Monday, March 16, 2015

DEATH AND ITS CAUSES

DEFINITION OF DEATH

Death is the cessation of life in a previously living organism
Medically and scientifically, death is not an event, it is a process. Historically death meant heart and respiration death but heart-lung bypass machine favored new concept ‘brain death’.
There are two aspects of death:
Clinical death
Cellular death

CELLULAR DEATH

means the cessation of respiration (the utilization of oxygen) and the normal metabolic activity in the body tissues and cells.
Cessation of respiration is soon followed by autolysis and decay
Skin and bone will remain metabolically active and thus be ‘alive’ for many hours
The cortical neuron, on the other hand, will die after only 3–7 minutes of complete oxygen deprivation.

SOMATIC DEATH/ CLINICAL DEATH:

The complete and irreversible stoppage of circulation, respiration and brain function.
No legal definition of death.
A person who can not survive upon withdrawal of artificial maintenance is dead.
The individual is irreversibly unconscious and unaware of both the world and his own existence.
The question of death is important in resuscitation and organ transplantation.
Cornea can be removed from the dead body within 6 hours, skin 24 hours, bone 48 hours, kidney and heart obtained soon after circulation has stopped.

Brain death is of 3 types:
  1. Cortical or cerebral death with intact brain-stem, vegetative state.
  2. Brain stem death- where the cerebrum will be intact, though cut off functionally.
  3. Whole brain death (1+2)

VEGETATIVE STATE:

If the cortex alone is damaged, patient passes into coma but the brain stem will function to maintain spontaneous respiration.
Death may occur months or year later.
They are not in need of life sustaining treatment but require nutrition and hydration.
Has stable circulation and shows cycles of eye opening and closing but is unaware of the self and environment.

BRAIN STEM DEATH:

1.The patient must be in deep coma.
2.Treatable causes such as depressant drugs, metabolic or
endocrine disorders (diabetic or myxoedema coma)
or hypothermia must be excluded.
3. The patient must be on mechanical ventilation, no movement and no spontaneous breathing.
4. Cessation of spontaneous cardiac rhythm.
5. No brain stem reflexes- corneal, vestibulo-occular, pupillary, grimacing, gag reflex.
6. Bilateral fixed dilated pupil.


DEATH CERTIFICATION

The format of certifying the cause of death is now defined by the World Health Organization (WHO) and is an international standard that is now used in most countries.



The system divides the cause of death into two parts:
Part I describes the condition(s) that led directly to death;
Part II is for other conditions, not related to those listed in Part I, that have also contributed to death.


The pathologist, forensic medical examiner and senior police officer at the scene of a sudden death.
Mode of death:

According to Bichat, there are 3 modes of death based on death begins in which of the 3 systems: (irrespective of what the remote cause of death may be)

Coma
Syncope
Asphyxia

According to Gordon (1994), the stoppage of vital functions depend upon tissue anoxia. It may be anoxic anoxia (strangulation, choking, drowning, hanging), anaemic anoxia (acute massive hemorrhage, CO), stagnant anoxia (heart failure, shock) and histotoxic anoxia (acute cyanide poisoning).
Anoxic anoxia due to lack of oxygen in the inspired air or mechanical obstruction to respiration is k/a asphyxia.

Coma:
  • State of unarousable unconsciousness.
  • Clinical symptom and not a cause of death.
  • Causes of coma are compression of brain, drugs like opium, cocaine, alcohol; metabolic disorders like uraemia, diabetes.
  • At autopsy, the lungs, brain and the meninges are conjusted, injuries of the brain or the disease may be present.


Syncope:
  • Sudden stoppage of the action of heart, may be fatal.
  • Is due to vaso-vagal attack from reflex para-sympathetic action
  • Blood pressure falls suddenly causing cerebral anemia and rapid unconsciousness, recovery is common.
  • Autopsy of syncope:
  • Heart is contracted and the chambers are empty when d/t anemia,
  • Chambers contain blood when d/t weakness of heart muscles,
  • The lungs, brain and abdominal organs are pale, capillaries conjusted.

Asphyxia:
  • Lack of oxygen in respired air or mechanical obstruction due to which the organs and tissues are deprived of oxygen.
  • Is a mode of death rather than a cause of death.
  • The rule of thumb is : breathing stops within 20 seconds of cardiac arrest and heart stops within 20 minutes of stopping of breathing.

Types of asphyxia:

  • Mechanical- closing of the nose and mouth with hand or mouth, hanging, drowning,
  • Pathological- entry of oxygen is prevented by the disease of URT or lungs eg. bronchitis, acute epiglotitis,
  • Toxic- eg. CO poisoning, opium paralysing respiratory center.
  • Environmental- eg. enclosed places, CO, CO2, high altitude
  • Traumatic- eg. pulmonary embolism,
  • Postural- eg. alcoholic lying down with upper half of the body lower than the remainder
  • Iatrogenic- associated with anaesthesia.

The ‘classical’ features of asphyxia are found where the air passages are obstructed by pressure applied to the neck or to the chest and where there has been a struggle to breathe. The classical features of ‘asphyxia’ are:

1.congestion of the face;
2. oedema of the face;
3.cyanosis (blueness) of the skin of the face;
4.petechial haemorrhages in the skin of the face and the eyes.
5.A fifth feature – increased fluidity of the blood – is now not accepted.


Petechial haemorrhages on the eyelid, conjunctiva in a case of manual strangulation.

Causes of death:

Disease or injury responsible for starting the sequence of events, which are brief or prolonged and which produce death.

Divided into:

Immediate cause- terminal events eg. trauma, peritonitis etc.
Basic cause- pathological process responsible for death at the time of terminal event eg. gunshot wound
Contributory cause- pathological process involved in or complicating but not causing the terminal event.

Manner of death:

Way in which the cause of death was produced.
May be natural or unnatural, violent.
Violence may be of suicidal, homicidal, accidental or undetermined origin.

Mechanism of death:
Congestion is the red appearance of the skin of the face and head, due to the filling of the venous system
Oedema is the swelling of the tissues due to transudation of fluid from the veins caused by the increased venous pressure as a result of obstruction of venous return to the heart.
Cyanosis is the blue colour imparted to the skin by the presence of deoxygenated blood in the congested veins.
Petechial haemorrhages (petechiae) are tiny, pinpoint haemorrhages, most commonly seen in the skin of the head and face and especially in the lax tissues of the eyelids. They are also seen in the conjunctivae and sclera of the eye.

Physiological or biochemical disturbance produced by the cause of death which is incompatible with life eg. shock, sepsis, fibrillation, respiratory paralysis, severe metabolic alkalosis/acidosis.

NEGATIVE AUTOPSY:
When gross and microscopic examination, toxicological analysis and lab investigation fail to reveal the cause of death.
2-5% of all autopsies are neagtive.

SUDDEN DEATH:
When a person not known to have suffering from any dangerous disease, injury or poisoning is found dead, or dies within 24 hours after the onset of terminal illness (WHO)
Some authors call sudden death as occuring instantaneously or within 1 hour of onset of symptoms. Causes are disease of CVS-50%, resp. system-20%, CNS-15%, GI system- 7%, miscellaneous- 5 to 10% eg. DM.

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