Mechanical asphyxia up to external findings of hanging

1. Mechanical Asphyxia 1
Dr. Ashutosh

2. Asphyxia
• A condition caused by interference with
respiration, or due to lack of oxygen in the
inspired air  organs & tissues are deprived
of oxygen with CO2 accumulation causing
unconsciousness or death

3. Types of Asphyxia
1. Mechanical asphyxia – mechanical blockage of
air passage
– Smothering, hanging, strangulation, chocking,
drowning, external compression – blocking
respiratory movements
2. Environmental asphyxia – insufficiency of oxygen
in inspired air
sewer gases, high altitude
3. Pathological asphyxia– entry of oxygen is
prevented by disease
Laryngeal spasm, respiratory muscle weakness

4. Types of asphyxia
4. Toxic asphyxia – poisonous substances prevent
use of oxygen
CO, opium, barbiturates
5. Traumatic asphyxia
Injury to chest – pneumothorax
Long bone fracture - pulmonary embolism, fat
embolism
6. Postural asphyxia – alcohol, stupefying agents
– Trunk of body at lower level than rest of the body
7. Iatrogenic asphyxia – anaesthesia

5. Asphyxia
Reduced O2 tension
Capillary
dilatation
Capillary
Stasis
Capillary
engorgementStasis of blood
in organs
Oedema
Diminished venous
return to heart
Reduced
pulmonary flow
Deficient
oxygenation in
lungs

6. Signs of asphyxia
A. Petechial haemorrhages
B. Visceral congestion & oedema
C. Cyanosis
D. Post-mortem fluidity of blood
E. Cardiac dilatation

8. Signs of asphyxia
A. Petechial haemorrhages – caused by raised
venous pressure from impaired venous return
 overdistension & rupture of venules – 0.1
to 2 mm
– skin, sclera, conjunctiva, outer and inner surface
of eyelid , mucosal surface mouth, visceral layer
of pleura & pericardium - Tardieu spots

9. Petechial haemorrhages

10. Petechial haemorrhages

11. B. Visceral congestion & oedema – obstructed
venous return

12. Signs of asphyxia
C. Cyanosis – bluish discoloration of skin,
mucous membrane, internal organs -
Reduced Hb - 5 gm /100 ml
D. Post-mortem fluidity of blood - increased
Fibrinolysin
E.Cardiac dilatation - Muscular flaccidity

13. Cyanosis

14. Cyanosis

15. Mechanical asphyxia
Mechanical blockage of air passage:
Hanging,
Strangulation,
Smothering,
Chocking,
Drowning,
External compression – blocking respiratory
movements

16. Hanging
• It is a type of mechanical asphyxia where a
• body is suspended by a ligature around the
neck and
• the force of constriction being
• the weight of the body

17. Types of Hanging
• Based on the position of the knot:
1. Typical – Knot at the nape of neck
2. Atypical – Knot anywhere except the nape of
neck

18. Types of Hanging
• Based on the position
of body:
1. Complete – whole
body is suspended
2. Partial – part of the
body touches the
ground

19. Complete hanging Partial Hanging

20. Partial Hanging

22. Causes of death due to hanging
1. Occlusion of airway (trachea) – 15 kg
2. Occlusion of jugular veins – 3.5 to 5 kg
3. Occlusion of carotid arteries – 3.5 to 5 kg
4. Vaso vagal inhibition
5. Occlusion of vertebral arteries – 16 kg
6. Injury to spinal cord – long drop

23. External autopsy findings
• Ligature mark on neck
• Stretching and elongation of neck
• Salivary dribble mark
• Swollen face with protrusion of tongue and eyeballs
• Bluish discoloration on lip, tip of tongue, nails
• Sub conjunctival hemorrhage
• Bleeding from nose and ears
• Dilated pupil – Le-Facie sympathique -– ipsilateral
eye opened and pupil dilated
• Glove and stocking type of Lividity

24. Ligature mark
• Depends on nature and position of ligature
material, and the time of suspension
• Situation: above thyroid cartilage, between
larynx & chin
• Obliquely placed forming inverted “V” near
the knot

25. Ligature mark

26. Ligature mark & cyanosis

27. External Features of death due to Hanging

28. Le facie sympathique