What is Asphyxia? Different Types of Asphyxia | All you need to know!

Asphyxia is the term which we usually denote to explain a condition called unconsciousness or death due to lack of oxygen. This condition of asphyxia usually

FORENSIC SCIENCEFORENSIC MEDICINES

Shubham Kumar

1/29/20245 min read

man in blue hoodie wearing eyeglasses
man in blue hoodie wearing eyeglasses
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person holding white and blue plastic bottle

Asphyxia is the term which we usually denote to explain a condition called unconsciousness or death due to lack of oxygen. This condition of asphyxia usually occurs with the hikers, when they were climbing the mountains. On mountains as they move upwards, with the decrease of atmospheric pressure, the concentration of oxygen in air also reduces, potentially causing fatigue, unconsciousness and sometimes death. However, have to ever wondered, that asphyxia can also occur even when someone is not present at heights.

In this article we are going to understand the true meaning of asphyxia and all the classifications of asphyxia.

Asphyxia | Definition

The term asphyxia refers to the condition cased by the interference with the respiratory system, or due to lack of oxygen in the respired air, due to which the organs and tissue gets deprived of oxygen (failed to eliminate CO2 in body), potentially causing unconsciousness and in worst cases, death. The terms asphyxia generally denotes the mode of death rather than the cause of death. The cause of death cane be strangulation, mugging, ligation, drowning, throttling, suffocation, and hanging.

You will be shocked to know that, the human brain weights about 1.4% of total body weight, however, uses 20% of total oxygen available in the body. Our whole body is in proper coordination with the neurotransmitters and nervous tissues. These Nerons are heavily dependent on the oxygen for proper functioning. The nervous tissues are affected first by the deficiency of oxygen and their functions are disturbed even by mild lack of oxygen. If we will calculate the total damage in brain due to lack of oxygen, it will be cessation of nerve cell functions in cerebral cortex after 8 to 15 seconds and in brainstem ganglia after 25 to 30 seconds.

Moreover, Irreparable damage occurs in the cells of cortex after about 3 minutes; in basal ganglia after 6 to 7 minutes and in vagal center after about 9 to 10 minutes. Subnormal oxygen in the blood supply to the brain causes rapid unconsciousness. In all forms of asphyxia, heart may continue to beat for several minutes after stoppage of respiration. The rule of thumb is: breathing stops within twenty seconds of cardiac arrest, and heart stops within twenty minutes of stopping of breathing. If the heart functions for several minutes after stoppage of breathing, the weight of the lungs may increase to 450 to 500 g.

Classification of Asphyxia

Asphyxia is classified into seven types. All these are various classification and events which eventually ended in death or unconsciousness due to lack of oxygen.

Mechanical Asphyxia

In this, the air passage is blocked by mechanical means:

Clouser of external respiratory tracts, this occurs by closing the nose and mouth either by hand, cloth or filling these opening by the mud or similar substances. This is regarded as smothering.

Clouser of air passages by external pressure on the neck. For example in hanging, strangulation, throttling and ligation.

Clouser of air passages by introduction of foreign materials in the larynx and pharynx. For example Chocking.

Prevention of the entry of air by the respiratory tracts due to blockade by fluid. For example in case of drowning. The air is blocked by the water.

The external pressure on the abdominal and chest area, tempering the respiratory movements. For example in Traumatic Asphyxia.

Pathological Asphyxia

This type of asphyxia occurs when the respiratory movements in the respiratory tracts are tempered by the thoracic disease. The disease in wind pipe and upper parts of lungs, can cause sever blockade to the respirable air. For example, infection in bronchitis, oedema of the glottis, laryngeal spasm, tumor and abscess. The paralysis in the muscles of the respiratory tract can also be cause of pathological asphyxia.

Toxic

In this classification, the respiratory movements in the respiratory tracts are tempered by the exposer of toxic substance.

The capacity of hemoglobin in the blood to bound with oxygen reduced. For example inhalation of carbon monoxide.

The enzymatic process by which the blood in the human body is utilized by the tissues and organs are blocked. For example- exposer with cyanides.

The respirator tracts may gets paralyzed or get poisoned by the indefinite consumption of opium, barbiturates and other narcotic and stimulant drugs.

The muscles of respiration may be paralyzed by poisoning by gelsemium.

Environmental

In this classification, the respiratory movements in the respiratory tracts are tempered by the abnormal concentration of oxygen in environment.

Insufficiency of oxygen in the area where an individual is being trapped. For example, if an individual is trapped in refrigerator, trunk etc.

Exposer to the irrespirable gases in atmosphere. For example- Bhopal Gas Tragedy and exposer to sewer gas, carbon mono-oxide and carbon di-oxide.

When individuals travel to high altitudes. They suffer with lack of oxygen, due to low atmospheric pressure on altitude.

Traumatic

In this classification, the respiratory movements in the respiratory tracts are tempered by the application of external pressure on the walls of abdomen and chest.

Postural

In this classification, the respiratory movements in the respiratory tracts are tempered by the uneven posture of upper half of the body. This is usually witnessed when an unconscious or stuporous person, either from alcohol, drugs and disease, lies with the upper half of the body lower than the remainder.

Iatrogenic

In this classification, the respiratory movements in the respiratory tracts are tempered by the introduction of Anesthesia.

How the compression of Neck Occurs

When pressure is applied to the neck, it blocks the jugular veins, preventing blood drainage from the head. However, the arteries (carotid and vertebral) supplying blood to the head continue to function. If the air passages are blocked, the lungs' ability to oxygenate blood is impaired, resulting in lower oxygen levels in the arteries. This reduction in oxygen triggers the dilation of capillaries, leading to blood stagnation in these vessels and venules, resulting in capillary-venous engorgement. The stagnant blood causes organ congestion, reducing the return of blood to the heart and causing oxygen deprivation (anoxia). This, in turn, leads to further capillary dilation, creating a cyclic pattern as illustrated in Figure below.

Way Forward

Asphyxia, often associated with oxygen deprivation in mountainous terrains, reveals a broader spectrum of implications. Expanding beyond its commonality, asphyxia encompasses various modes of death rather than a singular cause. The brain's significant oxygen dependency accentuates its role in sustaining neurological functions.

The seven classifications of asphyxia offer a nuanced understanding of conditions leading to unconsciousness or death due to oxygen deprivation. Mechanical, pathological, toxic, environmental, traumatic, postural, and iatrogenic asphyxia represent distinct scenarios, providing insight into the multifaceted factors contributing to this condition.

This exploration delves into the complexities of asphyxia, offering a concise yet comprehensive perspective on the diverse circumstances and physiological consequences associated with respiratory interference or lack of oxygen.

Reference

  • "Forensic DNA Typing" by John M. Butler

  • "The Forensic Casebook: The Science of Crime Scene Investigation" by Ngaire E. Genge

  • "Forensic Science: A Very Short Introduction" by Jim Fraser

  • "Practical Crime Scene Processing and Investigation" by Ross M. Gardner