form
of abnormal sexual behavior, usually masochism and transvestism.
Drowning
Drowning is a form of asphyxia due to aspiration of fluid into
air-passages, caused by submersion in water or other fluid.
Commonest type of drowning is accidental.
In immersion syndrome, death occurs by vagal
inhibition and cardiac arrest. Cold water drowning causes
immersion syndrome. In secondary drowning, death occurs in half
an hour to two days after resuscitation due to secondary changes
in lungs. In secondary drowning, sign of asphyxia absent. Victim
of drowning in a state of suspended animation can be revived in
as long as 10-20 minutes. The extent and direction of the
exchange through the alveolar lining depends on the difference
between osmotic pressure of the blood and the water.
The drowning in fresh water, water passes
rapidly from the lungs to the blood, leading to hemolysis and
dilution of the blood with an abrupt increase in blood volume.
Fresh water alters or denatures the protective surfactant which
lines the alveolar wall. When water is inhaled, vagal reflexes
cause increased peripheral airway resistance with pulmonary vaso-constriction,
development of pulmonary hypertension, decreased lung compliance
and fall of ventilation perfusion ratios. The concentration of
serum electrolytes (sodium and calcium) decreases, serum
potassium increases. The heart is subjected to hypoxia,
overfilling, sodium deficit and potassium excess. Cardiac
arrhythmias leading to ventricular tachycardia and fibrillation
occur, probably due to hypoxia and hemodilution. Hemodilution
leads to hemolysis, haemoglobinemia, and haemoglobinuria, marked
hyponatraemia and hyperkalaemia. The potassium and chloride
content of the left side of the heart is decreased.
Drowning in Sea water — Due to high salinity of
sea water (usually over 3% NaCI), water is drawn from the blood
into the lung tissue, and produces severe pulmonary oedema and
hypernatraemia and increase in magnesium ion. This causes
haemoconcentration. In sea water drowning, chloride content of
the left side of the heart is higher (as is Mg concentration).
Causes of Death: (1) Asphyxia, (2) Ventricular
fibrillation (3) Laryngeal spasm (4) Vagal inhibition (5)
Exhaustion (6) Injuries.
Fatal period: Death usually occurs in 4 to 8
minutes of complete submersion. Hyper-ventilation before
drowning can cause death.
Post-mortem appearance:
Gettler's test is used in drowning. Gettler's test is based on
the biochemical changes in blood in a case of typical drowning.
Gettler devised, a test to estimate the chloride content of
blood from both sides of the heart. A difference of 25 percent
in chioride content is considered significant.
— Limitations of Gettler's test:
1. There is progressive loss of chloride from blood after death.
To be maximal value therefore the test has to be made within a
reasonably short time after death.
2. Has no value in atypical drowning.
3. Has no value in congenital cardiac defects such as shunts &
patent foramen ovale where admixture of blood freely occurs
between two sides of the heart.
4. Has no value if drowning medium and blood contain the same
amount of chloride.
In homicidal drowning, multiple injuries may or
may not be present. Chloride estimation is not of any help after
12 hours. Absence of foam in drowning can be found in death due
to laryngeal spasm and immersion syndrome.
Regurgitation of gastric contents into the
larynx and trachea in cases of drowning is due to vomit reflex
due to medullary hypoxia. Cutis-anserina is seen in drowning.
Cutis-anserina proves that molecular death present at the time
of drowning. Wrinkling of limbs indicate that body was in water.
Most important evidence for drowning is water in lungs and
stomach. In drowning in unconscious state, there is no
ballooning of lungs. Water can be absent in stomach in cases of
drowning due to sudden death due to vagal inhibition. Presence
of water in stomach in case of drowning is found in 70% cases.
Deep inspiration above the water level and air pockets in
clothing may cause early floatation of the body. Post-mortem
staining is usually found on the face, the upper part of chest,
hands, lower arms, and feet. The colour of PM stain is
light-pink due to oxygenation, but in some cases it is dusky and
cyanotic. Petechial hemorrhages are seen in subpleural tissues
of lungs.
A fine white leathery froth is seen at mouth
and nostrils, most characteristic external sign of drowning. The
inhalation of water irritates the mucous membrane of air
passages; mucous gland produces large quantity of tenacious
mucous. Froth without mucous is seen in death due to
strangulation, acute pulmonary oedema, electrical shock, during
an epileptic fit, in opium poisoning and putrefaction.
Cutis anserina (goose skin or. goose flesh) in
which the skin has granular and puckered appearance may be seen.
Weeds, grass, sticks, leaves etc. floating in water may be
firmly grasped in the hands due to cadaveric spasm. It indicates
antemortem drowning. Bleaching of the cuticle becomes quite
evident after 12 hours of immersion. The skin becomes sodden,
thickened, wrinkled and white in colour, known as
“Washer-women's” hands, within 12-18 hours.
Wet drowning is due to entry of water into
lungs. In wet drowning, lungs are overdistended and alveolar
walls are torn. On section, an oedematous condition is seen.
This has been described as “emphysema aquosum”.
In dry drowning, death occurs due to laryngeal
spasm. There is no water entry into lungs. The alveolar walls
may rupture due to increased pressure during forced expiration
and produce sub-pleural haemorrhage known as 'Paltauf's
haemorrhages'. They are shining, pale bluish – red, and may be
minute or 3 – 5 cm in diameter. Usually present in the lower
lobes.
The stomach contains water in 70% of cases. The small intestine
may contain water in 20% cases. This sign is regarded as
positive evidence of death by drowning as it depends on
peristaltic movement which is a vital act. Haemorrhages are
found in middle ear and temporal bone. Temporal bone
haemorrhages are also seen in deaths due to hanging, head injury
and CO poisoning.
Diatoms:Presence of diatoms in tissue is a sign
of ante-mortem drowning. Diatoms are microscopic, unicellular,
silica coated algae. The bone marrow of long bones such as
femur, tibia, and humerus or sternum is examined for diatoms.
Diatoms are examined by acid digestion technique.
Diagnosis
The reliable signs of drowning at autopsy are:
1. Antemortem drowning is best demonstrated by fine, white froth
at the mouth and nose.
2. The presence of weeds, stones etc. grasped in hand, shows
ante-mortem drowning.
3. The presence of fine froth at lungs and air passages.
4. The voluminous water-loaded lungs.
5. The presence of water in stomach and intestine.
6. Finding of diatoms in the tissues.
The above signs are not found if death occurs due to vagal-inhibition.
In dry – drowning, the PM appearances are those of asphyxia.
The body floats in about 12 to 18 hours in summer and 18 to 36
hours in winter in India.
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