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Flashcards in Changes after death Deck (23):

Definition of somatic death

Death of the body
Cessation of respiration and circulation


Define cerebral death

Implies total destruction of the brain with loss of voluntary and reflex functions


Define irreversible coma

State of vegetation in which all functions attributed to cerebrum are lost, while vital functions are retained


Minimum criteria for brain death

- loss of spontaneous ventilation within 5 minutes of disconnecting ventilator
- lack of brain-stem reflexes
- rectal temp below 35
- any drugs in the last 12 hours that could affect ventilation or consciousness
- no doubt that cerebral state is due to irreversible cause


Brain stem reflexes that need to be tested

- pupil reaction to light
- pupil reaction to pain
- dolls eye moevement (cold caloric test)
- gag reflex


General physical changes after death

- pallor of skin
- muscle flaccidity
- contact flattening and pallor
- eye changes (pupils mid-position)


Body changes after death

- changes in fundus oculi
- post-mortem lividity
- rigor mortis
- digestion of undigested food
- environmentally induced changes


Three major early changes used to determine time of death

- cooling (algor mortis)
- stiffening (rigor mortis)
- discolouration (livor mortis)


Things that influence rate of cooling of a body

- environmental factors
- intrinsic factors (body build, nature of death)
- site of measurement (skin, sub-hepatic)


Pattern of temperature change

- initial plateau (1-3 hrs - heat produced by anaerobic glycgenolysis)
- falling straight line (3-12 hrs)
- slow-falling exponential curve


Average hours to environmental temperature in average conditions

- 28 for normal
- 41 for obese
- 19 for thin


Factors that can affect the rate of cooling

- air temp change
- water
- clothing
- poisoning
- septicaemia


Define rigor mortis

- the state of generalised muscle rigidity which follows primary flaccidity in all voluntary and involuntary muscles


Physiological mecanism of rigor mortis

Reduced ATP levels lead to chemical bonding between actin and myosin to for acto-myosin
- cause the muscles to become hard, still and a bit shortened


When does rigor mortis occur?

- small muscles 2-4 hrs
- obvious by 6-8 hrs
- fully established by 12 hrs
- passes by 24 hours


Things to differentiate from rigor mortis

- cadaveric spasm
- cold stiffening or freezing of joints
- heat rigor
- ankylosis of joints
- fat rigidity


Definition of post mortem lividity

- discolouration of the body after death due to gravitation of blood into the dependent capillovenous bed in the skin and subcutaneous tissues


When does post-mortem lividity usually occur?

- within 30 mins to 2 hours
- fully fixed at 8-12 hours


Medico-legal importance of lividity

- suggests positioning
- needs to be distinguished from bruising
- colour may suggest poisoning
- help estimation of TOD
- pressure effects must be differentiated from strangulation
- putrefaction sets in earlier in livid tissue


Late changes in the dead body

- autolysis
- adipocere
- mummificaiton


Describe adipocere

- hydrolysis and hydrogenation of body fat
- subcutaneous tissue becomes waxy when cold and oily when warm


Pathogenesis of adipocere

Clostridium welchii lecithinase activity on body fat
- formation of fatty acids which inhibit puterfaction
- associated with bodies in wet graves
- takes months


Other factors that can help estimating time of death

- animals (maggots)
- hair
- bones (C14)
- blood
- Ocular fluid (vitreous potassium)
- gastric contents