1. Postmortem changes

POSTMORTEM CHANGES • - cooling of the body • - paleness of the body • - bluish-red discoloration of the skin and organs • - rigidity (spasm) of the muscles • Postmortem clot • Postmortem

Algor mortis - cooling of the body • The rate of cooling is affected by a variety of factors, such as ambient temperature, airflow across the body, body fat, antemortem hyper- or hypothermia, etc. • The body will cool at 1.0 to 1.5 0C/hour for the first 12 hours, and subsequently lose 0.5 to 1 0C/hour for the next 12 hours

Pallor mortis - paleness of the skin and visible mucosal surfaces • After , the circulation of cessates. • The blood passively follows the gravity and pools in the capillaries of deep tissues

Livor mortis - bluish-red discoloration of the skin and organs Result of the blood settling or pooling by gravity in capillaries, which dilate following the cessation of circulation • Absent where the weight of the body against a supporting object (e.g., mattress, tight fitting diapers) compress the capillaries and prevent them filling with blood • First observed within an hour of death as purple blotches in gravidity dependent points of the body, reaches its peak between 8 and 12 hours: livor due to hypostasis • If the body has not been moved after 8 to 12 hours, the livor will become fixed because the tissues are stained by hemolysed blood: livor due to imbibition

Rigor mortis - rigidity (spasm) of the muscles • At the time of death, the muscles remain flaccid; after 4 to 48 hours, the muscles develop the rigidity, and, after 48 to 72 hours, the rigidity relents • Once rigor becomes fully developed, and has subsequently relented, it will not reform • Rigor starts in the muscles of the eyelids and the muscles of mastication, followed in the muscles of the shoulders and arms, and, finally, in the muscles of legs • Rigor fades in similar sequence • The onset and subsequent development of rigor may be accelerated by severe fever, convulsions, elevated environmental temperature; and can be delayed by the rapid cooling of the body

Postmortem clot • During , it is essential to differentiate between antemortem red thrombus and postmortem red clot • Antemortem clot: firm, though brittle, and has a dull, matt, striated surface from fibrin lamination; attaches to the vessel wall • Postmortem clot: dark red, soft, jelly-like, with a shiny, glistening surface; does not attach to the vessel wall

Postmortem decomposition • Takes two separate forms: autolysis and • Autolysis: fermentative processes that occur without the participation of bacteria. Histologically, disintegration of cellular structures is observed • Occurs very early in enzyme-producing organs, such as the pancreas and adrenals • Autolysis is accelerated if body or environmental temperature is raised, or there is jaundic liver disease

Maceration • When a foetus dies in an intact amniotic sac, decomposition, termed begins immediately • Since the amniotic sac does not normally contain bacteria, the decomposition is not putrefactive • Early changes are most obvious in the skin, characterized by the delamination of the epidermis from the dermis  skin slippage • As the RBCs haemolyze, the skin will develop a reddish discoloration, and eventually muscles, connective tissue, viscera, and the umbilical cord will develop a uniform similarity of colour

CLINICAL FEATURES OF DEATH Permanent absence of all ‘vital’ signs: • Spontaneous respiration is absent • Pulses cannot be palpated • Not be able to auscultate breath or heart sounds • The pupils are fixed in diameter and unresponsive to bright light • Corneal reflexes are absent • There is no gag or caugh reflex in response to pharyngeal, laryngeal or tracheal stimulation • There is no motor response within the cranial nerve territory to painful stimuli applied

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