Editing Asphyxia (section)

==Causes==
Situations that can cause asphyxia include but are not limited to: [[airway obstruction]], the constriction or obstruction of airways, such as from [[asthma]], [[laryngospasm]], or simple blockage from the presence of foreign materials; from being in environments where oxygen is not readily accessible: such as underwater, in a low oxygen atmosphere, or in a vacuum; environments where sufficiently oxygenated air is present, but cannot be adequately breathed because of air contamination such as excessive smoke.

Other causes of oxygen deficiency include 
but are not limited to:
* [[Acute respiratory distress syndrome]]
* [[Alcohol intoxication|Alcohol poisoning]]
* [[Carbon monoxide poisoning|Carbon monoxide inhalation]], such as that from a [[car exhaust]] and the smoke produced by a lit [[cigarette]]: carbon monoxide has a higher affinity than oxygen to the [[hemoglobin]] in the blood's red blood corpuscles, bonding with it tenaciously, and, in the process, displacing oxygen and preventing the blood from transporting oxygen around the body
* Contact with certain chemicals, including [[pulmonary agent]]s (such as [[phosgene]]) and [[blood agent]]s (such as [[hydrogen cyanide]])
* [[Choking]] by obstruction of a foreign body in the airway (for example: when eating)
* [[Cyanide poisoning]]
* [[Drowning]]
* [[Drug overdose]]
* Exposure to extreme low pressure or [[vacuum]] from [[spacesuit]] damage (see [[space exposure]])
* [[Hanging]], whether suspension or short drop hanging
* Self-induced [[hypocapnia]] by [[hyperventilation]], as in [[Freediving blackout#Shallow water blackout|shallow water]] or [[Freediving blackout#Ascent blackout|deep water blackout]] and the [[choking game]]
* [[Inert gas asphyxiation]]
* [[Congenital central hypoventilation syndrome]], or primary alveolar hypoventilation, a disorder of the autonomic nervous system in which a patient must consciously breathe; although it is often said that people with this disease will die if they fall asleep, this is not usually the case.
* [[Respiratory disease]]s
* [[Sleep apnea]]
* A [[seizure]] which stops breathing activity
* An [[Allergy|allergic reaction]]
* [[Strangling]]
* Breaking the [[wind pipe]]
* Prolonged exposure to [[Chlorine|chlorine gas]]

===Smothering===
{{Redirect|Smother}}
Smothering is a mechanical obstruction of the flow of air from the environment into the mouth or nostrils, for instance, by covering the mouth and nose with a hand, pillow, or a plastic bag.<ref name=Ferris>{{cite web | vauthors = Ferris JA |url= http://www.pathology.ubc.ca/path425/Others/MedicolegalInvestigationOfDeathAndForensic/AsphixiaDrJAJFerris.doc |title=Asphyxia |website=pathology.ubc.ca |access-date=March 1, 2006 |format=DOC |url-status=dead |archive-url=https://web.archive.org/web/20060614111606/http://www.pathology.ubc.ca/path425/Others/MedicolegalInvestigationOfDeathAndForensic/AsphixiaDrJAJFerris.doc |archive-date=June 14, 2006 }}</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. In a normal situation, smothering requires 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 sport]]s to distract the opponent, and create openings for [[transition (grappling)|transitions]], as the opponent is forced to react to the smothering.

In some cases, when performing certain routines, smothering is combined with simultaneous compressive asphyxia. One example is overlay, in which an adult accidentally rolls over onto an infant during [[co-sleeping]], an accident that often goes unnoticed and is mistakenly thought to be [[sudden infant death syndrome]].<ref name=Ferris/> 

Other accidents involving a similar mechanism are [[cave-in|cave-ins]], or when an individual is buried in sand, snow, dirt, or grain.

In [[homicide|homicidal]] cases, the term burking describes a killing method that involves simultaneous smothering and compression of the torso.<ref name=dimaio>{{cite book | vauthors = DiMaio V, DiMaio D | date = 2001 | chapter = Asphyxia | title = Forensic Pathology | edition = Second | chapter-url = http://www.datenschlag.org/howto/atem/english/DiM89.html | quote = Deaths Occurring Following the Application of Choke or Carotid Holds | archive-url = https://web.archive.org/web/20160513072917/http://www.charlydmiller.com/LIB/forensicpathasphyxia.html | archive-date= 13 May 2016 |publisher=CRC Press |location=Boca Raton  | isbn = 978-0-8493-0072-1 }}</ref> The term "burking" comes from the method [[Burke and Hare murders|William Burke and William Hare]] used to kill their victims during the [[Burke and Hare murders|West Port murders]]. They killed the usually intoxicated victims by sitting on their chests and suffocating them by putting a hand over their nose and mouth, while using the other hand to push the victim's jaw up. The corpses had no visible injuries, and were supplied to medical schools for money.<ref>{{Cite web|title = Burking Law & Legal Definition|url = http://definitions.uslegal.com/b/burking/|website = definitions.uslegal.com|access-date = 2015-08-07|archive-date = 24 June 2018|archive-url = https://web.archive.org/web/20180624112732/https://definitions.uslegal.com/b/burking/|url-status = live}}</ref>

===Compressive asphyxia===
{{see also|Positional asphyxia}}
Compressive asphyxia (also called chest compression) is mechanically limiting expansion of the lungs by compressing the torso, preventing breathing. "[[Traumatic asphyxia]]" or "crush asphyxia" usually refers to compressive asphyxia resulting from being crushed or pinned under a large weight or force, or in a [[Crowd collapses and crushes|crowd crush]].<ref>{{Cite news |title=Why the Mount Meron Disaster Happened, and How to Prevent Stampedes? Scientists Explain |vauthors=Ronel A |newspaper=Haaretz |date=2 May 2021 |url=https://www.haaretz.com/israel-news/.premium-how-stampedes-like-the-mount-meron-tragedy-can-be-prevented-1.9766997 |quote=likely to die from what is called traumatic asphyxia – strong pressure on the chest |access-date=22 May 2021 |archive-date=22 May 2021 |archive-url=https://web.archive.org/web/20210522154120/https://www.haaretz.com/israel-news/.premium-how-stampedes-like-the-mount-meron-tragedy-can-be-prevented-1.9766997 |url-status=live }}</ref> An example of traumatic asphyxia is a person who [[Jack (mechanical)|jacks]] up a car to work on it from below, and is crushed by the vehicle when the jack fails.<ref name=dimaio/> Constrictor snakes such as [[boa constrictor]]s kill through slow compressive asphyxia, tightening their coils every time the prey breathes out rather than squeezing forcefully. In cases of an adult co-sleeping with an infant ("overlay"), the heavy sleeping adult may move on top of the infant, causing compression asphyxia.

In fatal crowd disasters, compressive asphyxia from being crushed against the crowd causes all or nearly all deaths, rather than [[blunt trauma]] from trampling. This is what occurred at the [[1971 Ibrox disaster|Ibrox disaster]] in 1971, where 66 [[Rangers F.C.|Rangers]] fans died; the [[1979 The Who concert disaster]] where 11 died; the [[Luzhniki disaster]] in 1982, when 66 [[FC Spartak Moscow]] fans died; the [[Hillsborough disaster]] in 1989, where 97 [[Liverpool F.C.|Liverpool]] fans were crushed to death in an overcrowded terrace, 95 of the 97 from compressive asphyxia, 93 dying directly from it and 3 others from related complications; the [[2021 Meron crowd crush]] where 45 died; the [[Astroworld Festival crowd crush]] in 2021, where 10 died; and the [[Seoul Halloween crowd crush]] in 2022, where at least 159 died during [[Halloween]] celebrations.<ref>{{cite news | url=https://www.bbc.com/news/uk-26765007 | title=Hillsborough inquests: The 96 who died | work=BBC News | date=26 April 2016 | access-date=February 22, 2018 | archive-date=19 March 2018 | archive-url=https://web.archive.org/web/20180319115457/http://www.bbc.com/news/uk-26765007 | url-status=live }}</ref><ref>{{Cite news|url=https://abc13.com/astroworld-tragedy-festival-deaths-travis-scott-concert-victims-cause-of/11348897/|title=Astroworld Festival victims' deaths ruled as accident due to asphyxiation, medical examiner finds|date=December 16, 2021|access-date=December 16, 2021|publisher=[[KTRK-TV]]|archive-date=16 December 2021|archive-url=https://web.archive.org/web/20211216215342/https://abc13.com/astroworld-tragedy-festival-deaths-travis-scott-concert-victims-cause-of/11348897/|url-status=live}}</ref>

In confined spaces, people are forced to push against each other; evidence from bent steel railings in several fatal crowd accidents has shown horizontal forces over 4500 N (equivalent to a weight of approximately 450&nbsp;kg or 1000&nbsp;lbs). In cases where people have stacked up on each other in a human pile, it has been estimated that those at the bottom are subjected to around 380&nbsp;kg (840&nbsp;lbs) of compressive weight.<ref>{{cite web| vauthors = Fruin J  |url= http://www.crowddynamics.com/Main/Fruin%20-%20causes.htm |title=The Causes and Prevention of Crowd Disasters |website=crowddynamics.com |access-date=March 3, 2006 |url-status=dead |archive-url=https://web.archive.org/web/20060221133845/http://www.crowddynamics.com/Main/Fruin%20-%20causes.htm |archive-date=February 21, 2006 }}</ref>

"Positional" or "restraint" asphyxia is when a person is restrained and left alone prone, such as in a police vehicle, and is unable to reposition themself in order to breathe. The death can be in the vehicle, or following loss of consciousness to be followed by death while in a coma, having presented with anoxic brain damage. The asphyxia can be caused by facial compression, neck compression, or chest compression. This occurs mostly during restraint and handcuffing situations by law enforcement, including psychiatric incidents. The weight of the restraint(s) doing the compression may contribute to what is attributed to positional asphyxia. Therefore, passive deaths following custody restraint that are presumed to be the result of positional asphyxia may actually be examples of asphyxia occurring during the restraint process.

Chest compression is a technique used in various [[grappling]] combat sports, where it is sometimes called wringing, either to tire the opponent or as complementary or distractive moves in combination with [[grappling hold#Pinning hold|pinning holds]],<ref name=ohlenkamp>{{cite web | vauthors = Ohlenkamp N | url = http://judoinfo.com/chokes.htm | title = Principles of Judo Choking Techniques | work = judoinfo.com | access-date = 3 March 2006 | archive-date = 21 December 2008 | archive-url = https://web.archive.org/web/20081221213628/http://judoinfo.com/chokes.htm | url-status = live }}</ref> or sometimes even as [[grappling hold#Submission hold|submission holds]]. Examples of chest compression include the [[knee-on-stomach position]]; or techniques such as leg scissors (also referred to as body scissors and in [[budō]] referred to as ''do-jime'';<ref>{{cite web | title = Classification of Waza Names | quote = Do-jime is a prohibited technique in [[Judo]] nd is considered a 'slight infringement' according to IJF rules, Section 27: Prohibited acts and penalties, article 21. It should not be confused with ''[[do-osae]]'', which is a colloquial term for the [[guard (grappling)|guard position]] | work = The Kodokan Judo Institute | url = http://www.kodokan.org/e_waza/index.html | archive-url = https://web.archive.org/web/20120415033928/http://www.kodokan.org/e_waza/index.html | archive-date= 15 April 2012 | access-date = 4 March 2006 }}</ref> 胴絞, "trunk strangle" or "body triangle")<ref name=ijf>{{cite web | work = International Judo Federation | url = http://www.ijf.org/rule/rule_referee.php | title = IJF Referee Rules | archive-url = https://web.archive.org/web/20120415085045/http://www.ijf.org/rule/rule_referee.php | archive-date= 15 April 2012| access-date = 6 March 2006 }}</ref> where a participant wraps his or her legs around the opponent's midsection and squeezes them together.<ref>{{cite web | vauthors = Lewis B | url = http://www.bjj.org/lewis/shime.html | title = Katsuhiko Kashiwazaki – Shimewaza (Book Review) | archive-url = https://web.archive.org/web/20060215000845/http://www.bjj.org/lewis/shime.html | archive-date=February 15, 2006 | work = www.bjj.org | access-date = 4 March 2006 }}</ref>

[[Pressing (execution)|Pressing]] is a form of [[torture]] or [[execution]] using compressive asphyxia.

===Perinatal asphyxia===
{{Main|Perinatal asphyxia}}

Perinatal asphyxia is the medical condition resulting from deprivation of [[oxygen]] ([[Hypoxia (medical)|hypoxia]]) to a newborn infant long enough to cause apparent harm. It results most commonly from a drop in maternal [[blood pressure]] or interference during [[childbirth|delivery]] with blood flow to the infant's [[brain]]. This can occur as a result of inadequate [[circulatory system|circulation]] or [[perfusion]], impaired respiratory effort, or inadequate [[Ventilation (physiology)|ventilation]].<ref name="Davis" /> There has long been a scientific debate over whether [[Neonatal resuscitation|newborn infants with asphyxia should be resuscitated]] with 100% oxygen or normal air.<ref name="Davis">{{cite journal | vauthors = Davis PG, Tan A, O'Donnell CP, Schulze A | title = Resuscitation of newborn infants with 100% oxygen or air: a systematic review and meta-analysis | journal = Lancet | volume = 364 | issue = 9442 | pages = 1329–33 | year = 2004 | pmid = 15474135 | doi = 10.1016/S0140-6736(04)17189-4 | s2cid = 24825982 }}</ref> It has been demonstrated that high concentrations of oxygen lead to generation of oxygen [[free radicals]], which have a role in [[reperfusion injury]] after asphyxia.<ref>{{cite journal | vauthors = Kutzsche S, Ilves P, Kirkeby OJ, Saugstad OD | title = Hydrogen peroxide production in leukocytes during cerebral hypoxia and reoxygenation with 100% or 21% oxygen in newborn piglets | journal = Pediatric Research | volume = 49 | issue = 6 | pages = 834–42 | date = June 2001 | pmid = 11385146 | doi = 10.1203/00006450-200106000-00020 | doi-access = free | author-link4 = Ola Didrik Saugstad }}</ref> Research by [[Ola Didrik Saugstad]] and others led to new international guidelines on newborn resuscitation in 2010, recommending the use of normal air instead of 100% oxygen.<ref>ILCOR [[Neonatal resuscitation]] Guidelines 2010</ref><ref>{{cite web | url = http://www.norway.gr/News_and_events/Events/Older-articles/Norwegian-paediatrician-honoured-by-University-of-Athens-/ | title = Norwegian paediatrician honoured by University of Athens | archive-url = https://web.archive.org/web/20160304101405if_/http://www.norway.gr/News_and_events/Events/Older-articles/Norwegian-paediatrician-honoured-by-University-of-Athens-/#.Vtlf8C2l1qs | archive-date = 4 March 2016 | work = Royal Norwegian Embassy in Athens }}</ref>

=== Mechanical asphyxia ===
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Classifications of different forms of asphyxia vary among literature, with differences in defining the concept of mechanical asphyxia being the most obvious.<ref name=Sauvageau>{{cite journal | vauthors = Sauvageau A, Boghossian E | title = Classification of asphyxia: the need for standardization | journal = Journal of Forensic Sciences | volume = 55 | issue = 5 | pages = 1259–67 | date = September 2010 | pmid = 20561144 | doi = 10.1111/j.1556-4029.2010.01459.x | s2cid = 25283094 }}</ref>

In DiMaio and DiMaio's 2001 textbook on forensic pathology, mechanical asphyxia is caused by pressure from outside the body restricting respiration.<ref name=Sauvageau/> Similar narrow definitions of mechanical asphyxia have occurred in Azmak's 2006 literature review of asphyxial deaths and Oehmichen and Auer's 2005 book on forensic neuropathology.<ref name=Sauvageau/> According to DiMaio and DiMaio, mechanical asphyxia encompasses positional asphyxia, traumatic asphyxia, and "human pile" deaths.<ref name=Sauvageau/>

In Shkrum and Ramsay's 2007 textbook on forensic pathology, mechanical asphyxia occurs when any mechanical means cause interference with the exchange of oxygen and carbon dioxide in the body.<ref name=Sauvageau/> Similar broad definitions of mechanical asphyxia have occurred in Saukko and Knight's 2004 book on asphyxia, and Dolinak and Matshes' 2005 book on forensic pathology.<ref name=Sauvageau/> According to Shkrum and Ramsay, mechanical asphyxia encompasses smothering, choking, positional asphyxia, traumatic asphyxia, wedging, strangulation and drowning.<ref name=Sauvageau/>

Sauvageau and Boghossian propose in 2010 that mechanical asphyxia should be officially defined as caused by "restriction of respiratory movements, either by the position of the body or by external chest compression", thus encompassing only positional asphyxia and traumatic asphyxia.<ref name=Sauvageau/>