This document provides information on various types of asphyxia including mechanical, pathological, toxic, environmental, and miscellaneous causes. Mechanical asphyxia includes suffocation, hanging, strangulation, throttling, choking, and drowning. Hanging can be classified based on knot position and degree of suspension. Strangulation involves ligature or manual compression of the neck. Choking involves aspiration of a foreign body in the airway. Positional asphyxia involves abnormal body positioning preventing respiration. Drowning involves submersion in liquid leading to respiratory impairment. Autopsy findings for different types of asphyxia include petechiae, ligature marks, bone fractures, and fluid/bolus in airways.

1. Diaa Mohammad Srahin
6th year Medical Student
Al-Quds University
Forensic Medicine
September/ 2018

2. Asphyxia
 A condition in which there is interference in the
uptake or release of oxygen

3. Classification of Asphyxia
1- Mechanical/Violent
2- Pathological
3- Toxic or chemical
4- environmental
5- Miscellaneous
• Traumatic
• Positional/postural
• Iatrogenic

4. Mechanical Asphyxia
 Suffocation is Lack of oxygen in the inspired air
 Smothering
 Hanging
 Strangulation ‫خنق‬ (Ligature or Manual )
 Throttling / Mugging see picture next slide (‫خنق‬)
 Gagging : Level of obstruction is Nasopharynx
 Choking : Level of obstruction is Larynx
 Drowning ‫غرق‬
 Traumatic asphyxia

5. Mugging/ throttling

6. Mechanical Asphyxia
Failure of oxygen transportation (For example carbon monoxide poisoning)
Failure of oxygen utilization (For example cyanide poisoning)

8. Pathological Asphyxia
Entry of oxygen to the lungs is prevented by disease of
the upper respiratory tract or lungs, e.g. laryngeal
edema, spasm, tumors or abscess.

9. Toxic or chemical Asphyxia
Cessation of the respiratory movements due to paralysis
of the respiratory center in poisoning with morphine,
barbiturates or strychnine.
Inhibition of oxidative processes in the tissue preventing
the use of oxygen in the blood, e.g. cyanide poisoning

10. Environmental Asphyxia
 Breathing in vitiated atmosphere (‫منهك‬ ‫جو‬) , as
in high altitude, climbing or fling, or inhalation of
carbon monoxide (CO), sewer gas (‫الصحي‬ ‫الصرف‬ ‫غاز‬)
or pure helium

11. Traumatic Asphyxia
 Blunt trauma to the thorax may result in pneumothorax,
hemothorax or pulmonary embolism that will interfere
with oxygenation and ventilation by compressing
otherwise healthy parenchyma

12. Positional/postural Asphyxia
 Positional asphyxia is due to abnormal body position that
prevents adequate gas exchange.
- In alcoholics or addicts, where the person is unconscious and the upper portion
of the body is lower than rest, or neck is forcibly flexed on the chest which prevents
normal respiratory movements. Deaths in such cases are diagnosed based on
circumstantial evidence in combination with excluding other significant underlying
causes of death.
- Positional/restraint asphyxia may occur in hogtying (individual is placed in a
prone position, their hands are cuffed together behind their back, and their ankles
are bound and tied to their wrists).

13. Iatrogenic Asphyxia
 It is seen during anesthesia

14. Tardieu’s or Bayard’s ecchymosis/spots
Tardieu’s spots ( petechial hemorrhage ):
 They are usually round, dark-red, well-defied, pin-head sized spots, found
in those parts where capillaries are least supported, e.g. conjunctiva, face,
epiglottis, subpleural surface of lungs, heart, meninges and thymus.
 They are not pathognomic of asphyxia, and their absence does not exclude
asphyxia (rarely seen in drowning).
 It can be seen in other forms of death—electrocution, poisoning, coronary
thrombosis, in persons on anticoagulants, with bleeding disorders such as
scurvy, leukemia and thrombocytopenia, but distribution is more
generalized

16. Hanging
 Hanging is a form of asphyxia caused by suspension of
the body by a ligature which encircles the neck, the
constricting force being at least part of the weight of the
body.

17. Classification of Hanging
*** On the basis of position of the knot :
 Typical hanging: When the point of suspension is
placed centrally over the occiput, i.e. the knot is at
the nape of neck on the back.
 Atypical hanging: Knot of ligature is anywhere other
than on the occiput.

19. Classification of Hanging
*** On the basis of degree of suspension:
 Complete hanging: Body is fully suspended and no part of
body touches the ground. Constricting force is weight of the
body.
 Incomplete or partial hanging: Lower part of the body is
touching the ground (toes or feet touching the ground) or in
sitting, kneeling, lying down or prone position. Weight of the
head acts as the constricting force.

21. Classification of Hanging
*** On the basis of intent (‫النية‬) :
 Suicidal
 Homicidal
 Accidental
 Autoerotic
 Judicial ‫ممكن‬‫الشنق‬ ‫حكم‬ ‫يكون‬‫قضائي‬‫بعض‬ ‫في‬‫الدول‬

22. Cause of Death in Hanging
 Asphyxia: Constricting force of ligature causes compressive narrowing of
laryngeal and tracheal lumina, leading to asphyxia.
 Venous congestion: Jugular veins are blocked by the ligature which
results in stoppage of cerebral circulation; occurs if ligature is made up of
broad and soft material.
 Combined asphyxia and venous congestion: Commonest cause.
 Cerebral anemia: It occurs when ligature is made of thin cord.
 Reflex vagal inhibition leading to sudden cardiac arrest.
 Fracture/dislocation of cervical vertebrae: It is seen in judicial
hanging. ( C2,3,4)

23. Pathophysiology ( Not too important )
 Venous obstruction leading to cerebral congestion,
hypoxia and unconsciousness, which in turn, produces
loss of muscle tone leading to airway obstruction, occurs if
ligature is made up of broad and soft material.
 Arterial blockage due to pressure on carotid artery, leading
to cerebral anemia and collapse due to low cerebral blood
flow occurs when ligature is made of thin cord.
 Reflex vagal inhibition caused by pressure to the carotid
sinuses and increased parasympathetic tone leading to
sudden cardiac arrest (less common)

24. Cause of Death in Hanging

25. Fatal period in Hanging
Usual period is 3–5 min which may extend to 5–8 min of
suspension leading to death
 Death is immediate, if cervical vertebrae are fractured or if
the heart is inhibited.
 Death is rapid, if cause is asphyxia.
 Death is least rapid, if coma is responsible.

26.  Occlusion of jugular veins – 4.5 lbs of pressure ( 2kg )
 Occlusion of carotid arteries – 11 lbs of pressure ( 5 kg )
 Occlusion of trachea – 33 lbs of pressure ( 15 kg )
 Occlusion of vertebral arteries – 66 lbs of pressure ( 30 kg )
 The weight of the head (10 to 12 pounds) ( 4.5- 5.5 kg ) is in
fact sufficient to occlude the carotid arteries.

27.  Hyoid bone may be fractured in persons, more
commonly above the age of 40 years ( calcified ) . The
fracture is usually due to ligature forcing the hyoid bone
backwards, which results in increased divergence of greater
horns .
 Transverse carotid intimal tears may be seen in
obese victims, long drops and posteriorly placed
knots (Amussat’s sign).

28.  There may be hemorrhages on ventral surface of the
intervertebral disks beneath the anterior longitudinal ligament
in the lumbar spine (Simon’s sign–a vital sign of hanging). It
may also be seen in other traumatic elongation or
overextension of spinal column (e.g. traffic accidents),
drowning and putrefaction ‫تحلل‬ (‘false positive’).
 Ligature furrow angles upward behind ears – usually
above thyroid cartilage.
 May have no furrow with soft ligature.
 May see Tardieu spots in gravity-dependent areas.

29. Factors which influence the appearance of ligature
mark ??
 Ligature material: If it is tough and narrow, then the mark is deep and prominent.
If it is soft and broad, then mark is less prominent or deep.
 Period of suspension: Longer the suspension, deeper is the groove, and it is more
prominent and parchmentized (‫مشدود‬)‫؟؟‬
 Degree of suspension: Mark becomes more prominent and deep in case of total
suspension.
 Weight of the body: Heavier the body, more marked is the ligature impression.
 Position of knot: Main force applied to the neck by ligature is opposite to the point
of suspension.
 Slipping of ligature during suspension: Produces double impression of ligature.

30. Judicial Hanging
 In case of judicial hanging, the ligature is looped around the
neck with the knot under the chin (submental), but subaural
(below auricle) knot is also used.7 The drop is at least the
height of the person (5–7 feet, depending on the weight) and
the hanging is complete.
 The ligature around the neck causes a forceful jerky impact
on the neck at the end of the fall, so as to cause fracture of
cervical column (fracture dislocation of C2 from C3, rarely
C3 and C4 vertebrae—hangman fracture) with stretching or
tearing of cervical spinal cord, but not decapitation ‫الرأس‬ ‫قطع‬
 In judicial hangings, odontoid process of 2nd cervical
vertebra ( Axis ) is usually not fractured.

31. Hangman’s fracture
 Hangman’s fracture: It was found that when the
hangman’s knot was placed beneath the chin, death
occurred rapidly because of fracture of the pedicles/lamina
of C2 vertebra and a traumatic spondylolisthesis of the C2
over C3 (anterior subluxation/ dislocation).
 This knot placement became standard, and most efficient
method of execution ‫.اعدام‬ The mechanism of the injury is
forcible hyperextension of the head. This injury may also
be seen in sports, fall or road traffic accidents

33. Strangulation
 It is a form of violent asphyxial death caused by
constriction of air passage at the neck by means of a
ligature or by any means other than suspension of the
body.

34. ligature strangulation
 The Ligature mark ( furrow ) is usually horizontally placed across
the middle or lower part of neck, at or below the level of thyroid
cartilage. The mark is transverse, circular and continuous.
 Occludes jugular veins and carotids
 death is due to occlusion of the carotid arteries with cerebral
hypoxia.
 Loss of consciousness in 10-15 seconds
 Marked congestion above ligature – confluent scleral petechiae,
conjunctival petechiae, facial petechiae
 Fractures of the hyoid bone and thyroid cartilages in 12.5% of cases

35. Cause of death
 Asphyxia due to elevation of the larynx and tongue
closing the airway at pharyngeal level.
 Cerebral anoxia due to venous congestion.
 Vagal inhibition.
 Rarely, fracture dislocation of cervical vertebrae

36. Throttling or Manual Strangulation
 Asphyxia produced by compression of the neck by human hands.
Cause of death
 Asphyxia from obstruction of respiration.
 Cerebral anoxia from interference with cerebral circulation.
 Vagal inhibition from pressure on carotid nerve plexus consisting of fibers
of vagus, sympathetic and glossopharyngeal nerves.
 About half of the deaths are due to vagal inhibition.
 Pressure must be applied for 2 minutes (min) or more to cause death.

37.  Suicide is not possible as loss of consciousness would
result in release of the pressure on the neck.
 Virtually all cases are homicides. A higher percentage of
victims are women.
 Death is alleged to be due to stimulation of the carotid
sinuses with resultant bradycardia, vasodilatation,
hypotension and cardiac arrest.

38.  Congestion above level of compression – petechiae of
sclera, conjunctiva, face
 Hemorrhages in strap muscles of neck
 Fractures of hyoid bone and thyroid cartilages
 Abrasions and fingernail marks on skin
 Inward compression fracture of hyoid bone is the most
diagnostic finding of throttling

39.  The amount of force required to compress neck structures is
estimated as—
 jugular vein: 2 kg,
 carotid artery: 5 kg,
 trachea: 9 – 15 kg and
 vertebral artery: 30 kg.
This implies that venous flow is decreased before arterial and
airway obstruction occurs.
 For fractures of thyroid cartilage lamina: 14.3 kg
 and cricoid cartilage: 18.8 kg force is required.

40. Hyoid Bone Fractures
 Fracture of the hyoid bone occurs in 50–70% of cases
in subjects above 40 years of age.

41. AUTOEROTIC
 Autoerotic hangings are accidental in manner.
 The victim is usually a male, rarely a female.
 In these cases, the individual induces transient cerebral hypoxia, by
“hanging” himself or herself for a short period of time, in order to
increase the pleasure associated with masturbation.
 Almost always male – found nude or wearing female clothing
 Often have an escape mechanism in place – either escape
mechanism fails, or timing is miscalculated
 Usually pornography at scene

42. CHEMICAL Asphyxia
Carbon monoxide
o Colorless, odorless, tasteless
o Produced with incomplete combustion of burning products, fires,
automobile exhaust, defective heating equipment
o Competes with oxygen for binding sites on hemoglobin
o 250-300 times greater affinity for hemoglobin than oxygen
o Smokers have levels of 3-10%
o Death in levels >50% (may be fatal at 20-30% in elderly, cardiac
disease, respiratory disease)
o Autopsy
• Pinkish livor mortis
• Bilateral necrosis of the globus pallidus (with survival)
•
Other gases causing asphyxia – Helium, carbon dioxide, methane,
hydrogen, cyanide, hydrogen sulfide

43. CHOKING
 Aspiration of a foreign body – balloon, button, penny, et
 Aspiration of a food bolus
 Café coronary – individual eating in restaurant suddenly collapses, witnesses start
CPR, thinking the cause is cardiac “Heimlich maneuver”
 Alcohol or drug intoxication and neurological or mental impairment are
precipitating condition
 Must be large bolus lodged in airway (small amounts of food in airway are often
seen as part of end of life aspiration in many types of death)
 Bolus may have been removed by first responders
 Homicidal – gag in oral airway

44. SMOTHERING Asphyxia
 Mechanical airway obstruction or occlusion
 Homicide
 Suicide – usually plastic bag over head
 Accident – e.g.., child in enclosed space; environment with
increased oxygen consumption, such as underground well
with high CO2 content
 Autopsy findings – nonspecific or none.

45. POSITIONAL Asphyxia
 Infant trapped between mattress and railing
 Infant trapped in soft bedding
 Intoxicated person passes out in position incompatible
with chest Expansion
 Death due to mechanical inability to expand chest
cavity

46. Drowning
 Drowning is the process of experiencing respiratory impairment
from submersion/immersion in liquid.
 Outcome may include delayed morbidity, delayed
or rapid death, or life without morbidity.
 Drowning was previously defined as immediate death secondary
to asphyxia while immersed in a liquid, usually water, or within
24 h of submersion. The definition excluded aspiration of vomit,
blood, saliva, bile or meconium.

47. Classification of Drowning

48. Typical or wet drowning
Water is inhaled into the lungs and the victim has
severe chest pain (seen in 80–90% of cases). It is also
known as primary drowning.
 Fresh water and brackish (‫الملوحة‬ ‫قليل‬) water drowning
Sea (salt) water drowning
„

49.  In fresh water and brackish water drowning (0.5–0.6% NaCl),
the aspirated water is rapidly absorbed from the alveoli into
the circulation leading to hemodilution and hemolysis.
 Circulatory overload, hyponatremia, hyperkalemia, together
with myocardial hypoxia result in fall of systolic blood
pressure followed by ventricular fibrillation.

50. Mechanism of fresh water drowning

51. Mechanism of death in fresh water drowning

52.  In sea (salt) water drowning (3–4% salinity), the aspiration of
water results in withdrawal of water from the pulmonary
circulation into the alveolar spaces as a result of the osmotic
differential, while at the same time electrolytes (sodium,
chloride, magnesium from sea water) pass into the blood.
 There is hemoconcentration with crenation of RBCs, but not
hemolysis and little change in the sodium/ potassium balance.
The pulse pressure decreases slowly and is followed by AV
dissociation, but not ventricular fibrillation.
 In both fresh water and salt water drowning, there is
terminal pulmonary edema.

53. Mechanism of sea water drowning

54. Mechanism of death in sea water drowning

55. Atypical drowning
 Dry drowning.
 Immersion syndrome (Hydrocution, submersion
inhibition or cold water drowning).
 Near drowning (post-immersion syndrome or secondary
drowning).
 Shallow water drowning (submersion of the
unconscious).

56. Dry drowning
 In dry drowning, water does not enter the lungs due to laryngeal spasm
induced by small amounts of water entering the larynx.
 Seen in 1–2% of cases.
 Death may be extremely rapid and time elapsed is insufficient for typical
drowning to occur.
 Two mechanisms have been postulated:
1- Reflex cardiac arrest due to vasovagal stimulation.
2- Laryngeal spasm and airway closure causing lethal hypoxemia.
 In these cases, autopsy findings and tests for drowning are negative, and
the lung fields are dry.

57. Immersion syndrome
 (Hydrocution, submersion inhibition or cold water drowning): It refers
to syncope resulting from cardiac dysrhythmias on sudden contact with
water that is at least 5°C lower than body temperature.
 The syndrome occurs as a result of:
 Cold water stimulating the nerve endings of the surface of the body.
 Water striking the epigastrium.
 Cold water entering eardrums, nasal passages, pharynx and larynx.
 Falling or diving into water with feet fist or duck diving by the
inexperienced.

58.  Mechanism: Vagal stimulation leading to asystolic cardiac arrest
(‘diving reflex’), or ventricular fibrillation secondary to QT
prolongation after a massive release of catecholamine on contact
with cold water.
 The resultant loss of consciousness leads to secondary drowning.
 The findings of typical drowning are absent, and diagnosis of
hydrocution is difficult because aspiration of water into the lungs
does not occur.
 The syndrome particularly affects the middle-aged or elderly men
who have ingested some amounts of ethanol. Underlying cardiac
disease could increase the risk of sudden collapse.

59. Near drowning
 (post-immersion syndrome or secondary drowning)
 Near drowning refers to survival beyond 24 h after a submersion
episode.
 Death is caused by complications or sequelae (e.g. ARDS,
pneumonia, sepsis, hypoxic ischemic encephalopathy, cerebral
edema and DIC).
 Secondary drowning sometimes refers to a victim who initially
responds well to resuscitation but then suffers respiratory
decompensation.

60. Shallow water drowning
 (submersion of the unconscious):
 Alcoholics, drugged, epileptics, infants, children and
unconscious persons may die due to drowning in
shallow water in a pit or drain.

61. Epidemiology of drowning
 „Drowning victims are predominantly male (> 65%).
 It occurs in the summer months, more frequently
seen in rivers, lakes, ponds ‫برك‬ and creeks ‫جداول‬ .
 „The age groups affected are the children (< 4 years)
and young adults (15–24 years).
 Drugs and alcohol abuse among the teenagers are other
associated factors

62. Cause of Death
 Asphyxia: Most common cause of death.
 In fresh water drowning, death results from ventricular fibrillation. While
in salt water, it is due to cardiac arrest from fulminant pulmonary
edema and associated changes.
 Vagal inhibition due to impact with water.
 Laryngeal spasm.
 Concussion/head injury.
 Apoplexy: Subarachnoid hemorrhage from rupture of berry aneurysm or
cerebral hemorrhage by rupture of cerebral vessels from sudden on-rush
of blood to the brain due to excitement or sudden fall from height into cold
water.
 Secondary causes
Septic aspiration pneumonia
Sudden bursting of aneurysm.

63.  Symptoms: apart from recalling of memory of past events, there may be
mental confusion along with auditory and visual hallucinations, tinnitus
and vertigo.
 In wet drowning, there is chest pain.
 Treatment: First and immediate step consists of application of artificial
respiration with closed chest cardiac massage, even in absence of pulse and
respiration and irrespective of injuries sustained during drowning.
Defibrillator should be used when there is ventricular fibrillation.
 Fatal period
„Fresh water drowning: 4–5 min.36
„ Sea water drowning: 8–12 min.

64. Postmortem Examination
 The diagnosis of drowning is one of exclusion.
 Most of the signs are not specific of death due to
drowning and are rather signs of submersion of body
under water for some period. Any dead body, whatever
the cause of death, will develop signs of immersion if
left for a sufficient time in water.
 Moreover, some of the signs are not appreciable in
case of putrefaction.

65.  Postmortem staining: Light pink in color, present
over face, neck, front of upper part of chest, upper
and lower limbs as the body usually flats with face
down, buttocks up, legs and arms hanging down in
front of the body

66. Froth
 Froth: Presence of fine, copious white ‘shaving-lather’ like
froth at the mouth and nostrils is the
most characteristic antemortem external finding.
 Production of this tenacious, fie, lathery foam is a vital
phenomenon.
 The mass of foam, consisting of fine bubbles, does not
collapse when touched with the point of a knife.
 It may be absent when wiped off, but reappears again by
itself or by applying simple pressure on chest.

67. Mechanism of production of froth:
 The inhalation of water irritates the mucous membrane of air passages
due to which the tracheal and bronchial glands secrete large quantities
of tenacious mucus, and the alveolar lining cell irritation produces
edema fluid. Vigorous agitation of the seromucoid secretion,
surfactant, aspirated water and retained air converts the mixture of
endogenous and drowning medium into froth.
 Other conditions in which froth can be seen:
- Strangulation - Electric shock
- Putrefaction - Acute pulmonary edema
- Epileptic fit - Opium/OPC poisoning
 In all these cases, froth is not fine, not of such large quantity or
tenacious in nature as in drowning

68. Reference
 Review of Forensic Medicine and Toxicology 3rd edition