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Title: Suffocation, Asphyxia, and Fatal Pressure on the Neck


1
Suffocation, Asphyxia, and Fatal Pressure on the
Neck
2
The Nature of Asphyxia
  • asphyxia - absence of pulsation. The true
    meaning of the term is best described as pressure
    on the neck associated with cardiac arrest.
  • The long and short of it is that a lack of oxygen
    leads to cell death.
  • Anything that leads to lack of oxygen can be
    called asphyxia, but terms like hypoxia or anoxia
    are more accurate.

3
The Nature of Asphyxia
  • The following conditions may be considered to be
    defects in the chain or respiration and are
    examples of asphyxia
  • Absence of oxygen tension in the atmosphere such
    as reduced barometric pressure, or replacement by
    carbon dioxide.
  • Obstruction of the external respiratory orifices
    as in smothering or gagging.
  • Blockage of internal respiratory passages.
  • Restriction of respiratory movements.
  • Disease of the lungs that reduces gas exchange
  • Reduction in cardiac function
  • Reduced ability of the blood to transport oxygen
  • Inability of the peripheral tissue cells to
    utilize the oxygen being delivered to them.

4
Mechanical Asphyxia
  • The normal oxygen in the blood according to the
    age and health of the subject.
  • Young and middle aged adults have almost complete
    saturation of their arterial blood with oxygen.
  • 90 100 mmHg middle age
  • 60 85 mmHg persons over 60
  • Severe fatal hypoxia occurs when oxygen tension
    falls to below 40 mmHg

5
terms to know
  • A number of terms apply somehow to asphyxia, some
    of which are confusing and inexact
  • Suffocation the general term used to indicated
    death from lack of oxygen
  • Smothering (more specific) indicates blockage
    of the external air passages
  • Gagging fabric or adhesive tape occludes the
    external passages
  • Choking refers to blockage of the upper air way
  • Throttling refers to strangulation usually by
    hand
  • Strangulation is the most specific term
    indicating the use of either the hands or
    ligature as a means of applying external pressure
    to the neck

6
Classic Signs of Asphyxia
  • certain signs have become known as the classic
    signs of asphyxia
  • A pathologist needs to realize that little
    reliance can be placed on them (petichia) in the
    absence of other confirmatory evidence.
  • In many cases of undoubted asphyxia these signs
    are absent and, conversely, they are often
    present in some degree in deaths that can be
    shown to be non-hypoxic in nature.
  • In other words, each of the signs must be looked
    at IN DEPTH during autopsy.

7
Classic Signs of Asphyxia
  • Petechial Hemorrhages
  • Small pin-point collections of blood lying in the
    skin, sclera or conjunctivae and under the
    thoracic serous membranes.
  • A common misnomer is that they occur from the
    rupture of capillaries, when they in fact come
    from rupture of venules. (ruptured capillaries
    would be invisible to the naked eye)
  • Most commonly seen of the face and eyes.
  • Also known as Ocular Petechiae

8
Significance of Petechiae
  • Remember, the appearance of Petechiae must be
    noted but not always as an indicator to asphyxia.
  • Position of the body after death as well as an
    enumerable amount of other factors can lead to
    the appearance of Petechiae.
  • Typically, Petechiae are used in conjunction with
    other evidence to indicated asphyxia.

9
Petechial Hemorrhages
10
Classic Signs of Asphyxia
  • Congestion and edema
  • Even more nonspecific than Petechiae but is also
    the result of obstructed venous return.
  • Congestion of often associated with tissue
    swelling, and thus can often times be associated
    with trauma.
  • Conditions such as pneumonia will also lead to
    marked pulmonary edema.
  • Drug overdoses are also common causes of raised
    pulmonary edema

11
Classical Signs of Asphyxia
  • Cyanosis
  • Cyanosis is derived from the Greek word for Dark
    Blue.
  • The color of blood depends on the absolute
    quantity of oxyhemoglobin and reduced hemoglobin
    present in the erythrocytes.
  • Constriction of the neck traps venous blood with
    decreased oxygenated hemoglobin, which leads to
    the bluish color.
  • Cyanosis may be overshadowed by hypostasis.

12
Suffocation
  • Typically the reduction of oxygen in the
    atmosphere by physical replacement by other gases
    such as carbon monoxide or dioxide.
  • In domestic circumstances, death may be seen
    where a heating apparatus has removed oxygen in
    the absence of ventilation.
  • In a different variety of hypoxic deaths,
    children may asphyxiate by being confined in a
    small air space.

13
Smothering
  • This term refers to death from mechanical
    occlusion of the mouth and nose.
  • Death may occur either by occluding substance
    pressing down on the facial orifices, or by the
    passive weight of the head pressing down.
  • It is extremely hard to prove intent.
  • Pressure marks are rarely distinguished from
    normal post mortem changes.

14
Overlaying of infants
  • Condition with a pedigree as ancient as the old
    testament.
  • Mentioned in the book of Kings, in which two
    women who claim the same child, as the other
    infant was overlain.
  • The recent decline in SIDS deaths is attributed
    to mothers awareness of baby position as well as
    the use of cots and cribs.

15
Gagging
  • Variation on smothering where a pad or gag is
    fixed over the face.
  • At first the device admits air, but as gets
    soaked with either saliva or mucus becomes
    impervious and asphyxia occurs.
  • Often times related to robbery and violent crimes.

16
Choking
  • Refers to blockage of internal airways.
  • Usually occurs between the larynx and primary
    bifurcation of the main bronchus.
  • Foreign bodies account form most choking deaths.
  • False teeth and hemorrhages following dental or
    ear surgeries are common occurrences also.

17
Blockages
18
Traumatic Asphyxia
  • Refers to the mechanical fixation of the chest.
  • Important because it shows the most evident signs
    of classical asphyxia.
  • Signs include face and neck grossly discolored.
  • Eyes and sclera are engorged with blood to a
    point of obliterating the whites of the eyes.

19
Visible Signs
20
Traumatic Asphyxia Case history
  • A 58-year-old man who had visited an inmate in
    prison got into trouble with the prison officers.
  • The prison warden ordered him to leave the
    prison, but the visitor disobeyed this order and
    assaulted the warden.
  • Although the man was immediately arrested for
    obstructing the warden in the performance of his
    duties, he reacted extremely violently.
  • Therefore, six prison officers immediately
    restrained him in the prone position.
  • According to the statements of the prison
    officers, the victim lost some of his strength in
    1-2 min after being restrained and nearly
    completely in 7-8 min.
  • After about 10 min passed, the victim showed no
    signs of resistance, yet the prison officers had
    to keep restraining him following the order of
    their superiors, who had inspected the situation.
  • After 14-15 min had passed, a policeman arrived
    at the scene and the prison officers relaxed
    their restraint on the victim. The victim had
    already undergone cardiopulmonary arrest.

21
Mechanical Asphyxia
  • There have been reported cases where a violent
    struggle occurs between arresting officers and a
    drunken or drugged offender in which the death
    occurs later.
  • The death is obscure and almost untraceable at
    autopsy but has been described as
    catecholamine-induced cardiac arrhythmia from an
    exaggerated adrenal response.

22
Autopsy Findings Traumatic Asphyxia
General appearance of the victimshowing obvious
congestion of the face.
  • Petechiae observed in theleft upper conjunctiva.

23
Autopsy Findings Traumatic Asphyxia
  • Intramuscular bleeding in the back of the victim,
  • (a) right scapular region,
  • (b) left infrascapular region.

24
Autopsy Findings Traumatic Asphyxia
Multiple fractures of the ribs accompanying the
bleeding in the surrounding soft tissues (a)
right first through fourth ribs and (b) left
first and ninth ribs.
25
Postural Asphyxia
  • Closely tied to traumatic asphyxia.
  • When a person remains in a certain position long
    enough to stop respiration.
  • Such situations included being trapped, drunken
    or drugged state, or mechanical impediment.
  • Such positions usually entail inversion of at
    least the upper part of the body.

26
Postural Asphyxia
  • Drunk who attempted to climb through a window
    above his door when he could not locate his keys.
    He passed out in this position and died as a
    result

27
Mechanism Death by fatal pressure on the neck
  • Pressure on the neck may arise from manual
    strangulation, ligature, hanging, direct blows,
    arm-locks and a variety of accidental lesions.
  • Strangulation classically was thought of as
    occlusion of the airway, but now is thought to
    encompass many factors.

28
Airway occlusion
  • Occurs either from direct compression of the
    larynx or trachea or from lifting the larynx so
    that the pharynx is closed by the root of the
    tongue.
  • Various experiments have been done to try to
    estimate the amount of force needed to close the
    airway and blood vessels, but it is difficult to
    translate the varied results.

29
Occlusion of the neck veins
  • Factor most commonly associated with the
    classical signs of congestion, cyanosis and edema
    with obvious Petechial hemorrhages.
  • Experiments done have show that as little as 2kg
    of force applied to the neck is enough to destroy
    the jugular return.

30
Compression of the carotid arteries
  • Much less common than venous occlusion.
  • Arteries are typically blocked by the sterno
    mastoid muscles and thus require much more force
    to be occluded.
  • 4 minutes of carotid artery occlusion is enough
    to commit brain death.
  • Cases with severe hypothermia can extend the time
    of this occlusion with regards to recovery.

31
Nerve effects
  • Pressure on the baroreceptors situated in the
    carotid sinuses can result in a condition called
    bradycardia.
  • Bradycardia slowing of the heart.
  • This mechanism works through a reflex arch.
  • Because these impulses are a reflex arch, the
    brains need for oxygen is bypassed and the heart
    slows, significant oxygen reduction can be noted
  • Also called reflex cardiac arrest

32
Photo
33
Classical features when arrest is delayed
34
Manual Strangulation
  • Common method of homicide
  • Most often associated with power and size of
    assailant.
  • Most commonly seen in domestic homicides
  • Also common in sex related homicides.
  • Rarely committed by women unless committed on a
    child.

35
Autopsy appearances of MS
  • Bruising on the neck
  • Abrasions on the neck

36
Manual Strangulation with Decomposition present
37
Manual Strangulation
  • Manual strangulation with bruising from the
    assailant and fingernail abrasions from the
    victim. The face is pale as a result of rapid
    vasovagal cardiac arrest before congestive signs
    could appear.

38
Internal appearances in MS
  • Bruising may be visible internally
  • At autopsy, it is critical to release venous
    pressure before dissecting the neck to avoid
    artefactual hemorrhages.
  • This is done by excising the jugular after
    opening the neck.
  • Radiography may be performed before the neck is
    opened.
  • Careful layer by layer dissections can then be
    carried out.

39
MS bruising
40
Mucosal hemorrhages
41
Bleeding behind the larynx
  • Bleeding over the front of the larynx is usually
    genuine if venous pressure was released before
    dissection.
  • The best way to release this venous pressure is
    incising the jugulars or removing the brain.
  • Banding on the esophagus is also a common finding
    in normal autopsies and not to be confused with
    strangulation.

42
Artefactual Post-mortem hemorrhage
43
Injury to the larynx
  • Damage may occur in many ways
  • The superior thyroid horns are often fractured as
    a result of bi-lateral compression of the larynx.
  • Fractured hyoid bones are often observed
    although, in younger subjects, calcification has
    not fully set in.

44
Strangulation by ligature
  • May consist of a wide variety of objects, some
    not obviously suited for the purpose.
  • Cords, wires, ropes, and some belts are strong
    enough to cause death.
  • A U-shaped ligature is often times sufficient to
    occlude the airway.
  • In the majority of cases the ligature is crossed
    over itself after passing a full circle around
    the neck.

45
  • Fracture of the left laryngeal horn with a
    hemorrhage. The body was recovered from a lake
    based on the confession of the assailant.

46
External Appearances
After removal of ligature (scarf) the typical
bruises are observed.
  • Appearance of congestion cyanosed forehead.

47
The ligature Mark
  • The appearance at autopsy depends on the nature
    and texture of the ligature.
  • When there is a pronounced pattern such as a
    weave of a chord pattern abrasions are commonly
    noted.
  • Fabric sometimes leaves marks that are difficult
    to interpret.
  • Fabric may also leave a sharp mark which may be
    confused for a chord.

48
Types
  • Self strangulation by ligature with three turns
    around the neck and a complex knot. There was no
    doubt from the circumstances that the deceased
    committed suicide.

49
Types
  • Ligature strangulation by means of a Spanish
    windlass. A penknife has been thrust through
    the knot to twist the ligature tight.

50
Position of the ligature mark
  • The geometry of the mark is important to
    interpret the fatal events.
  • In cases of suicide, the ligature typically does
    not have a crossover mark.
  • In cases of homicide, the crossover is evident.
  • The cross may be at the side, front of back
    depending on the positions of the victim and
    assailant.

51
Hanging
  • Form of ligature strangulation in which the force
    applied to the neck is derived from the
    gravitational drag of the weight of the body or
    part of the body.
  • Total suspension is not needed
  • Judicial hangings often times saw victims
    families pulling on the legs of the victim to
    shorten the agony.

52
Suicidal and Accidental hanging
  • Today almost all hanging is accidental or
    suicidal.
  • Death is most often cause by reflex cardiac
    arrest from pressure on the carotid structures.
  • This is evident when victims are found with pale
    faces rather than hemorrhagic congested faces.

53
Common Methods Used
  • Most hangings are self suspensions
  • Typically a thin rope is attached to some high
    point.
  • The lower end is secured to the neck with some
    form of slip knot while the victim is standing on
    a support.
  • The support is then removed to suspend the
    weight.
  • Suspension is often times not high enough to keep
    the victims feet off of the floor.
  • The weight of the upper torso leaning into the
    noose is often sufficient to cause reflexive
    cardiac arrest.

54
  • Victim who used two neck ties to suspend himself
    from a hook placed on his door. The hook gave
    way and he was found lying on the floor dead.
  • Notice the pale, uncongested face indicating a
    rapid cardiac arrest.

55
  • Suspension with a fixed knot in the chord so that
    there is a segment of skin free from the mark
    where the chord rises toward the knot. This is a
    common feature in domestic homicides.

56
  • Inmate who had a torn up sheet and attached both
    ends to a water tap and is leaning into the loop
    in a sitting position.

57
  • A deep hanging mark showing the high position
    under the chin rising to the back of the neck.
    The spiral weave of the rope is clearly imprinted
    in the skin. The dark tint of the face is racial
    not congestive.

58
  • The position of the hanging mark on the neck can
    vary.
  • Top - is the usual position with a fixed noose
    and high suspension point
  • Middle if a slipknot is used the tightness of
    the deeply impressed loop tends to find the
    smallest circumference on the neck.
  • Bottom if the suspension point is low, the
    subject may lean away and the mark can be
    horizontal.

59
  • Hanging by frontal suspension.
  • A leather belt used as a noose.
  • Compression has occurred around the whole of the
    neck

60
Features of Sexual Asphyxias
  • The basic mechanism is the production of cerebral
    hypoxia.
  • This hypoxia is achieved by constriction of the
    neck by ligature which can be voluntarily
    tightened and loosened.
  • Some procedures use other means for creating
    hypoxia such as anesthetic agents such as
    huffing

61
Features of Sexual Asphyxias
  • The most common feature is a ligature connected
    to some compression device of the hands and feet
    which releases the ligature upon relaxing the
    legs and hands.
  • This feature allows for release in cases where
    the victim passes out.
  • Malfunctions in this release are what lead to
    accidental ligature deaths.
  • Often times hypoxia is produced by position or
    placing head in a plastic bag.

62
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