Death& Postmortem changes

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Forensic Pathology

April 6, 2009


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Definition of Death

A person is dead if:

He has suffered irreversible cessation of circulatoryand respiratory functions

Or, he as suffered irreversible cessation of allfunctions of the entire brain, including the brainstem

Brain death:

Coma and cerebral unresponsiveness, Apnea,Dilated pupils, Absent cephalic(brainstem)reflexes, Electrocerebral silence


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Reversibility of DeathDependent upon capability of tissues torecover from anoxia

Resistance of organs variable

CNS has high sensitivity

Approx. 4-6 min. between loss ofoxygen and irreversible brain damage

With cutting edge techniques maybe 15-16 minutes

Age and temperature cause variability--u to 30 min.


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Brain DeathPhysical characteristics:

Grayish appearance, marked swelling,herniation, anoxic damage,liquefaction

Brain death changes become apparent12-16 hrs. after end of cerebralcirculation

Persistent Vegetative State (PVS)

Different from brain death

Total permanent and total destruction


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Postmortem Changes

Once dead, bodily functions cease andbody begins to break down

Circulation stops, chemical compositionof body fluids changes, digestion ends,natural bacteria in gut takes over,

animals begin to feed on body

Happens in particular order--postmortem clock

Al M i


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Algor MortisBody cools to ambient temperature

Cools at rate of 1.5o F to 2o F per hour

Skin cools fastest, and isnt used in

body temp determination

Body core temps used--rectum, liver,brain

Rate of cooling changes with clothing,body fat, air currents, immersion inwater, size


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Ocular ChangesEyes show some of the earliest

postmortem changes

Settling of rbcs in capillaries

Thin film on cornea within 2-3 minutes,cloudiness within 2-3 hours

If open, exposed areas develop tachenoire (black spot)

Intraocular fluid--dries up in about 4

days


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Vitreous Potassium

Potassium levels in the eye much higherthan potassium levels in the blood

Due to the sodium-potassium pump

After death pump no longer works, so

potassium diffuses out

Known rate:

(7.14 x K+ concentration) - 39.1 = hours since death


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Livor MortisPurplish-blue discoloration due tosettling of blood by gravitational forceswithin capillaries

May be evident as early as 20 min. after

death

Fixed after 8-12 hours


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Rigor Mortis

Right after death, muscles flaccid

Fibers in muscles bind together

Takes energy to relax

Rule of thumb: takes 12 hours to appear fully,lasts 12 hours, takes 12 hours to disappear

Variable: previous exercise, convulsions,electrocution, heat


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Cadaveric Spasm

Sometimes rigor mortis hits withoutmuscle flaccidity

Occurs in deaths preceded by great

excitement or tension

Drowning, murder

Clenched fist holding object

St h C t t


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Stomach Contents

Stomach empties at known rate

Digestive processes cease after death

Solid food empties slower that liquid

Starchy and fatty foods empty more slowly

Light meals: 1 1/2-2 hours

Heavy meals: 3-4 hours

Liquid: 1/2 hour

D iti


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DecompositionDisintegration of body tissues

During life, biochemical process preserveintegrity of cellular membranes and organelles

After death, cell enzymes leak out and

microorganisms no longer killed

Autolysis--self dissolution by body enzymes

Putrefaction--decomposition changes producedby action of bacteria and microorganisms

Anthropophagy--destruction of body bypredators


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Autolytic ChangesFirst changes occur in organs rich inenzymes

Pancreas, stomach, liver

Digestive juices present at death beginto eat away at organs

Mucosal lining no longer produced


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PutrefactionDependent upon temperature and priorhealth of individual

Gasses produced: methane, CO2,

Hydrogen, Ammonia

Environment--body exposed to airdecomposes more rapidly than in water,

which is more rapid than in soil

1 week in air=2 weeks in water=8weeks in soil


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Stages of DecompositionEarly decomposition begins after 24-30hours

Greenish discoloration of abdomen

Breakdown of hemoglobin by bacteria


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Stages Cont.Bloat--after about 3 days

Dark discoloration of face

Purging of fluids from nose and mouth


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Marbling

Ski Sli & Di l i


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Skin Slippage & Discoloration


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MummificationIf environment dry, tissues wont

decompose as readily

Skin becomes leathery, shrunken anddark

Can last in this state a long, long time

Adipocere


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AdipocereWaxy fat (grave wax)--helps preservethe body

In high humidity and temperature, bodyfats turn into clay-like, gray substance

Bacterial enzymes convert unsaturatedfats into saturated solid fats

Takes from 3-6 months to develop

Sk l t i ti


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SkeletonizationOnce all soft tissue removed, only

skeleton remains

Rate of skeletonization depends onclimate

Temperate areas: 1 1/2 years

In hot and humid areas: as little as10 days


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