Module 6: Forensic: Asphyxia to end

Question 1

What is asphyxia?

Answer 1

Interference with the uptake or utilization of oxygen

Question 2

On type of asphyxia is hanging or strangulation which involves compression of the neck, what happens when the airway is occluded?

Answer 2

Arrest of arterial supply to brain and obstruction of venous return from brain

• -generalized cerebral edema (vasogenic edema) due to inflammatory disruption of the BBB with increased vascular permeability
• -cardiac arrhythmia via stimulation of carotid baroreceptors (carotid sinus reflex)

Question 3

During hanging or strangulation the patient will get petechiae why?

Answer 3

From post cap venules from acute rise in venous pressure

Question 4

In strangulation there is direct pressure on the neck manually or with ligature, who is the most common victim?

Answer 4

Female and usually sexual motive

Question 5

The next type of asphyxia is obstruction of airway due to smothering/choking or postural asphyxia, what is postural asphyxia?

Answer 5

Kinking or compression of airway by position of victim and inability to change position

Question 6

What are the last two types of asphyxia?

Answer 6

Compression of chest: traumatic or mechanical asphyxia

Exclusion of oxygen: local depletion of oxygen

Question 7

What is the mechanism of hydrogen sulfide?

Answer 7

inhibits cytochrome and reduction of oxyhemoglobin — methemoglobin
detergent suicides: H2S generated by mixing household chemical – hazardous to first responders

Question 8

What percentage of O2 intake is lethal?

Answer 8

less than 8%

8-10% = LOC

Question 9

H2S in inspired air, what are the effects?

Answer 9

Low = rotten egg odor and irritation 
150ppm = paralysis of olfactory nerves 
1000-2000ppm = rapid death

Question 10

There are asphyxial games, what is the motivation for these/

Answer 10

Euphoria through hypoxia

Question 11

What are the various methods for asphyxial games?

Answer 11

Manual strangulation
Ligatures
Chest compression

Question 12

What is the age group for asphyxial games?

Answer 12

Older children and adolescents (7-21 yr old)

–alone or in groups

Question 13

What are features of asphyxial games?

Answer 13

Headaches, unexplained bruising around neck, blood shot eyes, facial petechiae, disorientation after being alone, ligatures tied in strange knots or unusual places, wear marks on furniture

Question 14

Move on to electrics, what is electricity, voltage, resistance, and current?

Answer 14

Electricity: produced by stream of electrons flowing through a conductor

• -voltage: electrical pressure that causes current to flow
• –resistance- resistance to flow
• -current= rate of flow

Question 15

What is the requirements for electrocution?

Answer 15

Charged source, current path through vital organs and ground

Question 16

What is the mechanism of death in direct electrical effects, thermal burns, and blunt force injuries?

Answer 16

Direct electrical effects: Vfib, asphyxia (paralysis of resp muscles) and direct disruption of brainstem
Thermal burn: heat, ignition of clothing
Blunt force injuries: falls and blast effect

Question 17

What is the gross appearance of low voltage electrical burns?

Answer 17

May not be present

• -typical crater with central charring, abrasion like, second or third degree thermal burn
• -shape of conductor may be branded into skin

Question 18

What is high voltage electrocution?

Answer 18

3rd degree electrical burns
2nd degree contact burns 
Arcing "splash" electrical burns: bright fast traveling sparks with rhythmic cracking sound 
Skeletal fractures 
Asphyxia
Vascular thromboses 
Myocardical injury

Question 19

Compare high and low voltage

Answer 19

Low voltage: less than 600 to 1000 volts, small burns in 50%, less CNS injury, lag time and Vfib
High Voltage: greater than 600 to 1000 volts, extensive burns, more CNS injury, immediate effect, asystole/asphyxia

Question 20

What is lightening?

Answer 20

Negative charge build up in clouds vs positive charge of earth

• -10,000 to 100,000 amps DC
• -high voltage of short duration
• -high heat

Question 21

What types of burns do you get with lightening?

Answer 21

Serious burns infrequent b/c of short duration
Contact burns from metal objects
Ignition of clothing

Question 22

What is the shockwave/blast effect?

Answer 22

Shredded clothing
Tympanic membrane rupture
Secondary trauma

Question 23

What are Lichtenberg’s figures?

Answer 23

Fern-like aborescent, dendritiform, evergreen tree, keraunographic markings

• -5:30 cm long along BV
• –local hemolysis due to heat generated by current flowing through cutaneous blood vessels
• -may be transient
• -also in high voltage electrocution