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  1. Asphyxia
  2. Asphyxia: • ( The word Asphyxia comes from the Greek word, A + sphygmos(sphyxia). A means absence, Sphygmos( Sphyxia) means pulse, so asphyxia means no pulse, absence of pulse,or pulselessness) Definition: Supply of oxygen to the blood and tissues has been reduced appreciably below the normal working level by any interference with respiration.
  3. Violent asphyxia: • Prevention of exchange of air between the atmosphere & the lungs by violent mechanical means is called violent asphyxia.
  4. Classification of asphyxia • Pathological asphyxia: • eg: Respiratory: Pneumonia.COPD, Bronchial asthma, plural effusion etc. • CVS: Myocardial anoxia, anaemic heart failure etc. • Mechanical asphyxia. • eg:Violent asphyxial death: Hanging, strangulation, Drowning etc. • Toxic asphyxia: • eg: OPC, Alcohol, opium etc.
  5. • There are different types of violent asphyxia: • Compression asphyxia: • Hanging. • Strangulation. • Obstruction asphyxia: • Suffocation • Smothering • Choking • Drowning. • Others: • Crush (Traumatic) asphyxia. • Postural/positional asphyxia.
  6. • Cardinal features of violent asphyxial death: • a) Cyanosis. • b) Petechial haemorrhage/ Tardieu’s spot. • c) Congestion.
  7. Cyanosis
  8. • Cyanosis: • The term cyanosis means blueness of the skin and its cause is excessive amount of deoxygenated haemoglobin in the skin, blood vessel specially in the capillaries. • This deoxygenated haemoglobin has an intense dark blue purple colour that is transmitted through the skin. •
  9. • Petechial haemorrhages (Petechiae): • ( Tardieu’s spot) • These are small pinpoint collections of blood that vary in size from about a tenth of a millimetre to about 2 millimetres; larger than this, they are called “ecchymoses”. They are usually said to be caused by rupture of capillaries (but are actually thought to be due to rupture of small venules) due to an acute rise in venous pressure. They occur most commonly in areas where the vessels are least supported – in this case the face – especially the eyelids, the conjunctivae and sclera.
  10. Petechial haemorrhage
  11. • They are most commonly seen in asphyxial death related to compression of the neck or chest leading to increased venous pressure in the head. • History of Tardieu’s spot: • Auguste Ambroise Tardieu (10 April 1818 – 12 January 1879) was a French medical doctor and the pre-eminent forensic medical scientist of the mid-19th century.
  12. • Tardieu's specialties were forensic medicine and toxicology. Over his 23-year career, Tardieu participated as a forensic expert in 5,238 cases, including many famous and notorious historical crimes. Using his cases as a statistical base, Tardieu wrote over a dozen volumes of forensic analysis, covering such diverse areas as abortion, drowning, hanging, insanity, homosexality, poisoning, suffocation, syphilis, and tattoos. • In recognition of his first clinical descriptions of battered children, battered child syndrome is also known as Tardieu's syndrome. • Tardieu's ecchymoses, subpleural spots of ecchymosis that follow the death of a newborn child by strangulation or suffocation, were first described by Tardieu in 1859, and were so named in his honor.
  13. Auguste Ambroise Tardieu (10 April 1818 – 12 January 1879
  14. • Congestion: • The increase in venous pressure associated with asphyxia (due to obstructed venous return and/or impaired respiratory movements) causes generalized organ congestion +/- oedema. The blood is very dark (cyanosed). There is usually dilatation and engorgement of the right side of the heart. The lungs are congested and oedematous and there may be petechiae in serous membranes (pleurae, pericardium), meninges etc.
  15. Congestion
  16. Post- mortem findings of asphyxial death • External findings; • 1.Face is pale, edematous and cyanosed. • 2. Protrusion of eyeball and tongue may be found. • 3. Dribbling of saliva or blood stained froth may be found in the mouth. • 4.Cyanosis is well marked in face including lips,eyelids, nail bed. • 5.Petechial haemorrhage on the skin and mucosa of face, conjunctiva etc.
  17. Post-mortem findings
  18. • 6.Post-mortem hypostasis is well marked than any other death. • 7. Signs of involuntary discharge eg: urination, defaecation, ejaculation. • Internal findings: • 1.Blood is dark in colour and more fluidity due to increased CO2 and fibrinolysis respectively. • 2. Congestion of internal organ except spleen which is anaemic. • 3.The right heart and great veins are engorged with blood.
  19. • 4.Petechial haemorrhage/ Tardieu’s spot on the serosal surface, eg: epicardium, visceral pleura, intestinal mucosa etc. • The “classical” features of asphyxia at autopsy may not be seen in some deaths: • 1. Vagal inhibition. • 2. Highly decomposed body.
  20. Mechanism of vagal inhibition • Mechanism of vagal inhibition: • Compression or stimulation of the carotid sinus of carotid artery causes impulses to pass via Herring’s nerve to the afferent fibers of the 9th cranial nerve. This nerve in turn link in the brainstem to the nucleus of the 10th cranial nerve then parasympathetic efferent impulses than descent to the heart through the branch of vagus nerve. Stimulation of these fibers causes profound a result cardiac arrest.