Asphyxia

Many rapid deaths of medicolegal importance are fundamentally due to an interference with oxygenation of the tissues. Such deaths are classified according to how hypoxia (oxygen deficiency) or anoxia (complete absence of oxygen) is initiated.

Death occurs due to failure of proper oxygenation of tissues resulting from hypoxia or anoxia.

• Capillary dilation: Capillaries are highly sensitive to hypoxia/anoxia, leading to dilation and blood stagnation. This causes marked capillary congestion — a major feature of rapid hypoxic or anoxic death.
• Petechial haemorrhages: Injury to capillary walls often produces pinpoint hemorrhages.
• ↑ Capillary permeability → oedema.
• Cyanosis — bluish discoloration from deoxygenated blood.
• Postmortem fluidity of blood — due to incomplete coagulation.
• Cardiac dilatation — enlarged heart chambers from venous congestion.

• Mechanical Asphyxia — physical obstruction of breathing (e.g., strangulation, smothering, drowning).
• Environmental Asphyxia — due to reduced oxygen in environment (e.g., confined spaces, gas displacement).
• Pathological Asphyxia — due to disease conditions affecting breathing (e.g., airway infections, asthma, anaphylaxis).
• Traumatic Asphyxia — due to mechanical restriction of chest movement (e.g., crush injuries, crowd crush).