Suffocation

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  • Suffocation, Asphyxia and Fatal Pressure on the Neck
    • Asphyxia
      • pressure on the neck associated with cardiac arrest
      • absence of pulsation.
    • 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 (mouth and nose) 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
    • terms to know!
      • suffication
        • general term used to indicate death from lack of oxygen
      • smothering
        • indicates blockage of the external air passages
      • gagging
        • fabric or adhesive tape occludes the external passage
          • the device will admit air at first but as it gets soaked with saliva or mucus asphyxia occurs
      • choking
        • refers to blockage of the upper air way
          • between the larynx and primary bifurcation of the main bronchus
      • throttling
        • refers to strangulation usually by hand
      • strangulation
        • the use of either hands or ligature as a means of applying external pressure to the neck
    • signs of asphyxia
      • petechial hemorrhages
        • small pin point collections of blood lying in the skin
        • occur from ruptured venules
        • usually appear on face and eyes
        • also known as Ocular Petechiae
        • must be noted but not always an indicator to asphyxia
          • used in conjunction with other evidence to indicated asphyxia
      • congestion and edema
        • result of obstructed venous return
        • congestion is associated with tissue swelling and often times be associated with trauma
        • pneumonia can also lead to marked pulmonary edema (fluid in the lung)
        • drug overdoses are common causes of raised pulmonary edema (fluid in the lung)
      • cyanosis
        • constriction of the neck traps venous blood with decreased oxygenated hemoglobin - blood turns a bluish colour
          • skin appears blue when the tissue close to the surface has low oxygen saturations
        • the colour of blood depends on the quantity of oxyhemoglobin and reduced hemoglobin present in the red blood cells
        • may be overshadowed by hypostasis
          • Hypostasis: the accumulation of fluid or blood in the lower parts of the body or organs under the influence of gravity, as occurs in cases of poor circulation or after death.
    • Traumatic asphyxia
      • refers to mechanical fixation of the chest.
      • shows evident signs of classical asphyxia
        • face and neck grossly discoloured
        • eyes and sclera (white part of the eye) are engorged with blood - obliterates the whites of the eys
    • Manual strangulation
      • common method of homicide
        • commonly seen in domestic homicides or sex related homicides
          • features of sexual asphyxias
            • production of cerebal hypoxia - reduced supply of oxygen to the brain
              • constriction of the neck by ligature which can be tightened or loosened when the individual wants too
              • malfunctions in this can lead to accidental ligature deaths
              • plastic bag over the head is commonly used in these situations
      • associated with power and size of assailant
      • rarely committed by women unless committed on a child
      • bruising may be visible internally
    • Postural asphyxia
      • closely tied to traumatic asphyxia
      • person in a certain position long enough to stop respiration.
        • i.e. being trapped, drunken or drugged state or mechanical impediment
    • Mechanical asphyxia
      • death is obscure
        • catecholamine-induced cardiac arrhythmia
          • exaggerated adrenal response
        • usually occurs when a struggle has happened between a drunken or drugged offender and a sober offender
    • strangulation by ligature
      • cords, wires, ropes and some belts are strong enough to cause death
      • a u shaped ligature is often sufficient to occlude the airway
    • 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.
      • suicidal or accidental?
        • death is most often caused by relfex cardiac arrest from pressure on the carotid structures
          • victims have pale faces rather than congested faces

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