8. Fire, CO and explosions Flashcards

1
Q

What is The Fire Triangle made of

A
  1. fuel
  2. oxygen
  3. ignition
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2
Q

Give examples of fuel

A

solid: wood, paper
liquid: petrol
3. gases: methane

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3
Q

Give example of ignition:

A

to start the fire off: flame, spark, hot sruface, radiant heat, chemical

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4
Q

How do people die in fire (or are injured in them)? (3)

A
  1. most common: smoke inhalation
  2. burn
  3. other injuries
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5
Q

what toxic gases are found within smoke (3)

A

a bruning fire produces a great deal of smoke. anyone alive inside will be forced to breathe it in.

the smoke contains various toxic gases:
1. CO (most people die from this)
2. cyanide
3. nitrites

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6
Q

Mechanism of action of carbon monoxide

A
  1. produced in all fires and a product of incomplete combustion
  2. toxic levels can build up very quickly
  3. breathed into the lungs and gets into blood stream where it combines with Hb to form carboxy-haemoglobin
  4. haemoglobin has a much greater affinity for CO than O2
  5. carboxy-haemoglobin is of no use to the body i.e. the cells cant use it, so decreasing levels of oxygen have serious effect
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7
Q

normal level of CO in blood and abnormal

A
  1. normal level is up to 5% particularly in cigarette smokers
  2. when levels build up to 50% or above, as in a fire, they are likely to be fatal
  3. even lower levels if person has a significant natural disease
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8
Q

evidence of smoke inhalation

A

1.soot in the airway- a lining of black soot all the way down the trachea
2. raised level of CO in the blood (makes the blood and tisses red and makes external lividity pink)

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9
Q

people tend to die from burning in one of two circumstances (time)

A

in the fire: from physiological shock (a car fire or other flashover)

later in the hospital: from fluid loss, biochemical distrubance or infection

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10
Q

list factors that determine survival of those reaching hospital (3)

A
  1. severity and extent of burning
  2. co-existing illness
  3. age
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11
Q

how do we classify burns

A

by depth and extent of burning

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12
Q

describe classification of burns by depth:

A

superficial, part thickness, deep

appereances range from: reddening of the skin -> blistering -> epidermal loss -> subcutaneous tissue loss

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13
Q

how do we evaluate extent of burning?

A

we use the rule of 9s
rough general rule:
if the age of the person + percentage burning is >100, they are less likely to survive

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14
Q

what are the possibilities of people not escaping fire?

A
  • overcome by fumes at an early stage e.g. asleep
  • intoxicated and unaware of the fire
  • physically disabled, bedridden or injured
  • did not want to, i.e. suicide
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15
Q

What are the reason a person is dead before the fire (2)

A
  1. from natural causes (and their death triggered a fire e.g. cooker or a heater left on)
  2. homicide (the person has been murdered and the house set on fire to conceal the crime)
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16
Q

List 4 questions the pathologist will consider when dealing with a body or bodies from a fire

A
  1. Who is it
  2. did they die as the result of the fire and, if so, in what way
  3. was there any reason why they did not manage to get out of the fire?
  4. if they did not die from the fire then how did they die and were they dead beforehand?
17
Q

how to check who is the victim in fire?

A

bodies can suffer severe post mortem damage before being recovered.

identification will clearly be an issue here and will require the usual methods of personal possesions, x-rays, dental and DNA

18
Q

what are we looking for when we suspect the person died as the result of fire

A

evidence of inhalation of smoke and gases CO, burning and trauma

19
Q

what are we looking for if we think that there must be a reason they did not manage to get out of the fire

A

intoxication, illness, trauma, suicide

20
Q

in what situations could we suspect carbon monoxide poisoning? (2)

A
  1. accidental (using heater or generators that are faulty or in an enclosed space - shed, tent)
  2. suicide - inhaling fumes from a car exhaust , lighting a portable barbecue set in an enclosed room
21
Q

symptoms of carbon monoxide poisoning

A

nausea, abdominal pain, headache, drowsiness, confusion, unconsciousness

22
Q

what are the most common causes of explosions?

A

in many countries bombs
in UK gas leak

23
Q

when do explosions occur?

A

when there is a sudden release of previously confined energy
- energy which has been stored either within a chemical substance or physically compressed within a container
- the release is accompanied by a lot of heat, noise and shock waves

24
Q

describe mechanical explosion

A

when pressurised material suddenly excapes in an uncontrolled way - > sudden excape of gas or liquid from a steam boiler, LPG container, coprassed air cyllinder

24
Q

List two types of explosions

A

mechanical and chemical

25
Q

Describe chemical explosions

A

when a chemical reaction produced heat and gas faster than the surroundings can deal with them

26
Q

two forms of chemical explosions

A

dispersed (combusting materials are unconfined e.g. gases, fine dust)
condensed (chemical reaction occuring in a solid or liquid)

27
Q

example of dispersed chemical explosion

A

leakage or dangerous mix of gases in a :
domestic or industrial gas supply
mine shaft or tunnel
petrol bomb

28
Q

what are the characteristics of chemical explosives?

A

they are directional rather than generalised
they have specific point of origin, meaning that the most of damage is done close to the source, and damage is less further from source

29
Q

what are 2 types of chemical explosives?

A
  1. low explosives (deflagrating) e.g. gunpowder and pyrotechnics

burning of the material in an enclosed space produces an explosion

  1. high explosives (detonating) e.g. TNT, RDX, nitroglycerine
  • where the explosion is caused by a shock wave passing through the material and disrupting its molecules
30
Q

what are 3 effects of an explosion of any type?

A
  1. physical trauma
  2. blast (pressure wave striking the body and passing through it)
  3. heat (radiation of heat causing scalding and depper burns)