Asphyxia refers to hypoxia or anoxia caused by interference with breathing mechanics. Unconsciousness typically occurs within 2-3 minutes of asphyxia, with death within 4-5 minutes. Asphyxia can be classified as mechanical, pathological, toxic, environmental, traumatic, or positional. Mechanical asphyxia includes suffocation, smothering, choking, strangulation, hanging, and drowning. Positional asphyxia occurs when a victim is immobilized in a position that interferes with breathing. Common signs of asphyxia seen at autopsy include petechial hemorrhages, cyanosis, and congestion, though there are no wholly specific findings.

1. ASPHYXIA
ANDRINA VARGHESE PANICKER
FORENSIC MEDICINE

2. INTRODUCTION
 It is defined as hypoxia/ anoxia that is caused when the respiratory function is hampered by interference
with the mechanics of breathing.
 When a person is subjected to asphyxia, unconsciousness generally occurs in 2-3 minutes and death in
4-5 minutes.
 However death can be hastened by factors such as-
 Struggling- increased physical activity uses up available oxygen much faster
 If the individual has any pre—existing disease
 Poor general state of health from any cause

4. CLASSIFICATION
 Mechanical
 Suffocation
 Smothering
 Choking
 Strangulation
 Hanging
 Drowning

5. CLASSIFICATION
 Pathological – entry of oxygen in lungs decreased due to disease of upper respiratory tract or lung. E.g.
Bronchitis, acute edema of glottis, laryngeal spasm.
 Toxic- Poisonous substance preventing use of oxygen. Carbon monoxide poisoning, paralysis of
respiratory center by opium, barbiturates, strychnine etc.
 Environmental: Insufficient oxygen in inspired air. e.g., enclosed spaces, irrespirable gas in environment
as in sewer gas, high altitude etc.
 Traumatic: Bilateral Pneumothorax, pulmonary fat embolism from fracture of long bones, pulmonary
thrombo-embolism due to injury of lower limb etc.
 Postural asphyxia: in unconscious or stupors person, where upper half of body lower than remainder.
 Iatrogenic: anesthetic deaths

6. SUFFOCATION
 True suffocation ( also called environmental suffocation) occurs when there is insufficient
oxygen in the local atmosphere, usually in cases where the victim is trapped in a small,
unventilated space e.g. trapped in a cellar or mine, sealed in a truck or safe etc.
 Death usually occurs slowly and there are no specific autopsy findings
 Petechiae is absent

7. SMOTHERING
 Smothering and suffocation are often used interchangeably, but the term “smothering” is
best used for that form of asphyxia in which the nose and mouth are obstructed e.g. by a
hand, paper, clothes, pillow, plastic bag.
 Gagging people to keep them quiet may lead to smothering
 Signs of asphyxia are commonly absent or are only slight, and because marks of injury may
be few- if any at all.

8. STRANGULATION
 Death by strangulation is usually homicidal but less commonly may be accidental or suicidal.
 It is usually due to constriction of the neck by a force other than the weight of the body. One
may use a ligature but the hands may also be used ( throttling).
 The ligature mark is usually at a lower level and more horizontal than in hanging and is
usually located in the mid-larynx region i.e. at about the level of the thyroid cartilage. The
mark is usually ,less prominent than in hanging, especially if a soft ligature is used. However,
if a narrow wire is used, the mark may be deep and the skin may even be cut.
 Suicidal strangulation- is possible but uncommon. It may be achieved by using tourniquet
mechanism or adhesive ligature, e.g. Velcro-type bands.
 Accidental strangulation- does occur e.g. from clothing such as a necktie or scarf becoming caught in
moving machinery.

9. CHOCKING
 This is due to blockage of the internal air passages, usually by foreign material e.g. inhaled vomit, blood, food
particles- especially fruit seeds in children, the tongue in comatose patients etc.
 At autopsy the features of asphyxia are usually well developed and the offending foreign material is
demonstrated in the airway.
 Occlusion (partial or total) of the airways by foreign bodies, leading to respiratory blockage and potentially
death
 Can be observed in any age category but typically in the elderly and children
 Diagnosis is usually suspected based on the clinical history
 Diagnosis is confirmed at autopsy when the airway is found occluded and the foreign body is retrieved
 Accident is the most common manner of death in choking

10. COMPRESSION ASPHYXIA
 External pressure on the body prevents physiologic respiration
 Also called traumatic or crush asphyxia
 Usually due to external compression of chest / abdomen by heavy weight
 Commonly observed in soft drink vending machine tipping, motor vehicle accidents, cave related accidents
and mass disasters (earthquake, collapsed buildings)
 Primary mechanism of death is flail chest
 Adult male requires 2550 ± 250 N of chest applied distributed static force (260 ± 26 kg with earth gravity) or 4050 ± 320
N of dynamic force to cause flail chest from short term chest compression
 Frequently observed in children:
 Overlaying asphyxia: when a heavy sleeping adult may move on top of the infant, causing compression asphyxia
 Wedging: when the body is compressed between 2 firm surfaces, preventing breathing

11. POSITIONAL ASPHYXIA
 Occurs when the victim is immobilized in a position which causes mechanical interference with
pulmonary ventilation, leading to respiratory failure and death.
 Scene investigation typically gives relevant clues to determine the cause and manner of death
 Prolonged head down position of the body interferes with respiration and blood circulation due to intra-
abdominal organs compressing the diaphragm, causing increased intrathoracic pressure and
compression of inferior vena cava.
 Prolonged hyperflexion or hyperextension of the neck may result in airway obstruction.
 Unnatural chest positions may interfere with the physiologic rib cage expansion and retraction, resulting
in reduced gas exchange

12. SYMPTOMS AND SIGNS SEEN IN ASPHYXIA
 There are not many specific autopsy findings for asphyxia death except for the triad-
 Petechial hemorrhage
 Cyanosis
 Congestion
 Other non-specific signs of asphyxia
 Pulmonary edema
 Fluidity of blood
 Dilation of right chambers of heart

13. GENERAL POST MORTEM FEATURES OF ASPHYXIA
There are no specific autopsy findings for asphyxia death-
 External
 These are congestion, edema, petechiae (0.1-2 mm), ecchymosis (> 2mm), cyanosis, deep postmortem staining,
protrusion of tongue, bloody and frothy fluid from mouth and nose, swelling of face, Prominence of eye balls,
spontaneous defecation, urine & sperm excretion.
 The face is either pale in slow asphyxia, or distorted, congested often cyanosed.
 The eyes are congested with dilated pupils.
 Petechial hemorrhages, known as Tardieu Spots are most marked in areas where capillary congestion is most
prominent for mechanical reasons. Their distribution lies above the level of obstruction and commonly appears as
a rash-like shower in the scalp, eyelids and face in hanging and strangulation and in the zone above the level of
compression in cases of traumatic asphyxia.

14. GENERAL POST MORTEM FEATURES OF ASPHYXIA
 Internal
On dissection, the following findings may be seen depending on the type of violent asphyxia (they are
discussed in more details under specific headings).
 Tardieu spots, dark & fluidity of blood, congestion of organs, middle ear bleed, emphysematous lungs,
pulmonary edema, with froth in trachea and bronchi, bulky, crepitant and over-distended lungs, Right
ventricular dilatation etc.
 If heart stops before respiration the asphyxial signs will be less. The blood is dark in color and fluid
because of increase amount of CO2.
 There may be bursting of small vessels in the ear drums and nose due to increase in back pressure,
leading to bleeding.
 The larynx and trachea are usually congested and may contain varying amount of blood tinged mucus.
 The abdominal viscera show marked congestion.

15. GENERAL POST MORTEM FEATURES OF ASPHYXIA
 Histology-
 Under microscopic examination, the following non-specific findings will be seen.
 Disruption of alveolar septa with hemorrhage in alveoli and edema.
 Brick red discoloration of nerve cells in cortex.
 Pallor & Vacuolar degeneration of Purkinje cells in the cerebellum.
 Vacuolar degeneration of liver cells.
 Chemical marker- Hypoxanthine in blood & vitreous

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