Thermal Injuries/deaths In Fires, Blast Injuries, Mass Fatalities, Electrical Injuries

Front 1

Statistics on fire injury in US

Back 1

-4000 house fires/year, 80% are accidents
-Third most common source of fatal unintentional injury in US in ages 1-10
-House fires is most common circumstance

Front 2

Individuals most at risk for fire injuries

Back 2

Children and elderly

Front 3

Circumstances of thermal injury

Back 3

-House fires (cigarettes, candles, kitchen equipment, ignition of clothing)
-Vehicle fires with or without collision
-Explosion-related fires
-Flammable liquids
-Scalds
-Other: microwave, chemical, radiation

Front 4

How do fires kill?

Back 4

-Inhalation of gases, including carbon monoxide and oxygen-depleted air
-Some nitrogen-containing materials (synthetics) liberate cyanide when burned
-Burns

Front 5

First degree burns

Back 5

-Superficial and epidermis only (sunburn)
-Redness
-Edema
-No blistering

Front 6

Second degree burns

Back 6

-Deeper penetration involving epidermis and dermis with blistering
-Most painful

Front 7

Third degree burns

Back 7

-Full thickness of skin
-Collapsed blisters
-Skin sloughs off
-Red-brown color
-Will require grafting
-Nerve destruction may make less painful

Front 8

Fourth degree burns

Back 8

-Charring with tissue loss
-Looks like charcoal
-Usually will not be saved

Front 9

Carbon monoxide

Back 9

-Chemical asphyxiant
-Gas resulting from incomplete combustion of carbon-containing materials
-Binds to blood hemoglobin over 200% more avidly than oxygen, so that oxygen carrying capacity of red blood cells is disrupted
-Older vehicles, faulty heating systems, and cigarettes all produce significant amount of CO

Front 10

Case study: Singed nares, no soot in airways

Back 10

Flash fire caused by smoking with an oxygen tank on

Front 11

Case study: Soot in airway, tracheal bifurcation

Back 11

Smoke inhalation

Front 12

Skin splitting

Back 12

-Artifact of a fire, not antemortem injury
-Usually occurs parallel to muscle fibers

Front 13

Level of CO causing death

Back 13

Varies with age and health

Front 14

Level of CO for visible cherry red coloration of skin

Back 14

Generally about 30%

Front 15

Situation where there is little or no CO, but suffocation occurs due to consumption of oxygen in air

Back 15

Very hot or flash fire

Front 16

Back 16

-Used to determine what percentage of body is burned
-Second degree or above

Front 17

Baux score

Back 17

Age + Percent surface area with second degree or worse burns = percent mortality

Example: 50 year old with 20% BSA burns has 70% likelihood of dying

-Less accurate today with burn center treatment
-Does not take into account inhalation

Front 18

Range of changes seen in acute fire deaths

Back 18

-Soot deposits
-Skin slippage
-Heat fixation: pugilistic posture
-Tissue splitting
-Charring
-Heat fractures mimic blunt trauma
-Inhalation changes: soot in nares and lower airways, cherry-red liver and internal organs

Front 19

What is standard in an autopsy of decedents with severe burns? Why?

Back 19

-Full body radiographs
-Identification purposes (teeth, bone structures)
-To locate foreign objects (i.e., bullets)

Front 20

Case study: 78 year old female found on metal frame of chair in room of house mostly charred by fire. Cigarette butts around and under decedent. Autopsy showed no soot in airways.

Back 20

Death of natural causes and cigarettes cause fire after death

Front 21

Case study: 31 year old driver of a vehicle that struck two cars before overturning. Vehicle caught fire before driver could be rescues. No soot in airways. Autopsy showed surface charring and partial pugilistic posture, extensive skeletal fractures with hemorrhage, spinal cord transection. Tox shows 0.36 PCP and less than 10% of CO

Back 21

Died before the car caught on fire (because of no soot in airways)

Front 22

Time to injury with scald burns

Back 22

-Inversely related to water temperature
-10 minutes to full thickness at 120 degrees F
-30 seconds at 130 degrees F
-7 seconds at 140 degree F

Front 23

Scald burns indicating child abuse

Back 23

-When a child is placed in hot water, they will reflexively retract their legs, so you will see a certain burn pattern
-Sparing of back of knees

Front 24

Manner of death in fire deaths

Back 24

-Dependent on outcome of police/fire investigation
-How did fire/thermal injury occur?
-Accident
-Suicide
-Homicide (arson)

Front 25

DNA recovered from fire scenes

Back 25

-DNA survives high heat
-What looks like a useless burnt item may contain recoverable DNA evidence

Front 26

Thermal body changes in fire deaths may occur...

Back 26

-Before or after death
-May mimic injury such as blunt trauma and also may obscure injuries

Front 27

An important contributor to mortality

Back 27

Inhalation injury

Front 28

An important question the autopsy of a fire death may answer

Back 28

Was the decedent alive during the fire?

Front 29

_______ is often critical to determining manner of death and should be pursued vigorously from outset

Back 29

Body identification

Front 30

Definition of explosion

Back 30

-Chemical conversion of solid or liquid to a gas and resulting rapid release of energy
-Characterized by "positive pressure wave" that causes blast injury

Front 31

Explosion events with a high likelihood of multiple fatalities

Back 31

-Bombs
-Vehicles
-Vehicles driving into gas lines
-Suicides
-Trapped gas in homes, mines, etc.

Front 32

Primary blast injury

Back 32

-Occurs when energy from an explosion (positive pressure wave) acts on body
-Greatest injuries are to gas-filled structures

Front 33

Categories of blast injuries

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-Primary
-Secondary
-Tertiary
-Quarternary

Front 34

Categories of propagation of blast

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-Air blast
-Water blast
-Solid object in contact with body (steel deck, concrete floor)

Front 35

Injuries caused by air blasts

Back 35

-Characteristic "blast lung"
-Eardrum
-Retinal hemorrhages; secondary air emboli due to lung injury

Front 36

Injuries caused by water blasts

Back 36

-Lacerations of gastrointestinal tract
-Lacerations of urinary bladder

Front 37

Injuries caused by steel/concrete floor from subadjacent/adjacent explosions

Back 37

Simulate injuries from feet-first falls

Front 38

Secondary blast injury

Back 38

-Impact by flying objects propelled by blast
-Radiographs helpful in documenting foreign objects in body

Front 39

Tertiary blast injury

Back 39

-Acceleration/deceleration as body is thrown
-Similar to blunt injury of falls from height

Front 40

Quarternary/miscellaneous blast injury

Back 40

For example, building collapse

Front 41

Role of medical examiner in mass fatality events

Back 41

-Examine decedents
-Identify, document and collect evidence in/on bodies
-Determine and issue opinions on cause and manner of death
-Identify decedents
-Release bodies

Front 42

During a mass fatality event, the __________ continues at the medical examiner's office.

Back 42

Usual case load (role of D-MORT)

Front 43

D-MORT

Back 43

-Disaster Mortuary Operational Response Team
-Specialized personnel activated as temporary federal employees to assist local medical examiner/coroner; multidisciplinary as needed
-Provide victim identification and mortuary services: temporary morgue services, victim identification, forensic dental, pathology and anthropology, processing, preparation and release of remains

Front 44

Types of contaminated/hazardous remains

Back 44

-Radiation
-Microbial pathogens
-Toxins
-Chemicals

Front 45

Considerations while working with contaminated/hazardous remains

Back 45

-Use universal precautions
-Wear protective gear, decontamination procedures required vary
-Potential dangers to public, OCME and other agency personnel, funeral homes/families on release
-Limitation of autopsy: weighing need for evidence/documentation against risks to investigators, limited resources
-Perform “Index case”: full autopsy followed by limited exams with radiology of others
-Both real and perceived dangers of concern

Front 46

Electrocutions

Back 46

-Traditionally divided into low (less than 1000V) and high voltage
-Low voltage kills by ventricular fibrillation
-Sometimes, if there is prolonged contact with low voltage, death occurs due to muscle paralysis or asphyxia
-High voltage kills by cardiac arrest or electrothermal injuries

Front 47

Voltage range of lightning

Back 47

10-100 million V

Front 48

Voltage range of house wall outlets

Back 48

110 to 120 V

Front 49

Voltage range of third rail in Metro

Back 49

600 V DC

Front 50

Voltage range of electric chair

Back 50

2000 to 2200 AC @ current of 7-12 amperes

Front 51

Ohm's law

Back 51

-States that the current through a conductor between two points is directly proportional to the potential difference across the two points
-As resistance falls at a given voltage, current flow increases

Front 52

Injuries from low voltage electrocutions

Back 52

-Low resistance will show non-specific findings to subtle burns
-High resistance will show classic burns

Front 53

Injuries from high voltage electrocutions

Back 53

-Scorching of clothing/hair
-Dramatic burns
-Metal effects
-Arcing occurs and greater than 350 V
-Lichtenburg figure

Front 54

Lichtenberg figure

Back 54

-Transient characteristic mark in lightning injury
-Fern-like pattern
-Red mark on skin of unknown cause
-Usually appears after one hour and disappears after 24 hours

Front 55

Accidental electrocutions

Back 55

-Work/industrial settings
-Autopsy finding subtle in low voltage deaths involving low resistance skin
-High risk to fetus

Front 56

Scene investigation and reconstruction steps taken at an accidental electrocution

Back 56

-Evaluate danger and notify utility
-Examine clothing
-Examine/collect appliances involved

Front 57

____, _____ skin has higher resistance and exhibits more injury.

Back 57

Dry, thick

Front 58

Current of electrical weapons (taser, stun gun)

Back 58

Approximately 50,000 V, 2 to 10 milliamps

Front 59

TASER

Back 59

-Compressed nitrogen firing of two metal probes with insulated wires 15 or 21 feets long
-Can go through clothing but each probe must make contact
-Autopsy will show paired punctures

Front 60

Stun gun

Back 60

-Electrodes must be held against subject
-Autopsy will show paired red marks

Front 61

Are lightning strikes survivable?

Back 61

Yes (less than 50% are fatal)

Front 62

An inhaled substance responsible for many house fire deaths is _____. What physical finding may it cause?

Back 62

Carbon monoxide. Cherry red color in CO levels of about 30%.

Front 63

Cyanide

Back 63

Dangerous inhaled substance liberated in some fires