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Asphyxia (PowerPoint download)

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					                       Asphyxia
• Asphyxia – Lack of             • Causes of asphyxia.
  oxygen.??                      • 1. Absence or reduction in
                                   oxygen tension in external
• The purpose of respiration       atmosphere such as
  is transfer of atmospheric       reduced barometric
  oxygen to the peripheral         pressure or replacement of
  tissue. Any thing                oxygen by inert gases such
  interfering this can lead to     as nitrogen, CO2.
  asphyxia.                      • 2. Obstruction of external
                                   respiratory orifices as in
                                   smothering or gagging.
                                 • Block of internal passages
                                   at pharyngeal, laryngeal,
                                   tracheal, bronchial level.
                              • Reduction in cardiac
• Restriction of movement       function leading to
  of the thorax preventing      impairment of circulation
  the inspiration of air        of oxygenated blood.
  through the res passage in    called stagnant hypoxia.
  traumatic asphyxia or
  paralysis due to brain stem
  or spinal cord damage or • Reduced ability of the
  due to curare like drugs.     blood to transport oxygen
                                as in anemia, co poisoning
                                where O2 binding power
• Diseases of drugs that        of Hb is impaired.
  prevent gas exchange such
  as pneumonia, pul
  oedema, ARDS,               • Inability of the peripheral
  pulmonary fibrosis etc.       tissues to utilize oxygen in
                                blood such as in CN
                                poisoning cytochrome
                                oxydase enzyme system
                                are inactivated.
          Mechanical asphyxia
• Asphyxia caused by            • Gagging is a form of
  mechanical causes.              smothering where the
• Definition of terms:            fabric or adhesive tape
  a) Suffocation- death           occlude the mouth to
  from deprivation of O2          prevent speaking and
  either from lack of O2 in       shouting, the nasal
  the breathable                  passage is patent, but later
  environment or from the         blockage by mucus or
  obstruction of the external     oedema leads to death.
  air passages.                 • Choking – blockage of
• Smothering- obstruction         the upper airways by
  of the external air             foreign body.
  passages by hand or soft      • Throttling- strangulation
  fabric.                         of neck by hand(manual
                                  strangulation).
• Strangulation – the hand        • 4. Oedema
  or the ligature as a means      • Cyanosis occur due to lack
  of applying external              of oxygen and
  pressure of neck.                 oxygenated Hb. Seen
• Garroting – using                 under the nails, lips, ears,
  flexible rod to compress          tongue etc.
  the neck.                       • Oedema & congestion:
• Mugging- crooked arm is           anoxia-defect in Na, K
  used to compress the              pump in capillary
  neck(Arm lock).                   endothelium-increase Na
                                    in capillary endothelial
                                    cells-swelling of
                                    endothelial cells- increase
•   Signs of classical asphyxia     capillary permeability-
•   1. Cyanosis                     extravasation of fluid and
•   2. Congestion                   oedema.
•   3. Petechial haemorrhages
• Petechial hae’rhage They     • Petechia not seen in
  are small pinpoint
  collections of blood lying     parietal pleura and
  in the skin sclera or          peritoneum if occur it
  conjunctiva, pleura and        is due to some
  pericardium. 0.1 mm to 2       bleeding disorders not
  mm in size if bigger it is
  called ecchymosis.             due to asphyxia.
  Petechia lying in the
  visceral pleura are called
  Tadieu spots.
• Petechia: rise venous
  pressure-over distension
  and rupture of thin walled
  venules.
                      Suffocation
• Reduction of O2                 • Signs of asphyxia are
  concentration in respired         minimal.
  atmosphere.
• Occur in decompression in       • Mechanism of death is
  cabin failure in aircraft in      due to over
  high attitudes, physical          stimulation of the
  replacements of O2 by
  other gases, in fires, inside     chemo receptors
  unused tanks and ships.           leading to vaso vagal
• Mechanically obstructing          cardiac arrest.
  the external air passages is
  called smothering.
                    Smothering
• Mechanically by                  Contusion, abrasion or
  obstructing the external air     laceration of lips, around
  passages by hands, cloths,       the mouth and cheeks may
  pillow etc. in industrial        be seen.
  accident sands, mud etc.,      • Asphyxial signs may be
  collapsing of mine tips.         prominent.
• Infant, children, elderly,     • Overlaying of infants:
  women, debilitated               when the baby was
  people are more prone to         sleeping with the mother,
  be suffocated and killed.        mother could turn over on
  Pm: signs of resistant.          to the baby and baby
  Signs of pressure around         could die of smothering.
  mouth and nose in
  mechanical suffocation
          Plastic bag suffocation
• Commonly suicidal, could      • Smothering occur by a pad
  be accidental or                or gag is fixed over the
  homicidal.                      face,as happen in robbery
• Polythene or other plastics     with violence. Caretaker
  are put over the head.          or night watchmen may be
• Could be                        tied up and silenced by
  accidental(masochistic          tying a scarf or other
  practices), suicidal or         cloths around his face. At
  homicidal.                      first it admits air but when
                                  it is soaked with saliva it
• Pm signs are negative           is impervious and leads to
  except the bag around the       asphyxia.
  head and face.
• Gagging
Plastic bag suffocation
Sexual asphyxia (accidental) - naked body, opposite sex
                        dress
               “masochistic practices”
• If adhesive tape applied
  to the mouth or cloths
  packed into the mouth
  at the beginning the
  nasal airway is patent
  but with time the mucus
  obstructing the nasal
  passage and cause
  death.
    Autopsy signs of suffocation
• Signs of pressure on the      • Drunkenness, epilepsy,
  face such as bruising and       drug overdose, coma from
  abrasion around the             natural diseases etc.
  mouth, nose, chin.
                                • Congestion and cyanosis.
• Pressure of the lips on the   Fabrics tied around face or
  tooth leads to buccal           inside the mouth.
  surface to be bruised,        Mucus obstructing the nasal
  abraded or lacerated.           passage.

• Accidentally suffocation
  could occur in
  incapacitated persons
  lying face down on a
  surface such as in:-
Marbling – bluish purple lines appear over trunk spread
 to neck limbs due to decomposition of blood in veins
                    and hemolytic
             “early sign of putrefaction”
Choking/cafe coronary syndrome
• Blockage of the internal      • Foot bolus usually in
  airways from pharynx up         children, mentally retarded,
  to the trachea.                 incapacitated people due to
                                  alcohol, drugs, illnesses or
• Death due to hypoxia from       due to aging.
  occlusion of the air way or
                                • Accidentally during ENT
  neurogenic cardiac arrest.      surgeries blood obstructing
• Cyanosis, petechiae,            the airway.
  congestion may be             • Acute obstructive lesions of
  present.                        glottis and larynx such as
• Usually accidental rarely       acute hypersensitivity
  suicidal.                       reactions, acute infective
                                  conditions as diphtheria,
                                  haemophilus epiglottis.
                      Hanging
• Constriction of the neck      • partial hanging or
  by ligature, where the          incomplete hanging:-
  constricting force is whole     part of the body is
  or part of the body.            supported, suspended
• Complete hanging :-             from lower level such as
  whole weight of the body        door handle, window, etc.
  is suspended by ligature,       body will be in sitting,
  the are above the ground        crouching position and
  and the body is not             asphyxial signs will be
  touching the ground or          prominent as the force is
  other structure.                only enough to obstruct
•                                 the veins in the neck.
• Typical hanging:- knot is at      • Accidental – Rare occur in
  the back of the neck at mid         children caught in cloth
  position. This causes equal         lines, swings etc. adult in
  pressure on each side of            masochist activities.
  neck.
                                    • Homicidal – very
• Atypical hanging:- knot is          uncommon. Killing and
  in a position other than at the     subsequently hanging the
  back of the neck at mid             dead body to look like
  position. Either side of the        suicide occur. Hanging a
  neck, front of the neck etc.        healthy adult is difficult but
  Causes more pressure on one         after incapacitated by drink,
  side of the neck than on the        drugs, head injuries or feebly
  other side.                         old persons or children could
• Circumstances:- Suicidal –          occur.
  Very common                       • Judicial hanging:-execution
Atypical hanging with protruded
            tongue
Partial/incomplete hanging
Complete hanging
      Medico legal investigation
• History                        • If the body was brought
• Scene visit                      down before the examination
                                   circumstances at which the
• Transport of body to
                                   body was found, complete or
  mortuary.                        partial hanging, knot where
• Post mortem examination.         type of knot any attempts to
• History: from relatives,         remove the knot by cutting
  Police, people assembled         etc. any items removed from
  at the scene. Include:-          the scene before
                                   examination(Masochistic)W
  family history married or        hen the person was last seen
  not, occupation, spouse,         alive, time of last meal and
  habits, psychiatric illness,     type of food etc.
  past attempts, depressed,
  any reason for suicide, any
  suspicion etc.
                 Scene examination
• Photo, sketch and                • disturbance of dust at the
  description of the scene.          beam, type of knot at the
  Doors are locked or knot,          beam, Is there any support
  from in or out, where is the
  key, any possibilities entries     to tie the ligature high up
  through other ways such as         such as chair or any other
  roof, windows, lights are on,      platform, measurements of
  if living alone news papers        ground to feet, ground to
  and milk collected unto            beam, height of the
  when, calendar managed             platform etc. if the time of
  unto when, any notes left,
  any food left, any evidence        death is in doubt rectal
  of struggle, foot print,           temperature at ½ hourly
  cigarette used,butts, alcohol      interval( if no suspicion of
  bottle, glasses etc. any           sexual Abuse), rigor
  adjacent structures which          mortis, hypostasis and
  could have caused injuries         collect trace materials.
  during the process of
  hanging.                           Any blood stains.
      Ligature and ligature mark
• The rope cut at middle       • Level of the mark as
  preserving the knot and        above the thyroid cartilage
  hands are covered with         or below, horizontal,
  envelops and transported       rising to a side, oblique.
  to mortuary.                   Width, depth, any crossing
• Examination of ligature        of the marks, any vital
  type ligature, width,          signs, any other associated
  twisted or not, single or      injuries such as cuts while
  double, how many rounds        attempts to remove the
  around the neck, type of       ligature by relatives etc,
  knot(slip knot, fixed knot     nail marks, finger tip
  etc), place of knot after      marks etc. ligature mark
  that cut at the middle         will be parchment
  preserving the knot.           appearance.
           External examination
• More than the ligature and      • convulsion and could cause
  ligature mark. Increased          abrasion, contusion even
  salivation, congestion,           laceration. Self inflicted
  oedema, cyanosis, petechia        injuries. Caused by rats, ants.
  may be intense above the          In the process of removing
  ligature. Eyes bulged out and     the ligature from the neck by
  reddish in colour, face           relatives. Any nail marks at
  swollen, tongue protrude out,     the neck could be from the
  froth may be at nose and          deceased while trying to
  mouth, hypostasis will be at      remove or untie at the time
  lower limbs, scrotum, penis       of hanging or caused by
  and hands. Seminal                another person note the
  discharge may be present.         direction of the curvature.
  Any injuries caused by:In
  the process of hanging the
  body struck the adjacent
  structures due to
            Internal examination
• Special neck dissection:- • Fracture of hyoid is rare in
  first the skull is opened    cases of hanging. Fracture
  and blood from the neck is   could occur in elderly
  removed. Neck is             people where the bone is
                               calcified and due to pull of
  dissected layer by layer     the thyroid ligament,
  inspecting skin, platysma,   greater horn is the
  strap muscles,               commonest site of fracture
  sternomastoid, thyroid     • when there is violent drop
  gland, nerves, vessels,      and in judicial hanging
  laryngeal cartilages,        cervical spine fracture/
  bones, paravertibral and     dislocation occur.
  vertebral regions.         • Internally froth will be at
  Specially look for           the respiratory passage,
  haemorrhages, contusions,    submucosal haemorrhages
  fractures etc.               could be in epiglottis,
                               larynx, trachea.
            Mechanism of death
• Vagal stimulation at the     • Compression of the
  carotid bodies and             jugular veins leads to
  inhibition of heart.           congestion and stagnant
                                 hypoxia. Commonly in
• Asphyxia following             partial hanging
  compression of the airway
  by floor of the mouth        • Fracture dislocation of the
  pressed against the            upper cervical vertebrae
  pharynx.                       and cervical cord damage
• Compression of the             occurs when the drop is
  carotids and jugular veins     long or in Judicial
  leads to cerebral              hanging.
  ischaemia.
                Strangulation
• Manual strangulation      • Manual strangulation
  (throttling).             • Death caused by
                              compression of the neck
• Strangulation by            using hands. Always
  ligature.                   homicidal. Marks caused
                              by hands seen on the neck
• Mugging(arm lock),          such as finger nail marks,
  foot pressure on the        finger tip bruises. The
  neck, using sticks etc.     distribution of the nails
                              marks will vary depend on
                              the position of the
                              assailant and victims at the
                              time of the incidents,
                              whether there is struggle.
• There may be injuries due • All the asphyxial signs
  to counter pressure at the   could be seen. Bruise
  shoulder, back. There
  could be nail marks          and haemorrhagwes
  around the wrist, defense    involving the strap
  injuries, in female could    muscle could be seen.
  be associated with rape.
• The tongue may be partly • Death could be due to
  out or bitten. Submucosal    vagal inhibition or
  hae’age in the larynx,       asphyxia.
  fracture of the greater horn
  of the hyoid bone. Rarely
  the ribs are fractures due
  to the assailant applying
  knee pressure on the chest.
          Ligature strangulation
• Constricting force is        • The depth is usually
  produced by Appling            uniform around, if soft
  ligature around the neck       ligature is used marks may
  by an assailant.               be faint or even could be
                                 absent. The ligature may
• Almost always homicidal        be more than one round
  rarely accidental cord         around the neck or some
  round the neck, children       time may not go
  caught in cloth lines and      completely around the
  rarely suicidal                neck. Haemorrhage zone
  strangulation.                 may be seen above and
                                 below the ligature mark.
• Ligature mark is more          The asphyxial signs will
  horizontal and lower level     be marked above the
  than in hanging. Across or     ligature as face, scalp,
  below thyroid cartilage.       conjunctive etc.
• Internally: Bruising of       • Defense injuries may be
  neck muscles, # of              seen. Injuries could seen
  superior horn of thyroid,       around the wrist.
  cricoids, tracheal rings if
  higher level fracture of      • Injuries could be inflicted
  greater horn of the hyoid.      on the assailant.
  Engorgement of the root       • Finger nail clipping might
  of the tongue, oropharynx,      contain the assailant
  signs of asphyxia such as       tissues (for DNA).
  congestion, petechial
  haemorrhages, cyanosis        • In female sexual abuse
  well seen.                      should be excluded.

				
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Description: definition and causes of asphyxia and types of mechanical asphyxia and types of hanging and method of medicolegal investications and scene examination and mechanism of death.