Asphyxia and Asphyxial Death Overview

Asphyxia and Asphyxial Death

• Asphyxia is defined as interference with respiration or its function, resulting in lack of tissue oxygenation
• Key processes involved in respiration include receiving oxygen, using oxygen, and failure of tissue to utilize oxygen
• Asphyxia involves a breakdown in the respiration process, affecting aspects from oxygen intake, to blood transport, to oxygen use by tissues
• Key causes include defective cellular oxygenation (e.g., poisoning), mechanical obstruction by neck compression or closure of respiratory orifices (e.g., strangulation, hanging, smothering, crush asphyxia)

Learning Objectives

• Students should learn the definition, classifications, pathogenesis, and clinical picture of asphyxia
• Students should learn to diagnose asphyxia early to provide timely emergency treatment
• Students should be familiar with various types of violent asphyxia
• Students should understand drowning, including its mechanism, cause of death, post-mortem examination appearance, and medico-legal significance

Causes of Asphyxia

• Defective oxygenation at a cellular level, such as in poisoning
• Mechanical obstruction by the neck, such as hanging and strangulation (manual or by ligature)
• Mechanical airway obstruction, including closure of the external respiratory orifices (e.g., smothering)
• Mechanical obstruction interfering with respiratory movements (e.g., traumatic or crush asphyxia)

Stages of Asphyxia

• Dyspnea
• Convulsions
• Apnea
• Final stage

Pathophysiology of Asphyxia

• Increased carbon dioxide (PCO2) and decreased oxygen (PO2) levels
• Reduced haemoglobin (Hb) and cyanosis
• Respiratory and circulatory dysfunction
• Brain motor area malfunction, potentially leading to convulsions
• Centre paralysis
• Ultimately, death

Diagnosis of Asphyxia (General Signs)

• External signs:
  • Swollen, cyanosed face
  • Prominent eyeballs with conjunctival petechiae
  • Swollen tongue (sometimes bitten)
  • Froth oozing from the mouth/nostrils
  • Deeply cyanosed lips, ears, and fingernails
• Internal signs:
  • Pulmonary edema
  • Froth in air passages
  • Over-distended lungs
  • Right-sided heart failure
  • Right ventricular dilatation

Classical Signs of Asphyxia

• External: Petechial hemorrhages, frothy secretions, bluish discoloration (cyanosis)
• Internal: Dark blood and fluid in the heart, congested viscera, petechial hemorrhages, spots of cyanosis

Violent Asphyxia Deaths

• Violent asphyxia can be further categorized into
• Neck Violence (e.g., Hanging, Strangulation, Throttling)
• Drowning
• Suffocation (e.g., Smothering, Choking)
• Traumatic Asphyxia

Drowning

• Death from submersion of the mouth and nostrils under water
• Not necessarily complete body submersion
• Can be either "wet" (with aspiration of fluids causing hypoxic death- symptoms of drowning) or "dry" (without aspiration) (caused by laryngospasm: when water enters the nose and throat causing spasming of the larynx which prevents breathing)

Types of Drowning

• Primary drowning: Occurs within minutes of submersion. No successful treatment or resuscitation.
• Secondary drowning: Occurs within half an hour to several weeks of submersion. Death after successful treatment or resuscitation. Potential causes include severe lung infection, metabolic acidosis, pneumonia, or pulmonary edema.

Diagnosis of Drowning

• Signs of immersion (not sure signs of drowning): Cold, pale skin, granular/puckered skin, wrinkles/pleached skin, peeling of epidermis
• Highly suggestive signs: Cadaveric spasm, frothy secretions in the mouth/nose, elevated froth with increasing chest compression

Diagnosis of Drowning (Post-Mortem Internal and External Signs)

• Air passages: Full of froth, congested blood vessels in lungs, and debris (sand, mud, weeds).
• Lungs: Voluminous, filling the thoracic cavity, covering the heart, resembling emphysema.
• Lateral surfaces of lungs: Marked with rib impressions
• Diatom test: Detection of diatoms in the lungs and other organs; unreliable, use with caution and interpretation of results

Medico-Legal Investigation (MLI) of Drowning

• Determine if drowning was the cause of death
• Identify the manner of drowning (e.g., accidental, suicidal, homicidal)
• Determine the duration of immersion

Is the Drowning Case Suicidal, Homicidal, or Accidental?

• Difficult to determine but evidence from
  • History and circumstantial evidence
  • Previous suicidal attempts
  • Signs of struggle or body trauma is useful
• Accidents commonly involve children and fishermen.

This quiz covers the definition, classifications, and clinical aspects of asphyxia. Students will learn about the key processes involved in respiration and the various causes of asphyxial death. Important topics include diagnosis and management of asphyxia, including types of violent asphyxia and drowning mechanisms.