Changes after death

Question 1

Definition of somatic death

Answer 1

Death of the body

Cessation of respiration and circulation

Question 2

Define cerebral death

Answer 2

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

Question 3

Define irreversible coma

Answer 3

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

Question 4

Minimum criteria for brain death

Answer 4

• 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

Question 5

Brain stem reflexes that need to be tested

Answer 5

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

Question 6

General physical changes after death

Answer 6

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

Question 7

Body changes after death

Answer 7

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

Question 8

Three major early changes used to determine time of death

Answer 8

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

Question 9

Things that influence rate of cooling of a body

Answer 9

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

Question 10

Pattern of temperature change

Answer 10

S-shaped

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

Question 11

Average hours to environmental temperature in average conditions

Answer 11

• 28 for normal
• 41 for obese
• 19 for thin

Question 12

Factors that can affect the rate of cooling

Answer 12

• air temp change
• water
• clothing
• poisoning
• septicaemia

Question 13

Define rigor mortis

Answer 13

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

Question 14

Physiological mecanism of rigor mortis

Answer 14

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

Question 15

When does rigor mortis occur?

Answer 15

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

Question 16

Things to differentiate from rigor mortis

Answer 16

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

Question 17

Definition of post mortem lividity

Answer 17

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

Question 18

When does post-mortem lividity usually occur?

Answer 18

• within 30 mins to 2 hours

- fully fixed at 8-12 hours

Question 19

Medico-legal importance of lividity

Answer 19

• 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

Question 20

Late changes in the dead body

Answer 20

• autolysis
• adipocere
• mummificaiton

Question 21

Describe adipocere

Answer 21

• hydrolysis and hydrogenation of body fat

- subcutaneous tissue becomes waxy when cold and oily when warm

Question 22

Pathogenesis of adipocere

Answer 22

Clostridium welchii lecithinase activity on body fat

• formation of fatty acids which inhibit puterfaction
• associated with bodies in wet graves
• takes months

Question 23

Other factors that can help estimating time of death

Answer 23

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