Algor Mortis and Livor Mortis both are the processes that takes place in a dead body. Algor Mortis is the process of cooling of body after death and Livor Mortis is settling of the blood in body after death.
Algor mortis means cooling of the body. After death, the temperature of the body decreases until it reaches the ambient temperature. It is considered the second stage of death. This term was first used by Bennet Dowler.
In the year 1839, John Davy published measurements of the intervals of temperature after death. The temperature decreases because there is no heat generation due to the loss of all physical, chemical, and metabolic activity of the body. Body heat keeps dropping constantly until it matches the environmental temperature.
Conduction, convection, and radiation aids in the loss of body heat from the surface. Hourly recording of temperature can help estimate time since death. But this is not of much utility during summer seasons in India where the ambient environment temperature exceeds that of body temperature.
Livor mortis is also known as postmortem lividity, postmortem hypostasis, vibices, suggillation, postmortem staining. It is the purplish-blue or reddish-blue discoloration due to the settling of blood by the gravitational force within the dependant dilated and toneless small veins and capillaries of rete mucosum.
It is an intravascular phenomenon and occurs in the dependent part of the body. The areas that remain in direct contact with the ground doesn’t show staining. This is known as contact pallor. Lividity can occur in internal organs as well and hence can be confused with contusion of the organs or congestion. Post-mortem lividity does not appear over scars or scarred areas as these areas are devoid of blood vessels.
Difference Between Algor Mortis and Livor Mortis
Mechanism of Algor Mortis
After death, the outer surface of the body starts losing heat fast but the heat loss from the depth of the body is negligible. Heat is lost due to the stoppage of thermoregulation.
After some time, when a reasonable heat is lost from the surface, the fall of temperature of the inner body becomes regular and falls in a constant pattern. It takes about 3-4 hours to lose surface temperature and then the sharp fall of temperature due to loss of heat from the inner body will last for another 9-12 hours.
After this period, the rate of fall of inner core body temperature diminishes and by that time it becomes equivalent to the level of environmental temperature. A chemical thermometer is used to measure the temperature. It is 25 cm long with a range from 0 to 50 ℃. The rectum and subhepatic region are most suitable to measure the temperature.
Factors Affecting Algor Mortis
- Age: Maximum heat loss occurs in infants and children.
- Air movement and atmospheric temperature: The difference in the atmospheric temperature and the body affects the cooling. In presence of air breeze movement, cooling of the body occurs faster.
- Position of the body: The outstretched body will lose more heat.
- Clothing: The presence of clothing retains the heat and hence slows down cooling.
- Media of disposal: Optimum cooling occurs in water and then in the air. The least cooling occurs in bodies that are buried in the ground. The ratio of fall of body temperature in the three media- water:air:grave is 4:2:!. This is known as Casper’s dictum.
- Cause of death: If death occurs due to some infectious disease or bacteremia, or septicemia, the body temperature will be high and so heat loss from the body will be slower.
Mechanism of Livor Mortis
After death, the circulation system ceases and so the blood in the body accumulates in the dependent vessels due to gravity. The vessels are toneless because of the stoppage of CNS and spinal cord function. So there will be stasis in the blood vessels and capillaries in the dependent portion of the body.
When the body is left undisturbed the staining starts to appear in patches. It takes about 5-6 hours for complete staining of the body. Blanching cannot be done after the lividity gets fixed.
Factors Affecting Livor Mortis
- Position: Undisturbed and fixed body is required for lividity to fix in.
- Hemorrhage: If the person loses a lot of blood, or is in a hemorrhagic shock then postmortem lividity will not appear.
- Anemia: If the person who died suffered from anemia then lividity may not be visible.
- Complexion: It is more prominent and easily visible in fair people than in a person with a darker complexion.
- Cold: If the body is stored under cold conditions, then lividity may get fixed later. In such a situation, it is not a good parameter to estimate time since death.
Both algor mortis and livor mortis are signs of death and can be used to estimate the time since death. Lividity helps in identifying the relative position of the body. The color of the postmortem lividity can indicate the cause of death.
Early cooling of the body delays the process of rigor mortis and decomposition. Understanding these signs of death is important to find the time and cause of death along with the clues these signs provide that will help in the investigation.