660 mid-term exam

Davis drowning equation

human factors + environmental factors = drowning

human factors for drowning

mental health, medical condition, swimming ability, drug and alcohol use

environmental factors for drowning

water current, temperature and depth, dangerous marine life, electrical hazards and equipment failure

shallow water blackout breathing mechanism/trigger

depends on carbon dioxide (pH) and not oxygen. high CO2 triggers breathing centers in the brain (medulla oblongata)

hypocapnia (low CO2 in blood)

hyperventilation causes blood CO2 to decrease. the breathing center in the brain is not triggered and O2 level decreases to point of passing out

a body in _____ water will typically sink unless air is trapped in clothing. a body in ____ water is more likely to remain on surface or float beneath the surface

fresh ; salt

T/F: decomposition in water is slower than on land

true

rule of thumb for decomposition in different environments

1 week air = 2 weeks in water = 8 weeks in the ground

T/F: drowning is often called diagnosis of exclusion because all signs are not specific

true

autopsy findings associated with drowning

immersion changes of hands and feet (faster in warm water), sparse petechial hemorrhages, heavy lungs, foam around nose and mouth

T/F: changes only indicate that a body was in the water, not necessarily that the body drowned

true

fresh/brackish water drowning (0.5% NaCl)

hemodilution due to increased intravascular volume, electrolyte imbalance, cardiac arrhythmia

saltwater drowning (3-5% NaCl)

hemoconcentration, aspiration induced pulmonary edema

volume of the lungs at given depths

120 ccm at 1 atm. at 33 feet (2 atm) volume reduced by half (60 ccm), at 66 feet (3 atm) volume reduced by 1/3 (40 ccm), at 99 feet (4 atm) volume is reduced by 1/4 (30 ccm)

barotrauma

a physical damage to body tissues caused by a difference in pressure between a gas space inside, or in contact with the body, and the surrounding gas or fluid

what cases require an autopsy?

violent deaths (accidents, suicides, homicides), suspicious deaths, sudden/unexpected deaths without known history, death in an institution

cause of death

any injury or natural disease leading to death. examples include gunshot wound to the head, stab wound to abdomen, melanoma

manner of death

how cause of death came about. five manners are natural, accident, suicide, homicide, undetermined

mechanism of death

the physiologic derangement caused by the injury or a natural disease process which caused an individual to die. examples include sepsis caused fractured leg, internal bleeding due to gunshot wound, infection due to cancer

T/F: time of death can be determined with certainty

false

rigor mortis

the stiffening of the body after death. cold temperatures delay rigor

T/F: rigor mortis is most important to see if a body was moved after death

true

livor mortis

dependent areas resting on a firm surface will appear pale due to compression of the blood vessels preventing blood pooling

insect activity

fly eggs to maggots is about 1-2 days, maggots to pupa is 6-10 days, adults emerge in 12-18 days

adipocere

variation of putrefaction and develops in bodies immersed in water or in damp warm places

tache noire

when eyes are partly opened

body reaction to low oxygen in the air

normal concentration is 21%, 10-15% impaired judgement, 8-10% loss of consciousness, <8% death

burking

traumatic asphyxia combined with smothering

suffocating gases

these gases are not toxic by themselves, death caused by displacement of oxygen

T/F: it is not necessary to block the airways in strangulation, blocking the neck vessels are enough to cause death

true

pressure to occlude

carotid arteries 11 lbs, vertebral arteries 66 lbs, jugular veins 4.4 lbs, trachea 33 lbs

T/F: petechiae is not seen in complete suspension

true