Medicine - effects of injury

Question 1

Effects of physical injury - local damage

Answer 1

o Disruption of tissue
 Scraping
 Squashing
 Twisting

o Interruption of function
 Strangulation
 Traumatic asphyxia

Question 2

Effects of physical injury - haemorrhage - forensic issues (susceptibility, cause of death, cause for incapacity, contamination of scene and assailant)

Answer 2

o Forensic issues
 Susceptibility
* Bleeding limited mainly by blood clotting
* Blood clotting relies on two systems
o Platelets from bone marrow
o Clotting factors from the liver
* Increased susceptibility
o Liver disease (cirrhosis)
o Bone marrow disease (leukaemia)
o Medications (warfarin, aspirin)
 Cause of death
* Dangerous sites
o Intracranial – inside the head (does not need to be large amount of blood loss due to location)
o Airway – unconscious and so do not have usual protective mechanisms to prevent this
o Pericardial sac – protective sac around heart to protect it – if blood accumulates rapidly in sac, the heart cannot expand to allow blood to flow in and stops functioning
* Volume lost
o Volume lost = internal + external haemorrhage
o Heavy bruising and broken bones causes large volume lost
o Large volume lost if stabbed in heart
o Large volume lost if elderly
* Speed of loss
o Quicker if elderly or damage to heart
* Medical measures taken
o Delayed death
 Hypoxic/ischaemic brain injury
 Kidney failure
* Lack of blood/oxygen supply leads to failure in other organs
 Other organ damage
o Unclear causation
 Cause for incapacity
* Clinical assessment
o Normal -> Hypotensive (increase blood pressure) -> Shock
o Shock – causes organ damage or death
* Blood loss = internal + external
* Incapacity is not going to immediate if relying on blood loss
 Contamination of the scene and assailant
* Something hits blood scene surface hard causing blood splatters
* Arterial bleeding – e.g. quirts of blood up walls
* Blood stained shoe – usually from heavy bleeding or kicking victim
* Assailant likely to be covered in blood

Question 3

Effects of physical injury - infection (local, distant, forensic issues)

Answer 3

o Local
 At the injury site
 Treatment of infection
* Debridement – removal of dead tissue or dirt to minimise infection
* Antiseptic – clean injury to remove dirt
* Dressings – protect injury from environment and bacteria
* Antibiotics - If necessary if significant risk of infection or infection has already occurred
o Distant
 Pneumonia
* Likely to occur in people who had previous health concerns before injury e.g. elderly
 Urinary Tract infection
o Forensic issues
 Infection could be cause of death (especially if delayed)
 Would not cause death immediately
 Previously – year and a half after event occurs, the death could not be linked to original injury
 Now – can go back to original injury even years later to prove injury and caused death

Question 4

Effects of physical injury - embolism (Definition, forensic evidence)

Answer 4

o Embolism – process
o Embolus – noun
o Definition
 Something floating in the blood from one place to another lodging then blocking a vessel
o Forensic relevance
 Common after trauma
* Trauma causes death weeks later but still possible to link death with trauma
 Common after blood clot
* E.g. from flying in aeroplane
 May be fatal
 May be delayed (thrombus)

Question 5

Thromboembolism (4 points and process)

Answer 5

• Blood clot – reduced blood flow in vein
• If had trauma to body and have been bleeding, body will clot blood faster – this could be fatal if blood clots in wrong places and blocks veins
• Risk is if blood clot moves and ends up in heart and then is pumped to lungs, it then splits and gets stuck
• Usually occurs 14 days after trauma

Process
Any tissue injury - increased blood coagulability - thrombosis of deep calf veins - embolism to pulmonary arteries - sudden death or infarct
Immobility - decreased blood flow in leg - thrombosis of deep calf veins - embolism to pulmonary arteries - sudden death or infarct

Question 6

Fat embolism (5 points)

Answer 6

• Fat released from site of fracture or soft tissue crush injury
• This then travels through blood vessels to the lungs
• It then enters systemic circulation
• Then effects brain, kidneys, skin and heart
• Not common – requires multiple fractures bones to occur e.g. jumping from heights causing major trauma

Question 7

Air embolism (causes, volume needed, effect)

Answer 7

• Causes
  o Opening of neck vein (from trauma or surgery)
  o Higginson syringe (type of abortion technique)
  o Blood transfusion (air bubbles in blood)
  o Deep-sea divers (air crushed into the solution comes out and forms bubbles in the blood)
• Volume needed
  o >100ml air needed for this to occur
• Effect
  o Fills right atrium and ventricle – air lock

Question 8

Foreign body embolism

Answer 8

• IV drug users
  o Injecting things that are not meant to be intravenous e.g. crushing and dissolving tablets and injecting them
  o This blocks blood vessels
• Other rarities