• Asphyxia – Lack of • Causes of asphyxia.
oxygen.?? • 1. Absence or reduction in
oxygen tension in external
• The purpose of respiration atmosphere such as
is transfer of atmospheric reduced barometric
oxygen to the peripheral pressure or replacement of
tissue. Any thing oxygen by inert gases such
interfering this can lead to as nitrogen, CO2.
asphyxia. • 2. Obstruction of external
respiratory orifices as in
smothering or gagging.
• Block of internal passages
at pharyngeal, laryngeal,
tracheal, bronchial level.
• Reduction in cardiac
• Restriction of movement function leading to
of the thorax preventing impairment of circulation
the inspiration of air of oxygenated blood.
through the res passage in called stagnant hypoxia.
traumatic asphyxia or
paralysis due to brain stem
or spinal cord damage or • Reduced ability of the
due to curare like drugs. blood to transport oxygen
as in anemia, co poisoning
where O2 binding power
• Diseases of drugs that of Hb is impaired.
prevent gas exchange such
as pneumonia, pul
oedema, ARDS, • Inability of the peripheral
pulmonary fibrosis etc. tissues to utilize oxygen in
blood such as in CN
oxydase enzyme system
• Asphyxia caused by • Gagging is a form of
mechanical causes. smothering where the
• Definition of terms: fabric or adhesive tape
a) Suffocation- death occlude the mouth to
from deprivation of O2 prevent speaking and
either from lack of O2 in shouting, the nasal
the breathable passage is patent, but later
environment or from the blockage by mucus or
obstruction of the external oedema leads to death.
air passages. • Choking – blockage of
• Smothering- obstruction the upper airways by
of the external air foreign body.
passages by hand or soft • Throttling- strangulation
fabric. of neck by hand(manual
• Strangulation – the hand • 4. Oedema
or the ligature as a means • Cyanosis occur due to lack
of applying external of oxygen and
pressure of neck. oxygenated Hb. Seen
• Garroting – using under the nails, lips, ears,
flexible rod to compress tongue etc.
the neck. • Oedema & congestion:
• Mugging- crooked arm is anoxia-defect in Na, K
used to compress the pump in capillary
neck(Arm lock). endothelium-increase Na
in capillary endothelial
endothelial cells- increase
• Signs of classical asphyxia capillary permeability-
• 1. Cyanosis extravasation of fluid and
• 2. Congestion oedema.
• 3. Petechial haemorrhages
• Petechial hae’rhage They • Petechia not seen in
are small pinpoint
collections of blood lying parietal pleura and
in the skin sclera or peritoneum if occur it
conjunctiva, pleura and is due to some
pericardium. 0.1 mm to 2 bleeding disorders not
mm in size if bigger it is
called ecchymosis. due to asphyxia.
Petechia lying in the
visceral pleura are called
• Petechia: rise venous
and rupture of thin walled
• Reduction of O2 • Signs of asphyxia are
concentration in respired minimal.
• Occur in decompression in • Mechanism of death is
cabin failure in aircraft in due to over
high attitudes, physical stimulation of the
replacements of O2 by
other gases, in fires, inside chemo receptors
unused tanks and ships. leading to vaso vagal
• Mechanically obstructing cardiac arrest.
the external air passages is
• Mechanically by Contusion, abrasion or
obstructing the external air laceration of lips, around
passages by hands, cloths, the mouth and cheeks may
pillow etc. in industrial be seen.
accident sands, mud etc., • Asphyxial signs may be
collapsing of mine tips. prominent.
• Infant, children, elderly, • Overlaying of infants:
women, debilitated when the baby was
people are more prone to sleeping with the mother,
be suffocated and killed. mother could turn over on
Pm: signs of resistant. to the baby and baby
Signs of pressure around could die of smothering.
mouth and nose in
Plastic bag suffocation
• Commonly suicidal, could • Smothering occur by a pad
be accidental or or gag is fixed over the
homicidal. face,as happen in robbery
• Polythene or other plastics with violence. Caretaker
are put over the head. or night watchmen may be
• Could be tied up and silenced by
accidental(masochistic tying a scarf or other
practices), suicidal or cloths around his face. At
homicidal. first it admits air but when
it is soaked with saliva it
• Pm signs are negative is impervious and leads to
except the bag around the asphyxia.
head and face.
Plastic bag suffocation
Sexual asphyxia (accidental) - naked body, opposite sex
• If adhesive tape applied
to the mouth or cloths
packed into the mouth
at the beginning the
nasal airway is patent
but with time the mucus
obstructing the nasal
passage and cause
Autopsy signs of suffocation
• Signs of pressure on the • Drunkenness, epilepsy,
face such as bruising and drug overdose, coma from
abrasion around the natural diseases etc.
mouth, nose, chin.
• Congestion and cyanosis.
• Pressure of the lips on the Fabrics tied around face or
tooth leads to buccal inside the mouth.
surface to be bruised, Mucus obstructing the nasal
abraded or lacerated. passage.
• Accidentally suffocation
could occur in
lying face down on a
surface such as in:-
Marbling – bluish purple lines appear over trunk spread
to neck limbs due to decomposition of blood in veins
“early sign of putrefaction”
Choking/cafe coronary syndrome
• Blockage of the internal • Foot bolus usually in
airways from pharynx up children, mentally retarded,
to the trachea. incapacitated people due to
alcohol, drugs, illnesses or
• Death due to hypoxia from due to aging.
occlusion of the air way or
• Accidentally during ENT
neurogenic cardiac arrest. surgeries blood obstructing
• Cyanosis, petechiae, the airway.
congestion may be • Acute obstructive lesions of
present. glottis and larynx such as
• Usually accidental rarely acute hypersensitivity
suicidal. reactions, acute infective
conditions as diphtheria,
• Constriction of the neck • partial hanging or
by ligature, where the incomplete hanging:-
constricting force is whole part of the body is
or part of the body. supported, suspended
• Complete hanging :- from lower level such as
whole weight of the body door handle, window, etc.
is suspended by ligature, body will be in sitting,
the are above the ground crouching position and
and the body is not asphyxial signs will be
touching the ground or prominent as the force is
other structure. only enough to obstruct
• the veins in the neck.
• Typical hanging:- knot is at • Accidental – Rare occur in
the back of the neck at mid children caught in cloth
position. This causes equal lines, swings etc. adult in
pressure on each side of masochist activities.
• Homicidal – very
• Atypical hanging:- knot is uncommon. Killing and
in a position other than at the subsequently hanging the
back of the neck at mid dead body to look like
position. Either side of the suicide occur. Hanging a
neck, front of the neck etc. healthy adult is difficult but
Causes more pressure on one after incapacitated by drink,
side of the neck than on the drugs, head injuries or feebly
other side. old persons or children could
• Circumstances:- Suicidal – occur.
Very common • Judicial hanging:-execution
Atypical hanging with protruded
Medico legal investigation
• History • If the body was brought
• Scene visit down before the examination
circumstances at which the
• Transport of body to
body was found, complete or
mortuary. partial hanging, knot where
• Post mortem examination. type of knot any attempts to
• History: from relatives, remove the knot by cutting
Police, people assembled etc. any items removed from
at the scene. Include:- the scene before
family history married or hen the person was last seen
not, occupation, spouse, alive, time of last meal and
habits, psychiatric illness, type of food etc.
past attempts, depressed,
any reason for suicide, any
• Photo, sketch and • disturbance of dust at the
description of the scene. beam, type of knot at the
Doors are locked or knot, beam, Is there any support
from in or out, where is the
key, any possibilities entries to tie the ligature high up
through other ways such as such as chair or any other
roof, windows, lights are on, platform, measurements of
if living alone news papers ground to feet, ground to
and milk collected unto beam, height of the
when, calendar managed platform etc. if the time of
unto when, any notes left,
any food left, any evidence death is in doubt rectal
of struggle, foot print, temperature at ½ hourly
cigarette used,butts, alcohol interval( if no suspicion of
bottle, glasses etc. any sexual Abuse), rigor
adjacent structures which mortis, hypostasis and
could have caused injuries collect trace materials.
during the process of
hanging. Any blood stains.
Ligature and ligature mark
• The rope cut at middle • Level of the mark as
preserving the knot and above the thyroid cartilage
hands are covered with or below, horizontal,
envelops and transported rising to a side, oblique.
to mortuary. Width, depth, any crossing
• Examination of ligature of the marks, any vital
type ligature, width, signs, any other associated
twisted or not, single or injuries such as cuts while
double, how many rounds attempts to remove the
around the neck, type of ligature by relatives etc,
knot(slip knot, fixed knot nail marks, finger tip
etc), place of knot after marks etc. ligature mark
that cut at the middle will be parchment
preserving the knot. appearance.
• More than the ligature and • convulsion and could cause
ligature mark. Increased abrasion, contusion even
salivation, congestion, laceration. Self inflicted
oedema, cyanosis, petechia injuries. Caused by rats, ants.
may be intense above the In the process of removing
ligature. Eyes bulged out and the ligature from the neck by
reddish in colour, face relatives. Any nail marks at
swollen, tongue protrude out, the neck could be from the
froth may be at nose and deceased while trying to
mouth, hypostasis will be at remove or untie at the time
lower limbs, scrotum, penis of hanging or caused by
and hands. Seminal another person note the
discharge may be present. direction of the curvature.
Any injuries caused by:In
the process of hanging the
body struck the adjacent
structures due to
• Special neck dissection:- • Fracture of hyoid is rare in
first the skull is opened cases of hanging. Fracture
and blood from the neck is could occur in elderly
removed. Neck is people where the bone is
calcified and due to pull of
dissected layer by layer the thyroid ligament,
inspecting skin, platysma, greater horn is the
strap muscles, commonest site of fracture
sternomastoid, thyroid • when there is violent drop
gland, nerves, vessels, and in judicial hanging
laryngeal cartilages, cervical spine fracture/
bones, paravertibral and dislocation occur.
vertebral regions. • Internally froth will be at
Specially look for the respiratory passage,
haemorrhages, contusions, submucosal haemorrhages
fractures etc. could be in epiglottis,
Mechanism of death
• Vagal stimulation at the • Compression of the
carotid bodies and jugular veins leads to
inhibition of heart. congestion and stagnant
hypoxia. Commonly in
• Asphyxia following partial hanging
compression of the airway
by floor of the mouth • Fracture dislocation of the
pressed against the upper cervical vertebrae
pharynx. and cervical cord damage
• Compression of the occurs when the drop is
carotids and jugular veins long or in Judicial
leads to cerebral hanging.
• Manual strangulation • Manual strangulation
(throttling). • Death caused by
compression of the neck
• Strangulation by using hands. Always
ligature. homicidal. Marks caused
by hands seen on the neck
• Mugging(arm lock), such as finger nail marks,
foot pressure on the finger tip bruises. The
neck, using sticks etc. distribution of the nails
marks will vary depend on
the position of the
assailant and victims at the
time of the incidents,
whether there is struggle.
• There may be injuries due • All the asphyxial signs
to counter pressure at the could be seen. Bruise
shoulder, back. There
could be nail marks and haemorrhagwes
around the wrist, defense involving the strap
injuries, in female could muscle could be seen.
be associated with rape.
• The tongue may be partly • Death could be due to
out or bitten. Submucosal vagal inhibition or
hae’age in the larynx, asphyxia.
fracture of the greater horn
of the hyoid bone. Rarely
the ribs are fractures due
to the assailant applying
knee pressure on the chest.
• Constricting force is • The depth is usually
produced by Appling uniform around, if soft
ligature around the neck ligature is used marks may
by an assailant. be faint or even could be
absent. The ligature may
• Almost always homicidal be more than one round
rarely accidental cord around the neck or some
round the neck, children time may not go
caught in cloth lines and completely around the
rarely suicidal neck. Haemorrhage zone
strangulation. may be seen above and
below the ligature mark.
• Ligature mark is more The asphyxial signs will
horizontal and lower level be marked above the
than in hanging. Across or ligature as face, scalp,
below thyroid cartilage. conjunctive etc.
• Internally: Bruising of • Defense injuries may be
neck muscles, # of seen. Injuries could seen
superior horn of thyroid, around the wrist.
cricoids, tracheal rings if
higher level fracture of • Injuries could be inflicted
greater horn of the hyoid. on the assailant.
Engorgement of the root • Finger nail clipping might
of the tongue, oropharynx, contain the assailant
signs of asphyxia such as tissues (for DNA).
haemorrhages, cyanosis • In female sexual abuse
well seen. should be excluded.