Asphyxia

Asphyxia is a condition caused by interference with respiration, or due to lack of oxygen in respired air, due to which the organs and tissues are deprived of oxygen (together with the failure to eliminate Co2 causing unconsciousness or death.

Mechanical asphyxia is a broad term in which enough external pressure is applied to the neck, chest, or other areas of the body, or the body is positioned in such a way that respiration is difficult or impossible.

 

Causes of asphyxia:

No	Types	Causes
1.	Mechanical	1. Hanging 2. Drowning  3. Strangulation 4. Throttling 5. Choking 6. Smothering
2.	Pathological	1. Bronchitis 2. Laryngeal spasm 3. Acute edema of Glottis 4. Tumor and abscess Paralysis if respiratory muscle
3.	Toxic	1. CO poisoning  2. Cyanide poisoning 3. Barbiturate poisoning 4. Snake venom
4.	Environmental	O2 insufficiency in inspired air eg, enclosed place, trapping, Exposure to high altitude
5.	Traumatic	Injury to both lungs Pneumothorax from injures Pulmonary fat & air embolism
6.	Postural	Alcohol/drugs/diseases
7.	iatrogenic	Related with anesthesia

 

Asphyxia - Reduction in oxygen tension - capillary dilatation - capillary stasis - capillary engorgement - stasis of blood in organs - Diminished  venous return to the heart - reduced pulmonary flow - deficient oxygenation in lungs - leading to anoxia, which causes capillary dilatation and the vicious cycle goes on

 

Signs of asphyxia:

• Cyanosis 
• Tardieu's spot (Petechial hemorrhages) facial, palpebral, bulbar, subpleural and subepicardial petechiae,
• Visceral congestion

 

Petechial hemorrhages

Petechial hemorrhages are rounded, pin-headed size hemorrhagic spots develop due to raised venous pressure from impaired venous return resulting in overdistension and rupture of venules. A minimum of 15 to 30 seconds is required to produce congestion and petechiae.

Petechiae vary in size from 0.1 to 2 mm. If larger than this they are called ecchymoses.

Site for seeing Petechial hemorrhages:

• Skin,
• Conjunctiva,
• Sclera, face,
• Mucosal surfaces in the mouth,
• Sub-pleural surface of lung, heart

 

Hanging

Hanging is that form of asphyxia which is caused by the suspension of the body by a ligature which encircles the neck, the constricting force being the weight of the body.

Types of Hanging:

A. According to the degree of suspension:

• Complete
• Partial

B. According to the position of knot:

• Typical: knot at the nape of the neck
• Atypical: knot at any site of neck other than the nape of the neck

C. According to the nature:

• Suicidal
• Homicidal
• Accidental
• Judicial

 

Type of knot

1. Fixed-knot: Single, double, or more than two.

2. Slipping knot/ running noose

 

Signs – symptoms of hanging:

1. Loss of power orientation

2. Convulsion

3. Spasm

 

Weight need for Blockage

Jugular veins	2 kg
carotid arteries	4 - 5 kg
Trachea	15 kg
Vertebral arteries	20 kg

 

Causes of death in hanging:

Immediate causes:

• Asphyxia
• Venous congestion
• Combined asphyxia and venous congestion
• Cerebral anemia
• Reflex vagal inhibition
• Fracture or dislocation of the cervical vertebrae.

 

Delayed Death :

1. Aspiration pneumonia,
2. Infections,
3. Edema of lungs,
4. Edema of the larynx,
5. Hypoxic encephalopathy,
6. Infarction of brain,
7. Abscess of the brain,
8. Cerebral softening

 

Post-mortem findings in case of suicidal hanging:

	External	Internal
Neck findings	Ligature mark: oblique-non-continuous- high up on the neck. It is grooved. Bending of the neck.	Subcutaneous tissue underneath the ligature mark: Dry, white, firm, and glistening - Parchmentization All other organs lung, trachea, larynx, tongue are bluish, congested.
Other findings	a. Dribbling of saliva b. Tongue: protruded c. Face, tongue: pale, congested Distribution of postmortem staining. Involuntary discharge of semen, urine Petechial hemorrhage over skin, sclera.	a. Larynx and trachea: congested b. Lungs: congested, Tardieu’s spot present c. All organs: congested d. Brain: congested, edematous

Asphyxia occurs in hanging:

Pressure by rope – pressure in tongue – tongue obstructs the airway – asphyxia 

 

Surest sign of antemortem hanging:

Dribbling of saliva from the angle of the mouth of the opposite side of the knot

Ligature mark with petechial hemorrhage & ecchymosis into or around its substance.

Tear in the intima of the carotid artery with extravasation of blood.

Congestion & hemorrhage in a lymph node above & below the ligature mark.

Fracture & dislocation of cervical vertebrae

Absence of other fatal injuries

 

Causes of non-finding ligature mark:

• Broad ligature material 
• Purification
• Collar of shirt
• Decomposition
• Abased just after hanging
• Weight of body less

[If the body is hanged within 2 hours after death ligature mark may be found due to rigor mortis]

 

Ligature mark depends on

1. Composition of ligature
2. Width and multiplicity of ligature
3. The weight of the body suspended and the
4. Degree of suspension
5. Period of suspension
6. The tightness of encircling ligature
7. Position of the knot
8. Slipping of ligature during suspension

 

Ligature material used in hanging

Rope, Belt, necktie, bed sheet, scarf, sacred thread, electric wire, saree, metallic chain

 

Partial hanging:

When the body is partially suspended, the toes/feet touching the ground or in a sitting, kneeling, lying down, prone or any other posture, with only the head and chest off the ground. The weight of the body, being the constricting force.

 

Difference between Typical hanging and Partial hanging:

S.N	Traits	Typical suicidal hanging	Partial hanging
1.	Degree of suspension	Fully suspended	Not fully
2.	Position of knot	Nape of the neck	Any site other than the nape of the neck
3.	Congestive changes	Less	More
4.	Vessel obstruction	Carotid artery + vertebral artery + jugular vein	But except vertebral artery, it continues blood supply to the brain

 

Strangulation

It is a form of asphyxia which is caused from constriction of the neck by a ligature without suspending the body. It is homicidal.

 

Types of Strangulation:

• Ligature Strangulation proper
• Throttling
• Bansdola
• Mugging
• Garroting

Finding in strangulation

 

External	Internal
Circular, continuous, low down in the neck The ligature mark is a well-defined and slightly depressed mark at any level on the neck, but usually about the middle or below the thyroid cartilage.	Extravasation of blood in subcutaneous as well as in adjacent muscles of the neck. Carotid sheath & intima may be lacerated. presence of bruising of the neck muscle
Abrasion & ecchymosis in the skin adjacent to mark	Injury to hyoid bone is uncommon. Fracture of the superior horn of thyroid cartilage may occur
In case of throttling, marks of palm, finger tips on either side of the neck	Larynx, Trachea - congested & presence of Tardieu’s spot under the mucous membrane of the lumen
Face- congested & cyanosed Bloody froth from mouth, nostril Hands - clenched Protrusion of tongue Nail mark Petechial hemorrhage on skin, sclera.	Heart, lung, abdominal organs, brain - congested.

 

Difference between hanging and strangulation:

Traits	Hanging	Strangulation
Ligature mark	Oblique, non-continuous, high up in the neck	Circular, continuous, low down in the neck
Abrasions and ecchymoses about the edge of ligature mark	Not common	Common
Face	Usually pale and petechiae are not common	Congested with petechiae
Dribbling of saliva	Present	Absent
Seminal ejaculation	More common	Less common
Involuntary Discharge of urine and feces	Less common	More common
Subcutaneous tissue	Dry, white, firm, and glistening	Contused with gross extravasation (ecchymosed)
Bruising of neck muscles	Less common	More common
Hyoid bone	Fracture may occur	Uncommon
Thyroid cartilage	Fracture less common	More common
Larynx and trachea	Fracture rare	May be found if greater force is applied
Bleeding	Not	Nose, mouth, ear

The basic difference between hanging and strangulation:

Traits	Hanging	Strangulation
Constriction of force	By body weight	By other than body weight

 

THROTTLING OR MANUAL STRANGULATION

Asphyxia produced by compression of the neck by human hands is called throttling. Death occurs due to the occlusion of carotid arteries. Occlusion of the airway plays a minor role.

 

External

Abrasions & bruises on the front and sides of the neck, and are commonly at each side of the laryngeal prominence and just below the jaw­line.

The tips of the fingers produce bruises. Bruises made by tips of thumbs are more prominent than with other fingers.

Marks of struggle and external appearances of asphyxia are similar to those found in strangulation.

When pressure is prolonged, the classical signs of asphyxia may be seen—cyanosis, edema, and congestion of the face, Tardieu’s spot in the eyes and face, and sometimes bleeding from nose and ears.

Because of struggle and resistance, marks of bruising and abrasions may be found over the face, nostrils, lips, chin, cheeks, forehead, and lower jaw of the victim. These can also be caused in an effort to stop the victim from shouting or crying for help.

 

Internal Findings

Extravasation of blood in subcutaneous tissues underneath the external marks of bruising and abrasions is the most significant internal sign.

Inward compression fracture of the hyoid bone is the most diagnostic finding of throttling.

Fracture of superior horns of the thyroid cartilage is common, though both horns do not get fractured simultaneously.

Tear/laceration of platysma or sternomastoid muscles may be seen.

The tongue may be bruised/lacerated, may protrude out, and bitten by teeth.

Hemorrhages, varying from pinpoint ecchymosis to extensive extravasation may be found in the mucous membrane of the larynx, epiglottis, pharynx, and peritonsillar region.

The usual diagnostic signs of death due to manual strangulation are:

(1) Cutaneous bruising and abrasions.

(2) Extensive bruising with or without rupture of the neck muscles.

(3) Engorgement of the tissues at and above the level of compression.

(4) Fracture of the larynx, thyroid cartilage and hyoid bone.

(5) Cricoid cartilage is almost exclusively fractured in throttling.

(6) General signs of asphyxia.

 

Mugging

When strangulation is caused by compressing the neck in the elbow bend or knee bent is called mugging.

 

GARROTTING:

The victim is attacked from behind without warning. The throat may be grasped, or a ligature is thrown over the neck and quickly tightened, by twisting it with a lever (rod, stick, ruler, etc.), within the ligature.

Bansdola

It is a form of strangulation in which the compression of the throat is produced by placing two bamboos, one across the front and the other across the back of the neck and then both ends are tied with a rope strongly.

 

Suffocation

It is a general term to indicate that form of asphyxia which is caused by deprivation of O2 either due to lack of O2 in the environment or from obstruction of the air passages at the level of nose and mouth.

OR,

It is the form of asphyxia in which the passage of air between the air and lungs is prevented by any mechanical means other than constriction of the neck and drowning.

 

Types of suffocation

1. Gagging
2. Choking
3. Smothering
4. Traumatic asphyxia
5. Overlying
6. Positional/Postural asphyxia

 

Gagging:

It is a form of asphyxia which results from forcing clothes into the mouth/the closure of mouth and nose by a cloth or similar material, which is tied around the head.

 

Choking:

It is a form of asphyxia which is caused by an obstruction within air passages usually between the pharynx and bifurcation of the trachea.

Cause of Death:

(1) Cardiac inhibition is the common cause.
(2) Asphyxia.
(3) Laryngeal spasm
(4) Delayed death may result from pneumonia, lung abscess or bronchiectasis.

 

Smothering

It is a form of asphyxia which is caused by closing external respiratory orifice either by hand or by other means or blocking up the cavities of the nose and mouth by the introduction of foreign substance I.e., pillow, mud, paper, cloth, etc

 

Traumatic asphyxia/Landslide death

It is a form of asphyxia from respiratory arrest due to mechanical fixation of the chest by unyielding objects so that the normal movement of chest movement is prevented.

Circumstances/examples:

• House collapse
• Stampeded by crowd
• By vehicle
• The collapse of the wall inside a mine

 

Post-mortem findings of traumatic asphyxia

Externally	Internally
1. Cyanosis on the face 2. Haemorrhagic spots 3. Stain of dust and soil over the body 4. Abrasion 5. Laceration	1. Fracture of rib 2. Injury to the heart, lungs, liver 3. Blood may be found in the thoracic and abdominal cavities.

 

CAFE CORONARY:

This is a condition in which a healthy but grossly intoxicated person 1restaurant patron), who begins a meal, suddenly ~urns blue, coughs violently, then collapses and dies, without much fuss. Death appears to be due to a sudden heart attack.

Barking is the method of homicidal smothering and traumatic asphyxia.

 

Sexual asphyxia

It is a peculiar type of hanging which causes partial asphyxia and causes some abnormal sexual pleasure in some perverted person.

- Victim usually young males with some form of abnormal sexual behavior.

 

POSTURAL OR POSITIONAL ASPHYXIA:

It occurs when an individual acquires a certain body position in which his breathing is impaired, often because of neck twisting with kinking or compression of the trachea and/or elevation of the tongue into the posterior hypopharynx. In addition, the normal venous return to the heart may be impaired.