Death and Postmortem Changes

• Presented at Misr University for Science & Technology's College of Medicine
• Topic is death and postmortem changes
• Presented by Ass. Pr. Sarah Khater

Pretest Topics

• Diagnosis of death
• MLI of post-mortem changes

Intended Learning Objectives

• Describe different phases of death
• Discuss molecular life
• List the diagnostic criteria for somatic death
• Discuss accurate tests for diagnosis of brainstem death and their application conditions
• Explain the medico-legal importance of diagnosis of death
• Discuss persistent vegetative state and its medico-legal importance
• Discuss sudden death and its different possible causes
• Realize the importance of accurately diagnosing death to avoid burying a patient in a coma
• Realize the value of accurately determining proper disconnection time from ventilators and life support
• Realize the importance of differentiating sudden death from unnatural death/natural death cases to notify authorities

Death Definitions

• Somatic death (clinical death) is the cessation of an individuals integrated functioning
• This is associated with permanent and irreversible cessation of circulation, respiration, and brain functions
• Molecular (cellular) death is the death of individual organs and tissues of the body after varying periods
• The periods vary depending on the ability of cells to sustain anoxia
• Brain and heart cells are first cells affected, dying after 3-7 minutes
• After somatic death, skin, bone, and muscles will remain alive for many hours
• Following somatic death, these cells can be successfully cultured for hours
• Molecular life is considered the period between somatic and molecular death

Evidence of Molecular Life

• Muscle contraction upon electric stimulation can still occur after somatic death
• Pupillary (ciliary) responses to atropine and physostigmine after somatic death
• Living sperm can be found in the epididymis after somatic death

Medicolegal Importance

• During the period of molecular life, organ transplantation can be done successfully.

Diagnosis of Somatic Death

• Cessation of circulation results in:
  • Loss of pulsations in big arteries (carotid or femoral).
  • No blood pressure.
  • Loss of heartbeats (Inability to hear heart sounds in the precordium for 5 minutes).
  • Flat line on all leads of electrocardiogram (ECG) for 5 minutes.
• Cessation of Respiration results in:
  • Apnea, checked by careful auscultation (larynx and trachea).
  • Arterial Blood Gas (ABG) Analysis (in hospital) reveals severe hypoxia and hypercapnia inconsistent with life.
• Cessation of brain function (brain death) results in permanent cessation of cerebral hemispheres and brain stem functions.

Somatic Death Conditions

• Somatic death resembles several other conditions
  • Apparent death/suspended animation
  • Coma after excess sedatives or hypnotics
  • Hypothermia in old age.

Brainstem

• The brainstem contains respiratory and vasomotor centers that control respiration and circulation.
• Someone with a dead brainstem is unable to breathe spontaneously or regain consciousness.

Persistent Vegetative State (PVS)

• Advances in care for long-term unconscious patients have led to the survival of unconscious, spontaneously breathing patients
• Persistent vegetative state (PVS) describes patients who lose higher cerebral powers of the brain
• Patients retain brainstem functions (respiration & circulation), as well as a cyclic state of circadian sleep & wake
• Heads and eyes can follow moving objects or sounds
• It occurs in massive cerebral infarcts, hypoxic encephalopathy, and head trauma

Postmortem Changes

• Changes that occur in the body after death
• Results from cessation of vital functions

Classification of Postmortem Changes

• Immediate
• Early
• Late

Immediate Changes

• Insensibility
• Respiratory arrest
• Circulatory arrest
• This has been discussed under diagnosis of somatic death

Early Postmortem Changes

• Eye changes
• Skin changes
• Postmortem cooling
• Postmortem lividity
• Muscle changes

Late Changes

• Putrefaction
• Adipocere formation
• Mummification

Early Postmortem Changes in the Eyes

• Loss of corneal and light reflexes
• Segmentation of retinal vessels and pallor of optic disk (starts after 15 minutes)
• Intraocular pressure decreases, causing sinking and flaccidity of eyeballs (starts 1½ hours after)
• Cornea becomes cloudy and opaque after 2 hours
• Within 3 - 4 hours, taches noire develops
  • This is a brownish discoloration of the exposed sclera
  • Results from accumulation of cellular debris and dust

Early Changes in the Skin

• Skin becomes pale due to stoppage of circulation and drainage of blood
• The skin loses elasticity

Early Primary Flaccidity

• Muscle relaxation and loss of reflexes at the moment of death
• Face acquires a peaceful look, jaw drops, and pupils dilate
• Electrical stimuli in the molecular life stage causes muscle contractions
• Loss of muscle tone causes compression of convex muscle parts against flat surfaces, which become flattened (contact flattening)

Early PM Cooling (Algor Mortis)

• Heat production stops due to oxidative processes and metabolism stopping (mechanism)
• Heat loss occurs by conduction, convection, and radiation.

Rate of Cooling

• The body loses 1-1.5°C/hour until reaching atmospheric temperature
• Occurs in about 18 hours in winter

Factors Affecting Rate of Cooling

• Infants cool quicker due to large surface area
• Females cool slower due to thick subcutaneous fat
• Subcutaneous fat is a poor heat conductor, leading to slower cooling in obese people
• Bodies in well-ventilated rooms cool faster than in closed rooms
• Water increases the rate of cooling
• Clothed bodies reduce the rate of cooling
• Asphyxia, electrocution, heat stroke, and carbon monoxide poisoning causes bodies to keep warm longer.

MLI Uses for PM Cooling

• Estimation of time of death.
• Differentiation between primary and secondary flaccidity
  • Secondary flaccidity will be lower
• Possible cause of death from cooling rate

Early PM Lividity (Hypostasis or Livor Mortis)

• Bluish discoloration and staining of the skin and tissues
• Occurs in the most dependent parts of the body
• Caused by gravitation of fluid blood and stagnation in the capillaries and veins

Hypostasis Timeline

• Hypostasis starts happens immediately after death (after 1 hour), and start to appear
• It first appears as patches that gradually increase and coalesce
• Stains the entire dependent surface; sites of compression are excluded because compression means blanching
• Becomes maximum and fixed after 8 hours when blood clots
• After that, repositioning the body will not alter hypostasis

MLI Uses Early PM Lividity

• It is a sure sign of death
• Denotes time passed after death starts
  • Appears after 1 hour
  • Maximal and fixed after 8 hours
• Denotes the position of the body during the first 8 hours after death
• If the body repositions before fixation, blood shifts to new dependent areas and changes lividity sites

Body Positions

• Hypostasis will appear in the back in supine position
• In prone position, hypostasis will appear in anterior aspect.
• In hanging, it will appear in the lower body (lower abdomen, limbs and forearms).
• In drowning, hypostasis appears in the upper body (head, neck, chest and upper limbs).

Hypostasis Color

• Light blue in natural death
• Deep blue in asphyxia
• Red in carbon monoxide or cyanide poisoning and in death from cold (red asphyxia)
• Brown in poisoning by nitrites (met hemoglobinemia).

Hypostasis Extent

• More marked in asphyxia.
• Ill-defined in hemorrhage

Differentiating Hypostasis from Bruises

• Hypostasis appears in the first 3 hours are differentiated by the prescence of purple patches

Comparing Hypostasis to Bruises

PM Rigidity (Rigor Mortis)

• Progressive rigidity of voluntary and involuntary muscles following primary flaccidity, preceding secondary flaccidity

Rigor Mortis Mechanism

• Chemical changes involving muscle proteins (actin and myosin)
• Depletion of ATP leads to fusion of actin & myosin filaments in a dehydrated stiff gel
• Normally, ATP inhibits the activation of the linkages between actin and myosin
• When the muscle tissue becomes anoxic and all oxygen dependent processes cease to function
• ATP is maintained by anaerobic glycolysis
• Muscle glycogen is depleted, and the level of ATP falls below a critical level beyond which rigor rapidly develops

Rigor Mortis Order and Timeline

• It starts after two hours
• Small muscles of the face are impacted first
• Proceeds in order to the neck, then limbs, then the trunk (last to be involved)
• Takes 12 hours to develop
• Muscles soften gradually due to autolysis with secondary flaccidity sets in

MLI Uses for Rigor Mortis

• It is a sure sign of death
• Denotes time passed since death
• Extent and rate of disappearance
• Denotes the position of the body after death
• May denote the cause of death
  • Occurs very rapid in all convulsive conditions occurring before death (strychnine, tetanus and electrocution) due to already depletion of ATP.
• Distinguished from other causes of muscle rigidity

Types of Muscle Rigidity

• Cold stiffness
  • Freezing of all tissues in very cold weather
  • Rigor mortis occurs when temperature rises
• Heat stiffness
  • Occurs in death due to burn
  • Causes coagulation of muscle protein and shortening of muscles
  • Flexion attitude (boxer attitude) results
  • Rigor mortis does not occur
• Cadaveric spasm

Cadaveric Spasm

• Muscle contraction of a group of voluntary muscles (usually hands)
• Most cases involve high levels of emotional or physical stress immediately before death
• Possible neurogenic mechanism, but no scientifically satisfactory explanation has been given

MLI Uses for Cadaveric Spasm

• Tracing of assailant
  • By examination of things grasped in the victim's hand (hair, button, etc.)
• Diagnosis of suicide
  • The used weapon is firmly grasped by the victim
• Diagnosis of drowning
  • Presence of mud, sand and aquatic weeds are found in the hand

Comparing Cadaveric Spasm to Rigor Mortis

Factors Affecting Rigor Mortis

• Temperature
  • Rapid in hot weather due to rapid autolysis of ATP
• Muscle bulk
  • Rapid in infants and senile persons
  • Slow in athletes (due to much ATP)
• Cause of death
  • Rapid in convulsive states before death
  • Cases of strychnine toxicity and tetanus due to already depleted ATP

Secondary Flaccidity

• Muscles become soft and flaccid again
• Does not respond to mechanical or electrical stimuli
• Synchronous with the onset of putrefaction

Muscle Changes

• Primary flaccidity are relaxed responsive muscles
• Rigor mortis are rigid and irresponsive muscles
• Secondary flaccidity are relaxed irresponsive due to autolysis of tissues proteins. This stage is synchronous with the onset of putrefaction.

Differences Between Primary and Secondary flaccidity

Late PM changes: Putrefaction (PM Decomposition)

• The final decomposition of soft tissues leaving nothing except bones.

Putrefaction Mechanism

• Autolysis results as enzymes post death are released
• Results in softening and liquefaction of the body tissues.
• Bacterial action result in aerobic and anaerobic bacteria that are present in the human body
• Bacteria, specifically in air passages and the alimentary tract, produce large quantities of enzymes
• Results in breaking down body tissues and produces gases.

Effect of putrefactive gases

• Expulsion of a fetus from a gravid uterus
• Flotation of drowned bodies
• Expulsion of feces from rectum and gastric contents from stomach
• Tongue and eyes protrusion with dark foul bloody froth on mouth and nose.

MLI Uses for PM Putrefaction

• It is a sure sign of death
• It can estimate the time passed since death by putrefaction extent
• After 2 days in Winter / 1 day in Summer
• Greenish discoloration in the right iliac region of abdominal wall appears
• Caecum is full of bacteria & fluid feces.
• Marbling/arborization, distention, discoloration, and altered blood is found in vessels

Putrefaction - Arborization

• Veins of the abdominal wall are distended by putrefactive gases
• Distended with colored altered blood (sulph-Hb.)

Extended Putrefaction Timeline

• After one week in winter/3-4 days in summer the following is observed
  • Greenish discoloration of body
  • Distension of the abdomen and external genitalia
  • Swelling of the face
  • Protrusion of tongue and eyeballs
  • Appearance of coarse foul forth from the mouth and nostrils
  • Blurring makes identification of near relatives difficult
• After two weeks in winter/one week in summer the following is observed
  • Peeling of the skin bullae, falling of nails and hair
  • Bursting of abdomen, and viscera liquefies
  • Worms/larvae of hatched eggs, appear at body orifices
• After 6 months all soft tissues are liquefied, leaving only bone attached by ligaments
• After one year bones separate from the ground

Putrefication Rate

• Causes of death can be determined from the rate of putrefaction
• Rapid putrefaction is caused by septicemia as well as edema and ascites
• Slow putrefaction is caused by emaciated dehydrated bodies (poisoning)

Factors that Affect Putrefaction

• Putrefaction thrives between 25-40°C -- Arrested above 50°C and below 10°C
• Most putrefactive organisms are aerobes -- Occurs faster in drowned bodies and sealed coffins
• Presence of water -- Dehydrated bodies show delayed putrefaction -- ascites and edema enhance putrefaction
• Newly born infants putrefy slowly
• Septic conditions lead to rapid putrefaction
• Arsenic poisoning results in delayed putrefaction

Conditions that can Replace Putrefaction

• Adipocere can form in cases of submersion in water
• Mummification in case of death in deserts
• Maceration can be found in intrauterine fetal deaths

Adipocere

• Postmortem change that occurs in water submerged or wet ground bodies in fatty areas
• Occurs in cheeks, buttocks, etc
• Replaces putrefaction
• A waxy yellow greasy material with a characteristic odor

Adipocere Mechanism

• Saturated fatty acid (stearic) from unsaturated fatty acid (palmitic and oleic) by action of hydrogen from water forms and hardens

MLI Uses for Adipocere

• Preserves facial features for personal identification
• Identifies the cause of death
• Can indicate that the location was in water
• Estimates time of death
  • Starts 3 months after submersion
  • Completed after 6 months

Mummification

• Occurs in dry, hot, deserts
• Replaces putrefaction
• Water is partially evaporated and partially absorbed by sand
• Process of putrefaction stops
• Body becomes dried with brown wrinkled skin

MLI uses for Mummification

• Personal idenfitication
• Cause of death preservation
• Time passing is measured three months to a year after death is completed depending on body size etc

Maceration

• In cases of intrauterine fetal death resulting from aseptic autolysis the fetus is enclosed in sterile membranes
• It replaces putrefaction, but its effect is temporary because if they fetus is exposed to air, it will putrefy
• Also, the fetus is brown, edematous, flaccid, and has an odor

Maceration MLI Usage

• The fetus was born dead
• Excludes infanticide

Estimation of Post-Mortem Period

The time passed since death can be estimated by the average postmortem changes:

Forensic Entomology Timeline

• The probable time of death is in the region of days to months
• The populations and stages of development of the various insects that invade the body are examined
• Different species of flies are attracted by the smell of putrefied bodies
• They lay their eggs around moist body orifices
• Give larvae, then pupae in about 21-24 days

Biochemical Changes

• Analysis of blood, CSF, vitreous humor content of sugar, electrolytes, amino acids, lactic acid, non-protein nitrogen and some enzymes show variable changes
• Variable changes can help to estimate p.m. period when plotted against worked out graphs

Self Learning

• Describe Sudden death

Rap Up

• The importance of diagnosis of different types of death needs to be understood
• It is imporatnt to familiarize yourself with The MLI of post mortem changes