Asphyxia
(Except neck and lungs)
Dr. Muditha Vidanapathirana
MBBS, DLM, MD, MA, MFFLM (UK)
Senior Lecturer
Department of Forensic Medicine,
Faculty of Medicine, Galle.
Asphyxia -Definition
Mechanically induced
cerebral hypoxia with
signs of increased venous
pressure.
Asphyxial signs are due to- raised
venous pressure.
Appear in 15-30 seconds
Asphyxial signs are,
Petechiae,
Congestion
Oedema,
Bluish discoloration
Overt haemorrhages.
Raised venous pressure is due to
Neck compression• venous obstruction
• arterial obstruction
• Heart failure due to RSCD (Remotely Stimulated Cardiac
Dysfunction)
Air way or Chest compression• If struggle to breath – increased intra thoracic pressuredecreased venous return- raised venous pressureasphyxial features
• If no struggle to breath- no asphyxial features.
Petechiae in eye lids
Petechiae on gums
Petechiae behind ears
Petechiae on visceral pleura – usually
appear in fissures
Mechanisms of death in asphyxia
Suffocation (reduction of oxygen in the environment),
Smothering (obstruction of both nose and mouth externally),
Gagging (obstruction of only the mouth externally or internally),
Choking (obstruction of air passages internally from larynx to bifurcation of trachea),
Strangulation (obstruction of the blood vessels and air passages of the neck by external pressure),
Traumatic asphyxia (cessation of respiration by external pressure),
Traumatic asphyxia and smothering together– Eg.
• overlaying a child during sleep by mother
• Burking – killing a person by smothering while sitting on the trunk).
1. Suffocation
Death due to reduction
of oxygen concentration
in the environment.
Circumstances
1. Accidental• during solvent abuse with bag
• sexual asphyxias with plastic bags.
• Saliva seal in prone sleeping
2. Suicidal• Plastic bag suffocation
• method of euthanasia (alcohol+ sleeping tablets+ bag die in
15- 20 minutes)
3. Homicidal
• Plastic bags over child’s head.
Accidental suffocation
Circumstances
a. Adults –
• Saliva seal in prone sleeping- Alcoholics or epileptics• sexual asphyxias with plastic bags.
b. older children –
• plastic bag suffocation with solvent abuse.
c. Infants• nose and mouth can cover with heavy clothes.
• nose and mouth can cover with mattress of the cot
when the mattress is smaller than the cot.
PM features• Usually no injuries or asphyxial signs.
• Investigations- BAC (Blood alcohol concentration)
Suicidal suffocation
circumstances
1. Plastic bag suffocation
2. Use as a method of euthanasia
(alcohol+ sleeping tablets+ bag
die in 15- 20 minutes)
Mechanism of death in suffocation
asphyxia due to
suffocation
Preliminary investigations
a.
Photographs,
b.
Swabs,
C. X-ray neck
Postmortem technique Prinsloo-Gordon technique
Describe the ligature, if present and remove sparing the knot.
Remove the brain & allow blood to drain out from cranial and chest ends.
Then dissection of the neck by a V- dissection in a blood less field,
Layer by layer in-situ
look for neck injuries
Facial dissection is done – look for facial injuries in smothering.
Musculo-skeletal dissection - look for bodily injuries .
Postmortem features
Usually no asphyxial features and no injuries.
Only the bag present.
+/- Knot .
No PM findings except the bag.
if the plastic bag is removed before the PM- cannot diagnose suffocation at the PM
Little amount of water can be found inside the bag. But it does not indicate that he was alive at
the time of the incident as in both AM or PM application of the bag can result the same finding
2. SMOTHERING
Definition- Death due to obstruction of both nose and mouth
externally.
• Eg.
smothering with Pillow,
smothering with hand
Smothering by pressing the head on a surface
Circumstances – only homicidal
A. Unintentional homicidal smothering(gagging) – only mouth is obstructed
B. Deliberate homicidal smothering• both mouth and nose are obstructed.
A. Gagging (Unintentional homicidal smothering)
Definition- only the
mouth is obstructed
externally or
internally.
If obstructed externally (external gagging)
eg. obstruction of mouth with
tapes or cloths• air can enter via nose.
• But later, due to secretion of mucous
and oedema of tissues, cause
obstruction of the nasal passage too.
Victims are usually elderly people
who cannot struggle or remove it.
This method is usually used by
burglars
If obstructed Internally (internal gagging)
eg. Cloth or paper is stuffed in
mouth- later the cloth or paper
can be soaked with saliva and
slide down to pharynx and
obstruct the air way completely.
Generally the aim is to
prevent shouting.
B. Deliberate homicidal smotheringboth nose and mouth are obstructed
taping or cloth applied over both nose and mouth.
It is extremely difficult to smother a healthy adult.
So the target group is ‘who cannot resist’. Eg.
• i. Children – DD of SIDS- little or no signs, usually circum-oral
pallor. But no fingertip bruises or nails abrasions. Eg.
Munchausen syndrome by proxy.
• ii. Old people,
• iii. Incapacitated (drugged/ drunk/ restrained/ debilitated)
Methods
Pillow-smothering
• usually no injuries and no asphyxial signs.
• DD. SIDS, homicidal smothering, or accidental overlaying.
Hand-smothering• a. If very old or very young children- no injuries or asphyxial signs.
• b. if healthy adults - due to struggling, injuries (nail abrasions and finger
tip contusions or palm contusions around nose and mouth) and
asphyxial signs can be present.
Head is pressed on the bed• Usually no findings at the postmortem.
• Some times, pallor around nose position.
1.
mechanism of death- asphyxia.
2.
preliminary investigations= as above.
3.
technique= as above
4. Smothering- postmortem features.
Cloth or tape over mouth or
clothe or paper stuffed in mouth
Young people
• can have asphyxial features due to raised venous pressure due
to struggling.
In elderly,
• usually no asphyxial features and if some one remove the gag,
difficult to prove at PM.
lab investigation-
blood for alcohol and
drugs
(3) CHOKING
Definition- death due to obstruction of
pharynx, larynx or trachea internally
Circumstancesi. Homicidal- rare• Assault on mouth causing dislocation of teeth and fall into pharynx causing complete
obstruction of the airways
ii. Natural choking- rare• Laryngeal obstruction by sudden enlargement of a tumors,
• tonsilar disease,
• acute fulminating epiglotitis or laryngeal oedema.
iii. Accidental choking- Commonest
• obstruction of pharynx or larynx by food or foreign body.
• Children
• some times with toys or food.
• Adults – café coronary
• usually while eating. As they die suddenly especially in cafeterias, these deaths are called
‘cafe coronary’. Some times bad fitting dentures can obstruct airways. Usually these adult
victims are mentally retarded, alcohol intoxicated, dementic, neurological injuries, eating
greedily, or senile.
• Their cough and gag reflexes are poor. So cannot cough out the obstructing agent
Some times choked with finely grinded
materials like corn seeds or saw dust.
(Usually healthy people not die of choking,
due to reflex protective mechanism such
as cough and gag reflexes)
PM features
Obstruction to the air
ways can be found. But
usually no asphyxial signs
are found.
Therefore if obstructing
agent is removed, cannot
diagnose choking at the
PM
Diagnosis of AM food aspiration
It is difficult.
25% of PMs have agonal food aspiration as a PM or agonal
phenomenon.
Therefore, if independent eyewitnesses are not available, the
diagnosis is achieved by,
• a. Food is found from larynx to down, obstructing the airways completely or histology
shows food in alveoli.
• b. Reason for loss of cough reflex- eg.
• Drug or alcohol intoxication,
• head injury etc.
• c. Vomitus can be present at scene or on clothes
(4) Postural asphyxia
Death due to obstruction of the respiration due
to position. Compress due to own body weight.
• Alcoholics- sleeping at the edge of a bed or stool.
• Torture- Inverted suspension.
Postural asphyxia – PM features
AM asphyxial features due to chest compression and PM
asphyxial artifacts are due to dependent hypostasis.
More Facial Congestion and oedema due to dependent
oedema
More Facial Cyanosis – due to dependent hypostasis
More Facial petechiae - due to dependent petechiae
(5) Traumatic asphyxia
Death due to prevention of
respiration due to external
forces on chest and abdomen
eg.
• Burial during landslides
• Stampedes in crowds.
PM features of Traumatic asphyxia
maximum signs of asphyxia
Chest compression drives back blood to face, neck and upper limbs. In
upper limb veins, no valves are found. Therefore, blood can move
towards hand if chest is compressed.
• Congestion, oedema and petechiae
• Cyanosis
• There may be overt haemorrhages (nasal and ear bleeding)
4. Features are found above the sternal notch area
Thank you