Asphyxia

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Suffocation redirects here, for the band, see Suffocation (band).

Asphyxia (from Greek a-, "without" and sphuxis, "pulse, heartbeat") is a condition of severely deficient supply of oxygen to the body that arises from being unable to breathe normally. Asphyxia causes generalized hypoxia, which primarily affects the tissues and organs most sensitive to hypoxia first, such as the brain, hence resulting in cerebral hypoxia. Asphyxia is usually characterized by air hunger but this is not always the case; the urge to breathe is triggered by rising carbon dioxide levels in the blood rather than diminishing oxygen levels. Sometimes there is not enough carbon dioxide to cause air hunger, and victims become hypoxic without knowing it. In any case, the absence of effective remedial action will very rapidly lead to unconsciousness, brain damage and deathTemplate:Ref. The constriction of the artieries and/or veins in the neck, such as in certain types of strangulations, do not cause asphyxia but rather direct cerebral hypoxia. Asphyxiation or suffocation refer to the process of asphyxia, where the body becomes increasingly hypoxic.

Contents 1 Causes of asphyxia 2 Smothering 3 Compressive asphyxia 4 Notes 5 References 6 External links

Causes of asphyxia

Asphyxiation is typically the result of various accidents. It is also the desired effect of various asphyxiation techniques, in which the aim is to cause asphyxia by partially or fully interfering with normal breathing. Asphyxiation techniques are used to maim or kill in capital punishment, suicide, torture, violence and warfare. They are also used non-fatally in martial arts, combat sports, BDSM and erotic asphyxia. Asphyxiation is typically caused by one of the following three mechanisms:

1. Inadequate oxygen in the environment.

2. Chemical interference with breathing mechanism or with the chemical absorption of oxygen in the lungs.

3. Physical obstruction of the flow of air to the lungs.

Typical examples of these include:

1. Inadequate oxygen in the environment

• The filling of cryogenic vessels with liquified, oxygen-free gases such as nitrogen in an enclosed space.
• Workers entering a brewery fermentation vat unaware that the space is filled with carbon dioxide.
• Workers descending into a sewer or the hold of a ship containing heavier than air, oxygen-free gases usually methane or carbon dioxide.
• The misuse or failure of closed-circuit diving rebreather sets where the recirculated breathing gas contains insufficient oxygen.
• Breathing a hypoxic breathing gas mixture while diving in shallow water where the partial pressure of oxygen is too low to support consciousness; hypoxic bottom gasses are designed only to be breathed at depth where larger amounts of oxygen become toxic under pressure.
• Inhalation of overwhelming amounts of non-oxygen gases such as helium or CO₂ fire extinguishers for recreational or amusement purposes.
• Loss of aircraft cabin pressure; cabin pressure of commercial aircraft is usually kept at an altitude equivalent of between 5-8,000ft, unconsciousness can occur without awareness if a malfunction allows the cabin altitude to rise above 20,000ft.
• Exposure to a vacuum, such as the decompression of a spacecraft or space suit (see Soyuz 11).

2. Chemical or physiological interference with the breathing mechanism or with the chemical absorption of oxygen in the lungs

• Carbon monoxide inhalation, such as from a car exhaust, carbon monoxide has a higher affinity than oxygen to the haemoglobin in the blood's red blood corpuscles bonding with it tenaciously, displacing oxygen and preventing the blood from tranporting it around the body.
• Contact with a pulmonary chemical agent.
• Self-induced hypocapnia by hyperventilation, such as in shallow water or deep water blackout and the choking game.
• A seizure which stops breathing activity.
• Sleep apnea.
• Drug overdose.
• Ondine's curse, central alveolar hypoventilation syndrome, or primary alveolar hypoventilation, a disorder of the autonomic nervous system in which a patient must conciously breathe and will die if they fall asleep.

The two categories of causes above are particularly dangerous as the victim may be completely unaware of the onset of hypoxia and experience no urgent need to breathe.

3. Physical obstruction of the flow of air to the lungs

• Crushing or constriction of the chest or abdomen (compressive asphyxia)
• Smothering, where the external respiratory orifices are covered.
• Drowning caused by violence or accidents.
• Choking due to food in the airway.
• Strangling where the airway is constricted, especially in certain types of chokeholds called air chokes.
• Hanging or ligature strangulation may lead to asphyxia.
• Reduction of the airways due to anaphylaxis or asthma.
• Inhalation of vomit.
• Positional asphyxia.
• The practice of erotic asphyxiation, also called breath control play.
• Situations where a newborn infant experiences inadequate respiration during childbirth can lead to asphyxia neonatorum.

Smothering

Smothering refers to the mechanical obstruction of the flow of air from the environment into the mouth and/or nostrils, for instance by covering the mouth and nose with a hand or a plastic bag<ref name=ferris>Ferris, J.A.J. Asphyxia. www.pathology.ubc.ca. URL's last accessed March 1 2006 (DOC format)</ref>. Smothering can be either partial or complete, where partial indicates that the person being smothered is able to inhale some air, although less than required. Normally, smothering requres at least partial obstruction of both the nasal cavities and the mouth to lead to asphyxia. Smothering with the hands or chest is used in some combat sports to distract the opponent, and create openings for transitions, as the opponent is forced to react to the smothering. It is also used in BDSM as a type of facesitting.

In some cases, smothering is combined with simultaneous compressive asphyxia. One example is overlay, in which an adult accidentally rolls over an infant during co-sleeping; an accident that often goes unnoticed and is mistakenly thought to be sudden infant death syndrome<ref name=ferris>Ferris, J.A.J. Asphyxia. www.pathology.ubc.ca. URL accessed on March 1 2006. (DOC format)</ref>. Other accidents involving a similar mechanism are cave-ins or when an individual is buried in sand or grain. In homicidal cases, the term burkingTemplate:Ref is often ascribed to a killing method that involves simultaneous smothering and compression of the torso.<ref name=dimaio>DiMaio, Vincent; DiMaio, Dominick (2001). Forensic Pathology, Second Edition. Selected Pages from CHAPTER 8 and from Deaths Occurring Following the Application of Choke or Carotid Holds. www.charlydmiller.com. URL last accessed March 2 2006.</ref>

Compressive asphyxia

Image:Image943-knee mount.jpg Compressive asphyxia (also called chest compression) refers to the mechanical limitation of the expansion of the lungs by compressing the torso, hence interfering with breathing. Compressive asphyxia occurs when the chest or abdomen is compressed posteriorly <ref name=jones>Jones, Richard. Strangulation. www.forensicmed.co.uk. URL last accessed February 26 2006.</ref>. In accidents, the term traumatic asphyxia or crush asphyxia is usually used to describe compressive asphyxia resulting form being crushed or pinned under a large weight or force. An example of traumatic asphyxia include cases where an individual has been using a car-jack to repair a car from below only to be crushed under the weight of the vehicle<ref name=dimaio/> when the car-jack slips. In fatal crowd disasters, such as the Heysel Stadium disaster, traumatic asphyxia is called riot-crush<ref name=dimaio/>. Contrary to popular belief, it is not the blunt trauma from trampling that causes the large part of the deaths in such cases, but rather the compressive asphyxia from being crushed against the crowd. In confined spaces, people push and lean against each other; evidence from bent steel railings in several fatal crowd accidents have shown horizontal forces over 4500 N (comparative weight approximately 460kg). In cases where people have stacked up on each other forming a human pile, estimations have been made of around 380kg of compressive weight in the lowest layer. <ref>Fruin, John. The Causes and Prevention of Crowd Disasters. www.crowddynamics.com. URL last accessed March 3 2006.</ref>

Chest compression is also featured in various grappling combat sports, where it is sometimes called wringing. Such techniques are either used to tire the opponent, or as complementary or distractive moves in combination with pinning holds<ref name=ohlenkamp>Ohlenkamp, Neil Principles of Judo Choking Techniques. judoinfo.com. URL last accessed on March 3 2006</ref>, or sometimes even as a submission holds. Examples of chest compression include the knee-on-stomach position, or techniques such as leg scissors (also referreed to as body scissors and in budo referred to as do-jimeTemplate:Ref, 胴絞, "trunk strangle"<ref name=ijf>International Judo Federation. IJF Referee Rules. www.ijf.org. URL last accessed March 6 2006</ref>) where you wrap the legs around the opponent's midsection and squeeze them together<ref>Lewis, Bill. Katsuhiko Kashiwazaki - Shimewaza (Book Review). www.bjj.org. URL last accessed March 4 2006.</ref>.

Notes

References

External links

• Do-Jime. Image of a torso compression technique.
• Cross-side to chest compression chokeda:Strangulation

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