Suffocation

Created by: meganjayne15
Created on: 30-04-14 09:21

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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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Suffocation

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