Asphyxia

Asphyxia:
• ( The word Asphyxia comes from the Greek word,
A + sphygmos(sphyxia). A means absence,
Sphygmos( Sphyxia) means pulse, so asphyxia
means no pulse, absence of pulse,or
pulselessness)
Definition:
Supply of oxygen to the blood and tissues has
been reduced appreciably below the normal
working level by any interference with
respiration.

Violent asphyxia:
• Prevention of exchange of air
between the atmosphere & the lungs by
violent mechanical means is called violent
asphyxia.

Classification of asphyxia
• Pathological asphyxia:
• eg: Respiratory: Pneumonia.COPD,
Bronchial asthma, plural effusion etc.
• CVS: Myocardial anoxia, anaemic
heart failure etc.
• Mechanical asphyxia.
• eg:Violent asphyxial death: Hanging,
strangulation, Drowning etc.
• Toxic asphyxia:
• eg: OPC, Alcohol, opium etc.

• There are different types of violent asphyxia:
• Compression asphyxia:
• Hanging.
• Strangulation.
• Obstruction asphyxia:
• Suffocation
• Smothering
• Choking
• Drowning.
• Others:
• Crush (Traumatic) asphyxia.
• Postural/positional asphyxia.

• Cardinal features of violent asphyxial death:
• a) Cyanosis.
• b) Petechial haemorrhage/ Tardieu’s spot.
• c) Congestion.

Cyanosis

• Cyanosis:
• The term cyanosis means blueness of the
skin and its cause is excessive amount of
deoxygenated haemoglobin in the skin,
blood vessel specially in the capillaries.
• This deoxygenated haemoglobin has an
intense dark blue purple colour that is
transmitted through the skin.
•

• Petechial haemorrhages (Petechiae):
• ( Tardieu’s spot)
• These are small pinpoint collections of blood
that vary in size from about a tenth of a
millimetre to about 2 millimetres; larger than
this, they are called “ecchymoses”. They are
usually said to be caused by rupture of
capillaries (but are actually thought to be due to
rupture of small venules) due to an acute rise in
venous pressure. They occur most commonly in
areas where the vessels are least supported –
in this case the face – especially the eyelids,
the conjunctivae and sclera.

Petechial haemorrhage

• They are most commonly seen in asphyxial
death related to compression of the neck or
chest leading to increased venous pressure in
the head.
• History of Tardieu’s spot:
• Auguste Ambroise Tardieu (10 April 1818 –
12 January 1879) was a French medical doctor
and the pre-eminent forensic medical scientist
of the mid-19th century.

• Tardieu's specialties were forensic medicine and
toxicology. Over his 23-year career, Tardieu participated
as a forensic expert in 5,238 cases, including many
famous and notorious historical crimes. Using his cases as
a statistical base, Tardieu wrote over a dozen volumes of
forensic analysis, covering such diverse areas as abortion,
drowning, hanging, insanity, homosexality, poisoning,
suffocation, syphilis, and tattoos.
• In recognition of his first clinical descriptions of battered
children, battered child syndrome is also known as
Tardieu's syndrome.
• Tardieu's ecchymoses, subpleural spots of ecchymosis
that follow the death of a newborn child by strangulation or
suffocation, were first described by Tardieu in 1859, and
were so named in his honor.

Auguste Ambroise Tardieu (10 April 1818 –
12 January 1879

• Congestion:
• The increase in venous pressure associated
with asphyxia (due to obstructed venous return
and/or impaired respiratory movements) causes
generalized organ congestion +/- oedema. The
blood is very dark (cyanosed). There is usually
dilatation and engorgement of the right side of
the heart. The lungs are congested and
oedematous and there may be petechiae in
serous membranes (pleurae, pericardium),
meninges etc.

Congestion

Post- mortem findings of asphyxial death
• External findings;
• 1.Face is pale, edematous and cyanosed.
• 2. Protrusion of eyeball and tongue may be found.
• 3. Dribbling of saliva or blood stained froth may be
found in the mouth.
• 4.Cyanosis is well marked in face including
lips,eyelids, nail bed.
• 5.Petechial haemorrhage on the skin and mucosa of
face, conjunctiva etc.

Post-mortem findings

• 6.Post-mortem hypostasis is well marked than
any other death.
• 7. Signs of involuntary discharge eg: urination,
defaecation, ejaculation.
• Internal findings:
• 1.Blood is dark in colour and more fluidity due
to increased CO2 and fibrinolysis respectively.
• 2. Congestion of internal organ except spleen
which is anaemic.
• 3.The right heart and great veins are engorged
with blood.

• 4.Petechial haemorrhage/ Tardieu’s spot on the
serosal surface, eg: epicardium, visceral pleura,
intestinal mucosa etc.
• The “classical” features of asphyxia at autopsy
may not be seen in some deaths:
• 1. Vagal inhibition.
• 2. Highly decomposed body.

Mechanism of vagal inhibition
• Mechanism of vagal inhibition:
• Compression or stimulation of the carotid sinus
of carotid artery causes impulses to pass via
Herring’s nerve to the afferent fibers of the 9th
cranial nerve. This nerve in turn link in the
brainstem to the nucleus of the 10th cranial
nerve then parasympathetic efferent impulses
than descent to the heart through the branch of
vagus nerve. Stimulation of these fibers causes
profound bradycardia.as a result cardiac arrest.