Suffocation is a general term to indicate that form of asphyxia, which is caused by deprivation of oxygen, either due to lack of oxygen in the environment or from obstruction of the air-passages.
This is a form of asphyxia which is caused by closing the external respiratory orifices either by the hand or by other means, or blocking up the cavities of the nose and mouth by the introduction of a foreign substance, such as mud, paper, cloth, etc.
Suicide by Smothering: Suicidal smothering by the hand is impossible. Suicide is possible by burying the face in a mattress or lying against the bed clothing to obstruct the nose and the mouth, it is usually seen in the mental patients or prisoners. Sometimes, in cut-throat wounds, the trachea may be completely cut and the soft parts may obstruct the trachea and the victim is smothered. Suicidal suffocation can be effected by tying a polythene or similar bag over the head.
Accidental Smothering: Most fatal smothering is accidental. Rarely, infants during the first month of life, especially when premature may be smothered by the weight of the bed clothes when they cover the nose and the mouth. Suffocation also occurs when the infant 3 months or less, turns on its face and buries it in soft pillow or mattress, it is not necessary that the mouth and nostrils should be completely closed at the start, for as obstruction increases and congestion develops, saliva, mucus, oedema fluid, and traces of blood will pour out into te mouth and cause obstruction to breathing. An epileptic or intoxicated person may smother himself accidentally by burying his face in a pillow or covering with bed clothes. A person may accidentally fall into a large quantity of semisolid or finely divided material like mud, ashes, grain, sand, coal dust, etc., so that his mouth and nose are covered by the substance. The victim may struggle, inhale some of the material into his air-passages, and swallow some into his stomach in an effort to breathe. Children may be suffocated accidentally while playing with plastic bags. Death may occur even if the open end of the bag is not tied around the neck due to cardiac inhibition. Smothering from plastic bags may occur due to the addictive habit of “glue-sniffing”, in which the organic solvents of certain glues is used as an intoxicant, by putting obtain a high concentration of vapor. In such cases, chemical analysis is essential. Plastic bags may be applied to the head for experiment or auto-erotic exercise, as partial asphyxia is believed to increase sexual sensation. It also occurs if the membranes remain round the head of the newborn after delivery.
Environmental Suffocation: Asphyxia is due to insufficient oxygen in the environment. Deaths are almost always accidental. An oxygen concentration of 16% or less is dangerous, and with 5% concentration, consciousness is lost rapidly and death occurs within a few minutes. Smothering occurs in airtight place or one in which ventilation is negligible. This may occur when children become locked in old disused refrigerators or when they lock themselves into large boxes or trunks during play. Suffocation due to lack of oxygen in the atmosphere may occur in the vicinity of lime kilns and wells or excavations in chalk rock, where the oxygen is displaced by CO2. In a confined space, such as tanks, grain-bins, silos, deep tanks of a ship, fermenters, tanning vats, unused wells, sewers, etc., hazardous gases, vapour, dust or fumes may accumulate or the oxygen may be deficient. A person may be suffocated on entering such a confined space. Inhalation of irrespirable gases, such as CO2, CO, hydrogen sulphide, or smoke from a burning house, or entering into disused wells produce suffocation. CO2 and methane are the most commonly encountered suffocating gases. Suffocation may occur in decompression, such as cabin failure of aircraft at high altitudes. It also occurs in ship’s tanks or other industrial metal chambers, in which oxygen is replaced by nitrogen. In deaths associated with replacement of oxygen with an inert gas, rapid death is common before hypoxia had any physiological effect. In hypoxic death petechial haemorrhages are absent. Congestion and cyanosis may or may not be present.
Homicidal Smothering: Homicide is possible where the victim is incapacitated from drink or drugs, very weak, child or old person, in ill-health and when the victim is stunned by a blow. Usually, the mouth and nose are closed by a hand or cloth, or the face may be pressed into a pillow.
Autopsy: Obstruction by bed clothing, a pillow, a cushion, etc., applied with skill, may not leave any external signs of violence, especially in the young and the old, except signs of asphyxia. When the face is pressed into a pillow, the skin around the nose and mouth may appear pale or white due to pressure, with cyanosis of the face. Saliva, blood, and tissue cells may be found on the pillow. If the orifices are closed by the hand, there may be scratches, distinct nail marks, or laceration of the soft parts of the victim’s face. The lips, gums and tongue may show bruising or laceration. slight bruising may be found in the mouth and nose, which should be confirmed by microscopy. The asphyxial signs and symptoms are severe, because death usually results due to slow asphyxia and often the fatal period is 3 to 5 minutes. The head and face may show intense congestion and cyanosis with numerous petechial haemorrhages in the skin of the face and beneath the conjunctivae. Blood may ooze out from the mouth and nose. The tongue may be protruded and may have been bitten. Petechiae are usually present, even in cases where hypoxic changes are slight. Often, the head and face enclosed in a plastic bag are pale, with few petechial haemorrhages in the eyelids and pericardium. In some cases, death is rapid due ot reflex cardiac arrest, and asphyxial signs are absent. In environmental suffocation, congestion and cyanosis may or may not be present; petechial haemorrhages are rare.
Internal: Blood-stained frothy fluid is present in air-passages. Mucus may be found at the back of the mouth. Slight acute emphysema and oedema of the lungs with scattered areas of atelectasis, petechiae and congestion are the major findings. The internal organs are deeply congested and sometimes show small haemorrhages.
Homicidal smothering is extremely difficult to detect. The autopsy may reveal asphyxia, but there may not be any corroborative medical evidence to prove foul play. The pathological changes must be interpreted keeping in view the medical history of the deceased, the scene of death, and the specific circumstances surrounding the death.