10. Asphyxia Flashcards
What is asphyxia
Asphyxia describes the situation in which the body is being deprived of oxygen.
Either no air, or insufficient air, is getting into it, resulting in a lack of oxygen to the brain
it occurs when there is an obstruction at the stage of oxygen getting into the lungs -> mechanical obstruction to breathing
List 5 causes of asphyxia
- no oxygen in the air - environmental
- pressure on the chest - crush asphyxia
- blockage of the nose and mouth (suffocation)
- constriction of the neck - strangulation, hanging
- blockage of internal airways - chocking, inhalation
examples of environemntal asphyxia
container, the hold of a ship, a mine or a tunnel where the air has perhaps beem slowly replaced over time by methane
examples of individual and multiple victim crush asphyxia
crush asphyxia occurs due to heavy weight on the chest and chest cannot expand
- individuals:
- accident at work, under machinery or a vehicle
- road traffic accident when the vehicle overturns
- avalanche of snow or sand - multiple victims
- crowds collapsing or stampeding e.g. football matches, pop concerts, religious festivals etc.
what is a positional/postural asphyxia?
when the breathing becomes compromised by lying in an awkward position
usually in people intoxicated by alcohol or drugs who fall asleep upside down or slumped over furniture
what is suffocation and what are its 3 forms
suffocation is a blockage of the mouth and nose, preventing any air getting into the body
1. accidental
2. suicidal
3. homicidal
describe constriction / compression of the neck (4)
here the constriction o all internal structures of the throat occurs: both airways and vessels
constriction of larynx prevents air entry,
constriction of carotid arteries stops blood flow to the brain
constriction of jugular veins stops venous drainage from the head
constriction of vagus nerve can trigger cardiac arrest
describe in short hanging
most common suicide mode
death probably due to compression of carotid arteries and direct pressure on the larynx, not due to a broken neck
ligature can be a rope, belt, clothing, dog leash, shoelaces, sheet etc..
what are 2 forms of strangulation
- ligature strangulation- compressing the neck by tightening an item around it e.g. rope, clothing, belt
- manual strangulation - compressing the neck by a hand(s)
blockage of internal airways 3 causes
- gagging - items stuffed into the mouth (.e.g robbery to keep quiet)
- choking - food impacting larynx, blocking it and usually triggering a cardiac arrest
- inhalation of vomit or other items
how do we recognize asphyxial deaths - in either living or death?
we look at general asphyxial signs and specific signs
- general signs include those that are common to different types of asphyxia and when we see them, we should at leas consider that the person may have suffered some form of asphyxial event
- congestion of the face
- cyanosis
- petechial hemorrhages
specific signs for environemntal asphyxia
typically, no asphyxial signs and no specific signs - diagnosis of exclusion
specific signs of crush asphyxia (5)
- intense congestion
- cyanosis
- petechial hemorrhages in the face and neck
- external injuries on the chest (abrasions, bruising)
- internal injuries (fractured ribs, damage to the lungs)
specific signs of suffocations in suicide and homicide
- suicide - no physical evidence apart fromt e findings at the scene
- homicides - minimal asphyxial signs (important in potentially smothered babies), there could be injuries inse the mouth from struggling
specific signs of asphyxia in hanging (2)
- ligature mark on the neck - deep groove with friction abrasion that runs upwards at angle on both sides and is not complete all around (unlike ligature strangulation)
- pale face
