Topic 3: Asphyxia — Hanging, Strangulation, Suffocation, Drowning, Signs of Asphyxial Death
Definition and Mechanism of Asphyxia
Asphyxia is a state of oxygen deficiency in the blood (hypoxemia) and tissues (hypoxia), accompanied by accumulation of carbon dioxide (hypercapnia). The resulting physiological cascade progresses through distinct stages: initial hyperventilation and distress, loss of consciousness, convulsions, paralysis, and ultimately death. The common thread in all asphyxial deaths is the interference with the delivery of oxygen to the tissues — whether by obstruction of the external airway, compression of the neck structures, or displacement of oxygen by other gases.
1. Hanging
Hanging is defined as suspension of the body by a ligature encircling the neck, where the body’s own weight provides the constricting force. In complete hanging, the body is fully suspended with no contact with the ground. In partial (incomplete) hanging, some part of the body — feet or knees — remains in contact with the ground.
Mechanism of Death
The mechanism involves multiple simultaneous processes:
- Compression of carotid arteries → rapid cerebral anoxia → loss of consciousness within seconds
- Compression of jugular veins → venous congestion → cerebral oedema → exacerbates anoxia
- Compression of the airway (particularly in typical hanging where the ligature crosses the anterior midline) → direct obstruction
- Stimulation of the carotid sinus → vagal inhibition → cardiac arrest (this is particularly relevant in elderly individuals)
In most cases, death results primarily from cerebral anoxia rather than airway obstruction alone. Deaths can occur within seconds to a few minutes.
Types by Ligature Position
Typical hanging (approximately 80% of cases): The ligature passes over the anterior midline of the neck, running from both sides upward toward the suspension point. Atypical hanging: The ligature passes on one side or over the occiput. Both types can be suicidal, accidental (e.g., in sexual asphyxia), or — rarely — homicidal.
Postmortem Findings in Hanging
External findings:
- Ligature mark: Oblique, V-shaped; the highest point corresponds to the position of the knot; characteristically interrupted at the knot position (a key distinguishing feature from strangulation). The mark is parchment-like, dry, brownish, and corresponds in width to the ligature used.
- Face: Congested, cyanotic, with petechial haemorrhages (Tardieu’s spots) in the conjunctivae and skin of the face and upper body
- Tongue: May be protruded, bitten, or dark-coloured
- Gargoyle eyes (petechiae in conjunctivae and eyelids)
- Pallor is unusual in hanging — congestion is the norm
Internal findings:
- Soft tissue bruising of the sternocleidomastoid muscles and strap muscles of the neck
- Fracture of the hyoid bone (especially greater cornua) is possible, particularly in victims over 40 years of age or those weighing more than 100 kg
- Fracture of the thyroid or cricoid cartilage is uncommon in hanging (unlike strangulation)
- Fractures of the cervical vertebrae are rare except in vehicular accidents or heavy body weights
Antemortem vs. Postmortem Hanging
Antemortem hanging is confirmed by the presence of haemorrhage in the subcutaneous tissue at the ligature mark (vital reaction), petechial haemorrhages in the conjunctivae, and congestion of the face and neck. Postmortem hanging (suspension of the body after death, e.g., to simulate suicide) shows no vital reaction in the ligature mark, absence of petechiae, and often inconsistent positioning.
2. Strangulation
Strangulation is the external compression of the neck by force applied through hands, a ligature, or an object — without the body weight acting as the constricting force. Unlike hanging, strangulation is almost always homicidal.
Types of Strangulation
Manual strangulation (Throttling): Compression by hands, forearm, or elbow. External findings include fingernail abrasions, crescentic nail mark abrasions on the neck, contusions, and contusions in a clustered pattern on the neck. Internal findings include fractures of the hyoid bone (greater cornua most commonly — this is a hallmark finding), fractures of the thyroid cartilage (especially superior horns), and fractures of the cricoid cartilage. Petechial haemorrhages are prominent because compression is often sustained.
Ligature strangulation: A loop of rope, cloth, electrical cord, or other material is tightened around the neck. The key distinguishing feature from hanging is that the ligature mark is horizontal and encircles the neck at a uniform level, and it is continuous — not interrupted at the knot position (unlike hanging where the knot creates a gap). Petechiae are prominent.
Bansdola: A method of strangulation where a stick is twisted into a cloth or rope looped around the neck. Named after the device historically used. Found in certain regions of India.
Postmortem findings specific to strangulation: Fractures of laryngeal cartilages (hyoid, thyroid, cricoid) are significantly more common than in hanging. The ligature mark is at a uniform level around the neck.
3. Smothering
Smothering is the obstruction of the external respiratory orifices (nose and mouth), preventing air from entering the lungs. There are no neck findings — this is a key distinguishing feature from hanging and strangulation.
Causes include hand or palm pressed over the nose and mouth, occlusion by soft objects (pillow, cloth, plastic bag), overlaying (an adult rolling onto an infant during sleep — a cause of sudden unexpected death in infancy), and burking (pressure on the chest while covering the face).
Postmortem findings include: external injuries around the nose and mouth (abrasions, contusions), fluid blood-tinged froth from nose and mouth, congestion of the face and neck, and petechial haemorrhages. Congestion of the lungs and pulmonary oedema are typically present.
4. Traumatic Asphyxia (Crush Asphyxia)
This occurs when the chest and abdomen are compressed, preventing respiratory movements. The mechanism involves forced expiration against a closed glottis → extreme intrathoracic pressure → rupture of capillaries → massive venous congestion of the head and upper body.
Classic findings: Cyanosis and congestion of the head and neck (brick-red or purplish discolouration), petechiae in the conjunctivae and face, subconjunctival haemorrhages, swelling of the face, and petechiae on the upper body below the clavicle. Associated injuries such as rib fractures and abdominal injuries may be present.
Traumatic asphyxia is typically seen in stampedes, crowd crushes, excavation collapses, and when a heavy object falls onto a person’s chest.
5. Drowning (Submersion Asphyxia)
Drowning is defined as the liquid (almost always water) entering the respiratory passages, preventing air exchange. Wet drowning (water entering the lungs) accounts for approximately 90% of drowning cases. Dry drowning (laryngospasm preventing water entry — only a small amount of water reaches the sinuses and hypopharynx) accounts for the remaining cases. Secondary drowning describes a victim who appears to recover but dies hours later from pulmonary oedema.
Postmortem Findings in Drowning
- Washerwoman’s hands and feet: Pale, wrinkled, waterlogged skin appearing after 1–2 hours of immersion
- Cutis anserina (goose skin): Hair follicles erect due to contraction of arrectores pilorum muscles — not reliable as it can occur after death from any cause in cold water
- Fine froth (cup froth): White or pink stable froth at the nose and mouth — a reliable sign; persists even when wiped away
- Water in the stomach: Present in approximately 90% of drowning victims — indicates water was actively inhaled
- Paltauf’s spots: Subpleural haemorrhages — petechial haemorrhages on the surface of the lungs
- Lungs: Overinflated, pale pink, with frothy fluid; froth in the bronchi
Freshwater vs. Saltwater drowning: Freshwater rapidly absorbs from alveoli into the circulation causing haemodilution, hypervolaemia, haemolysis, and cardiac arrhythmias. Saltwater draws fluid into the alveoli by osmotic gradient, causing pulmonary oedema and hypovolaemia.
Diatom Test
Diatoms (siliceous algae) present in water enter the bloodstream through the lungs and are deposited in organs including the bone marrow. Their presence in the bone marrow (most reliably from the femur) is the most reliable indicator of antemortem drowning — they cannot reach the bone marrow after death.
Signs Common to Vital Asphyxial Deaths
- Cyanosis of the face and nails — due to venous congestion
- Petechial haemorrhages (Tardieu’s spots) — small capillary haemorrhages in the skin, conjunctivae, epicardium, pleura, thymus, and brain; caused by rupture of capillaries due to raised venous pressure
- Congestion of the face, lips, and neck
- Fluid froth from the nose and mouth
- Haemorrhages in the deeper tissues of the neck
Tardieu’s spots are named after Ambroise Tardieu and are considered a hallmark of vital asphyxial deaths. They are found most reliably in the conjunctivae — the most accessible and therefore most important external sign.
Manner of Death in Asphyxia
| Type | Most Common Manner |
|---|---|
| Hanging | Suicide (most common) |
| Strangulation | Homicide (usually) |
| Smothering | Homicide (infants: overlay) |
| Traumatic Asphyxia | Accident (stampede) |
| Drowning | Suicide, accident, rarely homicide |
IPC Sections Related to Asphyxial Deaths
- Section 302 IPC: Punishment for murder — where death is caused with clear intention
- Section 304 IPC: Culpable homicide not amounting to murder — where death results from an act with intention to cause injury but not death
- Section 325 IPC: Voluntarily causing grievous hurt
- Section 326 IPC: Grievous hurt by dangerous weapons or acids