Notes :
Classification
Mechanical asphyxia
Pathological asphyxia
Toxic asphyxia
Environmental asphyxia
iatrogenic asphyxia
Mechanical asphyxia
Suffocation
Hanging
Strangulation
Sexual asphyxia
Drowning
Biochemistry of asphyxial death
Low PO2 , High PCO2
pH decreased
increased Blood sugar
Na+ decreased , K+ increased
Suffocation
Smothering
Gagging
Choking
Hangin
Types of hanging
On the basis of knots
Typical
Atypical
On the basis of degrees of suspension
Complete hanging
Partial hanging / incomplete hanging
Pressure needed to occlud neck structure
Jugular veins -4.409 lb ( 2kg )
Carotid artery - 11 lbs ( 4-5 kg )
Trachea - 33 lbs ( 15 kg )
Ligature marks
Type
Site
Knot
Direction
Strangulation
Ligature strangulation
Throttling
Mugging
Bansdola
Garroting
Drowning
Typical
Atypical
Secondary
Time since death from drowning
A waterproof wrist watch.
Cooling rate is twice as high compared to air.
Rigor mortis sets early.
Wrinkling of skin
Bleaching of cuticle
Sodden appearance of epidermis.
Floating of the body.
Body infested with fleas and lices.
Putrefactive changes.
Skin of the hands and feet loose and peels like gloves and stocking.
Asphyxial Deaths
Asphyxia can be many types based on etiology such as mechanical , pathological , toxic , environmental , and iatrogenic.Death is caused by unavailability of the oxygen to the different vital organs of the body for a longer period of time.fatal asphyxiation can be divided into different phases. In the first phase , due to lack of oxygen respiratory drive overexcited causing the respiratory center to increase both rate and depth of respiratory movement.Cyanosis starts to appear.
In the second phase , the body struggles to breath and the cyanotic areas also increases.The neck veins appear to be engorged and generalised congestion and petechial hemorrhage starts to appear.The patient will have altered sensorium and eventually get unconscious.
In the third phase which is unconscious , the breathing becomes shallow and irregular which leads to coma and eventually death.
During the course of asphyxiation, The partial pressure of the oxygen is reduced and the carbon dioxide accumulates in the blood . This leads to acidosis , decreased blood sugar , hyponatremia and hyperkalemia.
There are non specific pathological changes that can be seen in a victim who died of asphyxia. The skin appears red due to obstruction of the venous drainage, edema can be seen due to transudation of the fluid from the veins. Cyanosis and petechiae will be seen.
For a forensic science , pathological changes like signs of compression as in hanging , strangulation & throttling , blockage of mouth and nose as in smothering , presence of foreign body as in choking , flooding of airways in drowning , penetrating or non penetrating trauma on the chest are of medicolegal important aspects.
Suffocation
It is manual obstruction to the air passage caused by closure of external orifices of nose and mouth causing unavailability of Oxygen to the lungs.It is of two types:
a. smothering
b. Gagging
c. Choking
Smothering is defined as closing of air passage externally by hands or by soft materials.this eventually leads to anoxic anoxia leading to asphyxiation of the victim.It can be either accidental which can be seen in infants and children where mother presses the child too closely to the breast, hands or bodies leading to asphyxiation of the babies . The other type is accidental where alcoholics bury their face in a soft bed in an inebriated state of mind. It can also be seen with epileptic patients. In case of homicides , signs of Nail scratches , abrasions , bruises , lacerations of the soft part of the face can be seen. Lips and gums may show lacerations or bruising. Bruising on the inner aspects of lips from pressure against the teeth can be seen in homicidal smothering. But the signs of violence are absent when clothes,soft material or pillow is used. Autopsy may reveal edema , congestion and petechial hemorrhage in the lungs.
Gagging is stuffing of the mouth with a cloth or with any soft material.gag blocks the mouth and also prevents the entry of air through the back of the throat coming through the nostrils which leads to pharyngeal obstruction. Autopsy findings depend upon struggle to death. There may be present Traces if material in the mouth between the teeth. Mucosal bruising , abrasions or lacerations can be seen on the lips , soft palate and in the pharynx.
Choking refers to internally blockage of upper respiratory tract by some solid or semisolid material.The victim dies any one or the constellation of the mechanism like anoxic anoxia , reflex cardiac arrest due to vagal inhibitions as seen in Café coronary syndrome or laryngeal spasm.It is seen in children mostly , and victims like alcoholics , mentally ill or intoxicated person. It can be iatrogenic as seen in dental procedures , tracheotomy.
Hanging
Hanging is constriction of the neck by a ligature with force generated by the weight of the body. It can be either complete hanging where feet do not touch the ground or partial hanging when feet touches the ground and constriction is caused by weight of the head and partial body weight. Death is caused by cerebral congestion due to compression of jugular veins , cerebral anoxia due to compression of the carotid arteries and eventually leads to hypoxic hypoxia , reflex cardiac arrest due to compression of carotid sinus or the vagus nerve.The tongue base may be pressed against the palate. In judicial hanging , fracture displacement of the third and fourth cervical vertebrae results in injury to the spinal cord and eventually death. Autopsy reveals stretched neck, congestion of face ,head and neck , petechial hemorrhage , cyanosis of the lips,nose and fingers. The tongue may be dry , protruded and bluish or black. Postmortem lividity can be observed. Ligature marks can be seen with the object used to compress the neck like rope ,wire etc. Patterns of the ligature imprinted on skin as pressure abrasion is called mirror image phenomena. The edges are often congested and hyperemic. The head is inclined opposite the knot. Autopsy reveals fractured hyoid Bone , laryngeal cartilages and hyperemic trachea , epiglottis and lymph nodes. In antemortem hanging , there are abrasions , vital reactions and areas of hyperemia and ecchymosis. But in suicidal hanging ,signs of struggle are absent and often the place is locked inside and with a suicidal note. Other types of hanging includes
Judicial Hanging
Auto erotic hanging
Strangulation is violent asphyxia which is caused by constriction of the neck by some means other than neck. It can be various types : Ligature strangulation , throttling , mugging ,Bansdila , garroting. Autopsy reveals cyanosis , visceral congestion , petechiae, swollen protruded tongue may be bitten, bleeding from ears and raised body temperature.
Throttling is constriction of the neck by another person with one or both hands . Death is similar to hanging except there are rarely broken bones. Fingernails' impression can be observed with bruises . The lymph nodes surrounding shows hemorrhage on cut section.Injuries can be seen to the cervical tissue.
Drownings
It is involved by flooding the airways with fluid . Thr fluid may be water , oil z ll, dye , chemical solution.
It can be of following types :-
Typical (wet type)
Atypical (dry)
Death is caused by laryngeal spasm but not by water into the lungs. The death is instantaneous.
Types - Dry drowning , immersion syndrome ( vagal inhibitions) , submersion of unconscious
Secondary
Person was survived and died due to complications like Metabolic acidosis , hypoxic encephalopathy , chemical pneumonitis , severe infections.
Signs of drowning
Fine froth can be seen at mouth and nostrils however it is absent in dry drowning. There is presence of weed , mud tightly clenched hands ( instantaneous rigor ) cadaveric spasm) , goose skins( cutis anserina)
, Sodden & wrinkled feet and hands.
Autopsy reveals changes in the lungs like ballooning of the lungs , impression of ribs on the lungs and Tardieu spots on the subpleural hemorrhage due to rupture of the walls , foreign materials in the lungs and regurgitated food particles.
In the heart , large veins are distended. Stomach may contain water . In dead bodies , it is not possible for water to get beyond the cardiac sphincter into the stomach and intestine .
There is hemodilution , decreased viscosity of blood and RBCs lysed and chloride content of the left heart side is decreased while they are reversed in salt water drowning.
In getter's test , the chloride content of the ventricles changes 25 mg/100 ml ( normal 600 mg / 100 ml) .
Diatoms can be seen in femoral or sternal bone marrow .