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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