Mechanical asphyxia.pptx

Forensic Medicine

1. Dr Nikita Prabhakaran FM 2.20 – FM 2.23

2. Anoxia complete deprivation of adequate oxygen supply at tissue level. Hypoxia deprivation of adequate oxygen supply at tissue level that results from asphyxia. Asphyxia ( Gk a, not; sphyzein , to throb) Defective oxygenation of the blood ( Exclusion of air from lungs) Literal meaning is without throbbing or pulse, which occurs soon after asphyxia.

3. Types of asphyxia Mechanical – eg : Hanging Pathologial – eg : disease of upper or lower airway Toxic/ chemical- eg : causing diaphragm paralysis Environmental - eg : high altitude Traumatic - eg : pneumothorax Position/ postural - eg:restraint torture Iatrogenic – eg : anaesthesia

4. What is mechanical asphyxia ??? Broad term denoting an interference Referring to a condition where Any external pressure applied to neck, chest or other areas of the body In such a way that respiration is difficult or impossible

5. Causes of mechanical asphyxia Hanging Strangulation Smothering Gagging Choking Traumatic asphyxia Drowning

6. Hanging aka Self-suspension Definition: It is that form of asphyxia Which is caused by suspension of body By a ligature which encircles the neck Constricting force being the weight of the body

7. Types (1) Depending on degree of suspension (a) Complete hanging - no part of the body touching the ground (b) Partial hanging -partially suspended -some part of the body touches the ground -only head and chest off the ground (whole weight of the body is not necessary)

8. Complete Hanging Partial Hanging

9. (2) Depending on the position of the knot (a) Typical hanging knot is just below the occiput on the central part of the back of neck (b) Atypical hanging knot is anywhere other than the occiput

10. Typical hanging Atypical hanging

11. (3) According to manner of death 1. Suicidal hanging 2. Homicidal hanging 3. accidental hanging

12. Fatal period Usually 3 to 5 minutes

13. Causes of death in hanging Asphyxia  trachea  15 kg (most common) Venous congestion  jugular veins 2kg Cerebral anaemia  carotid arteries 4 to 5kg  vertebral artery 20 kg 4. Reflex vagal inhibition 5. Fracture or dislocation of cervical vertebra sudden drop and long fall

14. Delayed death Aspiration Pneumonia Pulmonary edema Laryngeal edema Infarction of brain Hypoxic encephalopathy Brain absecess

15. I. Specific finding II. Findings indicating ante-mortem status III. Non- specific findings

16. I. Specific findings (a) External appearance Most characteristic finding is LIGATURE MARK Type : pressure abrasion around the neck Factors: numerous factors like Material Number of turns Any entangled materials Duration of suspension

17. Patterned abrasion

18. Typical appearance in hanging – oblique Above thyroid cartilage Usually discontinuous Inverted V at the knot More prominent on the opposite side of the knot If Patterned  identifying material If prolonged suspension parchment like appearance

19. (b) Internal findings Neck is dissected under blood less field Subcutaneous tissue under the pressure abrasion is pale and dry No prominent haemorrhages/ muscular contusions underneath

20. Amussat’s sign Transverse carotid intimal tears Long drops

21. Hyoid fracture – abduction fracture Thyroid cartilage superior horns- can also be fractured Hangman’s fracture Fracture dislocation of C2 from C3 Sudden and long drop As in judicial hanging

22. Histopathology Suspension within 2 hours of death Perimortem period Similar mark Confirmed by tissue reaction in microscopy enzyme histochemistry

23. Pseudo-ligature mark Skin folds on the neck May resemble a ligature mark Especially after refrigeration When there is coagulation of subcutaneous fat Conditions: Obese individuals, Infants, Decomposition

24. Infant neck folds

25. Simon’s sign Haemorrhage on the ventral surface of the IV disc Beneath the anterior longitudinal ligament In lumbar spine In elongation and overextension

26. II. Signs of ante-mortem hanging Le-facie sympathique  knot presses on cervical sympathetic eyes partly open pupils dilated Sign of ante-mortem hanging

27. Salivary dribble mark  Stimulation of pterygopalatine ganglion submandibular gland gets activated Increased salivary secretion Seen extending from the angle of mouth Opposite to the site of knot Sign of ante-mortem hanging

28. Inflammatory change around pressure abrasion Microhaemorrhages in the subcutaneous tissue

29. III. Non- specific findings Face- congested , cyanosed, petechial haemorrhages Tardieu’s spots  face and inner aspects of inner eyelids

30. Glove And stocking hypostasis Seminal discharge++ Urine or faecal discharge ++

31. Cardinal signs of asphyxia Cyanosis Congestion Edema Petechial haemorrhages Postmortem fluidity of blood

32. Internal findings: Lungs congested, edematous and tardieu ’ spots Subpleural haemorrhages especially in the interpleural surface All other organs congested, edematous

33. Cyanosis

34. Congestion of internal organs Pulmonary congestion

35. Petechial hemorrhages external and on internal organs

36. Definition Asphyxia caused by constriction of neck And the constriction force being an external force and not the weight of the body

37. Types: (1) Ligature strangulation external force is ligature around the neck (2) Manual strangulation / Throttling External force- compression by human hands

38. (3) Garroting (4) Mugging

39. (5) Bansdola

40. Compression by a ligature tied around the neck Constricting force being an external force applied

41. Postmortem appearance (a) External Ligature mark middle / below thyroid cartilage completely encircles the neck transversely Bruising around Wide area of bruising – bruising

42. (b) Internal findings Neck dissection- internal layers shows bruising/ haemorrhages Hyoid bone fractures Thyroid cartilage fractures

43. Hanging Ligature strangulation Ligature mark Oblique, discontinuity Above thyroid cartilage, pale looking Horizontal, continuous, below TC, bruising around and inside Subcutaneous tissue Pale Ecchymosis under the mark Hyoid bone Fracture++ -- Thyroid cartilage Fracture less common More common Emphysematous changes in lungs ----- ++++ Carotid arteries Damage +

44. Compression of the neck caused by human hands

45. Typical External findings Six penny bruises  Oval/ round (1.5 to 2cm wide) contusions Present on the neck due to compression from pulp of fingers Helps in identifying the position of the victim and assailant

46. Finger nail abrasions Crescentic abrasions Regularly curved comma like abrasions If nails skid  parallel linear lines of abrasions

47. Along with all other findings of violent asphyxia

48. Classification: (1) Inward compression fracture (2) Antero-posterior compression fracture (3) Avulsion fractures

49. Inward compression fractures Seen in throttling Fingers of the grasping hands squeeze the greater horns towards each other Periosteum on the outside gets fractured Fragment is displaced inwards Called as adduction fracture

50. Antero-posterior compression fracture Seen in cases of hanging Hyoid bone is forced directly backwards Greater horns hit against the vertebrae and gets diverged Inner periosteum breaks Fragment displaced outwards Called as abduction fracture

51. Avulsion Fracture Violent lateral or downward movements of thyroid cartilage Or there is traction in thyro -hyoid ligaments Causes are miscellaneous

52. Palm of one hand  placed horizontally over the mouth and nostrils Reinforced by keeping another palm on the top of it at right angles Heel of the upper palm on the front of neck Findings similar

53. One bamboo stick kept on the back of neck Another one on the front Ends are tied to cause compression Sometimes, one bamboo stick is placed on the front and at the back- pressure applied using a foot

54. Victim is attacked from behind without warning Either by throwing a ligature and tying it and twisting it with a lever or rod Mode of judicial execution in Spain “ Spanish windlass technique”

55. Strangulation is caused by holding the neck of the victim in the bend of the elbow Attack usually from behind

56. It is a general term used to indicate that form of asphyxia where entry of air to the lungs is prevented by any means other than pressure on the neck or drowning .

57. Modes Smothering Gagging

58. Overlaying Choking Traumatic asphyxia

59. (1)Smothering Form of asphyxia caused by closing the external respiratory orifices either by hand Or by other means, or blocking up the cavities of nose and mouth by introduction of a foreign substance

60. Postmortem appearance Circum -oral pallor Pallor around nose Pressed against pillow– findings can be obsolete Petechiae and congestion are seen in persons who threw a struggle before death

61. Pillow  blood. Saliva and epithelial cells If hands used scratches from nails Lips and gums show bruising and laceration Frenulum tears Face intensely congested Toungue may be bitten

62. Internal findings: All that of asphyxia ++ Blood stained frothy fluid  airpassages Mucus back of mouth Emphysematous changes in lungs

63. (2) Gagging Asphyxia resulting from forcing a cloth/ other material into the mouth sufficiently deep to block the pharynx Initially through nose airway is patent, once saliva and mucus comes and blocks complete asphyxia

64. Autopsy findings Congestion of face, petechiae on the face Injuries to nose and mouth may be present Blood may seep into back of throat Gag may be found soaked and hardened Profuse mucus All asphyxial findings

65. (3) Overlaying Results due to compression of chest so a sto prevent breathing Usually happens with mother and infant on bed Smothering findings like flattening of face and mouth may be present Blood stained froth++++

66. (4) Choking Form of asphyxia caused by an obstruction within the airpassages Usually between pharynx and bifurcation of trachea. Usually seen as accidental Treated by Heimlich’s maneuver

67. PM appearance Asphyxial changes profound in cases of prolonged struggle Foreign body found wrapped in blood stained mucoid Mucus in airpassages

68. Healthy but grossly intoxicated person Who begins a meal, Suddenly turns blue, coughs violently, then collapses Appears to be a heart attack

69. Mechanism: Decreased gag reflex  poorly chewed food bolus is seen obstructing the airpassages PM Appearance: Foreign body seen occluding airpassages Similar to choking

70. (5)Traumatic Asphyxia Results from respiratory arrest Due to mechanical fixation of the chest By an unyielding substance or object Chest movements are prevented

71. Causes Crushed in a mob on the floor Crushing by falls of earth or stone Building collpases

72. Postmortem appearances Intense congestion, petechial and confluent haemorrhages on the head, neck and upper chest  above the level of compression Areas of pallor seen at the levels of compression Asphyxial findings++

73. A method of homicidal smothering and traumatic asphyxia Derived from the story of William Burke

74. William Burke and William Hare were friends Use to have body supply for medical schools Inorder to keep up with it they use to kill people Invited people were offered alcohol

75. After throwing their victim to the ground Burke used to sit on them and close their nose and mouth Hare used to drag the body through the room

76. When the victim is in a certain position Breathing is impaired Eg : upside down hanging torture In addition  venous return venous return to the heart may be impaired.

77. Definition It is a form of asphyxia due to aspiration of fluid into air-passages Caused by submersion in water or other fluid. Complete submersion is not necessary

78. TYPES Wet drowning Dry drowning Near drowning/ Secondary drowning Immersion syndrome

79. Typical drowning/primary drowning Water is inhaled into lungs Death occurs within minutes due to cardiac arrest/ fibrillation

80. Here, water does not enter the lungs Death happens due to sustained laryngeal spasm Due to inrush of water into the nasopharynx or larynx

81. Near drowning Refers to a submersion victim who is resuscitated and survives for 24 hours Hypoxemia  brain damge Electrolyte disturbances Pulmonary edema Cardiac arrhythmias Death may occur due to complications

82. Hydrocution / submersion inhibition Death results from cardiac arrest due to vagal inhibition As a result of (a)cold water stimulating the nerve endings on the surface (b) water striking epigastrium

83. (c)cold water entering the ear drums, nasal passages and the pharynx and larynx

84. Mechanism of Asphyxia Basic  deprivation of oxygen caused by obstruction of alveolar spaces is a factor in all types of drowning

85. Fresh water drowning (1) Blood concn < waterconcn

86. (2) water denatures the pulmonary surfactant  hence even after resuscitation alveolar collapse happens

87. Sea water / salt water drowning Blood conc < water conc Water is drawn from blood into lungs Severe pulmonary edema is caused Hemoconcentration  salts from lungs pass into bloodstream  Na+ increases  Bradycardia

88. 1. Asphyxia 2. Ventricular fibrillation~ 3 to 5 mins 3. Laryngeal spasm 4. Vagal inhibition- icy cold water 5. Exhaustion 6. Injuries  head striking forcibly against some solid object

89. Postmortem appearance External: Postmortem lividity  light pink in colour Froth  fine lathery persistent tenacious froth at nostrils

90. Cutis anserina / goose skin  Puckered appearance Spasm of erector pilae muscles due to cold water Hair is upright

91. Cadaveric spasm Weeds, gravel and other foreign bodies firmly grasped in hands Sign of ante-mortem drowning

92. Washer womans hands Soddening of the skin occurs due to Water entering the outer layers of skin

93. Signs of submersion Wrinkling  shortly after submersion Bleaching of epidermis 4 to 8 hours Soddening  fingertips in 2 to 4 hours Spreads upwards in about 24 hours Skin becomes soddened , thickened and wrinkled in 20 hours

94. Foreign bodies in air passages  antemortem sign (till the least dissectable portion) Or atleast after tracheal bifurcation

95. Lungs Become volumionous Doughy Crepitant Ballooned out Congestion, edema and haemorrhages+++

96. Drowning fluid  penetrates alveolar walls  enters tissues and blood vessels Emphysema aquosum 80 % cases Presumptive evidence of death from drowning

97. If the victim is unconscious at the time of death, no froth occurs but mere flooding Knows O edema aquosum

98. Alveolar walls may rupture due to increased pressure during forced expiration Blood vessels rupture  hamorrhages Subpleural haemorrhages  Paltauf’s Haemorrhages

99. Fresh water drowning Sea water drowning Ballooned out but light Ballooned out and heavy Pale pink Purplish emphysematous Soft and jelly like Shape retained after removal from body Not retained flattens up Sectioning- crepitus is heard Copious fluid oozes

100. When a dead body is thrown into water Water can seep into the lung due to hydrostatic pressure Resembles a drowning lung A drowning lung with a froth fluid on sectioning  diagnostic of drowning

101. Unicellular microscopic alagae found in water Complex structure of cell walls Contain silica, chlorophyll and diatomin Corroborative evidence in Ante-mortem drowning

102. Demonstration Bone marrow is directly digested by nitric and sulfuric acid Water squeezed out from lungs  centrifuged and sedimented Observed under microscope

103. Cadaveric spasm Foreign bodies in air passages Lungs- typical appearance Positive diatom test