Describe suffocation and its varieties including smothering, choking and traumatic asphyxia.

Definition and Varieties

• Burking — named after William Burke, who with Hare murdered people in Edinburgh to supply anatomy schools. It is a combination of smothering and traumatic asphyxia: the assailant sits or kneels on the chest while closing the mouth and nose with the hands. It produces the findings of both, and few external marks

Findings

• Smothering — abrasions, bruises and nail marks around the mouth and nostrils and on the cheeks and chin; bruising and laceration of the inner surface of the lips against the teeth, and a torn frenulum, which is a valuable and frequently missed sign; injury to the gums; and abundant petechiae where the death was slow. Where a soft pillow was used there may be NO external mark whatever. Fibres from the pillow or cloth may be recovered from the mouth and nostrils
• Choking — the foreign body found in the larynx, trachea or bronchi, and the face is deeply congested and cyanosed. The airway must be examined IN situ before the neck organs are removed, or the object may be dislodged and lost
• Traumatic asphyxia — a striking and characteristic appearance: deep purple-blue congestion and swelling of the head, neck and upper chest, with a sharp line OF demarcation at the level of the compression, and masses of petechiae in the face, conjunctivae and scalp — the so-called "masque ecchymotique". There may be subconjunctival haemorrhage, bleeding from the ears, and remarkably little internal injury, since death is from fixation of the chest rather than from crushing
• The victim of traumatic asphyxia may survive if released in time, and the appearance resolves over days

The Difficulty of Diagnosis

• Suffocation is the hardest group of asphyxial deaths to diagnose, because the mechanism frequently leaves NO marks at all and the general signs of asphyxia are unreliable. The diagnosis therefore rests on the scene, the history and the exclusion of everything else far more than on the autopsy
• Smothering of an infant, of an elderly person or of anyone drugged or intoxicated may produce nothing whatever — no marks, no petechiae, no internal finding — and is then indistinguishable at autopsy from SIDS or from natural death. This is the central problem in forensic paediatric pathology
• What raises suspicion — a previous unexplained infant death in the same family; a history that changes or does not fit; blood-stained fluid at the nose or mouth; injuries elsewhere or of different ages; a delay in seeking help; and the infant found in an unexpected position
• What must be done — a full autopsy with skeletal survey, histology, toxicology and microbiology; examination of the scene and of the sleeping arrangements; a detailed history taken separately from each carer; and review of the medical and social records
• The honest position is that the autopsy often cannot distinguish deliberate smothering, accidental overlaying and sudden infant death syndrome; and a report should say so rather than choose between them on inadequate evidence. Both over-diagnosis and under-diagnosis have caused grave injustice

Manner and Applied Aspects

• Smothering is usually homicidal in an infant or a helpless person, and accidental in a plastic bag over a child's head or in a collapse of earth; suicidal smothering is rare and requires a fixed apparatus
• Choking is almost always accidental, and the "cafe coronary" is the classical instance; homicidal choking occurs by forcing material into the mouth
• Traumatic asphyxia is accidental — and in India crowd crushes at religious gatherings, festivals and stampedes are a recurring cause of mass casualties, in which the mechanism is compression of the chest by the press of bodies rather than trampling
• Examine the airway IN situ before removing the neck organs in any suspected choking; a dislodged bolus is the commonest reason the diagnosis is missed
• Look inside the lips and at the frenulum in every suspected smothering, particularly in a child; the injury is on the inner surface and is missed unless the lip is everted
• Investigate the scene in every infant death; smothering, overlaying and SIDS cannot be distinguished at autopsy, and the sleeping arrangements, the position in which the infant was found and the family history are part of the diagnosis
• Be alert to positional asphyxia in restraint and custodial deaths; prone restraint with weight on the back has caused death, the autopsy findings are minimal, and such a death requires a magistrate's inquest, a board and videography
• Take toxicology in every case; intoxication and drugs are the common factor in choking, overlaying and positional asphyxia, and explain how the person came to be unable to save themselves
• Burking combines smothering with traumatic asphyxia — kneeling on the chest while closing the mouth and nose — and leaves few marks
• Traumatic asphyxia gives the masque ecchymotique, with a sharp line of demarcation at the level of compression and little internal injury
• Crowd crushes kill by chest fixation, not by trampling, which is why stampede victims in India may be entirely unmarked
• Fibres from the pillow or cloth may be recovered from the mouth and nostrils in smothering, and should be sought before the face is cleaned
• A torn frenulum in an infant is a valuable sign of pressure on the mouth, and is missed unless the lip is everted
• The victim of traumatic asphyxia may survive if released in time, and the appearance resolves over days
• Prone restraint has caused custodial deaths with minimal findings; such a death needs a magistrate inquest, a board and videography
• Gagging is usually meant to silence, not to kill, but the death is homicide however the intention is described
• Overlaying and SIDS cannot be separated at autopsy, which is why the sleeping arrangements and the scene are part of the diagnosis
• A repeated unexplained infant death in one family is investigated rather than assumed, in either direction
• Smothering with a soft pillow may leave nothing, and the absence of marks is therefore not evidence against it
• Both over-diagnosis and under-diagnosis have caused injustice in infant deaths, and an honest report says what cannot be distinguished
• Choking is commonest in children and the elderly, and in the intoxicated and neurologically impaired
• Examine the airway before removing the neck organs; a dislodged bolus is the commonest reason the diagnosis is missed
• Take toxicology in every case; intoxication and drugs explain how the person came to be unable to save themselves
• Traumatic asphyxia may leave little internal injury, since death is from fixation of the chest rather than from crushing
• Look inside the lips against the teeth in suspected smothering; the bruising is on the inner surface and needs the lip everted
• Burking leaves the findings of both mechanisms and few marks, which is precisely why it worked
• A plastic bag over a child head is a recognised accident, and the circumstances usually distinguish it from smothering
• Postural asphyxia needs an incapacitated person who cannot correct their position — the drugged, the drunk, or the restrained
• Environmental entrapment kills rescuers too, and a second body in a well or a tank is a recognised and preventable pattern
• Grain silos and disused wells produce oxygen depletion, and a person entering to rescue another commonly becomes the second victim
• Record the position in which the body was found in every suspected positional asphyxia; it is the diagnosis, and it is lost once the body is moved
• Choking may kill by vagal inhibition rather than obstruction, which is why death can occur within seconds of the bolus impacting