1. Death and postmortem changes (I)
Dr. Asmaa Fady
Ph D., MSC., M.B, B.Ch

2. Learning objectives: By the end of the lecturer, the students should
Define death
Understand Types of death including somatic, molecular & brain death, under each one, we have to know, its criteria and medico-legal importance.
Recognize Postmortem changes, under each one we have to know, its definition, mechanism, medico-legal importance & factors affecting it.
اسم ورقم المقرر – Course Name and No.
7/9/2019

3. Death (Definition & Types)
Definition of death: It is irreversible cessation of brain and brain stem functions.
Death is classified into:
1- Somatic death
2- Cellular death.
اسم ورقم المقرر – Course Name and No.
7/9/2019

4. 1-Somatic death: (clinical death)
The individual is irreversibly unconscious, and unaware of himself and the world (death of the human body).
It is due to complete & irreversible cessation of all vital functions of the brain, heart & lung.
During this period, cells respond to chemical & electrical stimuli and the pupils dilate with atropine.
اسم ورقم المقرر – Course Name and No.
7/9/2019

5. 2- Cellular (molecular) death:
It occurs when all cells stop respiration and metabolism (death of all cells).
All cells do not die simultaneously, different cell types can live for different times after cardiac arrest.
Nervous cells will die within 37 minutes after complete oxygen deprivation.
Molecular death is manifested by postmortem changes.
The period between somatic and molecular death is called molecular life, during which organ transplantation can be done.
اسم ورقم المقرر – Course Name and No.
7/9/2019

6. Suspended animation - Definition:
Molecular life: The period between somatic and molecular death is called molecular life, during which organ transplantation can be done.
Suspended animation - Definition:
It is death like state in which there is temporary suspension of heartbeats & respiration (yoga practitioners, hypothermia)
اسم ورقم المقرر – Course Name and No.
7/9/2019

7. Medicolegal Importance of determination of clinical death:
1. To write death certificate.
2. To stop life support measures.
3.To determine the moment of death (e.g. inheritance)
4. For organ transplantation considering the concept of brain stem death.
5. For rapid burial in cases of mass disasters and epidemics e.g. cholera.
6. In criminal responsibility to determine if the victim died or not.
اسم ورقم المقرر – Course Name and No.
7/9/2019

8. Primary flaccidity of skin
How to Diagnose Death
Diagnosis of death
Immediate signs
Skin and eye changes
Primary flaccidity of skin
Cessation of
RS, CVS & CNS
Postmortem changes
*Coolness
*Hypostasis
*Rigor Mortis
*Putrefaction
اسم ورقم المقرر – Course Name and No.
7/9/2019

9. Immediate signs of death I- (skin & eye changes)
- Skin: Pallor and loss of elasticity
- Eye:
a) Absence of corneal and light reflexes of the eyes.
b) Reduction in the intra-ocular tension.
c) Absence of blinking of eyelids → accumulation of mucus over the cornea.
d) Trucking of blood in the retinal vessels:
- Sudden cessation of circulation → segmentation of the blood inside blood vessels all over the body (observed in retinal blood vessels by ophthalmoscope)
- It is evident within 10 seconds of clinical death (sure sign of death)
اسم ورقم المقرر – Course Name and No.
7/9/2019

10. Immediate signs of death II- Primary flaccidity of the muscles
Mechanism:
Due to loss of muscle tone it will lead to the followings:
Dropping of the lower jaw.
Contact flattening:
The flaccid muscles flatten over the areas that are in contact with the surface on which it rests.
It is usually seen over the shoulders blades, buttocks and calves.
اسم ورقم المقرر – Course Name and No.
7/9/2019

11. Immediate signs of death III- RS, CVS & CNS
Permanent cessation of circulation: a) No Pulse is an unsafe indication of death b) Absence of heart sounds, as determined by repeated auscultation during a period of not less than ''5'' minutes. c) flat ECG. Permanent cessation of respiration: a) No respiratory movement (by careful inspection of chest & abdomen). b) No respiratory sounds (by hearing over trachea or chest for at least 5 minutes). Permanent cessation of vital functions of the brain: a) Absence of reflexes all over the body. b) Flat EEG.
اسم ورقم المقرر – Course Name and No.
7/9/2019

12. Postmortem changes 1- Cooling of the body
After death, the body becomes an inert substance, it will lose heat until it becomes in equilibrium with the surrounding environment.
Cooling and PM interval:
Time passed since death depending on body temperature can be estimated by using the following formula:
Time since death (hrs)= 37 - rectal temperature (C) + 3
اسم ورقم المقرر – Course Name and No.
7/9/2019

13. *Tache noir: A film of cell debris and mucus forms two triangle on sclera at each side of the iris with base toward the margin of cornea and apex towards medial and lateral canthus of eye. This sign becomes evident (6-8) hours postmortem.
اسم ورقم المقرر – Course Name and No.
7/9/2019

14. Postmortem changes 2- Postmortem hypostasis (PM lividity)
Definition:
It is discoloration of the skin of the most dependent parts of the body and internal organs after death.
Mechanism:
When somatic death occurs, circulation of the blood ceases due to loss of pumping action of the heart  gravitation & accumulation of blood in the capillaries and small veins in the dependent parts of the body  purple or bluish purple color to the adjacent skin.
N.B: Hypostasis does not occur in areas of contact flattening
اسم ورقم المقرر – Course Name and No.
7/9/2019

15. Postmortem hypostasis (lividity)
اسم ورقم المقرر – Course Name and No.
7/9/2019

16. Postmortem changes 2- Postmortem hypostasis (PM lividity)
-It occurs immediately after death and becomes well established within 6-8 hours.
Medicolegal importance of hypostasis:
1- It is a sure sign of death.
2- It helps in estimating the time passed since death.
3- It indicates the position of the body after death.
4-It gives an idea about cause of death (colour)
4- It may be mistaken with bruises
اسم ورقم المقرر – Course Name and No.
7/9/2019

17. Postmortem changes 2- Postmortem hypostasis (PM lividity)
It occurs immediately after death. - Within 1/2 hour: hypostasis appears as mottled patches. - Within 2 hours: the patches enlarge and coalesce to produce extensive discoloration. - From 6 to 8 hours: hypostasis becomes well established.
a) If the body position was changed before 2 hours, hypostasis will develop on the new position.
b) If body position was changed during the period from 2-8 hours after death, it will develop on both sites.
c) If body position was changed after 8 hours, no change in the pattern of its distribution, so the site of hypostasis will not coincide with the position of the body.
اسم ورقم المقرر – Course Name and No.
7/9/2019

18. Postmortem changes 2- Postmortem hypostasis (PM lividity)
i- In CO, cyanide poisoning and death from cold, hypostasis is bright cherry red in color (red death or red asphyxia). ii- In nitrites, nitrates, potassium chlorate, sulphur and aniline dye poisoning, hypostasis is brown in color (methemoglobinemia). iii- In asphyxia hypostasis is dark blue even black in color (reduced hemoglobin). iv- In severe hemorrhage & severe anemia, hypostasis is faint and ill defined
اسم ورقم المقرر – Course Name and No.
7/9/2019

19. Postmortem hypostasis
اسم ورقم المقرر – Course Name and No.
7/9/2019

20. Postmortem changes 3- Rigor mortis (PM rigidity)
Definition:
It is a physiochemical process of simultaneous stiffening and shortening of the muscles, following the period of primary flaccidity and affecting both voluntary & involuntary muscles.
اسم ورقم المقرر – Course Name and No.
7/9/2019

21. Postmortem changes 3- Rigor mortis (PM rigidity)
Mechanism:
It is a physiochemical reaction involving muscle proteins (actin & myosin).
For muscle relaxation, ATP is required to break cross bridges between actin & myosin.
After death, ATP generation stops  fusion of actin & myosin into a dehydrated, stiff gel-like material (acto-myosin gel)  muscle stiffening.
(rigor mortis) persists till autolysis of both proteins during the process of putrefaction.
اسم ورقم المقرر – Course Name and No.
7/9/2019

22. Rigor mortis (PM rigidity)
اسم ورقم المقرر – Course Name and No.
7/9/2019

23. Rigor mortis and Post Mortem interval:
2 hours after death: Rigor mortis starts to appear in small muscles of the face (eye lids & lower jaw). Then progress gradually to other muscles.
About 12 hours: It is usually completed all over the body.
It disappears in the same order About 24 hours in the summer and about 36 hours in the winter (Secondary flaccidity, onset of putrefaction).
اسم ورقم المقرر – Course Name and No.
7/9/2019

24. Medico-legal importance of rigor mortis
1- It is sure sign of death.
2- Estimation of the time passed since death (see above).
3- It fixes the dead body at its position indicating if it has been changed after rigor has set in.
4- It may suggest the cause of death, which is of rapid onset in death following exhaustion (tetanus, strychnine poisoning or violent deaths).
5- It may be mistaken with other conditions of stiffness as: Cadaveric spasm.
اسم ورقم المقرر – Course Name and No.
7/9/2019

25. Cadaveric spasm
It is stiffening of a group of voluntary muscles performing an action (strong contraction) at the moment of death.
- It occurs in deaths associated with extreme nervous tension such as:
i- Suicidal cases, the weapon used is firmly clenched in the victim's hands.
ii- In drowning,
the victim grasping weeds
or gravel
اسم ورقم المقرر – Course Name and No.
7/9/2019

26. Differences between rigor mortis & cadaveric spasm
Rigor mortis
Cadaveric spasm
Mechanism
Physiochemical reaction
Sever stimulation of the nervous system
Type of death
It occurs in all types of death
Death with nervous tension
Type of muscle
In all types of muscles
In voluntary muscles only
Extension
Muscles all over the body
In a group of muscles
Onset
It starts about 2 hours after death.
It occurs at the moment of death.
Primary flaccidity
Primary flaccidity followed by rigor mortis
No primary flaccidity in the affected muscles.
7/9/2019