Heat, electricity and cold Flashcards
(10 cards)
Heat:
Local effects: - to the skin
- Dry - burn - mostly on hands and forearms - moist - scald (hot water, steam)
Systematic effects:
- Direct effects not relevant - Indirectly can cause death - hot weather - old ppl
Medicolegal importance of burns/scalds:
- Accidental v inflicted v negligent
- Can be serious and sometimes fatal injuries e.g children and old ppl
- Common issues = causation, how long burn took to occur
Time needed:
- Normal body temp = 37
- If exceeded by 7 degrees = burn if applied long enough (as low as 44)
- Time halves each degree
- 60 degrees only a few seconds
Classification:
Severity:
- 1st degree = reddening and blistering
- 2nd degree = destruction of skin
- 3rd degree - destruction of soft tissue
Extent:
- Rule of nines
- Body is divided up into areas that occupy 9% of body e.g head = 9, each leg = 18, genitals = arm = 9, front and back = 18
- Determines how patient = treated, most common = fluids given
- Mortality = larger surface area born, higher mortality
Scalds:
- Liquid - 55 degrees
- Similar to burns but no charring
- Reddening blistering
- Fluid levels
- Effect of clothing - if absorbent, worse, if waterproof then better
- Children most often effected
Fires:
Very variable - heat, smoke, explosion
Causes of death:
- Smoke inhalation - carbon monoxide poisoning
- Heat and flame
- Fluid loss from burns
- Infection from burns or pneumonia
Trachea = full of soot if alive as breathing smoke in but if dead then no black inside
Smoke:
- Carbon dioxide in house fire makes up 0.5-2% of air but lethal gas, binds to hemoglobin
- CO + Hb –> COHb (doesn’t carry oxygen anymore)
- Car exhaust fumes - 5% CO but very difficult now to die from this now
- Hydrogen cyanide - normally in furniture but regulations now = not common
- COHb changes colour of body - pink
70-80% death
60% coma
40% Convulsion, stupor
20% Breathlessness, confusion, instability, nausea, vomiting
10% Headache e.g. traffic
5% Symptomless - normal smoker
0% Non smoker
Electrical injury:
Establishing the diagnosis = impossible/difficult as not very common and leaves very little marks on the body
Local effects:
- Burns - Skin = electricity insulating - resistant
- Blister
- Spark burn
Systematic injury: (electrocution)
- Usually cardiac arrest
- Most important factor = current
- Time current passes
- Route of current - don’t want it to go through your heart
- 10mA - pain and twitching - 30mA - muscle spasm - issue = hand can grip what is electrocuting you - 50mA - ventricular fibrillation - AC > DC - arrhythmia
Thick dry skin = more resistant than wet skin
Lightning:
- Duration: 0.001 seconds and 10 - 20,000 amps
- 1/3 ppl killed
- Electrocution, burns, explosions, eats, eyes, unconscious
Hypothermia:
- Local effects - frost bite
- Systemic effects - hypothermia - core body temp 35 or below
- Exposure to cold
- Alcohol/drug - blood vessels dilate
- Natural disease - underactive thyroid
- Impacts young infants, young adults or the old
- Maintenance of body temp controlled by brain
1. Vasoconstriction in skin and muscles - body constricts blood vessels, redirects to central part of body
2. Shivering - designed to generate heat
Medicolegal issues:
- Misdiagnosis of death
- Negligence - e.g. nursing homes
- Bizarre behaviour - hallucinations e.g. feel hot so take off clothes
Post mortem findings:
- Red patches on trunk and limbs
- Acute pancreatitis
- No findings - if dies quickly from hypothermia
- Gastric ulceration/haemorrhage
