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Asphyxia: Classification, Post-mortem Findings, PowerPoint

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What is Asphyxia?

Asphyxia means the absence of pulsation due to decreased O2 supply to the body’s tissues. There are other similar terms like anoxia and hypoxia. The hindrance in oxygen transport can be:

  • Internal/External
  • Physical/Chemical
  • Atmospheric/Cellular
  • Due to any disease

There are the following classical signs seen in asphyxial conditions;

  • Congestion
  • Edema
  • Cyanosis
  • Petechiae

N.B. All these signs are only suggestive but not specific.


  1. Environmental: Low O2 tension in the air-vitiated environment sewers, high altitude, wells, etc
  2. Mechanical: Physical (force/obstruction) of various parts: Decrease O2 supply due to Hanging, Strangulation, Drowning, Traumatic, positional, etc.
  3. Pathological Diseases: Decrease O2 supply due to pathological conditions such as Anemia, Pneumonia, Cardiac failure, etc.
  4. Chemical: Toxins or Poisons or Gases: Decrease O2 supply due to some chemicals such as CO, Methane, H2S, Cyanide, Strychnine, Morphine, etc.

Mechanical Asphyxia

  1. External Mechanical Asphyxial Conditions
    • Smothering: Obstruction over nostril and mouth
    • Hanging: Neck pressure by force of own weight
    • Strangulation: Neck pressure by an external force
      • Manual strangulation/Throttling
      • Mugging/Arm lock/Chokehold & Carotid Sleeper hold
      • Ligature strangulation
      • Garrotting
      • Bansdola
    • Traumatic asphyxia/Overlaying: decreased breathing due to external force
    • Positional/Postural asphyxia: ↓breathing due to body position
    • Mixed/Burking: Smothering + Traumatic asphyxia
  2. Internal Mechanical Asphyxial Conditions
    • Gagging: Obstruction inside nose & mouth
    • Choking: Obstruction at or below the larynx
      • Café coronary
    • Drowning: Obstruction at the level of alveoli


Asphyxia is caused by mechanical occlusion of the external respiratory opening (nostril and mouth). The mechanism of death is due to the blockade of respiration and Reflex cardiac arrest. The manner of death may be accidental, homicidal, or suicidal can determine postmortem findings. Accidental conditions are seen due to intoxicated/epileptic/unconscious persons sleeping in a prone position, buried by sand/mud during disasters, Fetuses born with intact amniotic membranes, and Children covering their heads with plastic bags while playing. Homicidal condition attending due to hand/pillow/plastic bags. Suicidal conditions have been shown with plastic bags or burials. 

Post mortem Findings
In a person dying in a prone position, the skin around the mouth and nose may appear pale due to contact pallor, and salivary secretion is seen over the pillow. In a burial case, sand and mud particles are present inside the nose, mouth, and respiratory tract.  In homicidal smothering by hands around the mouth and nose, the following features are noticed crescentic abrasions or nail marks, scratch marks, ovoid contusions, torn frenulum, lacerations, and abrasions.

Traumatic asphyxia

Restriction of respiratory movements due to compression or mechanical fixation of the chest wall by external pressure or agent. The abdominal wall may or may not be compressed. Actual injury need not be constructed over the chest. The signs of asphyxia are most pronounced. The mechanism of death asphyxia is due to the absence of respiratory movement. The manner of death was either accidental, homicidal, or suicidal.

Postmortem findings
External injuries over the chest and abdomen by a crushing agent. Mud or sand is present over the body. Marked signs of asphyxia above the level of compression are called Masque Ecchymotique. Fractured ribs or Organ injuries due to compression of the chest. Congestion and petechiae of internal organs pleura or pericardium. Some cases have shown oedema glottis.

Positional Asphyxia

Asphyxia due to certain body positions causes difficulty in normal respiration. It occurs due to the bending of the airway, the elevation of the tongue against the pharynx, and compression of the chest and abdomen. Usually accidental due to common among alcoholics or mentally retarded or sub-conscious persons. It may occur when a person is trapped in an abnormal body position → ditch/between the walls. The postmortem findings are abnormal body posture, evidence of alcohol intake, or marked signs of asphyxia.


Asphyxia caused by obstruction between larynx and tracheal bifurcation. It was usually accidental but sometimes homicidal. The mechanism of death was vagal inhibition, laryngospasm, airway obstruction, or delayed infections. Choking is common in children or epileptic patients, artificial dentures or injuries & surgeries of the oral cavity and nose, anaphylaxis, diseases of the airway or vomit regurgitation in the unconscious. Accidental choking by food particles while eating symptoms may look like acute coronary syndrome. Predisposing factors are inadequate chewing, poor cough/gag reflex, and intoxication/decreased consciousness level. Postmortem findings were asphyxial signs or the choking agent present in the airway.


Hanging is a form of asphyxiation resulting from the application of pressure to the neck by a ligature, which can involve either the entire or a portion of the body’s weight. This act can be categorized as suicidal, homicidal, or accidental and can manifest as complete or partial hanging or suspension.

Complete suspension refers to instances in which no part of the body makes contact with the ground, with the entirety of the body’s weight applying constriction to the neck.

Partial hanging, on the other hand, occurs when some part of the body remains supported or touches the ground, and a portion of the body’s weight contributes to the constriction of the neck, often facilitated by sitting, kneeling, lying down, or assuming a prone position.


Asphyxia is the result of neck pressure exerted by a force other than the body’s own weight. This can occur through various means, such as ligature strangulation, manual strangulation, mugging, garroting, or bansdola. In the context of hanging, it is a form of ligature strangulation where the force is generated by the gravitational pull of either the complete or partial body weight. The mechanism of death in cases of ligature asphyxia is identical to that of hanging.

In terms of the manner of death, homicidal instances are more common in ligature asphyxia cases, followed by accidental occurrences and then suicidal incidents. Signs of asphyxia tend to be more pronounced in ligature asphyxia compared to traditional hanging cases.

External Postmortem Finding
Facial features in cases of ligature asphyxia exhibit distinct characteristics, including marked congestion, cyanosis, and edema. Multiple petechiae are often observed on the face and conjunctiva, accompanied by bleeding from the nose, ears, and mouth, which can result in prominent eyes and a protruded tongue.

The ligature mark itself, which is a critical indicator, is typically horizontal, positioned lower on the neck, often at or below the Adam’s apple, and completely encircles the neck. In some instances, there may be a crossing of two ligature marks, and these marks can even exhibit patterns.

Signs of a struggle and disturbance at the crime scene are common, evidenced by torn clothing and deep purplish postmortem staining. Abrasions over the neck can occur due to actions by either the assailant or the victim during the struggle. Additionally, associated smothering injuries and defence injuries over various body parts may be present, further revealing the intensity of the struggle. In cases involving sexual violence, genital injuries may also be evident, and any other injuries found on different body parts should be carefully documented and analyzed in the forensic assessment.

Internal Postmortem Finding
In cases involving neck findings, a range of significant observations may be made. Hemorrhaging and tears can occur in the soft tissues and muscles located just beneath the ligature mark and knot. However, it’s uncommon to find fractures of the thyroid cartilage and hyoid bone in these instances.

In some cases, especially when a deep and penetrating thin ligature material is involved, carotid intimal tears may be evident. Additionally, contusions may be observed at the root of the tongue and the floor of the mouth, and there may be ecchymosis, petechiae, or edema present in the mucosal lining of the larynx.

Furthermore, it’s important to note that non-specific congestion, edema, and petechiae may be detected in various organs, resembling findings seen in cases of hanging. These neck findings provide valuable insights for forensic analysis and can contribute to understanding the circumstances surrounding the individual’s demise.


Drowning represents a type of asphyxiation resulting from immersion in a liquid medium, typically water. Often, the diagnosis of drowning is arrived at through a process of exclusion, particularly in cases involving deceased individuals recovered from bodies of water, when no other notable cause of death can be determined. It is important to note that the likelihood of drowning being accidental is higher than it is a result of suicide or homicide.

Dry Drowning
Dry drowning is triggered by the abrupt entry of water into the larynx, leading to a specific mechanism of death. This mechanism involves the occurrence of severe laryngospasm and vasovagal cardiac arrest. It is possible for a physical blockage of mucus, foam, or froth to develop in the process. In cases of dry drowning, death occurs swiftly, and notably, the lungs remain comparatively dry throughout the process.

Shallow Drowning
Shallow-water drowning refers to the occurrence of drowning in relatively shallow bodies of water, such as pits, drains, or trenches. It’s noteworthy that even a brief immersion of the nose and mouth in such shallow water can lead to fatal drowning incidents. This type of drowning is particularly prevalent among individuals who are under the influence of alcohol, children, epileptics, or those who are under the influence of drugs. What sets these cases apart is that individuals affected by these conditions often struggle to rescue themselves from what might otherwise be considered a manageable situation.

Wet Drowning
Drowning, often referred to as wet drowning or primary drowning, involves the inhalation of water into the lungs, where it penetrates into the bronchi and alveoli, leading to a mechanical obstruction of respiration at the alveolar level. This drowning can be categorized into different types, depending on the nature of the water involved, including freshwater or brackish water drowning, as well as saltwater or seawater drowning.


  1. Gautam Biswas, Review of forensic medicine and toxicology, 4th Edition
  2. Nagesh Kumar G Rao, Textbook of Forensic Medicine and Toxicology, 2nd Edition
  3. Dr KS Narayan Reddy, The Essentials of forensic medicine and Toxicology
  4. Krishnan Vij, Textbook of Forensic Medicine and Toxicology, 5th edition

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